Welcome to our NEW Website!

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We’ve got a new logo AND A NEW HOME!

The Prairie Pest Monitoring Network is excited to share our new website as we continue to update and expand! We have a few VERY IMPORTANT DETAILS below – please read on and Subscribe!

Re-Subscribe to receive our Weekly Updates – Due to Canada’s Anti-Spam Legislation and just plain good manners, we cannot copy your subscription from the old Blog to this new website. Please go to our homepage, click the red “subscribe today” button, type your email address in the white box, confirm you’re NOT a robot, then watch your Inbox or Spam folder to confirm your subscription. Subscribers receive the Weekly Update, Insect of the Week, and any new updates delivered to their Inbox in our new newsletter format.

Same great information – The new website is organized like the Blog. Risk maps, insect monitoring protocols, Weekly Updates, and Insect of the Week features are all easy to find. We’re still working in the background on the new website so don’t be surprised if you link back to the PPMN Blog – we’re keeping it but all new content will move to the new website as of July 10, 2020.

You made us a success – Thank you for using the Blog since it was launched in 2015! We are able to transition to a website now because the Blog is so popular. The new website overcomes some of the Blog shortcomings (e.g., data storage limits). In the future, we hope to introduce new tools to improve insect pest monitoring and insect pest management. Over the coming months, we will work to add information, pictures and links.

And, as usual…… Questions or problems accessing the contents of this Weekly Update? Please email Meghan.Vankosky@canada.ca or Jennifer.Otani@canada.ca . Past “Weekly Updates” can be accessed on our Weekly Update Blog Page.

Weather synopsis

This week, June 29-July 5, 2020, prairie temperatures were warmest in Manitoba and eastern Saskatchewan and seven day cumulative rainfall varied across the prairies (Table 1). Average 7-day temperatures continue to be warmest across Manitoba and eastern Saskatchewan and coolest across most of Alberta (Fig. 1). The weekly average temperature at Winnipeg (24.5 °C) was 6.6 °C warmer than the long term average value and was 10.9 °C warmer than the 7-day observed temperature at Grande Prairie (Table 1; Fig. 1). The average weekly temperature for Lethbridge was 13.8 °C and 2.3 °C cooler than normal (Table 1).

Figure 1. Observed average temperatures across the Canadian prairies the past seven days (June 29-July 5, 2020).

Average 30-day (June 6-July 5, 2020) temperatures continue to be cooler in Alberta than southern Saskatchewan and Manitoba (Table 2). The average 30-day temperature at Winnipeg and Brandon continued to be greater than locations in Alberta and Saskatchewan (Table 2; Fig. 2). June 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 southeastern Saskatchewan and southern Manitoba (Table 2; Fig. 3). Based on growing season temperatures (April 1 – July 5, 2020), conditions were warmest for southern locations (Table 3).

Figure 2. Observed average temperatures across the Canadian prairies the past 30 days (June 6-July 5, 2020).
Figure 3. Mean temperature difference from Normal for the month of June 2020.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (05Jul2020). 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 western regions of Saskatchewan (Table 1; Fig. 4). Lethbridge reported 69.4 mm. Cumulative 30-day rainfall continued to be greatest across central regions of Alberta (Table 2; Fig. 5). Rainfall amounts were lowest across the most of Saskatchewan.

Figure 4. Observed cumulative precipitation across the Canadian prairies the past seven days (June 29-July 5, 2020).

Total 30-day rainfall at Saskatoon, Lethbridge, Lacombe and Grande Prairie exceeded 100 mm (Table 2; Fig. 5). Saskatoon has reported 156.6 mm (277% of normal) in the past 30 days (Table 2). Growing season rainfall (percent of average) is below normal southern Saskatchewan and most of Manitoba. Rainfall amounts are above average across central regions of Saskatchewan and across Alberta.

Figure 5. Observed cumulative precipitation across the Canadian prairies the past 30 days (June 6-July 5, 2020).
Figure 6. Percent of average precipitation for the growing season (April 1-July 5, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (05Jul2020). 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 6, 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 6, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (09Jul2020). 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. 8).

Figure 8. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-July 8, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (09Jul2020). 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 wheat midge development

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

Wheat midge model runs indicate that, where wheat midge are present, pupation is occurring across Alberta, northwest Saskatchewan and southern Manitoba (Fig. 1). Simulations suggest that, though still less than 15%, adult emergence has begun, most notably across Alberta (Fig. 1). Females lay eggs on developing wheat heads. This typically occurs in evenings when winds are calm. Wheat midge monitoring protocol suggests that wheat fields should be inspected for adults in late June and early July as wheat heads are emerging. The next three weeks are very important for monitoring wheat midge populations for the purpose of making management decisions.

Figure 1. Predicted percent of population of wheat midge (Sitodiplosis mosellana) at adult stage across the Canadian prairies (as of July 5, 2020).

Simulations were run to July 21 to assess population development over the next two weeks (Figs. 2-4). The first graph illustrates development of wheat midge populations near Saskatoon (Fig. 2). Adult emergence has begun and should peak next week, suggesting that monitoring fields for adults should begin in the next few days. Oviposition has just started and larvae will occur soon after.

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

The second graph compares synchrony between wheat midge and wheat for fields near Lacombe (Fig. 3). The graph indicates that adult emergence and oviposition may occur this year when the crop is most susceptible.

Figure 3. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Lacombe AB projected to July 21, 2020.

The last graph compares phenology of wheat midge adults near Saskatoon with the phenology of Macroglenes penetrans, a parasitoid of wheat midge (Fig. 4). The parasitioid wasp lays is eggs inside wheat midge eggs. The graph shows that the timing of emergence and oviposition of wheat midge adults is similar to the emergence and oviposition timing of M. penetrans. All of this information can be used as a guide to determine when fields should be monitored.

Figure 4. 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 5, 2020, the grasshopper model estimates that hatch is essentially complete. Development is slowest in the Peace River region where the simulation indicates that approximately 30% of the population is still in the egg stage (Fig. 1). Across the prairies, the majority of the nymphal population is predicted to be in the second to fourth instar stages (Table 1; Fig. 1). Development in Manitoba is predicted to be well ahead of most locations across Alberta (Table 1; Fig. 1). Recent warm temperatures in eastern Saskatchewan and Manitoba have resulted in higher rates of grasshopper development. This week, adults are predicted to occur at locations across southern Manitoba and southeastern Saskatchewan (Table 1; Fig. 1). Across the prairies, populations are predicted to be 11, 9, 25, 25, 22, 8 and less than 1% in egg, first, second, third, fourth, fifth and adult stages, respectively (Table 1).

Figure 1. Predicted average instar stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 5, 2020).

