Weather synopsis

The 2020 growing season, April 1 – July 12, 2020, has been cooler and wetter than normal across many locations in Alberta and Saskatchewan. Conditions in Manitoba have been warmer and dryer than normal. This past week (July 6-12, 2020) prairie temperatures were warmest in Manitoba and eastern Saskatchewan (Table 1; Fig. 1). Average 7-day temperatures continue to be warmest across Manitoba and eastern Saskatchewan and coolest across most of Alberta (Table 1; Fig. 1).

Figure 1. Observed average temperatures across the Canadian prairies the past seven days (July 6-12, 2020).

Average 30-day (June 13-July 12, 2020) temperatures continue to be cooler in Alberta than in southern Saskatchewan and Manitoba (Table 2; Fig. 2). The average 30-day temperature at Winnipeg and Brandon continued to be greater than locations in Alberta and Saskatchewan (Fig. 2). Temperature anomalies indicate that temperatures have been below normal across most of Alberta and Saskatchewan and were 0 to 2 °C warmer than average across eastern Saskatchewan and southern Manitoba (Table 2; Fig. 3). Based on growing season temperatures (April 1 – July 12, 2020), conditions have been warmest for southern locations (Table 3).

Figure 2. Observed average temperatures across the Canadian prairies the past 30 days (June 13-July 12, 2020).
Figure 3. Mean temperature difference from Normal the past 30 days (June 16-July 13, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Cumulative rainfall for the past 7 days was lowest across southern regions of Alberta and across most of Manitoba (Table 1 Fig. 4). Lethbridge reported 4.2 mm and Winnipeg reported 1.4 mm (Table 1). Cumulative 30 day rainfall continued to be greatest across central regions of Alberta (Table 2; Fig. 5). Rainfall amounts were lowest across southern regions of the prairies (Table 2; Fig. 5).

Figure 4. Observed cumulative precipitation across the Canadian prairies the past seven days (July 6-12, 2020).

Total 30-day rainfall at Brandon, Winnipeg and Swift Current was less than 100 mm (Table 2; Fig. 5). Lethbridge has reported 122.3 mm (261% of normal) in the past 30 days (Table 2). Growing season rainfall (percent of average) is below normal across eastern Saskatchewan and localized areas of Manitoba.

Figure 5. Observed cumulative precipitation across the Canadian prairies the past 30 days (June 13-July 12, 2020).
Figure 6. Percent of average precipitation for the growing season (April 1-July 13, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (14Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-July 13, 2020) is below (Fig. 7):

Figure 7. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-July 13, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (16Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 10 ºC, April 1-July 13, 2020) is below (Fig. 8):

Figure 8. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-July 13, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (16Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The highest temperatures (°C) observed the past seven days ranged from <15 to >33 °C in the map below (Fig. 9).

Figure 9. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-July 13, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (16Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

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

Predicted bertha armyworm development

Model simulations for July 12, 2020 indicate that 35% of the population is in the egg stage (37% last week) and 65% of the population is in the larval stages (14% last week). Across the Parkland and Peace River regions, BAW populations are predicted to be primarily in the egg stage (Fig. 1). Populations across southern regions are primarily in the larval stage (Fig. 1).

Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population in the larval stage as of July 12, 2020.

The two graphs below demonstrate that larval development near Brandon is predicted to be ahead of fields near Grande Prairie. In Brandon, populations are primarily in the larval stage (Fig. 2) while BAW populations near Grande Prairie are predicted to be predominantly in adult and egg stages (Fig. 3).

Figure 3. Predicted bertha armyworm (Mamestra configurata) phenology at Brandon MB as of July 12, 2020.
Figure 3. Predicted bertha armyworm (Mamestra configurata) phenology at Grande Prairie AB as of July 12, 2020.
Figure 5. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies.  Click each province name to access moth reporting numbers observed in AlbertaSaskatchewan and Manitoba (as they become available). Check these sites to assess cumulative counts and relative risk in your geographic region but remember in-field scouting is how the economic threshold is applied to manage this pest.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images above (Fig. 5) to help identify the economically important larvae.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

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.

Predicted wheat midge development

Wheat midge model runs indicate that, where wheat midge are present, adult emergence is well underway and oviposition is occurring across most prairie locations. The map suggests that, as of July 12, 2020, populations are primarily in the egg stage (Fig. 1). Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities.

Figure 1. Predicted percent of population of wheat midge (Sitodiplosis mosellana) at adult stage across the Canadian prairies (as of July 12, 2020).

The next 10-14 days are very important for monitoring wheat midge populations for the purpose of making management decisions. Simulations were run to July 26 to assess population development over the next 10 days (Table 1). The following table indicates that 50% emergence of adults should occur this week at Saskatoon and next week at Lacombe (Table 1). This week populations in Manitoba are predicted to be at 90% adult emergence (Table 1).

The two graphs below illustrate the development of wheat midge populations near Saskatoon (Fig. 2) and Lacombe (Fig. 3). Adult numbers are currently peaking near Saskatoon while adult emergence near Lacombe is not expected to peak until next week.

Figure 2. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK projected to July 21, 2020.
Figure 3. Predicted wheat midge (Sitodiplosis mosellana) phenology at Lacombe AB projected to July 21, 2020.

The next two graphs compare the synchrony between wheat midge and wheat for fields near Lacombe (Fig. 4). The graph indicates that peak adult emergence and oviposition may occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 4).

Figure 4. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Lacombe AB projected to July 21, 2020.

The last graph compares phenology (Saskatoon) of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge (Fig. 5). The parasitoid wasp lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 5). This information can be used as a guide to determine when fields should be monitored.

Figure 5. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and its parasitoid, Macroglenes penetrans, at Saskatoon SK projected to July 21, 2020.

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.

Predicted grasshopper development

As of July 12, 2020, the grasshopper model estimates that development across the prairies ranges from 1st instar stage to adults. Based on the model simulations, development has been slowest in the Peace River region where average nymph development ranges between the 2nd and 3rd instars (Fig. 1; Table 1). Across the southern prairies, the majority of the nymph population is predicted to be in the 3rd to 5th instar stages, with adults predicted to occur across southern Manitoba where populations are active (Fig. 1; Table 1). Across the prairies, populations are predicted to be 6, 6, 11, 27, 24, 21 and 5% in egg, first, second, third, fourth, fifth and adult stages, respectively.

Figure 1. Predicted average instar stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 12, 2020).

Table 1 indicates that predicted development at Brandon and Winnipeg is well ahead of Lacombe and Grande Prairie. The two graphs compare grasshopper development in Saskatoon (Fig. 2) and Winnipeg (Fig. 3). Grasshopper populations near Saskatoon are predominantly in the 4th and 5th instars with first appearance of adults beginning to occur (Fig. 2). Populations near Winnipeg are expected to be primarily adults (Fig. 3).

Figure 2. Predicted grasshopper (Melanoplus sanguinipes) phenology at Saskatoon SK. Values are based on model simulations (April 1-July 12, 2020).
Figure 3. Predicted grasshopper (Melanoplus sanguinipes) phenology at Winnipeg MB. Values are based on model simulations (April 1-July 12, 2020).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan 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” (Philip et al. 2018) as an English-enhanced or French-enhanced version. 

Lygus bug monitoring

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 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.

Field heroes


The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!  

Real Agriculture went live with a Pest and Predators podcast series!

• Access Episode 1 – Do you know your field heroes?

• Access Episode 2 – An inside look at the Prairie Pest Monitoring Network.

• Access Episode 3 – How much can one wasp save you?

• Access Episode 4 – Eat and be eaten — grasshoppers as pests and food

• Access Episode 5 – Killer wasp has only one target — wheat stem sawfly

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

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through humanmosquitobird and horse surveillance.  Link here to access the most current weekly update (July 4, 2020). The screenshot below was retrieved 16Jul2020 as reference but access that information here.

This image has an empty alt attribute; its file name is 2020Jun28-Jul04_WNV_Weekly_HealthCanada-1024x593.png

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas).  As of July 13, 2020, areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge.  Plan to protect yourself by wearing DEET!  

Figure 1. Predicted development of Culex tarsalis, across the Canadian prairies (as of July 13, 2020).

