11941Weekly Update ( 2021 Week 16 )

Week 16 and this marks the final Weekly Update of the 2021 growing season! Watch the website in late February when 2022 forecast maps will begin to be released and the Weekly Update will return in May 2022. An even easier option is to subscribe to the website to receive updates automatically!

This week, please pay special attention to the Provincial Insect Pest Report section – provincially-led surveys continue for grasshoppers and wheat midge but also find links to permit land access and to help monitor in 2022! Once again, we thank the many folks who participated in insect monitoring in field crops grown across the prairies! We also thank the key individuals who worked to create the data and information presented within the Weekly Updates!

As swathers and combines continue to move across the prairies, we wish everyone good weather and a safe harvest! Be sure to catch the Insect of the Weekit’s the Japanese beetle!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11943Weather synopsis ( 2021 Week 16 )

TEMPERATURE: This past week (August 9 – 15, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. Across the prairies, the average 30-day (July 17 – August 15, 2021) temperature was 1.5 °C warmer than climate normal values. The warmest temperatures were observed across the southern prairies (Fig. 1). A comparison of temperature anomalies (difference between average and observed temperatures) for this period indicated that southern Alberta and northeast Saskatchewan were approximately 3 °C warmer than normal (Fig. 2). Average temperatures around Peace River, Edmonton, and southern Manitoba were most similar to climate normal values.

Figure 1. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 17– August 15, 2021.
Figure 2. Temperature anomalies (difference from climate normal values) for average temperature (°C) observed across the Canadian prairies for the period of July 17 – August 15, 2021.

The 2021 growing season (April 1 – August 15, 2021) has been 1.5 °C warmer than average (Fig. 3). Growing season temperature anomalies indicate that Parkland and Peace River regions have been 1.5-2.5 °C warmer than normal (Fig. 4).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 15, 2021.
Figure 4. Temperature anomalies (difference from climate normal values) for average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 15, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 9, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (August 12-18, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -1 to >11 °C while the highest temperatures observed ranged from <20 to >37 °C. Check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 11, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: Weekly (August 9-15, 2021) rainfall amounts were generally less than 5 mm. Rainfall amounts for the period of July 17 – August 15 (30-day accumulation) have been well below average with most of the prairies reporting rain amounts that were less than 40 mm (Fig. 5). Growing season precipitation has been below average across most of the prairies with cumulative rain amounts that have been less than 100 mm. A region extending from Lethbridge to northeastern Saskatchewan has had less than 100 mm of rain (Fig. 6).

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 17 – August 15, 2021
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 15, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11955Predicted diamondback moth development ( 2021 Week 16 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Model runs based on climate normals data indicate that most DBM populations should be in the third generation with second-generation DBM predicted for areas within the Peace River region and localized areas of fourth-generation DBM occurring across southern Alberta, Saskatchewan and Manitoba (Fig. 1). Model simulations based on current growing season weather indicate that, compared to climate normal results, there has been an additional generation (fourth) of non-migrant adults that are currently occurring across the Canadian prairies (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) that are expected to have occurred across the Canadian prairies as of August 15 (based on climate normals data).
Figure 2. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 15, 2021.

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11957Predicted grasshopper development ( 2021 Week 16 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development and oviposition as of August 15, 2021. Above-average temperatures during June, July, and early August continue to result in a noticeable increase in the rates of oviposition.

Grasshoppers generally begin to lay eggs in early August. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July. Earlier oviposition can result in above-average production of eggs and increased overwintering survival of eggs. This may result in potential increased grasshopper risk for the 2022 growing season. Model runs for the 2021 growing season (April 1 – August 15) indicated that oviposition should now be occurring across most of the prairies and is predicted to be greatest in southeastern Alberta (Fig. 1).

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 8, 2021. Higher values indicate greater potential for oviposition.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11949West nile virus risk ( 2021 Week 16 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. By this week, all regions across the prairies have now accumulated sufficient degree-day heat units for Culex tarsalis to develop to adult stages, if present in the region (Fig. 1).

As of August 15, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across all areas of the Canadian prairies. Outdoor enthusiasts falling within areas highlighted red OR in areas that have accumulated >400 degree-days for C. tarsalis to emerge should wear DEET to protect against WNV!

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 15, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date August 13, 2021; retrieved August 19, 2021). The screenshot below (retrieved 19Aug2021) serves as a reference and reports one human case of WNV, two positive wild birds, and positive mosquito pools in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (reporting date August 18, 2021; retrieved 19Aug2021) which reports 3 positive birds collected in both Ontario and Quebec.

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

10615Early detection of invasive insect species ( 2021 Week 16 )

Many of Canada’s economically important species of insect pests originated as invasive species that managed to relocate and establish self-sustaining populations. Over time, they became increasingly widespread and so frequently abundant that they became part of the annual list of species we monitor and attempt to manage.

Examples of invasive species that now exist as part of our field crop landscape include wheat midge, cereal leaf beetle, cabbage seedpod weevil, pea leaf weevil, swede midge – in fact, the list of invasive species is far longer! It’s important to consider the impact of invasive species AND recognize that a growing list of species will likely affect field crops in Canada. Globalization, adaptation, and the development of new cultivars suited to Canada’s growing regions, climate change, plus many other factors will contribute to the reality: we can expect more invasive species to continue to arrive.

Where can you play a role??? Early detection and accurate identification are key steps involved in mitigating the risks associated with new invasive species. Many levels of government are active in the ongoing battle against invasive species. Even so, initial detections often arise from keen in-field scouting by producers or agrologists so access these resources to help identify the “that’s weird” or “I haven’t seen that before”. And be sure to thank the many entomologists – regional, provincial, federal, and some amazing amateurs PLUS the folks at Canadian Food Inspection Agency (CFIA) who ALL work to stand on guard for thee!

Canadian Food Inspection Agency’s (CFIA) main Plant Health section can be accessed here.

• More specifically, CFIA’s Plant Pests and Invasive Species information is accessible here.

• Did you know…. CFIA’s top field crop invasive species include anything falling under the List of Pests Regulated by Canada which is accessible here. Caveats are that (i) some species may be on the list (e.g., codling moth) that are not necessarily a high priority but remain to maintain regulatory policy or (ii) list may include species yet to be removed.

• Anyone can access diagnostic information for invasive species at CFIA’s Plant Pest Surveillance section accessible here.

HERE’S WHERE YOU CAN HELP – Experienced producers and agrologists make important discoveries every day! Keep Canadian agriculture strong and support the detection of invasive species using this important information and the three options when encountering unusual damage symptoms or unknown insect species:

Important details to be ready to report: Be ready to include details to make a “report” – Sightings need to be validated so providing as much detail as possible will help the expert confirm identifications and relocate the site, if the issue demands urgent attention.
◦ Date of observation
◦ Nearest town and province
◦ Latitude x longitude values
◦ Host plant(s)
◦ Good photo(s) – lateral, dorsal, damage symptoms, host plant, etc., with some sort of size reference is ideal
◦ Chronological photos (i.e., that tell the story of detection and how and when symptoms or specimen came to your attention)
◦ A specimen may be needed by your provincial entomologist or CFIA

Option 1: Contact your provincial entomologist to confirm identifications and details – they are able to help and historically have acted to triage reports then direct relevant information to CFIA counterparts:
◦ Manitoba (John.Gavloski@gov.mb.ca )
◦ Saskatchewan (james.tansey@gov.sk.ca)
◦ Alberta (shelley.barkley@gov.ab.ca)

Option 2: Alternatively, reports can be sent directly using one of the following paths:
◦ Using CFIA’s Report A Pest website form
◦ Contact a local CFIA office
◦ Or contact CFIA’S general surveillance account email at cfia.surveillance-surveillance.acia@canada.ca
◦ Or contact CFIA’s Survey Biologist for the Western Area (david.holden@canada.ca)

Option 3: Another alternative is to consider documenting your query using iNaturalist.ca (read more here). The basic steps involved are:
◦ Create an account at iNaturalist.ca (https://inaturalist.ca/signup)
◦ Watch your Inbox for a basic how-to guide.
◦ Upload photos or videos (e.g., bird calls) to create an “Observation”
◦ iNaturalist subscribers considered to be experts will help identify your observation.