The two graphs compare predicted development for Saskatoon (Fig. 2) and Winnipeg (Fig. 3). Grasshopper populations near Saskatoon are expected to be predominantly in the third and fourth instars (Fig. 2) while populations near Winnipeg are expected to be primarily in the fifth instar with some adults beginning to appear (Fig. 3).

Figure 2. Predicted grasshopper (Melanoplus sanguinipes) phenology at Saskatoon SK. Values are based on model simulations (April 1-July 5, 2020).
Figure 3. Predicted grasshopper (Melanoplus sanguinipes) phenology at Winnipeg MB. Values are based on model simulations (April 1-July 5, 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. 

Predicted bertha armyworm development

Model simulations for July 5, 2020, indicate that 5 % of the population is in the pupal stage (26 % last week), 43 % is in the adult stage (52 % last week), and 37 % of the population is in the egg stage (20 % last week). In southern Manitoba and southeastern Saskatchewan, larval stages are predicted to increase this week (14 % compared to 2 % last week). Across the Parkland and Peace River regions, BAW populations are predicted to be mostly adults with oviposition occurring in these areas (Fig. 1). Operation of BAW traps in these areas should continue until adult emergence is complete. Populations across southern regions are primarily in the larval stage (Fig. 2).

Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population in the adult stage as of July 5, 2020.
Figure 2. Predicted percent of bertha armyworm (Mamestra configurata) population in the larval stage as of July 5, 2020.

The two graphs demonstrate that larval development near Brandon (Fig. 3) is predicted to be ahead of fields near Lethbridge (Fig. 4).

Figure 3. Predicted bertha armyworm (Mamestra configurata) phenology at Brandon MB as of July 5, 2020.
Figure 4. Predicted bertha armyworm (Mamestra configurata) phenology at Lethbridge AB as of July 5, 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.

Diamondback moth

Once diamondback moth is present in the area, it is important to monitor individual canola fields for larvae.  Warm growing conditions can quickly translate into multiple generations in a very short period!

Wind Trajectory Updates – Completed for 2020 growing season as of Week 09 (released June 22, 2020).

Weekly Pheromone-baited Trapping Results – Early season detection of diamondback moth is improved through the use of pheromone-baited delta traps deployed in fields across the Canadian prairies.  Click each province 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.

Monitoring: 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 ~8 mm 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 m² (approximately 1-2 larvae per plant).

Figure 3. Diamondback moth.

Biological and monitoring information for DBM is posted by Manitoba AgricultureSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  

More information about Diamondback moths can be found by accessing the pages from the  “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.

Pea leaf weevil

Models runs predicting spring adult activity, oviposition and larval development for this pest are completed as of Week 9 (June 21, 2020).  Use the following information to aid in-field scouting for larvae.

The pea leaf weevil is a slender greyish-brown insect measuring approximately 5 mm in length (Fig. 1, Left image). Pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen.  All species of Sitona, including the pea leaf weevil, have a short snout.  

Figure 1.  Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).

Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge.  Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.

Larvae develop under the soil and are “C” shaped and milky-white with a dark-brown head capsule ranging in length from 3.5-5.5 mm (Figure 2).  Larvae develop through five instar stages.  After hatching, larvae seek and enter the roots of a pea plant.  Larvae will enter and consume the contents of the nodules of the legume host plant. It is the nodules that are responsible for nitrogen-fixation which affect yield plus the plant’s ability to input nitrogen into the soil. Consumption of or damage to the nodules (Figure 3) results in partial or complete inhibition of nitrogen fixation by the plant and results in poor plant growth and low seed yields.

Figure 2. Larva of pea leaf weevil in soil (Photo: L. Dosdall).
Figure 3. Damaged pea nodules (Photo: L. Dosdall).

Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.

Also refer to the pea leaf weevil page within the “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. 

Cereal Aphid Manager

Aphids can cause significant damage to fields and increase crop losses but low densities in a grain field sometimes have little economic impact on production. This is especially true if the aphid’s natural enemies (beneficial insects) are present in the field because they can keep the aphids 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) 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.

Frequent in-field scouting, supported by the app’s dynamic threshold, allows growers to weigh the above factors and the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

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

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 09Jul2020 as reference but access that information here.

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.  As of July 8, 2020, areas highlighted yellow 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 8, 2020).

Scouting charts for canola and flax

Reminder – Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.

We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:

1. CANOLA INSECT SCOUTING CHART

2018_ScoutingChart_Canola

 
2. FLAX INSECT SCOUTING CHART

2018_ScoutingChart_Flax

These charts feature hyperlinks directing growers to downloadable PDF pages with photos within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“.

Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.

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

• NEW – 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!

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 8, 2020 report. The summary indicates that, “Armyworms are being found at high levels in many cereal and forage grass fields in the Eastern, Interlake, Central, and Southwest regions. High levels of grasshoppers continue to be found and controlled in some areas.”

Saskatchewan‘s Crop Production News and read Issue 4 which includes 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 reports

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 7, 2020 report.

• Saskatchewan Agriculture  or access a PDF of June 30-July 6, 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 6, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the July 7, 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)

    • Crop protection guides (Wk02)

    • Cutworms (Wk02)

    • Flea beetles (Wk02)

    • John Doane (Wk10)

    • Monarch migration (Wk10)

    • 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)

Forage Grass Pests / Feature Entomologist: Chrystel Olivier

This week’s Insect of the Week feature crop is forage grasses: common Prairie plants know to be robust, adaptive, and tolerant to grazing. Our feature entomologist this week is Chrystel Olivier.

Crested wheatgrass
cc by 2.0 Matt Lavin

The total cattle population in the Prairie region is 7.7 million animals: over three times the combined population of Atlantic Canada, according to the 2016 census. In order to feed millions of cattle and other livestock, forage is an important component to Prairie agriculture. Forage grasses include native and nonnative grass species grown for grazing, as well as hay and silage production. Sometimes doubling as cover crops in order to prevent soil erosion and nutrient loss, forage grasses are resilient, multi-purpose crops used to sustain livestock: either as a nutritional source in-pasture or as hay and silage used to supplement or replace grazing during the off-season. Common species include timothy grass, crested wheatgrass, and orchard grass.

A number of pests target forage grasses. 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.

Hay bales
cc by 2.0 Bruce Guenter
Forage Grass Pests
  • Army cutworm
  • Armyworm
  • Aster leafhopper
  • Black grass bugs
  • Cereal leaf beetle
  • Chinch bug
  • Corn leaf aphid
  • Dingy cutworm
  • Fall armyworm
  • Glassy cutworm
  • Grasshoppers
  • Green grass bugs
  • Greenbug
  • Hessian fly
  • Mormon cricket
  • Rice leaf bug
  • Russian wheat aphid
  • Variegated cutworm
  • Wheat head armyworm
  • Wheat stem maggot
Cereal leaf beetle – Boris Loboda

Entomologist of the Week: Chrystel Olivier

Name: Chrystel Olivier
Affiliation: AAFC-Saskatoon
Contact Information: Chrystel.olivier@canada.ca

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

We are monitoring the aster leafhopper (Macrosteles quadrilineatus) that vectors aster yellow (AY) diseases and two species of flea beetles, the crucifer flea beetle (Phyllotreta cruciferae) and the striped flea beetle (Phyllotreta striolata) that feed on canola seedlings. We monitor for these species throughout SK using sweep nets and sticky cards. We record the emergence dates of the flea beetles in spring and their abundance in spring and fall. We also note when migratory aster leafhoppers arrive in the spring and their rate of AY infection. 