Provincial insect pest report links

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

Manitoba‘s Crop Pest Updates for 2020 are available. Access the July 15, 2020 report. The summary indicates that, “Armyworms and grasshoppers continue to be the biggest insects concern on crops in Manitoba. Scouting for diamondback moth continues, with just one report of spraying for diamondback moth. Spraying for goosefoot groundling moth and a stem borer maggot has been reported from quinoa. Green cloverworm has been found on soybeans in eastern Manitoba, but not at levels that would be economical. Pupal clusters of Cotesia, a parasitoid of armyworms and other caterpillars, have been reported to be quite abundant in some of the fields that had armyworms.”

Saskatchewan‘s Crop Production News and read Issue 5 which includes articles on Bertha armyworm, Cabbage seedpod weevil,  FieldWatch – Fostering Communication Between Applicators and Producers, and Look What the Wind Blew in! Diamondback Moths Arrived Early This Spring. Issue #4 included articles on Pest Scouting 101: Mid-Summer, and The Wheat Midge.

•  Alberta Agriculture and Forestry’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.

Crop report links

Click the provincial name below to link to online crop reports produced by:

• Manitoba Agriculture and Rural Initiatives – Other viewing options include subscribing to receive or access a PDF of July 14, 2020 report.

• Saskatchewan Agriculture  or access a PDF of July 7-13, 2020 report.

• Alberta Agriculture and Forestry or access a PDF of June 29, 2020 report.

The following crop reports are also available:

• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the July 13, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the July 14, 2020 edition). 

Previous posts

Click to review these earlier 2020 Posts (organized alphabetically):

    • 2019-2020 Risk and forecast maps

    • Alfalfa weevil (Wk08)

    • Aster leafhopper (Wk05)

    • Beetle data please! (Wk03)

    • Cereal aphid APP (Wk11)

    • Crop protection guides (Wk02)

    • Cutworms (Wk02)

    • Diamondback moth (Wk11)

    • Flea beetles (Wk02)

    • John Doane (Wk10)

    • Monarch migration (Wk10)

    • Pea leaf weevil (Wk11)

    • Pea leaf weevil – predicted development (Wk09)

    • Prairie provincial insect webpages (Wk02)

    • Scouting charts – canola and flax (Wk02)

    • Ticks and Lyme Disease (Wk06)

    • Wind trajectories (Wk09)

Alfalfa Pests / Feature Entomologist: Tyler Wist

This week’s Insect of the Week featured crop is alfalfa: a perennial legume known as “the Queen of Forage Crops.” Our feature entomologist this week is Tyler Wist.

Alfalfa – AAFC

A crop indispensable to Canadian livestock production, alfalfa is a high protein forage used for pasture, hay and silage. Since 1950, improved alfalfa cultivars have been developed for growth in the Prairie region. In particular, Variegated alfalfa is a subspecies developed by cross breeding Flemish alfalfa with Siberian alfalfa. The resulting cultivar is known for both its winter hardiness and resilience to drought and is grown across Western Canada. Because alfalfa is so integral to livestock industries, alfalfa seed is a notable Canadian export, with almost all seed production occurring in Manitoba, Saskatchewan and Alberta.

Several pest insects target alfalfa. Monitoring and scouting protocols as well as economic thresholds (when available) are found in Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management and the Cutworm Pests of Crops on the Canadian Prairies: Identification and Management Field Guide. Additional monitoring protocols exist to control certain pests.

Alfalfa field – AAFC
Alfalfa Pests
  • Alfalfa blotch leafminer
  • Alfalfa caterpillar
  • Alfalfa looper
  • Alfalfa weevil
  • Army cutworm
  • Armyworm
  • Aster leafhopper
  • Beet webworm
  • Bertha armyworm
  • Black cutworm
  • Black grass bugs
  • Blister beetles
  • Clover leaf weevils
  • Clover root weevils
  • Dingy cutworm
  • Fall field cricket
  • Grasshoppers
  • Green cloverworm
  • Lygus bugs
  • Mormon cricket
  • Pale western cutworm
  • Pea aphid
  • Pea leaf weevil
  • Potato leaf weevil
  • Potato leafhopper
  • Redbacked cutworm
  • Saltmarsh caterpillar
  • Superb stink bug
  • Sweetclover weevil
  • Twospotted spider mite
  • Variegated cutworm
Alfalfa looper – AAFC

Entomologist of the Week: Tyler Wist

Name: Tyler Wist
Affiliation: Agriculture and Agri-Food Canada Saskatoon Research and Development Centre
Contact Information: Tyler.Wist@canada.ca

How do you contribute in insect monitoring or surveillance on the Prairies?

I’m involved in insect surveillance, including a project to ground-truth the use of wind trajectories to predict the arrival of aster leafhoppers (and diamondback moths) in the spring. I also monitor for aphids in cereals and pea crops in July and August as part of projects that I run as a Field Crop Entomologist with AAFC.

In your opinion, what is the most interesting field crop pest on the Prairies?

I’ve always been fascinated by aphids because in North America, our pest species are all female. Unlike the majority of insects, these female aphids are born pregnant and they give birth to live, ready-to eat your crop, clones of themselves. Those freshly-birthed offspring already have little clones of themselves starting to mature within them. Thanks to this reproductive strategy, aphid populations can increase quickly and overwhelm their host plants. Right now I’m really interested in pea aphids and their effect on lentils and faba bean. We had high enough pea aphid pressure in my plots last season (2019) that many of our plots yielded nothing which reinforces that this insect is worth studying in these crops.

What is your favourite beneficial insect?

My favourite beneficial insect is the green lacewing larva, which is a generalist predator, so generalist that one once tried to eat me. It is such a fierce predator that female green lacewings have to lay their eggs on the underside of leaves on stalks so that the first-hatched green lacewing larvae do not eat their siblings! The lacewing larva feeds by piercing it’s prey with huge mandibles, then injects a digestive enzyme that liquefies the prey inside its hard, outer exoskeleton. Once their food is liquefied, the larva proceeds to suck the prey dry until all that remains is an empty shell of the insect prey. 

Tell us about an important project you are working on right now.

I’ve alluded to two projects already, one funded by WGRF to look at the origins and arrivals of aster leafhoppers to the prairies and see if they are flying in on the same winds as the diamondback moth and one funded by ADF and WGRF to evaluate the yield loss caused by pea aphids. Another important project is to find alternative wheat resistance against wheat midge so that agriculture is not so heavily reliant on using wheat with the Sm1 gene.

What tools, platforms, etc. do you use to communicate with your stakeholders?

I communicate to stakeholders with reports to funding agencies, PowerPoint presentations at grower/agronomist meetings, using Twitter, email and sometimes even over the phone!

Weather synopsis

Temperatures this week, June 18-24, 2019, were similar to last week. Over the past seven days temperatures were cooler than normal. The warmest temperatures were observed across MB while temperatures were cooler in western SK and across AB (Fig. 1). The is a complete reversal to last week.  

Figure 1. Average temperature (°C) across the Canadian prairies the past seven days (June 16-24 2019).

Average 30 day temperatures were warmest across southern MB and SK (Fig. 2). Cooler temperatures were reported across eastern and northern AB. The mean temperature differences from normal (May 21 – June 17, 2019) have been zero to two °C warmer than normal for AB and SK while temperatures in MB have been zero to two °C cooler than normal (Fig. 3). 

Figure 2. Average temperature (°C) across the Canadian prairies the past 30 days (May 26-June 24 2019).
Figure 3. Mean temperature difference from Normal across the Canadian prairies over the past 30 days (to June 17, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Growing season temperatures (April 1-June 24, 2019) have been warmest across the southern prairies (Fig. 4). The warmest growing season temperatures have been reported for southern AB and an area south of Winnipeg MB. Across the prairies, the average growing season temperature has been 1.2 °C below normal.

Figure 4. Average temperature (°C) across the Canadian prairies for the growing season (April 1-June 24 2019).

This past week significant rainfall amounts were reported for most of SK and across central  regions of AB (Fig. 5). Across the prairies, rainfall amounts for the past 30 days (May 26 – June 24, 2019) have been near normal (Fig. 6). The Edmonton region has been the wettest. 