11999An APP with a difference – iNaturalist.ca ( 2021 Week 16 )

Smartphones and their evolving photographic capacity continue to enhance our ability to learn about the environment around us. Millions of APPs have been developed to harness information and agriculture continues to benefit.

iNaturalist.ca is beneficial to download. It helps users identify terrestrial organisms by connecting to “experts” who help identify and provide information to users but there’s an underlying secondary benefit: Researchers, institutions, and active research projects can set up Lists and access observations within iNaturalist. As the homepage says, “Every observation can contribute to biodiversity science, from the rarest butterfly to the most common backyard weed.” We reached out to the Canadian Food Inspection Agency (CFIA) who are already using and accessing valuable data from this resource.

What’s best – iNaturalist.ca OR iNaturalist.com? Canadian Food Inspection Agency (CFIA) and the team that focuses on the detection of invasive species generally recommends iNaturalist.ca because it allows Canadians better access to Canadian experts and Canadian data.

Is iNaturalist.ca worth using to identify unknown insects encountered in field crops? iNaturalist.ca is going to be the leader in early detections and is a fairly intuitive and usable tool for everyone. It’s not perfect for all organisms but works well for many. CFIA staff are actively monitoring it and, in the near future, CFIA hopes to set up an account that might allow users to flag observations for their team to see more rapidly.

How does CFIA mine iNaturalist and what is the value? CFIA uses a script through the Intauralist API to query for any mentions of our targeted list under the project here: Important Pest Species List for Canada – Lookout · iNaturalist. CFIA staff members receive a daily email of all the target list mentions (i.e., includes insects, plants, and mollusks). In order to increase early detections, CFIA’s also trying to retrieve data from comments such as when someone mentions a new record or new detection. At this point, only a few pathogens are listed in our pest lookout because many of CFIA’s regulated pests would need more than a picture (so we didn’t add them). CFIA staff believe iNaturalist.ca is a great tool for early detection because the number of observations is very large and growing like crazy AND they are geographically widespread.

The basic steps involved are:
◦ Create an account at iNaturalist.ca (https://inaturalist.ca/signup).
◦ Watch your Inbox for a basic how-to guide.
◦ Upload photos or videos (e.g., bird calls) to create an “Observation”.
◦ iNaturalist subscribers considered to be experts will help identify your observation.

11947Crop Metrics Application ( 2021 Week 16 )

Reminder – Agriculture and Agri-Food Canada has released the Canadian Crop Metrics application. This product contains useful and interesting information about the current status of crops grown across Canada. The application also presents data for a number of pest insects including bertha armyworm, diamondback moth, grasshoppers and wheat midge.

Read over the synopsis of the Canadian Crop Metrics application to gain a sense of what the resource has to offer and how to optimize access. It allows users to look at specific regions and generate reports, graphs, and tables to compare current conditions to historical conditions for 11 different crop types. Weather data is updated regularly and yield estimates are updated monthly from July to October. Forecasts are made at the beginning of the months of July, August and September for all crops, and an additional forecast is made for corn and soybeans (late season crops) at the beginning of October. Forecasts are jointly produced by Agriculture and Agri-Food Canada and Statistics Canada using historical yield, climate and satellite data as inputs.

Screenshots of the application are below for reference. Get started here!

11945Provincial insect pest report links ( 2021 Week 16 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the August 11, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
The late-season grasshopper survey is underway in Manitoba – Anyone interested can access the survey protocol posted here.

SASKATCHEWAN’S Crop Production News is available. Access Issue #5 online which includes information describing supporting pollinators in an agriculture habitat. Be sure to bookmark their insect pest homepage to access important information!
PLEASE participate in the fall wheat midge soil core survey by registering fields at the pest survey sign-up webpage! – Producers need to sign up to allow access to their land to help build the 2022 forecast map!
PLEASE volunteer to monitor bertha armyworm in 2022 by emailing pestsurveys@gov.sk.ca – Please state that you would “like to participate in the BAW survey”.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am (through the growing season).
Consider getting involved with annual insect surveying by signing up to allow access to your land– Producers who participate help build population maps of pest insects. Email shelley.barkley@gov.ab.ca to sign up for 2022!

11951Crop report links ( 2021 Week 16 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the August 17, 2021 report; retrieved 19Aug2021).
Saskatchewan Agriculture (or access a PDF copy of the August 10-16, 2021 report; retrieved 19Aug2021).
Alberta Agriculture and Forestry (or access a PDF copy of the August 10, 2021 report; retrieved 19Aug2021).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the August 16, 2021 edition; retrieved 19Aug2021).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 17, 2021 edition; retrieved 19Aug2021).

11953Previous posts ( 2021 Week 16 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm (Wk12)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Calls for survey help (Wk14)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk15)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Fuzzy white “eggs” on barley or wheat (Wk13)
Grasshopper diversity and scouting photos (Wk08)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk15)
Midges in canola (Wk11)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Praire-wide survey of stored grain pests (Wk13)
Pre-Harvest Intervals (Wk15)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Thrips in canola (Wk12)
Weather radar mapping interface (Wk06)
Wheat midge – predicted development (Wk08)
Wheat midge – predicted development (Wk15)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11912Weekly Update ( 2021 Week 15 )

Week 15 and swathers and combines are now running across the prairies! Be sure to catch the Insect of the Weekit’s the mormon cricket!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11874Weather synopsis ( 2021 Week 15 )

TEMPERATURE: This past week (August 2-8, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. The warmest temperatures were observed across southern and central regions of Alberta, Saskatchewan, and Manitoba (Fig. 1). Across the prairies, the average 30-day (July 10 – August 8, 2021) temperature was 2.5°C warmer than climate normal values (Fig. 2). The 2021 growing season (April 1 – August 8, 2021) has been 1.6 °C warmer than average (Fig. 3).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of August 2- 8, 2021.
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 10 – August 8, 2021.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 8, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 9, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (August 5-11, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <22 to >34 °C. Check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 11, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: Weekly (August 2-8, 2021) rainfall amounts were generally less than 5 mm (Fig. 4). Rainfall amounts for the period of July 10 – August 8 (30-day accumulation) have been well below average with most of the prairies receiving less than 40% of the average amount for this time period (Fig. 5). Growing season precipitation has been below average across most of the prairies. A region extending from Regina to the USA border is the only region reporting near-normal rainfall for the period of April 1 – August 8, 2021. A region extending from Lethbridge to northeastern Saskatchewan has had less than 100 mm of rain (Fig. 6) in 2021.

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 2 – 8, 2021.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 10 – August 8, 2021
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 8, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11932Lygus bug monitoring ( 2021 Week 15 )

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps. In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.

Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids!  Both posts include tips to discern the difference between when doing in-field scouting!

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

11901Predicted diamondback moth development ( 2021 Week 15 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. The model, based on climate data, indicates most DBM populations should be in the third generation (Fig. 1). Model simulations to August 8, 2021, predict an additional generation for the current growing season PLUS a third and fourth generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 8 (based on climate normals data).
Figure 2. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 8, 2021.

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11897Predicted grasshopper development ( 2021 Week 15 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of August 8, 2021. Compared to average growing season temperatures, above-average temperatures during June, July, and early August continue to result in a noticeable increase in the rate of grasshopper development.

Oviposition generally begins in early August. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July. Earlier oviposition can result in above-average production of eggs resulting in potential risk for the following growing season. Climate data suggests that, as of August 8, oviposition would be expected to occur across most of the southern prairies (Fig. 1). Model runs for the 2021 growing season (April 1 – August 8) predicted that oviposition should now be occurring across most of the prairies (Fig. 2).

Figure 1. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 8 (based on climate normals data).
Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 8, 2021.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11907Predicted wheat midge development ( 2021 Week 15 )

Wheat midge model simulations to August 8, 2021, predict that wheat midge populations should be in one of two larval stages. Where wheat midge is present, most larvae (55 %) will be in wheat heads, feeding on developing kernels. Development of this stage is predicted to be greatest across eastern Saskatchewan. Larvae that have completed development in wheat heads will be dropping to the soil where they will transition to larval cocoons (44 % of the prairie population). The occurrence of larval cocoons should be greatest across northwestern Saskatchewan and eastern Alberta. This stage will overwinter in the soil.

Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) larval population that is predicted to be in wheat heads as of August 8, 2021.
Figure 2. Percent of the wheat midge (Sitodiplosis mosellana) larval population that is predicted to be in the soil (larval cocoons) as of August 8, 2021.

Monitoring: The window for scouting and application of the economic threshold for wheat midge (i.e., during the synchrony between wheat anthesis and midge flight period) has now drawn to a close for 2021. 

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

11892Crop Metrics Application ( 2021 Week 15 )

Agriculture and Agri-Food Canada has released the Canadian Crop Metrics application. This product contains useful and interesting information about the current status of crops grown across Canada. The application also presents data for a number of pest insects including bertha armyworm, diamondback moth, grasshoppers and wheat midge.