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

The most interesting field crop pest is the aster leafhopper. It is a small insect (about 4 mm long) that migrates from the southern US states to the Canadian prairies, carried by the wind. It is an efficient vector of the economically important aster yellow disease. Aster yellow phytoplasma infect over 300 plant species, including canola, cereals and many vegetables grown in Canada. Phytoplasma are fascinating because they modify the feeding and reproduction behavior of their insect vectors to their own advantage. For example, AY-infected aster leafhoppers live longer, lay more eggs and can feed on plants they usually don’t feed on, all to increase spread of the pathogen.  

What is your favourite beneficial insect?

My favourite beneficial insects are dragonflies. They are sky acrobats, and can fly in every direction, even backwards.

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

An important project I am working on right now investigates if hairy lines of brassicas can be used to protect seedlings from feeding and oviposition of flea beetles, diamond-back moths and aster leafhopper. This project is funded by the Canola Agronomic Research Program (CARP). Trichomes (hairs) are known to deter herbivorous insects and have been used as a deterrent with success in several crops. Recently, natural lines of Brassica napus, and the related Brassica villosa species, that exhibited high level of hairs were identified as potential sources of natural resistance towards flea beetles, diamond-back moths and aster leafhoppers. This project involves both field trials and laboratory-based bioassays. 

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

Communication is mostly via peer-reviewed publications, written reports to the funding agencies, and oral presentations during grower/agronomist meetings and conferences. I often speak about insects to groups of all ages at parks and other community events across Saskatchewan.

Weekly Update

Greetings!

Another busy week of in-field monitoring, data collection, and field tour events for all our Staff!  A reminder that, from now until mid-July, the Weekly Update may need to be posted in multiple segments (i.e., at any point from Wednesday-Saturday).  Please bookmark the Blog or subscribe to receive the latest growing season information!

This week, special thanks to Ross Weiss (AAFC-Saskatoon) – entomologist and the integral modeler who works to generate all the weekly wind trajectory, meteorological, and predictive model updates supporting the Prairie Pest Monitoring Network. 

Please access the complete Weekly Update either as a series of Posts for Week 12 (June 27, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week – the rest of the growing season features doppelgangers to aid in-field scouting!

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 easy steps!

Weather synopsis

Temperatures this week, June 11-17 2019, were similar to last week and near normal (Fig. 1). The warmest temperatures were observed across AB while temperatures were cooler in eastern SK and across MB.  Average 30-day temperatures were warmest across southern MB and SK from Estevan to Saskatoon and west to Kindersley (Fig. 2). Cooler temperatures were reported across the Parkland region, and western areas in AB (Fig. 2). 

Figure 1. Average temperature (°C) across the Canadian prairies the past seven days (June 11-17, 2019).
Figure 2. Average temperature (°C) across the Canadian prairies for the month of May (May 19-June 17, 2019).

Seven-day cumulative rainfall indicated that minimal rain was observed across most of the prairies (Fig. 3). Many locations reported less than 10 mm.  Higher rainfall amounts were reported for eastern SK and western MB. 

Figure 3. Cumulative precipitation observed the past seven days across the Canadian prairies (June 11-17, 2019).

Across the prairies, rainfall amounts for the past 30 days (May 19 – June 17, 2019; Fig. 4) have been approximately 56 % of normal (Fig. 5). Western SK and eastern AB continue to be dry. 

Figure 4. Cumulative precipitation observed the past 30 days across the Canadian prairies (May 19-June 17, 2019).
Figure 5. Percent of Average precipitation across the Canadian prairies for 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 (18Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Growing season rainfall (April 1 – June 17) amounts have been well below average for most of the prairies, particularly in west central SK and eastern regions of AB (Fig. 6). Almost all of the prairies has had growing season rainfall that is 4 percent, or less, than average. Soil moisture values are low across most of the prairies. 

Figure 6. Accumulated precipitation (mm) across the Canadian prairies for the growing season (April 1 to June 17, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019).  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 5 ºC, April 1-June 17, 2019) is below (Fig. 7):

Figure 7. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-June 17 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Jun2019).  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 17, 2019) is below (Fig. 8):

Figure 8. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019).  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 8 to -2 °C in the map below (Fig. 9).

Figure 9. Lowest temperatures (°C) observed across the Canadian prairies the past seven 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 (18Jun2019).  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 18 to at least 31 °C in the map below (Fig. 10).

Figure 10. Highest temperatures (°C) observed across the Canadian prairies the past seven 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 (18Jun2019).  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.

Monarch migration

We continue to track the migration of the Monarch butterflies as they move north by checking the 2019 Monarch Migration Map!  A screen shot of the map has been placed below as an example (retrieved 18Jun2019) but follow the hyperlink to check the interactive map.  They are moving west in Manitoba and getting closer to Saskatchewan this week!

Access this Post to help you differentiate between Monarchs and Painted Lady Butterflies!

Visit the Journey North website to learn more about migration events in North America and visit their monarch butterfly website for more information related to this amazing insect.  

Weekly Update

Hello!

Our field research programs are now in full field research mode with in-field monitoring, data collection, and field tour events.  This means that, from now until mid-July, the Weekly Update may need to be posted in multiple segments (i.e., at any point from Wednesday-Saturday).  Please bookmark the Blog or subscribe to receive the latest growing season information!

Please access the complete Weekly Update either as a series of Posts for Week 11 (June 20, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week – the rest of the growing season features doppelgangers to aid in-field scouting!

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 easy steps!

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 20, 2019: Solstice Forage and Crops Field Tour to be held at the Beaverlodge Research Farm (Beaverlodge AB).  View event info/registration details Entomologists tentatively participating: Jennifer Otani, Keith Uloth


•  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, Shelley Barkley, 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.

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 2019 are posted here and includes an update posted June 5, 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, #2, and #3 now available and containing insect pest information for 2019.

•  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.

Crop report links

Crop reports are produced by:

The following crop reports are also available:

Previous Posts

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Alfalfa weevil – Week 10

Bertha armyworm – Week 10

Cabbage seedpod weevil – Week 10
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

Painted lady butterfly – Week 8
Pea leaf weevil – Week 10

Ticks and Lyme disease – Week 4

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Review Page for list of PDFs

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 this week with most locations having approximately 51% hatch (30% last week). Based on model runs, (i) approximately 30% (21% last week) of the population is in the first instar, (ii) 14.5% (7% last week) is predicted to be in the second instar, and (iii) 4.3% (1% last week) in the third instar.   