Figure 5. Cumulative precipitation observed the past seven days across the Canadian prairies (June 18-24 2019).
Figure 6. Cumulative precipitation observed the past 30 days across the Canadian prairies (May 26-June 24, 2019).
Figure 7. Cumulative precipitation observed for the growing season (April 1-June 24, 2019) across the Canadian prairies.
Figure 8. Modeled soil moisture (%) across the Canadian prairies as of June 24, 2019.

The growing degree day map (GDD) (Base 5 ºC, April 1-June 24, 2019) is below (Fig. 9):

Figure 9. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-June 24 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The growing degree day map (GDD) (Base 10 ºC, April 1-June 24, 2019) is below (Fig. 10):

Figure 10. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-June 24, 2019).Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The lowest temperatures (°C) observed the past seven days ranged from about 11 to 0 °C in the map below (Fig. 11).

Figure 11. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to June 24, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The highest temperatures (°C) observed the past seven days ranged from about 16 to at least 27 °C in the map below (Fig. 12).

Figure 12. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to June 24, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (24Jun2019).  Access the full map at http://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 Drought Watch Maps for the growing season.

Predicted grasshopper development

Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).

Across the prairies the grasshopper hatch is well underway with most locations having approximately 27% of the population in the egg stage. Based on model runs, approximately 33% (30% last week) of the population is in the first instar, 26% (14.5% last week) is predicted to be in the second instar, and 11% (4.3% last week) in the third instar and just over 1% are predicted to be in the fourth instar.   The following map indicates that grasshopper populations across the southern prairie are mostly in the second instar.

Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of June 24, 2019). 

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan 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” which is available as a free downloadable document in either an English-enhanced or French-enhanced version.

Predicted bertha armyworm development

Bertha armyworm (Lepidoptera: Mamestra configurata– Bertha armyworm adults should be emerging across the prairies and oviposition is predicted to have begun across most of the southern prairie regions of SK, AB and MB (Fig. 1).

Figure 1.  Predicted precent of bertha armyworm (Mamestra configurata)  populations at EGG STAGE across the Canadian prairies as of June 24 2019. 

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.

Again, thanks to John Gavloski (Manitoba Agriculture) who helped update the PPMN Bertha armyworm monitoring protocol.  Use the images below (Fig. 2) to help identify moths from the by-catch that will be retained in phermone-baited unitraps.

Figure 2. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Also be sure to review the Insect of the Week which features bertha armyworm and its doppelganger, the clover cutworm!

Wheat midge

Wheat Midge (Sitodiplosis mosellana) –  Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10).  Check that post for help with in-field scouting for this economic pest of wheat!  The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11).  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.

Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on wheat midge emergence. 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. Our wheat midge model indicates that dry conditions may result in:

  • Delayed adult emergence and oviposition
  • Reduced numbers of adults and eggs

The wheat midge model indicates that 70% (82% last week) of the population are in the larval  cocoon stage and 29% (18% last week) of the population is predicted to have moved to the soil surface. The first map presents wheat midge development as of last week (Fig. 1)

Figure 1.  Percent of larval population at the soil surface (as of June 17, 2019) across the Canadian prairies.

Results indicate that dry conditions delayed development of larval cocoons in SK. Adequate precipitation in AB and MB should have resulted in movement of larvae to the soil surfaceThe model indicates that recent rain has resulted in larval development (larval cocoons) across SK. The second map indicates that recent rain in SK should result in development of larval cocoons and subsequent movement of larvae to the soil surface (Fig. 2). The third map (Fig. 3) indicates that pupae may be present in some fields in southern AB and MB. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.

Figure 2. Percent of larval population at the soil surface (as of June 24, 2019) across the Canadian prairies.
Figure 3.  Percent of  population AT PUPAL STAGE (as of June 24, 2019) across the Canadian prairies.

Monitoring:
When monitoring 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 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). 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.

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

Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For 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 the larval damage. 

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.  

NEW – Alberta Agriculture and Forestry has also released a YouTube video describing in-field monitoring for wheat midge this week.  

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.

Cereal Aphid Manager (CAM)

Reminder  and Congratulations!  The Cereal Aphid Management (CAM) Mobile Application Team was recognized with an Agriculture and Agri-Food Canada Gold Harvest Award this month!  Team members included Ashraf Eid, Paul Faure, John Gavloski, François Jodoin, Elham Karimi, Eric Li, Jackson Macdonald, Nancy MacDonald, Owen Olfert, Chrystel Y. Olivier, Daniel Shen, Erl Svendsen, Gabriel Tobian, Tyler J. Wist.  

“The app is a culmination of innovative thinking, extensive research, and most importantly collaboration in order to design a tool that met the needs of the farming community. The team’s ability to work together and build this application will result in economic savings, a greener environment, and increased crop quality in the food production industry.”

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:

  • the number of aphids observed and how quickly they reproduce
  • the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
  • the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

Available in iOS and Android.

To learn more and to download, go to AAFC’s CAM webpage.

Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.

CAM Homepage
CAM monitoring report and recommendation
CAM icon

Provincial Insect Pest Report Links

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

Manitoba‘s Insect and Disease Updates for 2019 are posted here. Access Update #4 posted June 12, 2019.

Saskatchewan‘s Crops Blog Posts includes a segment on “Early season scouting of cutworms” by Sara Doerksen posted in April 2019 and “Economic thresholds” by Kaeley Kindrachuk posted in May 2019. Also access the Crop Production News with Issues #1 (featuring Diamondback moth monitoring), #2 (featuring Pest surveying and Pea leaf weevil in peas and faba beans), and #3 (featuring Bertha armyworm and Pea leaf weevil information).

•  Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Mr. Scott Meers. The most recent Call of the Land was posted March 18-22, 2019 but did not include an insect update. In the meantime, try Agri-News to access the June 10, 2019 edition including information pertaining to the value of in-field monitoring.

Crop report links

Crop reports are produced by:

The following crop reports are also available:

Field Events – Speak to an entomologist

Public summer field events – Coming to a field near you –  Prairie field crop entomologists are already scheduled to be at these 2019 field tour events from May-August (be sure to re-confirm dates and details as events are finalized):

•  June 26, 2019: 2019 CanolaPALOOZA to be held at the Lacombe Research and Development Centre (Lacombe AB).  View event info/registration details.  Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Meghan Vankosky, Scott Meers, Patty Reid, Sunil Shivananjappa, Hector Carcamo, Julie Soroka, Mark Cutts, Jim Tansey, Sherrie Benson and the Junior Entomologists.

•  July 9-12, July 16-18, 2019: Crop Diagnostic School. Held at the University of Manitoba Research Farm at Carman, Manitoba. An 2-week diagnostic school will complete units on entomology, plant pathology, weed science, soil fertility, pulse crop production, and oilseed production. View registration and event information. Entomologists participating: John Gavloski and Jordan Bannerman.

•  July 9, 2019: CanolaPALOOZA Saskatoon, to be held at the SRDC Llewellyn Farm. Read more about this event.  Entomologists presenting: Tyler Wist, James Tansey, Greg Sekulic, Meghan Vankosky

•  July 22, 2019: Pulse grower gathering held near Three Hills AB.  Check Alberta Pulse Growers Event Page for more information.  Entomologists presenting: Graduate students from Dr. Maya Evenden’s (U of A) working on pea leaf weevil.

•  July 23-24, 2019: Crop Diagnostic School, Scott Saskatchewan. Read more about this event.  Entomologists presenting: Meghan Vankosky, Tyler Wist.

•  July 24, 2019: Crops-a-Palooza. Held at Canada-Manitoba Crop Diversification Centre (CMCDC), Carberry, Manitoba. Read more about this event. Entomologist participating: John Gavloski, Vincent Hervet, Tharshi Nagalingam, Bryan Cassone.

•  August 8, 2019:  2019 Wheatstalk to be held at Teepee Creek AB.  View event info/registration details.   Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Boyd Mori.

  August 8, 2019. Horticulture School. Agriculture and Agri-Food Canada Research Farm, Portage la Prairie, Manitoba. View event info/registration details.  Entomologist presenting: John Gavloski, Kyle Bobiwash.