Read over the synopsis of the Canadian Crop Metrics application to gain a sense of what the resource has to offer and how to optimize access. It allows users to look at specific regions and generate reports, graphs, and tables to compare current conditions to historical conditions for 11 different crop types. Weather data is updated regularly and yield estimates are updated monthly from July to October. Forecasts are made at the beginning of the months of July, August and September for all crops, and an additional forecast is made for corn and soybeans (late season crops) at the beginning of October. Forecasts are jointly produced by Agriculture and Agri-Food Canada and Statistics Canada using historical yield, climate and satellite data as inputs.

Screenshots of the application are below for reference. Get started here!

11914West nile virus risk ( 2021 Week 15 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of August 8, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across the south of the prairies from Manitoba to Alberta. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation of >400 degree-days for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of August 8) should also start to use DEET this week!

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 1, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved August12, 2021). The screenshot below (retrieved 12Aug2021) serves as a reference and reports one human case of WNV, a positive wild bird, and positive mosquito pools in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 12Aug2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11379Field heroes ( 2021 Week 15 )

The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops.

Two NEW Field Heroes resources for 2021 include:

  1. Real Agriculture went live in 2021 with Season 2 of the Pest and Predators podcast series!
    • NEW – Episode 12 – Get a jump on grasshoppers (July 6, 2021; S. Haney and J. Tansey)
    • Episode 11 – Free farm labour (June 15, 2021; S. Haney and J. Gavloski)
    • Episode 10 – Good bugs relocate for work (June 1, 2021; S. Haney and H. Carcamo)
    • Episode 9 – Secret agents in the stubble (May 18, 2021; S. Haney and J. Otani)
    • Episode 8 – Good vs pea leaf weEVIL (May 4, 2021; S. Haney and M. Vankosky)
    • Episode 7 – Powerful parasitoids: Better than fiction (April 20, 2021; S. Haney and T. Wist)
    • Review SEASON 1 of the Pest and Predators podcast series!
  2. The NEW Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download a free copy to arm your in-field scouting efforts!

Access ALL the Field Heroes links here and be sure to follow @FieldHeroes!

11919Pre-Harvest Intervals (PHI) ( 2021 Week 15 )

Reminder – Before the harvest rush begins, start to consider pre-harvest intervals. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop.  The PHI recommends sufficient time for a pesticide to break down. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keeping It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop’s already been sprayed.
◦ To find a pesticide to suit your timeline.
• Provincial crop protection guides include the PHI for every pesticide x crop combination; Alberta, Saskatchewan, or Manitoba guides are downloadable as free, searchable PDF format.

11928Provincial insect pest report links ( 2021 Week 15 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the August 11, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!

SASKATCHEWAN’S Crop Production News is available. Access Issue #5 online which includes information describing supporting pollinators in an agriculture habitat. Be sure to bookmark their insect pest homepage to access important information!

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.

11921Crop report links ( 2021 Week 15 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the August 10, 2021 report; retrieved 12Aug2021).
Saskatchewan Agriculture (or access a PDF copy of the August 3-9, 2021 report; retrieved 12Aug2021).
Alberta Agriculture and Forestry (or access a PDF copy of the July 27, 2021 report; retrieved 12Aug2021).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the August 9, 2021 edition; retrieved 12Aug2021).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 10, 2021 edition; retrieved 12Aug2021).

11917Previous posts ( 2021 Week 15 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm (Wk12)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Calls for survey help (Wk14)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
European corn borer – nation-wide monitoring project (Wk07)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Fuzzy white “eggs” on barley or wheat (Wk13)
Grasshopper diversity and scouting photos (Wk08)
Ladybird beetles (Wk03)
Midges in canola (Wk11)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Praire-wide survey of stored grain pests (Wk13)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Thrips in canola (Wk12)
Weather radar mapping interface (Wk06)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11829Weekly Update ( 2021 Week 14 )

Week 14 and it’s been another hot week for most of the prairies! This week review the weather synopsis and the historic above-average values for temperature. Once again, notice both the number of days various areas of the prairies have experienced >25 °C or >30 °C but ALSO the number of consecutive days of >25 °C or >30 °C!

Be sure to catch the Insect of the Weekit’s the migratory grasshopper!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11795Weather synopsis ( 2021 Week 14 )

TEMPERATURE: This past week (July 26 – August 1, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. The warmest temperatures were observed across the southern and central regions of Alberta and Saskatchewan (Fig. 1).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of July 26 – August 1, 2021.

Across the prairies, the average 30-day (July 3 – August 1, 2021) temperature was 2.5 °C warmer than climate-normal values. The warmest temperatures were observed across the southern prairies (Table 1; Fig. 2). Temperature anomalies for July indicated that the entire Canadian prairies were warmer than normal (Fig. 3). The Peace River region, Edmonton area, and southern Manitoba experienced average temperatures most similar to climate-normal values. July average temperatures for southern Alberta and Saskatchewan (southwest and northeast) were 3-4 °C warmer than normal. Lethbridge and Swift Current average temperatures were 3.1 °C warmer than climate-normals.

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 3 – August 1, 2021.
Figure 3. Temperature anomalies (difference from climate-normal values) for average temperature (°C) observed across the Canadian prairies for the period of July 3 – August 1, 2021.

The 2021 growing season (April 1 – August 1, 2021) has been 1.5 °C warmer than average (Table 2; Fig. 4). Growing season temperature anomalies indicate that Parkland and Peace River regions have been 2-3 °C warmer than climate-normals (Fig. 5).

Figure 4. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 1, 2021.
Figure 5. Temperature anomalies (difference from climate-normal values) for average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 1, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 26, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 26-August 1, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >13 °C while the highest temperatures observed ranged from <25 to >37 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 1, 2021). At this point in the growing season, review the astonishing consecutive number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 1, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: Weekly (July 26 – August 1, 2021) rainfall amounts were generally less than 5 mm (Fig. 6). Rainfall amounts for the period of July 3 – August 1 (30-day accumulation) have been well below average with most of the prairies receiving less than 40 % of the average amount for this time period (Fig. 7). Accumulated rainfall varied significantly. Grande Prairie and Swift Current reported near-normal rainfall while Saskatoon (13.5 % of normal) and Winnipeg (21.6 % of normal) received minimal rainfall during July (Table 1).

Figure 6. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 26 – August 1, 2021.
Figure 7. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 3 – August 1, 2021.

Growing season precipitation has been below average across most of the prairies. A region extending from Regina to the USA border is the only region that has reported near-normal rainfall for the period of April 1 – August 1, 2021, whereas a region extending from Lethbridge to northeastern Saskatchewan has received less than 100 mm of rain (Table 2; Fig. 8).

Figure 8. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 1, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11792Predicted diamondback moth development ( 2021 Week 14 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Model simulations to August 1, 2021, indicate that the third and fourth generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Compared to long-term average data (climate normal) sufficient heat units have accumulated to produce a predicted an additional generation for the current growing season (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 1, 2021.
Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 1 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11782Predicted grasshopper development ( 2021 Week 14 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of August 1, 2021. Compared to average growing season temperatures, above-average temperatures during June and July continue to result in a noticeable increase in the rate of grasshopper development. Based on climate-normals, grasshopper populations near Saskatoon should have been in the fifth instar and adult stages on July 31 (Fig. 1).

Figure 1. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021, based on climate normals data).

Oviposition generally begins in early August. This year, the average July temperature at Saskatoon was 2.8 °C warmer than normal, resulting in advanced development of grasshopper populations. Based on a survey conducted across central, southern, and western regions of Saskatchewan, adults were observed during the first week of July. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July (Fig. 2).

Figure 2. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021.

The onset of oviposition earlier in a growing season can result in above-average production of eggs leading to higher risk of grasshopper issues the following growing season (e.g., 2022). Climate data suggests that, as of August 1, oviposition would be expected to occur in localized areas across the prairies (Fig. 3). Model runs for the 2021 growing season (April 1 – August 1) predicted, as a result of above-normal temperatures, that oviposition should now be occurring across most of the prairies (Fig. 4)

Figure 3. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021 (based on climate normals data).
Figure 4. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11836West nile virus risk ( 2021 Week 14 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of August 1, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across the south of the prairies from Manitoba to Alberta. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of August 1) should also start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 14 days for adults to become fully infective with the current warm weather (Fig. 2).