Figure 1.  Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of June 17, 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.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015).  Models predicting the development of Alfalfa weevil (AAW) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. 

Alfalfa weevil larval populations are developing into later instars (Fig. 1). Second instar development is nearing completion and this week there larvae should be in the third instar stage. This week larvae are mostly second (26%, 52% last week) and third instars (52%, 22% last week; Fig. 1). Model output indicates that fourth instar larvae are beginning to occur in southern SK and isolated areas in southern AB and MB.

Figure 1. Predicted average instar stage of alfalfa weevil (Hypera postica)  populations across the Canadian prairies as of June 17, 2019. 

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).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhanced or French-enhanced version.

Predicted bertha armyworm development

Bertha armyworm (Lepidoptera: Mamestra configurata– Pupal development is progressing and this week adults should be occurring across most of southern SK and localized areas in AB.  Most of the population is predicted to be in the pupal stage (89%). The BAW model indicates that 10% of the population is in the adult stage .

Figure 1. Predicted precent of bertha armyworm (Mamestra configurata)  populations at adults stage across the Canadian prairies as of June 17, 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!

Predicted wheat midge development

Wheat Midge (Sitodiplosis mosellana) – 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 midge emergence. 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. Two simulations were run to demonstrate the impact of rainfall and temperature on adult emergence and oviposition. The first graph illustrates adult emergence and oviposition based on long term (climate) data for Saskatoon (Fig. 1). The model indicates that emergence should begin in early July with oviposition beginning a few days later. 

Figure 1. Predicted adult emergence and oviposition of wheat midge (Sitodiplosis mosellana) based on LONG TERM DATA for Saskatoon SK.

The second graph (Fig. 2) shows how DRYER, COOLER conditions would result in:

  • Delayed adult emergence and oviposition.
  •  Reduced numbers of adults and eggs.
Figure 2. Predicted adult emergence and oviposition of wheat midge (Sitodiplosis mosellana) using LONG TERM DATA manipulated to both DRYER and COOLER conditions for Saskatoon SK.

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 (Fig. 3). 
  • Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. 
  • Inspect the field daily in at least 3 or 4 locations during the evening.
Figure 3. Adult wheat midge (Sitodoplosis mosellana) active on wheat head at anthesis stage
(Photo: AAFC-Beaverlodge; S. Dufton and A. Jorgensen).

REMEMBER in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember the parasitoid, Macroglenes penetrans (Fig. 4), 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 beneficial insects that help regulate midge populations.

Figure 4. The tiny parasitoid wasp, Macroglenes penetrans, is synchronized to emerge when wheat midge adults are present and the wasp seeks and oviposits on wheat midge eggs (Photo: AAFC-Beaverlodge; S. Dufton).

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 AgricultureAlberta Agriculture & Forestry) or access the Prairie Pest Monitoring Network’s monitoring protocol recently updated by Wist et al. 2019.  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

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.

Albertan growers can report and check the online map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 02Jul2019).

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

Insect of the Week – Doppelgangers: Wheat midge vs. Lauxanid

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.

The case of the wheat midge vs. Lauxanid fly:Wheat midge larvae, in high enough numbers, can significantly reduce yield and quality of a wheat crop. The time to control this pest is at the adult stage. The key to determining whether adult numbers exceed the economic threshold for control is to follow the recommended insect pest monitoring protocol.

One hiccup is that it can be easy to mistake lauxanid flies for wheat midge adults when doing in-field scouting. But their size, general body shape and colour differences will help enable a person to tell them apart.

Wheat midge:

  • Thinner “mosquito-like” body (Image 1, left)        
  • Long, thin legs
  • Between 1.5- 2 mm long        
  • Dark, vibrant orange when alive        
  • Large, black eyes that proportionally make up approximately 9/10’s of head

Lauxanid fly:

  • Bulkier body (Image 1, right)        
  • Shorter, compact legs   
  • Between 2 and 4 mm long        
  • Paler, less vibrant orange colour        
  • Smaller eyes that may be black, brown or red. Eyes proportionally make up approximately ½ of head
Image  1: Wheat midge (left) and Lauxanid (right).
Photo Credit: Bob Elliott (ret.), AAFC

Wheat midge larvae (Image 2) will feed on developing wheat kernels and can be found inside the wheat head. Lauxaniid larvae are not recorded as pests of any field crop and tend to be found in decaying leaf litter. Wheat midge larvae can be identified by their bright orange colour, and presence of spatula structure (Fig. 2; y-shaped structure circled below).

Image 2: Wheat midge larvae
Photo credit: AAFC-Jorgensen
Image 3: Wheat midge laying eggs on wheat head.
Photo credit: AAFC-Dufton

More information on wheat midge, other crop pests and their natural enemies, is available by accessing the updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide. Also refer to https://MidgeTolerantWheat.ca for the latest information on fighting wheat midge using tolerant wheat varieties.

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

Post contributed by Amanda Jorgensen.

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 1990s.

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 11-17, 2019:

1. Pacific Northwest – Currently there is limited stripe rust development in the PNW, a low number of recent wind trajectories from the PNW, and relatively dry Prairie weather conditions, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage.  Thus, as of June 17, 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 harvesting has been completed, and thus winter wheat crops in these areas will become less of a source of rust inoculum.  There has been a limited number of recent wind trajectories from this area, relatively dry Prairie weather conditions, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage.  Thus, as of June 17, 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 – Leaf and stripe rust development in winter wheat continues in Kansas, although the winter crop is starting to turn colour in many regions.  Although rusts have only been recently reported in Nebraska, levels are on the rise, and thus over the next few weeks this region could act as a significant source of rust inoculum for the Prairie region.  From June 11-17, 2019 there has been a low number of wind trajectories from this area.  In general, weather conditions have been relatively dry across the Prairies, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage.  Thus, as of June 17, 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; however, further development of rust Nebraska may increase the risk.  

4. Where farmers or consultants noticed stripe rust development on winter wheat in the fall of 2018 it is recommended to scout winter wheat fields this spring.  Scouting is especially critical where the variety being grown is susceptible to stripe rust.  Currently, there are no reports of stripe rust in commercial fields of winter or spring wheat across the Prairie region.

5.  Access the full downloadable report.

Insect of the Week – The new canola flower midge (Contarinia brassicola, Diptera: Cecidomyiidae)

This week’s Insect of the week is a new find on the prairies, tentatively called the canola flower midge, Contarinia brassicola (Diptera: Cecidomyiidae). The canola flower midge has been found throughout central Alberta, Saskatchewan, and the Swan River Valley in Manitoba. The female lays eggs on developing canola flower buds. Upon hatching, the larvae feed within the developing flower and cause the formation of a “pop-bottle”-shaped gall. To date, this is the only damage associated with the midge, and it has been minimal across the prairies.