Previous Posts

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Alfalfa weevil – Week 11

Bertha armyworm – Week 11

Cabbage seedpod weevil – Week 11
Cereal aphid APP – Week 10
Cereal leaf beetle – Week 9
Crop protection guides – Week 6
Cutworms – Week 5

Field heroes – Week 6
Flea beetles – Week 5

Grasshoppers – Week 10

Insect scouting chart for Canola – Week 5
Insect scouting chart for Flax – Week 5

Monarch migration – Week 11

Painted lady butterfly – Week 8
Pea leaf weevil – Week 10
Prairie Crop Disease Monitoring Network – Week 11

Ticks and Lyme disease – Week 4

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Review Page for list of PDFs

Insect of the Week – Doppelgangers: midge vs. parasitoid

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger. 

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different. 

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Is that a midge or a parasitoid? Why does it matter?

Small insects (i.e., less than 5 mm) are difficult to identify, even for trained specialists and professional entomologists. Especially if they are alive, flying around. Or in a sweep net sample quickly assessed in the field. In the case of midge and small-bodied parasitoids, they can be easily mistaken for one another, but their roles in agriculture tend to be very different. 

Some of the most well-known prairie midge species are agricultural pests, such as the orange coloured wheat midge (Sitodiplosis mosellana), black-coloured Hessian fly (Mayetiola destructor), and alfalfa blotch leafminer (Agromyza frontella). Other midge species found on the prairies include biting midge like no-see-ums (Ceratopogonidae), black flies (Simuliidae), and non-biting midge (Chironomidae). Midge that are not considered agricultural pests may provide some ecosystem services (i.e., pollination), while other midge are disease vectors and are pests of medical and veterinary concern. 

A – Hessian fly – adult
Scott Bauer, USDA Agricultural Research Service, Bugwood.org
B – Swede midge – adult
Susan Ellis, USDA APHIS PPQ, Bugwood.org
C – Wheat midge – adult
Mike Dolinski, MikeDolinski@hotmail.com

Parasitoids are natural enemies of other insects. Thus, many parasitoids are important because they help control agricultural pest populations. Adult parasitoids lay eggs, usually singly, onto or into their host. The larvae that hatch from the eggs develop using the host as food, and eventually kill the host. An individual host usually provides enough food for just one parasitoid larva. For this reason, parasitoids species are rarely larger in size than their host species. On the prairies, important parasitoid families that may be mistaken for midge or other small, black insects include: Aphidiinae, Braconidae, Chalchididae, Encyrtidae, Eulophidae, Platygasteridae, Pteromalidae and Trichogrammididae. Sticky cards or sweep net samples may contain hundreds or thousands of small, black, winged insects. Many are probably parasitoids and not pests so look closely when scouting. A few key differences to watch out for include:

  • Parasitoids have two pairs of wings while midge have only one pair of wings     
  • Parasitoids are often shiny or metallic shades of black, blue, purple or green     
  • Midge may look hairy; parasitoids rarely look hairy.  
1 – Aphidiinae – adult (Aphidius avenaphis)
Tyler Wist, AAFC
2 – Braconid wasp – adult
Alberta Agriculture and Rural Development
3 – Chalcid wasp – adult (Phasgonophora sulcata)
Michael Gates, Encyclopedia of Live, EOL.org
4 – Tetrastichus julis – adult parasitizing a cereal leaf beetle larva
Swaroop Kher, University of Alberta/AAFC
5 – Ichneumonid – adult (Banchus flavescens)
John Gavloski, Manitoba Agriculture, Food and Rural Development
6 – Platygasterid – adult (Inostemma sp.)
Tyler Wist, AAFC
7 – Pteromalid – adult (Pteromalus puparum)
Koorosh McCormack, Natural History Museum: Hymenoptera Section, EOL.org
8 – Trichogrammid – adult (Trichogramma sp.) parasitizing an egg  
Jack Kelly Clark, University of California Statewide IPM Program

Specific information on these families of parasitoids and on the species of midge listed here can be found in updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide.

Review previously featured insects by visiting the Insect of the Week page.

Post contributed by Dr. Meghan Vankosky.

Wind Trajectories

Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990’s.

In a continuing effort to produce timely information, the wind trajectory reports are available in two forms:

Prairie Crop Disease Monitoring Network

The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of our prairie pathologists who work together to support in-field disease management in field crops.  

In 2019, the PCDMN will release a series of weekly Cereal Rust Risk Reports throughout May and June.  Information related to trajectory events based on forecast and diagnostic wind fields and cereal rust risk is experimental, and is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY. 

Background:  Agriculture and AgriFood Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s. Trajectory models are used to deliver an early-warning system for the origin and destination of migratory invasive species, such as diamondback moth. In addition, plant pathologists have shown that trajectories can assist with the prediction of plant disease infestations and are also beginning to utilize these same data. An introduction will be presented of efforts to identify wind trajectory events that may bring rust urediniospores into Western Canada from epidemic areas in the central and Pacific northwest (PNW) regions of the USA. Identification of potential events as well as an assessment of epidemic severity from source locations, and prairie weather conditions, will be used to assess the need for prompt targeted crop scouting for at-risk regions of the Canadian Prairies.

Two documents are available from the PCDMN:

Summary of wind trajectory and cereal rust risk assessment and the need for in-crop scouting in the Prairie region, June 18-24, 2019:

1. Pacific Northwest – Currently there is limited stripe rust development in the PNW, although there has been a moderate number of recent wind trajectories from the PNW.  Rainfall did occur in SK and some regions of Alberta.  Winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of stripe rust appearance from the PNW is relatively low and scouting for this disease is not urgent.  

2. Texas-Oklahoma corridor – In general, crops are advancing towards maturity, while in many areas of Texas and Oklahoma crops have been harvested or are being harvested, and thus winter wheat crops in these areas are less of a source of rust inoculum.  There were no recent wind trajectories from this area, while rainfall did occur in SK and some regions of Alberta.  Winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is low and scouting for these diseases is not urgent.  

3. Kansas-Nebraska corridor – Kansas crops are starting to mature with harvesting starting in some regions. In Nebraska, leaf and stripe rust development continues, and thus over the next few weeks this region could act as a significant source of rust inoculum for the Prairie region.  From June 18-24, 2019 there has been a low-moderate number of wind trajectories from this area.  Rainfall did occur in SK and some regions of Alberta, while winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is relatively low and scouting for these diseases is not urgent.  Although further development of rust in Nebraska may increase the risk, the crop will soon start to progress towards maturity and will become less of a source of the cereal rusts.  It should be noted that rust symptoms have been observed in research plots in St. Paul, MN (Cereal Rust Survey, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, Dr. O. Fajolu, USDA-ARS Cereal Disease Lab, June 18, 2019).  Stripe and leaf rust have also been observed in research plots at the South Dakota State University Research Farm, while no rust was observed in commercial fields in southeastern and southcentral regions of the SD (Cereal Rust Survey, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, Dr. E. Byamukama, South Dakota State University, June 18, 2019).

4. Currently, we are not aware of reports of stripe or leaf rust in commercial fields of winter or spring wheat across the Prairie region.

5.  Access the full downloadable report.

Corrections and updates to Weekly Update

Hello – This week three weather maps were incorrectly posted and the Saskatchewan bertha armyworm map was updated.  These items are now available for viewing:

Weather synopsis (Wk 12 for Jul 26th)

2018 Cumulative pheromone trap interceptions for Saskatchewan (as of July 18th)

Access the complete Weekly Update either as a series of Posts for Week 12 (July 26, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 12!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Meghan Vankosky or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these three steps!

Insect of the Week – Natural enemies of the canola flower midge

This week’s Insects of the Week are two parasitoid wasps, an Inostemma sp. (Hymenoptera: Platygastridae) and a Gastrancistus sp. (Hymenoptera: Pteromalidae). These parasitoids are natural enemies of the canola flower midge (Contarinia brassicola, Diptera: Cecidomyiidae), a newly discovered fly species that uses canola as its host plant. The parasitoids have been found throughout the Prairies emerging from infested galls created by the canola flower midge. Little is known about these two species, but parasitism rates as high as 30% have been noted in northeast Saskatchewan.