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 1, 2021).
Figure 2. Predicted days for virulence of West Nile Virus to develop within Culex tarsalis, if present within a region (as of August 1, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved August 4, 2021). The screenshot below (retrieved 04Aug2021) serves as a reference and reports one human case of WNV, a positive wild bird, and positive mosquito pools in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 04Aug2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11834Pre-Harvest Intervals (PHI) ( 2021 Week 14 )

Before the harvest rush begins, start to consider pre-harvest intervals. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop.  The PHI recommends sufficient time for a pesticide to break down. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keeping It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop’s already been sprayed.
◦ To find a pesticide to suit your timeline.
• Provincial crop protection guides include the PHI for every pesticide x crop combination; Alberta, Saskatchewan, or Manitoba guides are downloadable as free, searchable PDF format.

11838Provincial insect pest report links ( 2021 Week 14 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the August 4, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data is available here. Cumulative counts are categorized as “low risk” so far (i.e., 0-300 moths).
Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News is available. Access Issue #4 online which includes a crop protection lab update, and describes thrips in cereals. Be sure to bookmark their insect pest homepage to access important information!
Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is available here.
Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.
Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (22Jul2021).
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (22Jul2021).
Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

11840Crop report links ( 2021 Week 14 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the August 3 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the July 20-26, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the July 27, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the August 2, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 3, 2021 edition).

11827Previous posts ( 2021 Week 14 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm (Wk12)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
Diamondback moth – predicted development (Wk12)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk08)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Grasshopper diversity and scouting photos (Wk08)
Grasshopper – predicted development (Wk12)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk09)
Midges in canola (Wk11)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Thrips in canola (Wk12)
Weather radar mapping interface (Wk06)
Wheat midge – predicted development (Wk12)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11759Weekly Update ( 2021 Week 13 )

Week 13 and many of our staff are occupied elsewhere! This week, the unbelievable warm weather continues to advance both insect and plant development. Take a peak at how many days various areas of the prairies have experienced >25 °C compared to >30 °C! Some areas of the prairies are harvesting silage and preparing to harvest their grain.

Be sure to catch the Insect of the Weekit’s wheat stem sawfly!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11745Weather synopsis ( 2021 Week 13 )

TEMPERATURE: This week, staff are occupied elsewhere and unable to generate the full weather synopsis. The growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 26, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 22-28, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >14 °C while the highest temperatures observed ranged from <20 to >36 °C. Again, the incredible heat experienced is contributing to those heat units – check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-July 28, 2021).

PRECIPITATION: This past week (July 22-28, 2021), rainfall was reported in the far north of the Alberta side of the Peace River region, in central Alberta, the northwest and southeast of Saskatchewan, and in the northwest and far southeast of Manitoba yet the vast majority of the prairies’ arable acres recieved scant to no rain (Fig. 1). Rainfall amounts for the period of June 27 – July 28 (30-day accumulation) are represented in Figure 2. Precipitation for the growing season has been less than average across most of the prairies (Fig. 3).

Figure 1. Accumulated precipitation (mm) observed across the Canadian prairies the past 7 days (July 22-28, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (29Jul2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Figure 2. Accumulated precipitation (mm) observed across the Canadian prairies the past 30 days (June 27 – July 28, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (29Jul2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Figure 3. Accumulated precipitation (mm) observed across the Canadian prairies for the growing season (April 1 – July 28, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (29Jul2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11722Prairie-wide survey of stored grain pests ( 2021 Week 13 )

Scientists are looking for volunteers to help conduct a survey of stored grain pests on the Canadian Prairies. The goals of this survey are to:
1) detect potentially new invasive grain pests to the area,
2) know the nature of the insect species currently occurring in farm grain bins,
3) determine the prevalence of those species, and 4) determine the conditions under which these species occur.

The data collected will help assess current and future threats to the grain supply on the Canadian Prairies and help focus research efforts. Producers willing to participate will be notified of the results obtained on their farm, as well as the results of the overall survey.

This rusty grain beetle, Cryptolestes ferrugineus (Stephens), resting on a wheat kernel, measures ~2 mm in length. Photo: Canadian Grain Commission (retrieved 28Jul2021 from https://grainscanada.gc.ca/en/grain-quality/manage/identify-an-insect/primary-insect-pests/rusty-grain-beetle.html).

The survey involves a minimal amount of input for participants: Two grain probe traps are inserted into grain from the top, removed 2 to 4 weeks later, their contents emptied into 2 vials, then the vials containing the samples are mailed with a datasheet providing information about the conditions under which the grain was stored. The traps can be placed in grain from last year’s harvest, this year’s harvest, or into animal feed since many grain species also occur in animal feed. Participants will be mailed the two grain probe traps and two sampling vials plus an envelope with pre-paid postage will be provided for returning the samples. All information collected about the farm will remain strictly confidential.

Please contact Vincent Hervet (AAFC stored product entomologist) at vincent.hervet@agr.gc.ca, if you are willing to contribute to this survey.

11732Fuzzy white “eggs” on wheat or barley heads? ( 2021 Week 13 )

As wheat and barley fields continue to mature, fuzzy, white “egg-like” clusters may be observed (Fig. 1). Sometimes a dead caterpillar can be found alongside the fuzzy cluster. These white “egg-like” clusters are yet another species of @FieldHeroes! Cotesia parasitoid wasp cocoons arise from parasitoid larvae that develop within a single lepidopteran caterpillar then the parasitoid larvae burst out through the host’s body wall – in this case, likely from a wheat head armyworm (Dargida diffusa). Researchers are seeking intact parasitoid cocoons in order to learn what species of Cotesia is parasitizing the wheat head armyworm.

Figure 1. Fuzzy egg-like clusters which are Cotesia cocoons enclosing developing pupae. Photo: AAFC-Saskatoon T. Wist.

Request for help: If you find intact samples (i.e., developing Cotesia still within cocoons but NOT open as in Fig. 2), please contact Tyler.Wist@agr.gc.ca to arrange collection and shipping of the cocoons and any associated lepidopteran caterpillars. Remember, intact cocoons NOT with open ends are needed.

Figure 2. Empty Cotesia cocoons recently vacated by adult parasitoid wasps. Photo: AAFC-Saskatoon T. Wist.

11764Pre-Harvest Intervals (PHI) ( 2021 Week 13 )

Before the harvest rush begins, start to consider pre-harvest intervals. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop.  The PHI recommends sufficient time for a pesticide to break down. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keeping It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop’s already been sprayed.
◦ To find a pesticide to suit your timeline.
• Provincial crop protection guides include the PHI for every pesticide x crop combination; Alberta, Saskatchewan, or Manitoba guides are downloadable as free, searchable PDF format.

11753West nile virus risk ( 2021 Week 13 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of July 25, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across the south of the prairies from Manitoba to Alberta. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of July 25) should also start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 14 days for adults to become fully infective with the current warm weather (Fig. 2).

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 25, 2021).
Figure 2. Predicted days for virulence of West Nile Virus to develop within Culex tarsalis, if present within a region (as of July 26, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 29, 2021). The screenshot below (retrieved 29Jul2021) serves as a reference and reports one human case of WNV, a positive wild bird, and positive mosquito pools in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 29Jul2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11766Provincial insect pest report links ( 2021 Week 13 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the July 28, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. Cumulative counts are categorized as “low risk” so far (i.e., 0-300 moths).
Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News is available. Access Issue #4 online which includes a crop protection lab update, and describes thrips in cereals. Be sure to bookmark their insect pest homepage to access important information!
Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is available here.
Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.
Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (22Jul2021).
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (22Jul2021).
Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

11769Crop report links ( 2021 Week 13 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the July 27 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the July 20-26, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the July 13, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 26, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 27, 2021 edition).

11762Previous posts ( 2021 Week 13 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm (Wk12)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
Diamondback moth – predicted development (Wk12)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk08)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Grasshopper diversity and scouting photos (Wk08)
Grasshopper – predicted development (Wk12)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk09)
Midges in canola (Wk11)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Thrips in canola (Wk12)
Weather radar mapping interface (Wk06)
Wheat midge – predicted development (Wk12)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11621Weekly Update ( 2021 Week 12 )

Week 12 and our staff continue with surveying! This week, more warm weather continues to advance both insect and plant development. Some southern areas of the prairies are preparing to initiate harvest for their earliest crops and are carefully watching moisture meters! If you missed it, in Week 11 we thanked the many people who are busy monitoring in fields across the Canadian prairies!