Adult canola flower midges appear similar to swede midge (Contarinia nasturtii). They are tiny, delicate flies, 2-5 mm in size. They can be differentiated from swede midge based on the appearance of the female antennae, the damage symptoms they produce and genetically.

Many thanks to Scott Meers and Shelley Barkley (Alberta Agriculture and Forestry) for organizing the Alberta surveys for the canola flower midge.  

Submitted by Dr. Boyd Mori and Dr. Meghan Vankosky

Find out more about the insect pests that plague your crops and the natural enemies that keep them in check at the Insect of the Week page!

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

Weekly Update

Greetings!

Field crop entomologists across the prairies are on the move with surveying and at field events.  Access the complete Weekly Update either as a series of Posts for Week 11 (July 19, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 11!

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 9 – 16, 2018), the average temperature (16.7 °C) was almost 2 °C warmer than last week and marginally warmer than long term average values (Fig. 1). Once again, the warmest weekly temperatures occurred across MB. The 30-day (June 16 – July 16, 2018) average temperature (15.8 °C) was just slightly above long term average temperatures.  

Figure 1.  Weekly (July 9 – 16, 2018) average temperature (°C) . 

Weekly and 30-day total precipitation was less than average (Figs. 2 and 3).  The wettest region (30-day cumulative precipitation) was across eastern areas in Saskatchewan and southern Manitoba while western Saskatchewan and most of Alberta continue to be dry.

Figure 2.  Weekly (July 9 – 16, 2018) cumulative precipitation (mm).
Figure 3.  The 30-day (June 16 – July 16, 2018) cumulative precipitation (mm).

The map below reflects the Highest Temperatures occurring over the past 7 days (July 11-17, 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 11-17, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jul2018).  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 Lowest Temperatures occurring over the past 7 days (July 11-17, 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 11-17, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jul2018).  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 15, 2018) is below:

The growing degree day map (GDD) (Base 5ºC, March 1 – July 15, 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 16, 2018, the model output indicated that the average instar stage was 4.9, with populations being primarily comprised of fifth instar stage (37%) or adults (33%) (Fig. 1). 

Figure 1. Grasshopper development (average instar) based on model simulations, for April 1 – July 16, 2018.

Development is predicted to be more advanced across the southern prairies; primarily fifth instar stages and adults near Lethbridge AB and Saskatoon SK than in the Peace River region where they are predicted to be mainly fourth and fifth instar stages (Fig. 2).

Figure 2. Predicted grasshopper phenology at Saskatoon (A), Lethbridge (B) and Grande Prairie (C).
Values are based on model simulations, for April 1 – July 16, 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– The warm, moist conditions in Manitoba are predicted to be favourable for emergence of adults (Fig. 1) while dry conditions in Alberta and Saskatchewan should result in reduced emergence (Fig. 2). 

Figure 1. Predicted wheat midge emerged based on degree-days accumulated across the Canadian prairies (as of July 15, 2018).
Figure 2. Percent wheat midge in the early larval stage based on model simulations for April 1 – July 16, 2018.

In Manitoba and eastern Saskatchewan, populations should be primarily in the early larval stage (80%). Model runs for Saskatoon indicate the midge development, as a result of dryer conditions in June, is slower than predicted emergence at Brandon and Edmonton (Fig. 3). 

Figure 3. 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.) – As of July 16, 2018, the model output indicates that Lygus populations range from first instar stage to adults with most populations being comprised mainly of fifth instar stage and adult stages (Fig. 1). 

Figure 1. Lygus development (average instar) based on model simulations, for April 1 – July 16, 2018.

Warmer temperatures have resulted in more rapid development in southern Manitoba and southeast Saskatchewan. Model runs were conducted for Saskatoon, Lethbridge and Grande Prairie to compare site specific development. The Lygus model output suggests that populations in Lethbridge and Saskatoon should be primarily comprised of fifth instar and  adult stages while populations near Grande Prairie are predicted to be comprised of fourth and fifth instar stages with adults beginning to appear (Fig. 2) 

Figure 2. Predicted Lygus phenology at Saskatoon, Lethbridge and Grande Prairie.
Values are based on model simulations, for April 1 – July 16, 2018.

Remember – 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.

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.

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 18Jul2018 for reference):

Saskatchewan growers can check the 2018 bertha armyworm map (screenshot below retrieved 18Jul2018 for reference):

Manitoban growers can find bertha armyworm updates in that province’s Insect and Disease Updates.  The July 11th update summarized that, “out of the 99 traps, 93 currently have cumulative counts in the low risk category (less than 300), and six traps are in the uncertain risk category.  Most of the highest cumulative counts so far are in the western part of Manitoba. Trap counts in eastern Manitoba and the Interlake have generally been quite low.”

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 18Jul2018).

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

Cabbage 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.

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 (June 30, 2018) on 2018 testing (screenshot retrieved 18Jul2018 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 #7 (posted July 11, 2018) notes monitoring is underway for grasshoppers, armyworms in some cereal fields but no soybean aphids reported yet. Also find a summary of cumulative bertha armyworm counts from pheromone traps for 2018.

Saskatchewan‘s Crop Production News for 2018 is posted with Issue #4 now available. This issue includes a report from the Crop Protection Lab summarizing disease and insect samples submitted this growing season. Notable insects submitted so far include Enchytraeids, barley thrips, and red bugs identified as soft-winged flower beetles (Collops sp.) and white-margined burrower bugs (Sehirus cinctus). 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 12, 2018) identified that SOME bertha armyworm pheromone traps over a wide geographic range have started to intercept higher numbers of moths. This means in-field scouting will be critical in 10-14 days (as larvae move up from leaves to feed among canola pods). Processing of canola survey samples has begun; initial samples suggest lower diamondback moth and Lygus bug numbers so far compared to 2017 but higher numbers of small parasitoid wasps associated with diamondback moths, and a pocket of grasshoppers (clearwinged) near Carmangay AB.

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

Insect of the Week – Cereal leaf beetle

This week’s Insect of the Week is the cereal leaf beetle. Wheat is their preferred host, but they also feed on oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Adults and larvae feed on the leaf tissue of host plants. Yield quality and quantity is decreased if the flag leaf is stripped. It is also interesting to note that larvae carry all of their own fecal waste with them as protection from predators.


For more information on the cereal leaf beetle, see our Insect of the Week page.



Cereal leaf beetle larva (cc-by 2.0 Christophe Quintin)




Cereal leaf beetle damage (cc-by-nc-sa 2.0 CIMMYT)



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

Weekly Update – Greetings!

Greetings!