Gastrancistrus sp. (Hymenoptera: Pteromalidae)
(c) 2016 Boyd Mori, AAFC
Inostemma sp. (Hymenoptera: Platygastridae)
(c) 2016 Boyd Mori, AAFC

Submitted by Dr. Boyd Mori and Dr. Meghan Vankosky

Find out more about the natural enemies of the canola flower midge and more at the Insect of the Week page!

Weekly Update

Greetings!

In-field scouting remains critical as we move into August!  Access the complete Weekly Update either as a series of Posts for Week 12 (July 26, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 12!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Meghan Vankosky or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these three steps!

Weather synopsis

Weather synopsis – This past week (July 16 – 23, 2018) the average temperature (16.3 °C) was marginally warmer than long term average values (Fig. 1). The warmest weekly temperatures occurred across east-central AB and west-central/southern SK. The 30-day (June 23 – July 23) average temperature (15.8 °C) was similar to the long term average.  

Figure 1. Weekly (July 16-23, 2018) average temperature (°C).

Weekly and 30-day total precipitation was above average (Figs. 2 and 3).  The wettest region (30 day cumulative precipitation) was across eastern areas in SK and southern MB while central SK and most of AB continue to be dry.

Figure 2. Weekly (July 16 – 23, 2018) cumulative precipitation (mm).
Figure 3.  The 30-day (June 23 – July 23, 2018) cumulative precipitation (mm).

The map below reflects the Highest Temperatures occurring over the past 7 days (July 17-23, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 4). 

Figure 4. Highest temperature across the Canadian prairies the past seven days (July 17-23, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (24Jul2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

The map below reflects the Highest Temperatures occurring over the past 7 days (July 17-23, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 5). 

Figure 5. Lowest temperature across the Canadian prairies the past seven days (July 17-23, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (24Jul2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

The growing degree day map (GDD) (Base 10ºC, March 1 – July 22, 2018) is below:

The growing degree day map (GDD) (Base 5ºC, March 1 – July 22, 2018) is below:

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.

Predicted grasshopper development

Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).  

As of July 23, 2018, most grasshopper populations are predicted to be primarily in the fifth instar or adult stages (Fig. 1A). Development is well ahead of average population development (Fig. 1B). Normally the first appearance of adults occurs during the last week of July (central Saskatchewan).  

Figure 1. Grasshopper development (average instar) based on model simulations for the current growing season (A) and for long term normal climate (B) (April 1 – July 23, 2018).

Grasshopper development varied across the prairies, and was predicted to be more advanced across the southern prairies (e.g., Lethbridge; Fig. 2A) than in the Peace River region (fourth and fifth instar stages; Fig. 2). 

Figure 2. Predicted grasshopper phenology at Lethbridge and Grande Prairie.
Values are based on model simulations, for April 1 – July 23, 2018.
Figure 3.  Clearwinged grasshopper stages including egg, first to fifth instar stages and adult (left to right).

Grasshopper Scouting Steps: 

● 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.

● Starting 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 end point 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.

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.

Wheat midge

Wheat Midge (Sitodiplosis mosellana– Warm, moist conditions in Manitoba are predicted to be favourable for development wheat midge larvae (Fig. 1A). In Manitoba and eastern Saskatchewan larvae should be dropping into the soil (Fig. 1B). 

Figure 1. Percent wheat midge in the early larval stage (A) and larval cocoons (B) based on model simulations for April 1 – July 23, 2018.

Model runs for Saskatoon indicate the midge development, due to dryer conditions in June, is slower than predicted emergence at Brandon and Edmonton (Fig. 2). 

Figure 2. Predicted wheat midge phenology at Brandon, Saskatoon and Edmonton.
Values are based on model simulations, for April 1 – July 16, 2018.

Monitoring:

When monitoring 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 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). 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.

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

Economic Thresholds for Wheat Midge:

a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.

b) For 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 the larval damage. 

Click here to review the 2018 wheat midge forecast map.  

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.  Additionally, more information 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.

Lygus in canola

Lygus bugs (Lygus spp.) – The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
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. They 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.  For lygus bug monitoring, 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 C). 

If the total number is below the lower threshold line, 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 table.

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

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.

Table 1.  Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).

1 Canola crop stage estimated using Harper and Berkenkamp 1975).
2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).

Table 2.  Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).

 3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).

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-enhanced or French-enhanced versions are available.

Bertha armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata– Pheromone trapping across the prairies is almost complete for the 2018 growing season but now it is important to scout for larvae feeding on leaves and developing pods.

Monitoring:

  • Larval sampling should commence once the adult moths are noted. 
  • Sample at least three locations, a minimum of 50 m apart. 
  • At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae. 
  • Count them and compare the average against the values in the economic threshold table below:  

Scouting tips:

  • Some bertha armyworm larvae remain green or pale brown throughout their larval life. 
  • Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms. 
  • Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. 
  • Larvae eat the outer green layer of the stems and pods exposing the white tissue. 
  • At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

Albertans can access the online reporting map (screenshot below retrieved 24Jul2018 for reference):

Saskatchewan growers can check the 2018 bertha armyworm map (screenshot below retrieved 26Jul2018 for reference):

Manitoban growers can find bertha armyworm updates in that province’s Insect and Disease Updates.  The July 25th update summarized that, “out of the 99 traps, 87 currently have cumulative counts in the low risk category (less than 300), one trap is in the moderate risk range, and 11 traps are in the uncertain risk category.  Most of the highest cumulative counts so far are in the western part of Manitoba.”

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 new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Cabbage seedpod weevil

Cabbage seedpod weevil (Ceutorhynchus obstrictus) –  There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo).  Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.

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 online map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 24Jul2018).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.

Cereal Aphid Manager (CAM)

Reminder – Aphids can cause significant damage to fields and increase crop losses, but just because aphids are present in a grain field doesn’t mean they will have a negative economic impact on production. This is especially true if there are aphid’s natural enemies (beneficial insects) in the field to keep them under control.

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:

  • the number of aphids observed and how quickly they reproduce
  • the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
  • the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

Available in iOS and Android.

To learn more and to download, go to AAFC’s CAM webpage.

Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.

CAM Homepage
CAM monitoring report and recommendation
CAM icon

West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  Areas highlighted yellow then orange are approaching sufficient heat accumulation for mosquitoes to emerge while mosquitoes will be flying in areas in red so wear DEET to stay protected! 

Health Canada posts information related to West Nile Virus in Canada.  Health Canada also tracks WNV through humanmosquitobird and horse surveillance.  Link here to access the most current weekly update (July 7, 2018) on 2018 testing (screenshot retrieved 25Jul2018 provided below for reference only).

Reminder – The 2017 WNV surveillance map for human cases is available here but a screenshot is posted below for reference.

Figure 1.  As of surveillance week 49, ending December 9, 2017, the preliminary data indicated 197 human cases of WNV in Canada; twenty-five from Québec, 159 from Ontario, five from Manitoba, seven from Alberta, and one from British Columbia.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds.  As of June 28, 2018, 642 birds were examined and zero have tested positive for West Nile virus

Provincial Insect Pest Reports

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

Manitoba‘s Insect and Disease Updates for 2018 can be accessed here. Issue #9 (posted for July 25, 2018) includes a summary of cumulative bertha armyworm counts from pheromone traps for 2018 and importance of monitoring in canola (bertha armyworm and diamondback moth) and soybeans (spider mites) but an overall low level of insect concerns so far.

Saskatchewan‘s Crop Production News for 2018 is posted with Issue #5 now available. This issue includes a description of cereal leaf beetle in Saskatchewan. Growers can review articles on how to scout for cutworms, how to assess plant stand densities in flax or canola, and for flea beetles, pea leaf weevils. Also note the following diamondback moth pheromone trap interception counts from across the regions (updated June 27, 2018):

Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Scott Meers. The most recent Call of the Land (posted July 19, 2018) identified that SOME bertha armyworm pheromone traps over a wide geographic range have started to intercept higher numbers of moths. Elevated trap counts require further in-field scouting to accurately detect the number and staging of bertha armyworm larvae that will now feed on developing canola pods. Pea leaf weevil is a pest of several legume species so growers trying to establish seedling alfalfa in areas where pea leaf weevil has been confirmed are advised to scout. Early trends from the early flower canola survey include relatively lower numbers of cabbage seedpod weevil, lygus bugs, diamondback moth and leafhopper numbers compared to recent years but the prevalence of beneficial arthropods in some fields.