Be sure to catch the Insect of the Weekit’s pea aphids!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11623Weather synopsis ( 2021 Week 12 )

TEMPERATURE: This past week (July 11 – 18, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. The warmest temperatures were observed across southern and central regions across all three prairie provinces (Fig. 1. Across the prairies, the average 30-day (June 19 – July 18, 2021) temperature was almost 4 °C warmer than climate-normal values. The warmest temperatures were observed across southern Alberta and western Saskatchewan (Fig. 2). The 2021 growing season (April 1 – July 18, 2021) has been 1.5 °C warmer than average. The warmest temperatures have occurred across southeastern Manitoba, west-central Saskatchewan and southern Alberta (Fig. 3).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of July 12 – 18, 2021.
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 19 – July 18, 2021.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 18, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 19, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 14-20, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -2 to >14 °C while the highest temperatures observed ranged from <22 to >34 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-July 20, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This past week significant rainfall was reported across the Peace River region (Fig. 4). Rainfall amounts for the period of June 19 – July 18 (30-day accumulation) have been well below average with most of the prairies receiving less than 40 % of the average amount for this time period (Fig. 5). Growing season precipitation has been less than average across most of the prairies. Western Saskatchewan and most of Alberta have received less than 100 mm of rain this year (Fig. 6).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 12 – 18, 2021.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 19 – July 18, 2021
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – July 18, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11627Predicted grasshopper development ( 2021 Week 12 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 21, 2021. Above-average temperatures in late June and July continue to result in a noticeable increase in grasshopper development. Last week, simulations indicated that most of the population was expected to be in the 4th or 5th instar stages.

This week, grasshopper populations are predicted to be mostly 5th instar (35 %) and adult (35 %) stages (Fig. 1). As a point of comparison, grasshopper development based on long-term average values for this week are 11 % (5th Instar) and 1.4 % (adults) (Fig. 2).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average developmental stage, across the Canadian prairies as of July 18, 2021.
Figure 2. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average developmental stage, across the Canadian prairies as of July 11, based on climate normals data.

Adults should be present across all three provinces and the occurrence of adults is well ahead of long-term average values (Figs. 3 and 4). The model predicts that oviposition should have begun across the southern prairies (Fig. 5).

Figure 3. Percent of grasshopper (Melanoplus sanguinipes) population in the adult stage across the Canadian prairies as of July 18, 2021.
Figure 4. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population in the adult stage, across the Canadian prairies as of July 11 (based on climate normals data).
Figure 5. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of July 18, 2021.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11630Predicted diamondback moth development ( 2021 Week 12 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Model simulations to July 18, 2021, indicate that the third generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Compared to long-term average data (climate normal), an additional generation of DBM are predicted to develop during the 2021 growing season!

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of July 18, 2021.
Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of July 20 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11625Predicted wheat midge development ( 2021 Week 12 )

The recent warm temperatures have contributed to the rapid development of wheat midge populations. Where present, wheat midge populations should be predominantly in the egg and larval stages (Figs. 1 and 2). Last week the model predicted that 51 % of the population would be eggs. This past week eggs have transitioned to the larval stage and wheat midge populations will be primarily in the larval stage (54 % of the population). Larvae will be in wheat heads, feeding on developing kernels.

Figure 1. Percent of wheat midge (Sitodiplosis mosellana) population that is in the egg stage, across the Canadian prairies as of July 18, 2021.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the larval stage (in wheat heads), across the Canadian prairies as of July 11, 2021.

The model was projected to August 3 to determine potential development at Regina (Fig. 3), Lacombe (Fig. 4), and Grande Prairie (Fig. 5) over the next two weeks. Development is similar for each location. Results indicate that larvae (Sm L1-2) are expected to complete development by the end of July, at which time they will drop to the soil and develop into larval cocoons (overwintering stage).

Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan as of July 18, 2021 (projected to August 3, 2021).
Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) near Lacombe, Alberta as of July 18, 2021 (projected to August 3, 2021).
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) near Grande Prairie, Alberta as of July 18, 2021 (projected to August 3, 2021).

Monitoring: The window for scouting and application of the economic threshold for wheat midge (i.e., during the synchrony between wheat anthesis and midge flight period) has now drawn to a close for 2021. 

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

11646Thrips in canola ( 2021 Week 12 )

Thrips in canola (Thynsanoptera) – While scouting at this time of year, curled canola pods may be encountered.  The culprits are quite possibly thrips.

Figure 1. Thrips damage observed in canola in the northeast of Saskatchewan in July 2016 (Photo: AAFC-Saskatoon, Olfert 2016).

Damage: Flower thrips (Thysanoptera) are pests of a broad range of plants including cereals and broadleaved crops such as canola. Thrips are minute, slender-bodied insects with rasping-sucking mouthparts and feed by rasping the surface of canola buds and sucking up plant fluids. 

Biology: Thrips have six life stages: egg, two larval stages, a prepupal and pupal stage and an adult. Both adults and nymphs cause damage by feeding on the flower and buds. Limited surveys in 1999 in Saskatchewan and Alberta indicated that the predominant species were Frankliniella tritici (flower thrip) followed by Thrips tabaci (onion thrip) and T. vulgatissimus (no common name).

In canola, pods damaged by thrips are often curled and tend to drop prematurely.  Some species, such as T. vulgatissimus have been credited with contributing to pollination.

Read more about thrips in canola by accessing this article by Olfert et al. 1998).

11642Lygus bug monitoring ( 2021 Week 12 )

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs. In fact, sampling is most accurate when repeated at a total of 15 spots within the field.  Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure 3). 

Figure 3. Sequential sampling for lygus bugs at late flowering stage in canola.

If the total number is below the lower threshold line (Fig. 3), no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold tables (Tables 1 and 2).

The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted. Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production.  The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage.  In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids!  Both posts include tips to discern the difference between when doing in-field scouting!

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

11588Cabbage seedpod weevil ( 2021 Week 12 )

Monitoring is already underway for cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) in southern areas of the prairies – it was the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

11634Bertha armyworm ( 2021 Week 12 )

Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta. So far, interception counts remain mainly in the “low risk” categories across the Canadian prairies. Review the 2020 pheromone trapping cumulative moth counts here to identify potential high risk areas to target for scouting for larvae now!

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 1) to help identify the various stages.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png
Figure 6. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

11636West nile virus risk ( 2021 Week 12 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of July 18, 2021 (Fig. 1), C. tarsalis development continues to be most advanced in southern Manitoba, southern Alberta, and southwestern Saskatchewan. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of July 18) should also start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 14 days for adults to become fully infective with the current warm weather (Fig. 2).

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 18, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 22, 2021). The screenshot below (retrieved 22Jul2021) serves as a reference and reports one human case of WNV in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retried 22Jul2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11644Pre-Harvest Intervals (PHI) ( 2021 Week 12 )

Before the harvest rush begins, start to consider pre-harvest intervals. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop.  The PHI recommends sufficient time for a pesticide to break down. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keeping It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop’s already been sprayed.
◦ To find a pesticide to suit your timeline.
• Provincial crop protection guides include the PHI for every pesticide x crop combination; Alberta, Saskatchewan, or Manitoba guides are downloadable as free, searchable PDF format.

11590Timely IOTW to review ( 2021 Week 12 )

The Insect of the Week (IOTW) was originally launched as a tool to promote field guides affiliated with PPMN Network participants and to highlight entomological species occurring in field crops across the Canadian prairies. Almost immediately, the IOTW became one of the most popular ways PPMN shares information related to insect pests, beneficial arthropods AND the entomologists who study them. A surprising array of IOTW posts are available from 2015 to the present and remain available for review and to support scouting and identification – check them out!

11638Provincial insect pest report links ( 2021 Week 12 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the July 21, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. Cumulative counts are categorized as “low risk” so far (i.e., 0-300 moths).
Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News is available. Access Issue #3 online which includes a crop protection lab update, describes a new program to monitor european corn borer, and information related to pollinator planning in crop production. Be sure to bookmark their insect pest homepage to access important information!
Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is now available here.
Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.
Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (22Jul2021).
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (22Jul2021).
Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

11640Crop report links ( 2021 Week 12 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the July 20 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the July 13-19, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the July 13, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 19, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 20, 2021 edition).

11632Previous posts ( 2021 Week 12 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk08)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Grasshopper diversity and scouting photos (Wk08)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk09)
Midges in canola (Wk11)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Weather radar mapping interface (Wk06)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11444Weekly Update ( 2021 Week 11 )

Week 11 and our staff are again busy surveying! In fact, it’s appropriate that we take this moment to thank the MANY people who are busy checking traps, doing sweeps, and processing samples! It’s a massive undertaking that happens across the Canadian prairies and begins with dedicated individuals.