Please access the Weekly Update for July 13, 2017 (Week 11), as either a series of Posts for Week 11 (Jul 13, 2017) 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 – Although temperatures were warmer than last week, both the seven- and 30-day average temperatures were similar to long term averages.





Compared to 30-day average temperatures, Alberta was above normal, whereas Saskatchewan and Manitoba were slightly below normal.



Central and northern regions of all three provinces reported increased rainfall amounts. Total 30-day rainfall accumulations indicate that conditions are normal to dryer than normal for most of the prairies.



Growing season (April 1 – July 10, 2017) percent of average precipitation is average for most of Alberta and below average for most of Saskatchewan and Manitoba.


The lowest temperatures across the prairies over the past seven days (July 5-11, 2017) are mapped below.  


In contrast, the highest temperatures recorded over the past seven days (July 5-11, 2017) are presented below.  





The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 9, 2017) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – July 9, 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 – Predicted Bertha Armyworm Development

Bertha armyworm (Lepidoptera: Mamestra configurata– Bertha armyworm should be in the adult stage across the prairies this week.  The map illustrates predicted appearance of adults (percent of the population) across the southern prairies.

For those monitoring BAW pheromone traps, compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture:



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.

Weekly Update – Wheat midge

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


Model output indicates that wheat midge adult emergence has begun across the prairies. Cooler, dryer conditions in 2017 have resulted in lower emergence than the same time last year. Elliott et al. (2009) reported that adult emergence was delayed by inadequate rainfall amounts (May and June). The model was parameterized to take rainfall into account.  Model output indicates that midge emergence across most of SK has been limited by inadequate rainfall during June.





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 13Jul2017) is included below.

Weekly Update – Predicted Grasshopper Development

Grasshopper Simulation Model Output – Compared to last week, grasshopper development has progressed by approximately one instar (Fig. 1).  Based on model output, grasshopper development is slightly ahead of long term averages (Fig. 2).  

Figure 1. Predicted Melanoplus sanguinipes development across 
the Canadian prairies (July 4, 2017).



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



Across the prairies, grasshoppers should be predominantly in the third and fourth instar stages with more rapid development across southern Alberta (Fig. 3 and 4). This is the first week where the model has predicted appearance of adults. The greatest development was predicted to be across southern regions in all three provinces, particularly southern Alberta.  Current developmental rates are well behind last year.

Figure 3.  Predicted percent of Melanoplus sanguinipes at fourth instar 
development stage (July 10, 2017).



Figure 4.  Predicted percent of Melanoplus sanguinipes at fifth instar 
development stage (July 10, 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 – Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Across the prairies, the model indicates that 95% of the population should be in the pupal stage. This week adults should be appearing at most locations. Output indicates that adult emergence is well underway at many southern locations (Brooks, Estevan) , while adult emergence at many central locations (Saskatoon) has begun over the last five days.







In terms of degree-day heat units, the map below reflects the predicted development of alfalfa weevil across the Canadian prairies.


Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon) and additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015).  That guide is available in both a free English-enhanced or French-enhanced version.

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 #7 (posted July 5, 2017) noting the presence of thistle caterpillar (Vanessa cardui) and larval populations of diamondback moth reaching economically significant levels in the southwest of that province. Cumulative counts of bertha armyworm generated from weekly counts in Manitoba can be accessed here.

● Saskatchewan’s Crop Production News – 2017 – Issue #3 includes the insect update prepared by Scott Hartley and Danielle Stephens. That report includes an update on the red bugs in canola (also described in Week 8) and how to submit samples to that provincial lab, very low numbers of diamondback moth in pheromone traps across that province, initial low numbers of bertha armyworm in pheromone traps, and cabbage seedpod weevil.


● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (July 5, 2017) provided by Scott Meers. That report notes migration of painted lady butterflies which feed on thistles but also soybeans, sunflowers, and dry beans. Soybean and sunflower producers will need to carefully follow the development of a second generation of V. cardui as it could affect those crops by mid-July. Additionally, d
iamondback moth are more numerous than in previous seasons so careful scouting will be required during early pod stages in canola as that stage is the most susceptible to yield losses.


Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (July 10, 2017)
• Saskatchewan Agriculture Crop Report (June 27-July 3, 2017)

• Alberta Agriculture and Forestry Crop Report (July 4, 2017)


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 9, 2017areas highlighted in yellow 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.  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 6, 2017, 729 birds were examined and six have tested positive for West Nile virus in Ontario

Weekly Update – Previous Posts

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

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

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 13 July 2016) is included below.

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 and wheat midge descriptions (July 8, 2016, prepared by John Gavloski and Pratisara Bajracharya).

– Saskatchewan’s Insect Report which mentions redbacked cutworms but emphasizes scouting for cabbage seedpod weevil, wheat midge and grasshoppers (Issue 4, prepared by Scott Hartley).
– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on July 7, 2016including wheat midge, cereal leaf beetle and similar damage associated with slugs, and pea aphids.

Insect of the Week – Crab spiders

Crab spiders


Last year, the focus of the 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 Insects of the Week are crab spiders. These are generalist predators, capturing any insects (small flies, ants, bees, wasps, beetles, small moths, thrips) visiting flowers, including canola which is in full flower right now. They are called crab spiders because they walk sideways like a crab.

For more information about these spiders, the 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).

‘Will you walk into my parlor?’ said the [yellow crab] spider to the fly
– (c) AAFC, Tyler Wist


Weekly Update

Greetings!

A downloadable PDF version of the complete Weekly Update for Week 11 (July 11, 2016) can be accessed here.  

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


Notice too that the predictive model maps for Wheat midge from both Week 10 and Week 11 have been included this week!

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

Average temperatures for June 27-July 3 were warmer in Alberta than Manitoba. This week the trend was reversed with the warmest temperatures being reported from Manitoba. Prairie wide, the average temperature was similar to Long Term Normals (LTN). 



Seven day (July 4-10, 2016) cumulative rainfall was greater in Manitoba and eastern Saskatchewan and Alberta and western Saskatchewan. Average cumulative rainfall was marginally greater than LTN values.

The average 30 day temperature (June 10-July 10) was 0.5 °C warmer than LTN values.


The average 30 day rainfall was 20% greater than LTN values.



The average growing season temperature (April 1 – July 10) has been approximately 1 °C warmer than normal. Growing season rainfall has been approximately 10% above average. 


The map below shows the Lowest Temperatures the Past 7 Days (July 5-11, 2016) across the prairies:


The map below shows the Highest Temperatures the Past 7 Days (July 5-11, 2016):



The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 10, 2016) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – July 10, 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 – Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata– Reporting sites across the prairies have generally reported lower cumulative interceptions with some exceptions in Saskatchewan.  Scouting within fields now becomes important.


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.

Weekly Update – Grasshoppers

Grasshoppers (Acrididae) – Across the prairies, the predicted mean instar of Melanoplus sanguinpes is 4.5 with adults appearing in many areas across the prairies.  In central Saskatchewan, grasshopper development continues to be more than 2-3 weeks ahead of average development. 