Crop reports

Crop reports are produced by:

The following crop reports are also available:

Previous Posts

The following is a list of 2018 Posts – click to review:

Abundant parasitoids in canola – Week 10
Alfalfa weevil – Week 6

Cabbage seedpod weevil – Week 8 
Cabbage root maggot – Week 11 
Cereal aphid manager (CAM) – Week 2
Cereal leaf beetle – Week 5
Cereal leaf beetle larvae request – Week 8
Crop protection guides – Week 2
Crop reports – Week 8
Cutworms – Week 4

Diamondback moth – Week 7
Download the field guide – Week 10

Field heroes – Week 8
Flea beetles – Week 4

Monarch migration – Week 8

Pea leaf weevil – Week 8
PMRA Pesticide Label Mobile App – Week 4

Scouting charts (canola and flax) – Week 3

Ticks and Lyme Disease – Week 4

Weather radar – Week 3
White grubs in fields – Week 8
Wind trajectories – Week 6
Wireworm distribution maps – Week 6

West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of July 13, 2017areas highlighted in yellow on the map below have accumulated sufficient heat for the initial C. tarsalis to begin to fly whereas areas highlighted in orange have to C. tarsalis flying so wear your DEET to stay protected!




The Public Health Agency of Canada posts information related to West Nile Virus in Canada.  In 2016, 104 human clinical cases of West Nile Virus were reported.  The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 1, 2017).  

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds.  As of July 20, 2017, 833 birds were examined and eight have tested positive for West Nile virus; four from Ontario, one from Saskatchewan, and one from Quebec

Insect of the Week – Tetrastichus julis

This week’s Insect of the Week is Tetrastichus julis. They are a parasitoid enemy of the cereal leaf beetle. Mature larvae overwinter in infested cereal leaf beetle cocoons and emerge in spring to lay more eggs in cereal leaf beetle larvae. Adults feed on nectar and aphid honeydew.



For more information on Tetrastichus julis, visit our Insect of the Week page.

Tetrastichus julis – adult parasitizing a cereal leaf beetle larva
(Swaroop Kher, University of Alberta/AAFC)




Follow @FieldHeroes to find out how natural enemies are working for you for FREE to protect your crops!


Remember the NEW Cutworm Field Guide is free and downloadable in 2017!

Weekly Update – Greetings!

Greetings!

Please access the Weekly Update for July 20, 2017 (Week 12), as either a series of Posts  or a downloadable PDF.   


Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Owen Olfert or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these three easy steps!

Weekly Update – Weather Synopsis

Weather synopsis – Seven-day rainfall accumulations were generally greater than the previous week. Some areas in southern prairies received 10 to 30 mm of rain (Fig. 1). Total 30-day rainfall for June 17 to July 16, 2017, indicates that conditions are somewhat dryer than normal for most of the prairies. Figure 2 indicates that the regions with <40% of average rainfall (30-day) now include much of southern Saskatchewan, as well as large spots of southern Alberta and Manitoba. The percent of average precipitation for this growing season continues to be average for most of Alberta and below average for much of Saskatchewan and Manitoba (Fig. 3).

Figure 1.  Accumulated precipitation across the Canadian prairies the past  seven days (July 10-16, 2017).




Figure 2.  Accumulated precipitation across the Canadian prairies the past  30 days (June 17-July 16, 2017).




Figure 3.  Percent of average precipitation across the Canadian prairies from June 17-July 16, 2017.



Over the past week, the warmest temperatures occurred over a large area from Brandon to Edmonton and south to the Canada-USA border. Although temperatures were warmer (1°C) than last week, both the 7- and 30-day average temperatures were similar to long-term normal (LTN). Compared to 30-day average temperatures, Alberta was above normal whereas Saskatchewan and Manitoba were slightly below normal. 




The lowest temperatures across the prairies over the past seven days (July 13-19, 2017) are mapped below.  


In contrast, the highest temperatures recorded over the past seven days (July 13-19, 2017) are presented below.  


The growing degree day map (GDD) (Base 10ºC, March 1 – July 13, 2017) is below:



The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.

Weekly Update – Wheat midge

Wheat Midge (Sitodiplosis mosellana– Reminder – The previous Insect of the Week (Week 7) features wheat midge!  


Model output indicates that the emergence of adults is well underway across the prairies. Oviposition should be underway and larvae should be present. Dry conditions in Saskatchewan appear to have reduced potential adult emergence.  



Monitoring:
When monitoring 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 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). 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.



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





Economic Thresholds for Wheat Midge:

a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.


b) For 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 the larval damage. 

 
 

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.  

NEW – Alberta Agriculture and Forestry has also released a YouTube video describing in-field monitoring for wheat midge this week.  

 
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.

Cabbage seedpod weevil

Cabbage seedpod weevil (Ceutorhynchus obstrictus) –  There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo).  Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.




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.


Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.

Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has posted a live CSPW map and online reporting tool for growers.  A screenshot (retrieved 20Jul2017) is included below.

Weekly Update – Predicted Grasshopper Development

Grasshopper Simulation Model Output – Based on model output, development is slightly ahead of long term normal (LTN). Grasshoppers should be predominantly in the third and fourth instar stages with more rapid development across southern Alberta. Last week the mean instar was 3.4; this week it increased to 4.1. 

Figure 1. Predicted Melanoplus sanguinipes development across 
the Canadian prairies (July 16, 2017).



Figure 2. Predicted Melanoplus sanguinipes development prepared 
using Long Term Normal (LTN) data.

  

Figure 3.  Predicted percent of Melanoplus sanguinipes at fifth instar 
development stage (July 16, 2017).



This is the first week where the model has predicted appearance of adults. As of July 16, 2017 adults should be occurring across 45% of the prairies (compared to long term average value of 39%). 

Figure 4.  Predicted percent of Melanoplus sanguinipes at adult stage (July 16, 2017).



Grasshopper Scouting Steps: 

● 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.

● Starting 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 end point 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.





Reminder:  Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Food and Rural DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.

Weekly Update – Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) – Once the diamondback moth is present in the area, it is important to monitor individual canola fields for larvae


Remove the plants in an area measuring 0.1 m² (about 12″ square), beat them on to a clean surface and count the number of larvae (Fig. 1) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.


Figure 1. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.



Figure 2. Diamondback moth pupa within silken cocoon.



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  (approximately 1-2 larvae per plant).


Biological and monitoring information for DBM is posted by Manitoba Agriculture, Food and Rural DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.  

More information about Diamondback moths 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 Diamondback moth page but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.



Reminder – Pheromone traps attracting male Diamondback moths (Fig. 3) have been deployed across the prairies.  

Figure 3. Diamondback moth.


Across the prairies, provincial staff coordinate diamondback pheromone trapping during the growing season:

● Counts will be reported by the provincial staff in Saskatchewan.  
● Manitoba Agriculture and Rural Initiatives posted low DBM counts which can be reviewed here.  
● Alberta Agriculture and Forestry has a live 2016 map reporting Diamondback moth pheromone trap interceptions.  A copy of the map (retrieved July 20, 2017) is below for reference.

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information: 


● Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and read Issue #9 (posted July 19, 2017) noting the continued presence of thistle caterpillar (Vanessa cardui) and their webbing in some soybean fields, aphids in some cereal and pea fields and diamondback moth near the economic threshold in some canola fields in the Central region. Reminder – Cumulative counts of bertha armyworm generated from weekly counts in Manitoba can be accessed here.

● Saskatchewan’s Crop Production News – 2017 – Issue #4 includes information related to soybean pests prepared by Joel Peru. That report includes an update on scouting and management tips for painted lady butterflies (also described in Week 6) and Aphanomyces root rot. 


● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (July 20, 2017) provided by Scott Meers.
That report notes emergence of second generation of painted lady butterflies (V. cardui) which should be monitored closely in borage, soybeans and any plant in the sunflower family, but also watch volunteer thistle in canola since the larvae will move onto the latter if the thistle is consumed. Both cabbage butterfly and yellowish imported cabbage worm butterflies are active and laying eggs in cabbage and canola in that province. The wheat midge flight is nearly done but continue to scout late wheat that is still flowering. Finally, pea leaf weevil and cabbage seedpod weevil numbers appear to be lower in 2017 compared to 2016 which is good news.

Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (July 17, 2017)
• Saskatchewan Agriculture Crop Report (July 11-17, 2017)

• Alberta Agriculture and Forestry Crop Report (July 11, 2017)


Weekly Update – Active Wildfires

Active Wildfires – Natural Resources Canada posts live interactive maps like the one below. Access their webpage for more information and to stay current on the various active wildfires burning across Canada.

Weekly Update – Previous Posts

The following is a list of 2017 Posts – click to review:


Alfalfa Weevil (Week 11)

Brood X Cicadas


Cabbage seedpod weevil (Week 8)

Canola scouting chart
Cereal leaf beetle
Crickets with your popcorn
Crop protection guides
Cutworms

Diamondback moth


Flax scouting chart

Flea beetles

Iceberg reports

Lily leaf beetle


Monarch migration (Week 10)

Painted lady butterflies (Week 9)
Pea leaf weevil
PMRA Pesticide Label Mobile App

Nysius niger (Week 8)

Ticks and Lyme disease


Weather radar

White grubs in fields (Week 9)

Wind trajectories

Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata– Reporting sites across the prairies have generally reported lower cumulative interceptions and cumulative counts are summarized by provincial staff in Manitoba, Saskatchewan and Alberta.


Saskatchewan map as of July 13, 2016





Alberta map as of July 20, 2016


In-field monitoring for egg masses and newly emerged larvae (photo below) should initially focus on the undersides of leaves plus watch the margins of leaves for feeding.  Bertha armyworm larvae will also feed on newly developing pods so the whole plant should be examined.  Watch for the following life stages:





Scouting tips:
● Some bertha armyworm larvae remain green or pale brown throughout their larval life. 
● Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms. 
● Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instars cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. 
● Larvae eat the outer green layer of the stems and pods exposing the white tissue. 
● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

Monitoring:
– Larval sampling should commence once the adult moths are noted. 
– Sample at least three locations, a minimum of 50 m apart. 
– At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae. 
– Count them and compare the average against the values in the economic threshold table below:  


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 new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Cabbage seedpod weevil

Cabbage seedpod weevil (Ceutorhynchus obstrictus) –  Reminder – There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo).  Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.

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.


Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.

Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has released a new live CSPW map and online reporting tool for growers.  A screenshot (retrieved 20 July 2016) is included below.


Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of July 17, 2016, areas highlighted in yellow or orange on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!





The Public Health Agency of Canada posts information related to West Nile Virus in Canada.  The map of clinical cases of West Nile Virus in Canada in 2015 is posted while a screen shot is provided below.



The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus.  As of July 7, 2016, 20 birds were submitted for testing yet none have tested positive for West Nile virus. 

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information: 

– Manitoba’s Insect and Disease Update which includes alfalfa weevil, pea aphid, aphids in cereals and wheat midge descriptions (July 13, 2016, prepared by John Gavloski and Pratisara Bajracharya).



– Saskatchewan’s Crop Production News includes descriptions of aphids in field crops plus economic and action thresholds applicable in field peas, lentils, canaryseed, cereals or canola.  Aster yellows have also been observed this season.  Saskatchwan’s surveys and forecasts are also highlighted in Issue 5prepared by Scott Hartley.  Growers should note that the distribution of pea leaf weevil has increased this season in Saskatchewan plus the updated bertha armyworm pheromone map can be accessed in this report.


– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on July 14, 2016) that includes bertha armyworm, wheat midge, pea aphids in lentils, and European skipper.

Insect of the Week – Aphidius avenaphis

Aphidiidae


Last year, the focus of the Beneficial Insect of the Week
 was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] 

This week’s Insect of the Week are Aphidiidae wasps*. While you won’t likely see them flying about attacking aphids, this tiny wasp can parasitoidize 100-350 aphids during its relatively short lifetime.  The resulting aphid ‘mummy’ ceases causing crop damage and instead becomes a living host for the developing wasp. After 2 to 4 weeks of development, a new adult Aphidiidae wasp emerges and starts hunting for aphids to continue the cycle. To see an Aphidius avenaphis wasp in action, see: https://www.youtube.com/watch?v=T7PNlpEgvEM&feature=youtu.be

For more information about this natural enemy, other pests they control and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).

* this wasp genus only attacks aphids, not humans.



Adult Aphidius avenaphis© AAFC, Tyler Wist

English grain aphid mummy, cc-by-sa 2.0 Gilles San Martin

Weekly Update

Greetings!

A downloadable PDF version of the complete Weekly Update for Week 12 (July 20, 2016) can be accessed here.  

This edition includes the “Insect of the Week” featuring beneficial arthropods in 2016!


Subscribe to the Blog by following the instructions posted here!  You can receive automatic updates in your inbox through the growing season.



Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Owen Olfert or Jennifer Otani.  Past “Weekly Updates” are very kindly archived to the Western Forum website by webmaster, Dr. Kelly Turkington.  

Weekly Update – Weather Synopsis

The average temperature over the past seven days (July 11-17, 2016) was slightly cooler than Long Term Normal (LTN). 





Across the southern prairies, the 7-day average cumulative rainfall was well above LTN values.





The average 30 day temperature for June 17 to July 17, 2016, was similar LTN and rainfall was 20% greater than LTN.




The average growing season temperature (April 1 – July 17, 2016) has been less than 1°C warmer than normal. 





Growing season rainfall has been approximately 20% above average.



The map below is the modelled soil moisture map for the prairies (up to July 17, 2016).





The map below shows the Lowest Temperatures the Past 7 Days (July 13-19, 2016) across the prairies:




The map below shows the Highest Temperatures the Past 7 Days (July 13-19, 2016):



The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 17, 2016) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – July 17, 2015) is below:




The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.


Additional precipitation and temperature data or maps are provided by the following:
Manitoba AGriculture’s Crop Weather Report
Alberta Agriculture and Food’s Weather Stations
Environment Canada’s Historical Data Interface

Weekly Update – Lygus

Lygus bugs (Lygus spp.) The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).

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. They 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.


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.


Repeat the sampling in another 14 locations. 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 C). If the total number is below the lower threshold line, 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 table.

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



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.




Table 1.  Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).

1 Canola crop stage estimated using Harper and Berkenkamp 1975).
2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).




Table 2.  Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).

 3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).




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-enhanced or French-enhanced versions are available.

Weekly Update – Root maggot

Cabbage root maggot (Delia spp.) – Among root feeding pests of canola, historically five species of Delia flies have been identified across the Canadian prairies;  Delia radicum (L.), D. floralis (Fallén), D. platura (Meigan), D. planipalpis (Stein), and D. florilega (Zett.) have been observed in canola over 30 years of research (Liu and Butts 1982, Griffiths 1986a, Broatch and Vernon 1997; Soroka and Dosdall 2011).  A summary of root maggot biology, research, and pest management recommendations for canola production was published by Soroka and Dosdall (2011).  



Root maggots continue to be a problematic in canola production largely owing to the fact that (i) the species is composition varies by geographic latitude and local conditions, plus (ii) one or two generations per year will occur but varies by species.  The species complex is typically characterized by multiple, overlapping generations of Delia resulting in adults laying eggs in canola (Refer to upper left photo for adult and eggs) from late Spring to October and maggots feeding on roots from late rosette until late fall (Refer to upper right photo).  Root maggots pupate and overwinter within cigar-shaped, reddish-brown puparia 5-20 cm below the soil surface (Soroka and Dosdall 2011) so canola-on-canola rotations should be avoided.  In the spring, adults emerge from mid-May to mate and females lay oval, white eggs singly or in batches near the base of cruciferous host plants over a 5-6 week period.  The larvae develop through three instar stages which feed on root hairs then secondary roots initially whereas older maggots will feed into the taproot of a canola plant.  