Western Canada has one of the most expansive and historically deep data collections in agricultural entomology with grasshopper surveys extending over 100 years and many of our “recent” pests have data sets extending at least 5-40 yrs or more. That amazing data is used in so many ways but it directly supports the development of bioclimatic models for Canada’s most important economic agricultural insect pests and Canadians benefit with predictive model outputs that help growers time and prioritize in-field scouting. It also incrementally improves the ability to estimate insect pest risk from year to year. THANK YOU to everyone who contributes – just “see” how many sites were monitored in 2020!

Map by AAFC-David Giffen

Be sure to catch the Insect of the Weekit’s swede midge and the canola flower midge: Doppelganger pests!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11541Weather synopsis ( 2021 Week 11 )

TEMPERATURE: This past week (July 5 – 11, 2021), the prairies continued to experience record-setting temperatures and extremely dry conditions. The warmest temperatures were observed across southern Alberta and Saskatchewan (Fig. 1). Across the prairies, the average 30-day temperature (June 12 – July 11, 2021) was almost 3 °C warmer than climate normal values. The warmest temperatures were observed across southern Alberta and western Saskatchewan (Fig. 2). Southern and western areas of the Peace River region have been 4-5 °C warmer than average.

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of July 5 – 11, 2021.
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 12 – July 11, 2021.

The 2021 growing season (April 1 – July 4, 2021) has been 1.5 °C warmer than average. The warmest temperatures have occurred across southeastern Manitoba, west-central Saskatchewan and southern Alberta (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 11, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 12, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 6-12, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -1 to >10 °C while the highest temperatures observed ranged from <26 to >36 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-July 12, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This past week, significant rainfall was reported across southern and central Saskatchewan and Alberta (Fig. 4). Rainfall amounts for the period of June 12 – July 11 (30-day accumulation) have been well below average with most of the prairies receiving less than 40% average (Fig. 5). Growing season (April 1 – July 11) precipitation has been less than average across most of the prairies. Western Saskatchewan and most of Alberta have received less than 100 mm of rain (Fig. 6).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 5 – 11, 2021.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 12 – July 11, 2021
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – July 11, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11557Predicted wheat midge development ( 2021 Week 11 )

The continued warm temperatures have resulted in the rapid development of wheat midge populations. Where present, wheat midge populations are predicted to be predominantly in the egg stage across most of the prairies (Fig. 1). This is a substantial change from last week where only 12 % of the population was predicted to be in the egg stage. The initial appearance of larvae (in wheat heads) is predicted to be occurring (Fig. 2).

Figure 1. Percent of wheat midge (Sitodiplosis mosellana) population that is in the egg stage, across the Canadian prairies as of July 11, 2021.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the larval stage (in wheat heads), across the Canadian prairies as of July 11, 2021.

The model was projected to July 27 to determine potential development at Regina (Fig. 3), Lacombe (Fig. 4), and Grande Prairie (Fig. 5) over the next two weeks. The model output suggests that oviposition will continue to increase over the next 5-7 days and should peak sometime this week. Larvae (Sm L1-2) are expected to complete development by the end of July. Macroglenes penetrans, a parasitoid of wheat midge, is active in wheat fields when wheat midge adults are present. Simulation runs indicate that the parasitoid has begun to appear in wheat crops in fields near Regina.

Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan as of July 11, 2021 (projected to July 27, 2021).
Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) near Lacombe, Alberta as of July 11, 2021 (projected to July 27, 2021).
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) near Grande Prairie, Alberta as of July 11, 2021 (projected to July 27, 2021).

If not already underway, scout for wheat midge adults this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.  

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 7. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads 
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 8. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long.  (Photo: AAFC-Beav-S. Dufton).

Economic Thresholds for Wheat Midge:
a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

11550Predicted grasshopper development ( 2021 Week 11 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 11, 2021. Above-average temperatures in late June and early July have resulted in a noticeable increase in grasshopper development. Grasshopper development should be greatest across southern Manitoba where the majority of the population will be in the adult stage (Fig. 1). Adults should be present across all three provinces; more than 13.5 % of the population should be adults.

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development across the Canadian prairies as of July 11, 2021.
Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the adult stage across the Canadian prairies as of July 11, 2021.

The long-term average value for this week of the growing season is less than 1% of the population in the adult stage. Development, as of July 11, 2021, is well ahead of long-term average values (Fig. 3).

Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 11, based on climate normals data.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11566Predicted diamondback moth development ( 2021 Week 11 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season. Diamondback moth was the Insect of the Week for Wk10!

Model simulations to July 11, 2021, indicate that the second generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). A third generation is predicted for southern Manitoba. Based on climate normal inputs, development is well ahead of long-term average values (Figure 2). Based on current weather, the mean number of generations that have occurred is 2.1 compared to model runs, based on climate normals, predict that the number of generations should be 1.4.

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 11, 2021.
Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 13 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11584Bertha armyworm ( 2021 Week 11 )

Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta. So far, interception counts remain mainly in the “low risk” categories across the Canadian prairies. Review the 2020 pheromone trapping cumulative moth counts here to identify potential high risk areas to target for scouting for larvae now!

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 1) to help identify the various stages.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png
Figure 6. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

11571Midges in canola ( 2021 Week 11 )

The Insect of the Week features Swede midge and the canola flower midge as doppelganger pests this week!

Two species of midges (Diptera: Cecidmyiidae) are known to infest canola in Canada. Since 2000, swede midge (Contarinia nasturtii) has been established in southern Ontario with serious levels of damage observed in several species of Brassicaceae, including canola by 2003. Swede midge is also established in Quebec, Nova Scotia, and Prince Edward Island. Across the prairie region of Canada, a separate canola flower midge (Contarinia brassicola Sinclair) was identified initially as larvae feeding within the developing flower that caused the formation of a “pop-bottle”-shaped gall (Fig. 1). To date, this is the only damage associated with the canola flower midge, and it has been minimal across the prairies.

Figure. 1. “Pop-bottle”-shaped galls created by the canola flower midge.
(c) 2016 Boyd Mori, AAFC

Because of the serious threat that swede midge poses to canola production, it is vital that monitoring for swede midge continues across the Prairies. Monitoring is underway for 2021.

Tips for scouting canola for midges:
• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.

Access more information about midges in canola via these links:
Swede midge and canola flower midge: Doppelganger pests (2021; Wk 11)
New canola flower midge (2018; Wk 11)
Natural enemies of the canola flower midge (2018; WK 12)
Ontario’s swede midge fact sheet produced by Baute et al. 2016.
• Canola Council of Canada’s Canola Encyclopedia – Swede midge

11534West nile virus risk ( 2021 Week 11 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of July 11, 2021 (Fig. 1), C. tarsalis development continues to be most advanced in Manitoba, southern Alberta, and in a small pocket in southern Saskatchewan. The map will change very quickly to red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Areas highlighted yellow or orange in the map below (as of July 11) should start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 12 days for adults to become fully infective with the current warm weather.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 4, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 13, 2021). The screenshot below (retrieved 13Jul2021) serves as a reference.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retried 13Jul2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11575Provincial insect pest report links ( 2021 Week 11 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the July 14, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. The initial counts are categorized as “low risk” so far (i.e., 0-300 moths).
Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News are available. Access Issue #2 online which includes information on cabbage seedpod weevil, grasshoppers in Saskatchewan, and wheat midge. Be sure to bookmark their insect pest homepage to access important information!
Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is now available here.
Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. Some sites in central Alberta are beginning to report “high risk” adult counts so synchrony with anthesis will need to be carefully monitored(08Jul2021).
Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (08Jul2021).
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (08Jul2021).
Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

11577Crop report links ( 2021 Week 11 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the July 13 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the July 6-12, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the June 28, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 12, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 13, 2021 edition).

11573Previous posts ( 2021 Week 11 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk08)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Grasshopper diversity and scouting photos (Wk08)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk09)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Weather radar mapping interface (Wk06)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11446Weather synopsis ( 2021 Week 10 )

TEMPERATURE: This past week (June 28 – July 4, 2021) an extreme heatwave affected temperatures across most of western North America. The North American heat dome was associated with exceptionally hot weather and resulted in numerous record temperatures across the Canadian prairies. Compared to climate normal temperature values, observed weekly average temperatures were 7.4 °C warmer than average! The warmest temperatures were observed across southern Alberta and western Saskatchewan. Table 1 provides a comparison between observed and average temperatures for the ten warmest locations across the prairies.