The following graph shows grasshopper development at Saskatoon for 2016. The model indicates that fifth instar numbers are beginning to peak and that adult grasshopper densities are increasing. 




The second graph below illustrates grasshopper development (for Saskatoon) based on LTN data. Based on average weather, the population should be primarily in the third instar and fourth instars with increasing numbers of fifth instars.  Adults are not predicted to occur until July 19. 



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.  

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (shown 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.





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. 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.




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 June 26, 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 11, 2016)
– Saskatchewan Agriculture Crop Report (July 4, 2016)

– Alberta Agriculture and Forestry (for July 5, 2016)

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

2015 Saskatchewan Bertha Armyworm Map

Saskatchewan Agriculture just posted their 2015 Bertha Armyworm Map.  The relative risk appears to be low based on cumulative pheromone trap counts to date but scroll down the webpage to access a PDF copy of the map.

Weekly Update

Prairie Pest Monitoring Network Weekly Updates – July 15, 2015
Otani, Giffen, Svendsen, Olfert


  1. Greetings!  This week grasshoppers, cabbage seedpod weevil and wheat midge were important pests based on provincial reports and reminders for in-field scouting.  Rain fell in some areas of the prairies but many continue to wait for moisture.  Remember, a downloadable version of this Weekly Update can be accessed here.  


  1. Weather synopsis – Thanks to the folks who compile and manage the agroclimate maps posted by AAFC!  The map below shows the Accumulated Precipitation the past 7 days (i.e., July 7-13, 2015):


While the map below reflects the Accumulated Precipitation for the Growing Season (i.e., April 1-July 13, 2015):


The map below reflects the Percent of Normal Precipitation for the Growing Season (i.e., April 1-July 13, 2015) for comparison:

The map below shows the Lowest Temperatures the Past 7 Days (July 7-13, 2015) across the prairies:


While the map below shows the Highest Temperatures the Past 7 Days (July 7-13, 2015) across the prairies:
The updated growing degree day (GDD) (Base 5ºC, March 1 – July 12, 2015) map is below:


While the growing degree day (GDD) (Base 10ºC, March 1 – July 12, 2015) map is included below:




  1. Bertha armyworm (Mamestra configurata) – Low cumulative counts of BAW moths were again reported in pheromone traps throughout the prairies this week.


In-field monitoring for egg masses (Refer to photo below) 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:



Reminder:  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:  


Table 1.  Economic thresholds for Bertha armyworm in canola (courtesy Manitoba Agriculture, Food and Rural Initiatives).
Expected Seed Value – $ / bushel*
Spraying cost –
$ / acre
6
7
8
9
10
11
12
13
14
15
16
Number of Larvae / metre2 *
7
20
17
15
13
12
11
10
9
9
8
8
8
23
20
17
15
14
13
11
11
10
9
9
9
26
22
19
17
16
14
13
12
11
10
10
10
29
25
22
19
17
16
14
13
12
11
11
11
32
27
24
21
19
17
16
15
14
13
12
12
34
30
26
23
21
19
17
16
15
14
13
13
37
32
28
25
22
20
19
17
16
15
14
14
40
35
31
27
24
22
20
19
17
16
15
15
43
37
32
29
26
23
22
20
19
17
16
* Economic thresholds for bertha armyworm are based on an assumed yield loss of 0.058 bu/acre for each larva/metre2 (Bracken and Bucher. 1977. Journal of Economic Entomology. 70: 701-705).


  1. Grasshoppers (Camnulla pellucida, Melanoplus sanguinipes, M. bivittattus, M. packardii) – In-field scouting along field margins and in ditches AND within the field is critical now with the exceedingly dry growing conditions!  


Scouting – Remember only five or six grasshopper species of the 80+ that occur on the prairies are regarded as crop pests.  The lifecycles of these six economically important species are similar.  Nymphs hatch from overwintered eggs in the spring.  Nymphs develop through five stages or instars before becoming adults.  Typically, the most serious economic damage will occur from the third to fifth instar stages but all stages need to be monitored.  The life stages of the clearwinged grasshopper (Camnulla pellucida) are shown below.  Note that adults possess fully formed wings that extend the entire length of the abdomen.


Life stages of the clearwinged grasshopper include (left to right) eggs which overwinter, first instar nymphs that hatch in the spring followed by second, third, fourth and fifth instar nymphs which finally develop into the adult stage.


Need help distinguishing grasshopper nymph stages?  Saskatchewan Agriculture’s latest Insect Update includes line drawings to help!  It also includes a summary of economic thresholds for grasshoppers in various crops.


Economic thresholds for grasshoppers are posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.


  1. Diamondback Moth (Plutella xylostella) – In-field monitoring for DBM larvae should continue this week.


Larval Monitoring:
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 dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.  
Remember, parasitoid wasps attacking DBM larvae (Refer to photo below) are already present in fields.  Use the economic thresholds to preserve these beneficial wasps by NOT applying insecticide until DBM larval densities exceed the threshold.


Diamondback larva (upper left) and pupal silk cocoon (upper right), Diadegma insulare adult and early instar Diamondback moth larvae on canola leaf (lower left) and D. insulare pupae (N=2) within Diamondback moth pupal silk cocoons (lower right).



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


Please also refer to fact sheets for DBM posted by Manitoba Agriculture, Food and Rural Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.  


  1. Wheat Midge (Sitodiplosis mosellana) – This season, predictive modelling was used in an attempt to forecast wheat midge emergence.  In 2014, the degree-day model proposed by German researchers (Basedow) was used to predict adult midge emergence in the Peace River region compared to the 5°C base temperature model which corresponds well to midge emergence throughout central and southern areas of the 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.  


The map below indicates the predicted status of wheat midge emergence with 10% of resident midge population emerged in areas highlighted yellow (600-693 DD), 50% in areas highlighted gold (693-784 DD), and 90% of resident midge emerged in areas highlighted orange (784-874 DD) using current weather data (up to July 12, 2015).  Wheat midge emergence is predicted to be 100% completed (as of July 12, 2015) with the initial midge larvae now expected to be found within wheat heads growing in southern Alberta, southeast Saskatchewan, southwest Manitoba and to the south of Winnipeg.  Wheat midge emergence is predicted to be 90% completed (as of July 12, 2015) throughout most of the boreal region of the prairies and in the north Peace.  Wheat midge emergence is predicted to be 50% completed (as of July 12, 2015) throughout the remaining portions of the prairies.  



When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.  Additional wheat midge biology and monitoring information can be located by clicking here or linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture and Forestry).  More information related to wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  


REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (shown 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.



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. 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.


Economic Thresholds for Wheat Midge:
  1. To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
  2. 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.