Refer to the root maggot pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.



Weekly Update – Grasshoppers

Grasshoppers (Acrididae) – In central Saskatchewan, grasshopper development is currently more than 1-2 weeks ahead of average development. 

The following graph shows predicted grasshopper development at Saskatoon for July 17, 2016. The model indicates that fourth and fifth instar numbers have peaked and that adult grasshopper numbers are increasing. 





The second graph illustrates grasshopper development (for Saskatoon) based on Long Term Normal (LTN) data. Based on average weather, the population should be primarily in the fourth instar with increasing numbers of fifth instars and adults. 

Sentinel site results in Saskatchewan (July 13, 2016) indicated that the mean melanopline instar was 3.4. Melanoplus dawsoni was the dominant species (40.4%), followed by M. bivittatus (21.6%). Melanopline adults have been collected for M. dawsoni, M. bivittatus and M. sanguinipes.


Reminders:

– The following image showing various stages of Camnulla pellucida is provided below – note that adults have wings extending the length of the abdomen whereas nymphs lack wings but develop wing buds that will eventually mature to wings.  

Figure 1. Life stages of Camnulla pellucida which including eggs, first-fifth instar nymphs and adult (L-R).


– Generally, the economic threshold for grasshoppers in cereals is 8-12 per square metre but will vary by crop and growing conditions.


Biological and monitoring information related to grasshoppers in field crops is posted by the provinces of ManitobaSaskatchewanAlbertaBritish Columbia and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Weekly Update – Swede midge

Swede midge (Contarinia nasturtii)  – Pheromone traps captured the first swede midge of 2016 between May 25 and 31 in northeastern Saskatchewan This is substantially earlier (6-7 weeks) compared to 2014 and 2015. 

Emergence traps indicate high numbers of swede midge have emerged in northeastern Saskatchewan. Producers should monitor their canola fields for damage symptoms. We are currently unaware of the consequences the heavy rain this week will have on population numbers, but will continue to update the PPMN as results become available.



Figure 1. Swede midge infested canola buds which are enlarged with sepals fused together. 



Figure 2.  Swede midge large (~1mm long; yellowish-white) feeding within canola flower.


Swede midge scouting tips for in-field monitoring:

• 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.
• Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.


Weekly Update – Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) – Reminder – Cereal leaf beetle larvae hatch from eggs in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 1).  When the larva completes its growth, it drops to the ground and pupates in the soil.  The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.


Figure 1.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.

Monitoring:
Give priority to following factors when selecting monitoring sites:
   □ Choose fields and sections of the fields with past or present damage symptoms.
   □ Choose fields that are well irrigated (leaves are dark green in color), including young, lush crops. Areas of a field that are under stress and not as lush (yellow) are less likely to support CLB. 
   □ Monitor fields located along riparian corridors, roads and railroads. 
   □ Survey field areas that are close to brush cover or weeds, easy to access, or are nearby sheltered areas such as hedge rows, forest edges, fence lines, etc.

Focus your site selection on the following host plant priorities:
   □ First – winter wheat. If no winter wheat is present then;
   □ Second – other cereal crops (barley, wheat, oats, and rye). If no cereal crops are present then;
   □ Third – hay crops. If no hay crops or cereal crops are present then;
   □ Fourth – ditches and water corridors


Sweep-net Sampling for Adults and Larvae:
 ● A sweep is defined as a one pass (from left to right, executing a full 180 degrees) through the upper foliage of the crop using a 37.5 cm diameter sweep-net. 
 ● A sample is defined as 100 sweeps taken at a moderate walking pace collected 4-5 meters inside the border of a field.  
 ● At each site, four samples should be collected, totaling 400 sweeps per site.  The contents of each sample should be visually inspected for life stages of CLB and all suspect specimens should be retained for identification.  
 ● Because the CLB larvae are covered in a sticky secretion, they are often covered in debris and are very difficult to see within a sweep-net sample. 
 ● To help determine the presence of CLB, place the contents of the sweep net into a large plastic bag for observation.


Visual Inspection:
Both the adults and larvae severely damage plants by chewing out long strips of tissue between the veins of leaves (Fig. 1), leaving only a thin membrane. When damage is extensive, leaves turn whitish. 

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.

Weekly Update – Wheat midge

Wheat Midge (Sitodiplosis mosellana– Predictive modelling will be used again to help  forecast wheat midge emergence across the Canadian prairies.  The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.  


Monitoring:
When monitoring 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 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). 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.


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




Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.

b) For 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 the larval damage. 



Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps.  A screen shot below confirms that wheat midge are flying beyond the predicted model mapped above.


Additional 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.

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.

Weekly Update – Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Reminder – The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”.  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.  Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).



Updated – Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models.  The aim or the modelling is to predict the development of Alfalfa weevil (Hypera postica) across the prairies and to help growers time their in-field scouting as second-instar larvae are predicted to occur.  Compare the following predicted development stages and degree-day values copied below (Soroka 2015) to the map below.




For the week of July 17, 2016, the following map predicts the developmental stages for alfalfa weevil and corresponding degree-days.  Areas highlighted orange are predicted to find fourth instar larvae so scout for major leaf feeding then compare larval densities to the action threshold for alfalfa weevil!



Economic thresholds for Alfalfa weevil (adapted from Soroka 2015) vary by crop type (hay or seed), area fed upon and larval densities.

In hay fields, forage losses can be economic if one or more of the following symptoms are noted:
● if 25-50 % of the leaves on the upper one-third of the stem show damage, or
● if 50-70% of the terminals are injured, or
● if 1 to 3 third or fourth instar larvae occur per stem (with shorter stems having lower economic thresholds and 3 or more larvae requiring treatment no matter what the alfalfa height), or 
● 20-30 larvae per sweep occur when 12% leaf loss is acceptable.
● Also consider these two points:
      1. Early cutting of the first growth of alfalfa or insecticide treatment will reduce alfalfa weevil populations.
      2. If the hay crop value is high and weevil injury is seen or 2 or more larvae per stem reappear in regrowth after cutting, insecticide may be necessary (if a second cut is anticipated). 

In alfalfa seed fields:
● Economic thresholds are 20-25 third to fourth instar larvae per sweep or 35-50% of the foliage tips showing damage. 
● Thresholds increase with the height of the alfalfa, and decrease in drought conditions. 
● Also know that several small wasps parasitize alfalfa weevil larvae and adults, and in the past these natural control agents kept the weevil in check in most years. One of these wasps, Bathyplectes curculionis (Thomson), parasitizes alfalfa weevil in Alberta and Saskatchewan, and is now found in Manitoba.

Weekly Update – Crop reports

Crop reports are produced by:

– Manitoba Agriculture, Rural Development (July 18, 2016)
– Saskatchewan Agriculture Crop Report (July 11, 2016)

– Alberta Agriculture and Forestry (for July 12, 2016)

Weekly Update – Insects in our diets!

Usually we’re busy protecting our crops from the insects but, in the not-so-distant future, growers will produce crops of insects for food!  Kellogg’s, General Mills, Google – just a few names showing interest in Entomo Foods and the North American Edible Insect Coalition but read more in this article


The authors write, “two billion people worldwide currently eat insects regularly” and there are many “environmental and health benefits” to insects because they “are the most sustainable form of protein on the planet”.  The article notes the need for us to incorporate insects in our diets, if we are to sustain the ~9 billion people who will be on the planet by 2050.

Weekly Update – Previous Posts

The following is a list of previous 2016 Posts – click to review:

Cereal leaf beetle
Diamondback moth
Bertha armyworm development and flight
Grasshoppers
Canola scouting chart
Wind trajectories
Cutworms
Flea beetles in canola
Predicted cereal leaf beetle development
Predicted lygus bug development
Predicted wheat midge development
Pea leaf weevil monitoring
Crop protection guides
Using Environment Canada’s radar maps to follow precipitation events
Iceburg reports
Multitude of mayflies

Monarch migration

Insect of the Week – Bertha armyworm

This week’s Insect of the Week is the Bertha armyworm (Mamestra configurata (Walker)) (from the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide – download links available on the Insect of the Week page).