Similar to last week, the warmest temperatures were observed across Alberta (Fig. 1). Across the prairies, the average 30-day (June 5 – July 4, 2021) temperature was almost 3 °C warmer than climate normal values. The warmest temperatures were observed across southern Manitoba and southeastern Alberta (Fig. 2).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of June 28 – July 4, 2021.
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 5 – July 4, 2021.

The 2021 growing season (April 1 – July 4, 2021) has been characterized by temperatures that have been 1.5 °C warmer than average. The warmest temperatures have occurred across southeastern Manitoba, west-central Saskatchewan and southern Alberta (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 4, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 5, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 1-7, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <28 to >39 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-July 7, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This past week, minimal rainfall was reported across most of the prairies with most locations reporting weekly amounts of less than 2 mm (Fig. 4). Higher rainfall amounts were reported across central Alberta and northern areas across the Peace River region. Rainfall amounts for the period of June 5 – July 4 (30-day accumulation) have been well below average across most of the prairies. The lowest rainfall amounts have occurred across most of Saskatchewan as well as southern and northern regions of Alberta (Fig. 5).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 28 – July 4, 2021.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 5 – July 4, 2021

The average growing season (April 1 – July 4) precipitation was 90 % of normal with the greatest precipitation occurring across eastern Saskatchewan, including Regina. Below normal rainfall has been reported across western Saskatchewan, southern Alberta and the Peace River region(Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – July 4, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11470Predicted wheat midge development ( 2021 Week 10 )

The recent warm temperatures have resulted in rapid development of wheat midge (Sitodiplosis mosellana) populations. Dry conditions in the Peace River region have contributed to delayed development of larval cocoons with 30-75 % of the population not expected to emerge this growing season. Unlike the larval cocoon stage (located in the soil), development of pupal, adult, egg and larval stages (in wheat heads) is not dependent on moisture. Development of these stages are dependent on temperature.

Where present, wheat midge populations should be entering the adult stage across most of the prairies (Fig. 1). This is a substantial change from last week where less than 10 % of the population was predicted to be in the adult stage. Oviposition is predicted to be occurring across most of the prairies and the initial hatch is now expected for southern Manitoba and southeastern Saskatchewan (Figs. 2 and 3).

Figure 1. Percent of wheat midge (Sitodiplosis mosellana) population that is in the adult stage, across the Canadian prairies as of July 4, 2021.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the egg stage, across the Canadian prairies as of July 4, 2021.
Figure 3. Percent of wheat midge (Sitodiplosis mosellana) population that is in the larval stage (in wheat heads), across the Canadian prairies as of July 4, 2021.

The model was projected to July 20 to determine potential development at Regina (Fig. 4), Lacombe (Fig. 5), and Grande Prairie (Fig. 6) over the next two weeks. Output suggests that oviposition will rapidly increase over the next 10 days and wheat crops near all three locations may be susceptible for the next two weeks. Based on the predicted occurrence of adults and eggs, development is most rapid where populations were predicted to be greatest in 2021 (based on 2020 fall survey).

Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of July 4, 2021 (projected to July 20, 2021).
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Lacombe, Alberta as of July 4, 2021 (projected to July 20, 2021).
Figure 6. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Grande Prairie, Alberta as of July 4, 2021 (projected to July 20, 2021).

Macroglenes penetrans is a parasitoid of wheat midge that is active in wheat fields when wheat midge adults are present. Model simulations indicate that the parasitoid has begun to appear in wheat crops in fields near Regina (Fig. 7).

Figure 7. Predicted occurrence of wheat midge (Sitodiplosis mosellana) and Macroglenes penetrans adults near Regina, Saskatchewan as of July 4, 2021 (projected to July 20, 2021).

If not already underway, scouting for wheat midge adults should continue this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.  

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 7. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads 
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 8. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long.  (Photo: AAFC-Beav-S. Dufton).

Economic Thresholds for Wheat Midge:
a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

11467Predicted grasshopper development ( 2021 Week 10 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 4, 2021. Recent warm conditions have resulted in a noticeable increase in grasshopper development since last week. Grasshopper development, based on average instar, should be greatest across southern Manitoba and southeastern Saskatchewan (Fig. 1).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 4, 2021.

Across the prairies, more than 15 % of the population should be in the fifth instar (Fig. 2). Development, as of July 4, 2021, is well ahead of long-term average values (Fig. 3).

Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the 5th instar across the Canadian prairies as of July 4, 2021.
Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 4, based on climate normals data.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11483Predicted diamondback moth development ( 2021 Week 10 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season. Diamondback moth is the Insect of the Week for Wk10!

Model simulations to July 4, 2021, indicate that the second generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Across the prairies, development, as of July 4, 2021, is well ahead of long-term average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) that are expected to have occurred across the Canadian prairies as of July 4, 2021.
Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 4 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11505Previous posts ( 2021 Week 10 )

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
2020-2021 Risk and forecast maps
Alfalfa weevil – predicted development (Wk07)
Aphids in field crops (Wk09)
Bertha armyworm – predicted development (Wk09)
Cabbage seedpod weevil monitoring (Wk09)
Cereal aphid manager APP (Wk07)
Cereal leaf beetle – predicted development (Wk07)
Crop protection guides (Wk03)
Cutworms (Wk02)
European corn borer – nation-wide monitoring project (Wk07)
Field heroes (Wk08)
Flea beetles (Wk02)
Flea beetles – predicted geographic distribution and abundance (Wk04)
Grasshopper diversity and scouting photos (Wk08)
Ladybird beetles (Wk03)
Lygus bug monitoring (Wk09)
Monarch migration (Wk09)
Pea leaf weevil (Wk03)
Scouting charts – canola and flax (Wk03)
Slugs and their parasites (Wk04)
Weather radar mapping interface (Wk06)
Wind trajectories for monitoring insect movement (Wk02)
Wind trajectories – weekly reports (Wk09)
Wireworms (Wk02)

11489West nile virus risk ( 2021 Week 10 )

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of July 4, 2021 (Fig. 1), C. tarsalis development is most advanced in Manitoba, southern Alberta, and in small pockets in southern Saskatchewan. The map will change very quickly to orange then red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Given the forecast, areas highlighted yellow in the map below (as of July 4) should start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 12 days for adults to become fully infective with the current warm weather.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 4, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 8, 2021). The screenshot below (retrieved 08Jul2021) serves as a reference.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retried 08Jul2021).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

11502Provincial insect pest report links ( 2021 Week 10 )

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the July 7, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. The initial counts are categorized as “low risk” so far (i.e., 0-300 moths).
Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News are available. Access Issue #2 online which includes information on cabbage seedpod weevil, grasshoppers in Saskatchewan, and wheat midge. Be sure to bookmark their insect pest homepage to access important information!
Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is anticipated to be available here.
Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. Some sites in central Alberta are beginning to report “high risk” adult counts so synchrony with anthesis will need to be carefully monitored(08Jul2021).
Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (08Jul2021).
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (08Jul2021).
Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

11495Crop report links ( 2021 Week 10 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the July 6 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the June 29-July 5, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the June 28, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 6, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 7, 2021 edition).

11440Weekly Update ( 2021 Week 10 )

Week 10 and our staff are busy out surveying so this is an abridged report! The incredible heat supported the rapid development of field crop insect pests so scouting is absolutely critical! Be sure to review the entire Previous Posts section for help beyond this shorter report. Also catch the Insect of the Week – it’s diamondback moths!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11365Weekly Update ( 2021 Week 9 )

Week 9 and the unusually hot weather stretching over the Canadian prairies is making it difficult for plants to tolerate insect pest pressure! Scouting is critical under these conditions! Be sure to catch the Insect of the Week – it’s lygus bugs! This week find updates to predictive model outputs for wheat midge, grasshoppers, bertha armyworm, and diamondback moth plus a lot more to help prepare for in-field scouting!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

11307Weather synopsis ( 2021 Week 9 )

TEMPERATURE: This past week (June 21-27, 2021), weekly temperatures were warmer than normal and rainfall amounts were generally less than 5 mm. The warmest temperatures were observed across Alberta (Fig. 1).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of June 21- 27, 2021.

Across the prairies, the average 30-day (May 29 – June 27) temperature was almost 3 °C warmer than climate normal values. The warmest temperatures continue to be observed across southern Manitoba and southeastern Saskatchewan (Fig. 2). The 2021 growing season (April 1 – June 27, 2021) has been characterized by near-normal temperatures. The warmest temperatures have occurred across southern and central regions of the three prairie provinces (Fig. 3).