NEW – Wheat growers in Alberta can now access mapped cumulative counts from wheat midge pheromone traps.


  1. Cereal Leaf Beetles (Oulema melanopus) – Reminder – Fact sheets for Cereal leaf beetle (CLB) are posted by Alberta Agriculture and Forestry, and BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Descriptions of the various CLB stages and some monitoring tips are included below.  
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Refer to figure below). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-5ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals. 


Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. 


Larva: The larvae hatch 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 (Refer to figure below).  When the larva completes its growth, it drops to the ground and pupates in the soil.


Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. 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.


Cereal leaf beetle adult (left) and larva (right).


Leaf damage resulting from feeding by cereal leaf beetle larvae.


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 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 situated near 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.  Please note that, because the CLB larvae are covered in a sticky secretion, when they are caught in a sweep-net they are often covered in debris and are very difficult to see. 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, leaving only a thin membrane. When damage is extensive, leaves turn whitish (Figure 14). The plant may be killed or the crop may be seriously reduced. In addition to feeding damage, inspectors should be looking for all life stages of the CLB. In a field of host material the visual survey should be conducted between “sweep samples”.  Other locations to be examined include grass covered ditch banks and young host crops that are too low to sweep. Experienced surveyors should spend 15 minutes on visual inspection. Less experience surveyors should spend an additional 10 minutes on the visual component.


  1. Swede midge (Contarinia nasturtii) – Reminder – This season we again include scouting tips for in-field monitoring:
□  Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae (Refer to Figure below).
□  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.



In 2014, Canola School posted a swede midge update entitled “ Swede midge a pest on the rise”, featuring Dr. Julie Soroka (AAFC-Saskatoon).  The Ontario Canola Growers post swede midge information here.  Dr. Rebecca Hallett has posted a very helpful swede midge identification guide for those performing in-field monitoring and pheromone trapping.  Finally, canola management recommendations for swede midge in Ontario are posted by Rebecca Hallett and Brian Hall.


  1. 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.  They emerge from overwintering in the spring as soil temperatures warm to ~15°C.  CSPW utilize several flowering hosts including wild mustard, flixweed, hoary cress, stinkweed and volunteer canola.  CSPW move to canola during the bud to early flower stages and will feed on pollen and buds, causing flowers to die.  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.  


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. 


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




  1. 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.  


Remember there is no registered insecticide for root maggot control in canola.




  1. Lygus bugs (Lygus spp.) – The economic threshold for Lygus in canola is applied at late flower and early pod stages.  Biological and monitoring information can be linked by clicking here or you can access the Manitoba, or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  


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


Lygus Bug Nymph
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 Bug at Late Flowering Stage
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).


  1. Provincial Insect Pest Updates – The following provincial websites have their pest updates posted so click the links to access their reports:
●  Manitoba’s Insect and Disease Report  (July 7, 2015)
●  Saskatchewan’s Insect Update (July 7, 2015)
●  Alberta’s Insect Update (Call of the Land audio report of July 16, 2015)


  1. Insect of the Week – Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide (2015) by Hugh Philip is a new publication from Agriculture and Agri-Food CanadaThis growing season we will post an “Insect of the Week” in the form of short excerpts from the field guide. This week features several species of aphids (i.e., corn leaf, English grain, green peach, oat-birdcherry, pea, potato, soybean, turnip, greenbug).



Additionally, ladybird beetles were also featured in the Insect of the Week.



  1. Crop Reports –  The following provincial websites now have their Crop Reports posted so click the links to find their weekly updates:




  1. West Nile Virus Risk – Reminder – Now is the time for DEET!  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  Areas yet to be highlighted in red on the map below will have accumulated sufficient heat for C. tarsalis to fly. As of July 12, 2015, the predicted development of C. tarsalis is most advanced in the southern areas of our prairie provinces with adults predicted to emerge from 350-400 DD in the map below ( will be highlighted in red).


The Public Health Agency of Canada posts information related to West Nile Virus in Canada and their website is located here.  The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance.  As of this week, one bird in New Brunswick and one bird in Ontario tested positive for West Nile-related deaths (click here to view the report).





  1. Questions or problems accessing the contents of this Weekly Update?  Please e-mail or call either Owen.Olfert@agr.gc.ca (tel. 306-385-9355) or Jennifer.Otani@agr.gc.ca (tel. 780-354-5132).  Past and present “Weekly Updates” are very kindly posted to the Western Forum website by webmaster, Dr. Kelly Turkington.  Please click here to link to that webpage.
  1. Previous topics:
    1. The PPMN Blog is located at http://PrairiePestMonitoring.blogspot.ca   Subscribe to receive the most current information OR bookmark the site to visit later.
    2. Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide – The NEW Field Guide to Support Integrated Pest Management (IPM) in Field and Forage Crops is NOW available for download from www.publications.gc.ca.   Two downloadable (~8 MB) versions of the complete field guide are available as either a  ‘Regular’ (i.e., best for printing: EnglishFrench) or ‘Enhanced’ (i.e., best for viewing electronically with active internal and external hyperlinks: English-enhancedFrench-enhanced).
    3. Wind trajectories Related to Diamondback Moth (DBM) and Aster Leafhopper Introductions – Completed for the season.  Please refer to earlier Weekly Updates for details related to backward and forward trajectories associated with air parcels moving over western Canadian locations.
    4. Flea Beetles (Chrysomelidae: Phyllotreta species) – Helpful images produced by Dr. Julie Soroka (AAFC-Saskatoon) exemplifying percent of cotyledon leaf area consumed by flea beetles are posted at Canola Watch.  
    5. Cutworms (Noctuidae) – Cutworm biology, species information, plus monitoring recommendations are available at the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol.  Also refer to these cutworm-specific fact sheets (Manitoba Agriculture and Rural Initiatives, Alberta Agriculture, Food and Rural Development).  If cutworms are spotted in Albertan fields, please also consider using the Alberta Pest Surveillance Network’s “2015 Cutworm Reporting Tool” for online reporting located by clicking here.  Data entered at that website uploads to a live “Cutworm Map”.
    6. Pea Leaf Weevil (Sitona lineatus) –Link here for the Pea leaf weevil monitoring protocol which includes photos of related weevils.
    7. Crop Protection Guides – Access Saskatchewan’s Crop Production Guide,  Manitoba’s Guide to Crop Production,  Alberta’s Crop Protection or Blue Book,  or the Western Committee on Crop Pests Guidelines for the Control of Crop Pests.
    8. Canola Insect Scouting Chart – Reminder – The Canola Insect Scouting Chart has been updated with hyperlinks now directing growers to downloadable pages from the NEW Field Guide!
    9. Alfalfa Weevil (Hypera postica) – Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).

Insect of the Week – Aphids and ladybird beetles

This week’s Insect of the Week is a two-fer: aphids and their natural mortal enemies, ladybird beetles (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).