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of May 29 – June 27, 2021.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – June 27, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-Jun 28, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (June 22-28, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -32 to >7 °C while the highest temperatures observed ranged from <22 to >36 °C. Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This week, the highest rainfall amounts were reported across central Alberta, southeastern Saskatchewan and southwestern Manitoba. Minimal rainfall was reported across most of central Alberta and northwestern Saskatchewan (Fig. 4).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 21 -27, 2021.

Rainfall amounts for the period of May 29-June 27 (30-day accumulation) were near normal. Rainfall amounts have been below normal across Alberta and large areas of Saskatchewan. Eastern Saskatchewan and western Manitoba have continued to receive the greatest amount of rainfall (Fig. 4).

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 29 – June 27, 2021

Average growing season (April 1 – June 27) precipitation was 103 % of normal with greatest precipitation occurring across eastern Saskatchewan, including Regina. Below normal rainfall has been reported across western Saskatchewan, southern Alberta and the Peace River region (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-June 27, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

11324Weekly Wind Trajectory Report for June 28 ( 2021 Week 9 )

Access background information for how and why wind trajectories are monitored in this post.

1. REVERSE TRAJECTORIES (RT)
Since June 16, 2021, a decreasing number of reverse trajectories have moved north from the Pacific Northwest (Idaho, Oregon and Washington), Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Though these US regions can be a source of diamondback moths (DBM), the ECCC models predict air movement, not actual occurrence of diamondback moths. Fields (and DBM traps) should be monitored for DBM adults and larvae.

Figure 1. The average number (based on a 5 day running average) of reverse trajectories that have crossed the prairies for the period of May 28 – June 28, 2021.

a. Pacific Northwest (Idaho, Oregon, Washington) – This week (June 22-28, 2021) there were 3 trajectories that crossed Alberta, Manitoba and Saskatchewan that originated in the Pacific Northwest.

b. Mexico and southwest USA (Texas, California) – This week (June 22-28, 2021) there were 0 trajectories that originated in Mexico or the southwest USA that crossed the prairies.

c. Oklahoma and Texas – This week (June 22-28, 2021) there were 0 trajectories originating in Oklahoma or Texas that passed over the prairies.

d. Kansas and Nebraska – This week (June 22-28, 2021) there were 0 trajectories that originated in Kansas or Nebraska that passed over the prairies.

2. FORWARD TRAJECTORIES (FT)
a. Since June 9, 2021 there has been a steady decrease in the number of forward trajectories that are predicted to cross the prairies (Fig. 2). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line).

Figure 2. The average number (based on a 5 day running average) of forward trajectories that were predicted to cross the prairies for the period of May 28-June 28, 2021.

11348Predicted wheat midge development ( 2021 Week 9 )

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in:
a. Delayed adult emergence and oviposition
b. Reduced numbers of adults and eggs

This week, wheat midge model simulations indicate that the majority of the larval population has moved to the soil surface (Figure 1). Dry conditions in the Peace River region have resulted in delayed development of larval cocoon populations. Pupae should now be occurring across most of the prairies (Figure 2). First appearance of adults is predicted across Manitoba and most of Saskatchewan (Figure 3).

Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) larval population that has moved to the soil surface across the Canadian prairies as of June 27, 2021.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the pupal stage, across the Canadian prairies as of June 27, 2021.
Figure 3. Percent of wheat midge (Sitodiplosis mosellana) population that is in the adult stage, across the Canadian prairies as of June 27, 2021.

The model was projected to July 13 to determine potential development at Regina (Fig. 4), Lacombe (Fig. 5), and Grande Prairie (Fig. 6) over the next two weeks.

Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of June 27, 2021 (projected to July 13, 2021).
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Lacombe, Alberta as of June 27, 2021 (projected to July 13, 2021).
Figure 6. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).

Compared to Lacombe and Grande Prairie, Regina has been warmer and wetter for the period of May 1 – June 27, 2021, resulting in advanced development of larvae and pupae (Fig. 4). In the Regina and Lacombe areas, initial oviposition is predicted to occur this week (Figs. 4 and 5). Emergence patterns for southern Manitoba are predicted to be similar to Regina. Cooler and dryer conditions in the Peace River region are expected to have impacted the movement of larvae to the soil surface, resulting in reduced adult emergence and later appearance of adults. Oviposition in the southern Peace River region is predicted to occur during the first week of July (Figure 6). Wheat crops near all three locations may be susceptible for the next 14-17 days.

If not already underway, scouting for wheat midge adults should begin this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.  

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 7. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads 
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 8. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long.  (Photo: AAFC-Beav-S. Dufton).

Economic Thresholds for Wheat Midge:
a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

11345Predicted grasshopper development ( 2021 Week 9 )

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 27, 2021. The development of grasshopper nymphs, based on average instar, should be most advanced across southern Manitoba and southeastern Saskatchewan (Figure 1). Grasshopper populations south of Winnipeg are predicted to be mostly in the 4th and 5th instar stages. Across the prairies, nymph development, as of June 27, 2021 is well ahead of long term average values (Figure 2).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, 2021.
Figure 2. Long term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, based on climate normals data.

The model was projected to July 13 to determine potential development at Saskatoon and Grande Prairie over the next two weeks. Results suggest that by July 13, Saskatoon populations will primarily be in the fourth and fifth instars with first appearance of adults (Figure 3). Development near Grande Prairie is predicted to be slower, with populations being mostly in the third and fourth instars (Figure 4). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.

Figure 3. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan as of June 27, 2021 (projected to July 13, 2021).
Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11342Predicted bertha armyworm development ( 2021 Week 9 )

Model simulations to June 27, 2021 indicate that development of bertha armyworm (BAW) (Mamestra configurata) populations is transitioning to egg and larval stages. Model simulations indicate that BAW oviposition is occurring across most of the prairies with occurrence of larvae across southern regions of all three provinces (Figs. 1 and 2).

Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the egg stage (% of population) across the Canadian prairies as of June 27, 2021.
Figure 2. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the larval stage (% of population) across the Canadian prairies as of June 27, 2021.

BAW populations in southern Manitoba are predicted to be predominantly in the larval stage by early July whereas BAW populations near Grande Prairie will be in the adult and egg stages. Model projections to July 13 predict that development near Brandon will be more advanced than development near Lacombe (Figs. 3 and 4). Over the next few days adult populations should be declining in southern Manitoba. In central Alberta adults should continue to lay eggs over the next 10 days. Above average temperatures will result in rapid development of larval populations.

Figure 3. Predicted development of bertha armyworm (Mamestra configurata) populations near Brandon, Manitoba as of June 27, 2021 (projected to July 13, 2021).
Figure 4. Predicted development of bertha armyworm (Mamestra configurata) populations near Lacombe, Alberta as of June 27, 2021 (projected to July 13, 2021).

Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 6) to help identify the various stages.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png
Figure 6. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

11370Cabbage seedpod weevil monitoring ( 2021 Week 9 )

Monitoring is already underway for cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) in southern areas of the prairies – it was the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

11367Lygus bug monitoring ( 2021 Week 9 )

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally. The Insect of the Week featured lygus bugs for Wk 09 – be sure to take a look!

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs. In fact, sampling is most accurate when repeated at a total of 15 spots within the field.  Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure 3). 

Figure 3. Sequential sampling for lygus bugs at late flowering stage in canola.

If the total number is below the lower threshold line (Fig. 3), no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold tables (Tables 1 and 2).

The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted. Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production.  The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage.  In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids!  Both posts include tips to to discern the difference between when doing in-field scouting!

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

11359Predicted diamondback moth development ( 2021 Week 9 )

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Model simulations to June 27, 2021, indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies and that the start of the second generation is occurring in southern Manitoba and southeastern Saskatchewan (Figure 1).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) that are expected to have occurred across the Canadian prairies as of June 27, 2021.

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

11406Aphids in field crops ( 2021 Week 9 )

Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Over the years, both the Weekly Updates and Insect of the Week included aphid-related information so here’s a list of these items to access when scouting fields:

Cereal aphids (Insect of the Week; 2017 Wk09)

Aphids in canola (Insect of the Week; 2016 Wk13)

Lygus bug nymphs vs. aphids (Insect of the Week; 2019 Wk16)

Cereal aphid manager APP (Weekly Update; 2021 Wk07)

Ladybird beetles and mummies (Weekly Update; 2020 Wk15)

Ladybird larva vs. lacewing larva (Insect of the Week; 2019 Wk18)

Aphidius wasp (Insect of the Week; 2015 Wk15)

Syrphid flies (Insect of the Week; 2015 Wk16)

Hoverflies vs. bees vs. yellow jacket wasps (Insect of the Week; 2019 Wk19)