Weather synopsis

Ross Weiss, Serge Trudel, Tamara Rounce, Jennifer Otani and Meghan Vankosky
Categories
Week 13

This past week (July 13-19, 2020) prairie temperatures were warmest in Manitoba and eastern Saskatchewan (Table 1; Fig. 1). Average 7-day temperatures continue to be warmest across Manitoba and eastern Saskatchewan and coolest across most of Alberta(Table 1; Fig. 1).

Figure 1. Observed average temperatures across the Canadian prairies the past seven days (July 13-19, 2020).

Average 30-day (June 20-July 19, 2020) temperatures continued to be cooler in Alberta than eastern Saskatchewan and Manitoba (Table 2; Fig. 2). The average 30-day temperature at Winnipeg and Brandon continued to be greater than locations in Alberta and Saskatchewan(Table 2; Fig. 2). Based on growing season temperatures (April 1 – July 19, 2020), conditions continue to be warmest for southern locations (Table 3).

Figure 2. Observed average temperatures across the Canadian prairies the past 30 days (June 20-July 19, 2020).

Cumulative rainfall for the past 7 days was lowest across southern regions of Alberta and Saskatchewan. Cumulative 30-day rainfall was lowest across a large area ranging from southwest Saskatchewan to Saskatoon. Growing season rainfall (percent of average) is below normal across eastern Saskatchewan and localized areas of Manitoba.

Figure 4. Observed cumulative precipitation across the Canadian prairies the past seven days (July 16-19, 2020).
Figure 5. Observed cumulative precipitation across the Canadian prairies the past 30 days (June 20-July 19, 2020).
Figure 6. Percent of average precipitation for the growing season (April 1-July 19, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (21Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-July 13, 2020) is below (Fig. 7) while the growing degree day map (GDD) (Base 10 ºC, April 1-July 13, 2020) is shown in Figure 8.

Figure 7. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-July 22, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 8. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-July 22, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Jul2020). 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 across the Canadian prairies the past seven days ranged from <19 to >32 °C (Fig. 9). So far this growing season (up to July 22, 2020), the number of days above 25 ranges from 0-10 days throughout much of Alberta and into the BC Peace then extends up to 41-50 days in southern Manitoba (Fig. 10).

Figure 9. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-July 19, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 10. Number of days above 25 °C observed across the Canadian prairies this growing season (April 1-July 22, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

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

Predicted bertha armyworm development

Ross Weiss, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 13

Model simulations for July 19, 2020 (Fig. 1) indicate that 23% of the bertha armyworm (BAW) population is in the egg stage (compared to 35% last week) and 77% are predicted to be larvae (compared to 65% last week). Across the Parkland and Peace River regions, BAW populations are predicted to be primarily in the egg stage (Fig. 1). Other than the Peace River region, populations are primarily in the larval stage (Fig. 1). Fields near Carman, Winnipeg and Morden in Manitoba are expected to have first appearance of pupae, suggesting larval development is advanced (Fig. 1).

Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population in the larval stage as of July 19, 2020.

The two graphs below demonstrate that BAW populations near Winnipeg (Fig. 2) are more advanced than populations near Grande Prairie (Fig. 3). In Winnipeg populations are primarily in the larval stage with first appearance of pupae (Fig. 2). BAW populations near Grande Prairie are predicted to be in adult, egg and larval stages (Fig. 3).

Figure 2. Predicted bertha armyworm (Mamestra configurata) phenology at Winnipeg MB as of July 19, 2020.
Figure 3. Predicted bertha armyworm (Mamestra configurata) phenology at Grande Prairie AB as of July 19, 2020.

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 required to apply the economic threshold to manage both this pest and its natural enemies. For convenience, screen shots of the above maps or data have been placed below for Alberta, Saskatchewan, and Manitoba.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images above (Fig. 4) to help identify the economically important larvae.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png
Figure 4. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

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

Predicted wheat midge development

Ross Weiss, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 13

This week (as of July 19, 2020), regions of the Canadian prairies are either at a sensitive time for wheat midge monitoring OR the opportunity to scout and apply insecticides to prevent adult midge from laying eggs may have passed. Scouting remains essential now, especially in areas where wheat midge development was slightly delayed according to last week’s model output (Table 1). Note that the model predicted populations near Lethbridge, Grande Prairie and Lacombe would be at 90% emergence on July 23, July 25, and July 26, respectively.

This week, wheat midge model runs indicate that, where wheat midge are present and rainfall has been adequate, adult emergence is well underway and oviposition is occurring, and early instar larvae may be present and beginning to feed on developing wheat kernels. Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities, according to our model.

Figure 1. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK.
Values are based on model simulations (April 1-July 19, 2020).
Figure 2. Predicted wheat midge (Sitodiplosis mosellana) phenology at Lacombe AB.
Values are based on model simulations (April 1-July 19, 2020).

Figure 3 compares synchrony between wheat midge and wheat development for fields near Saskatoon. The graph indicates that peak adult emergence and oviposition are likely to occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 3). Figure 4 compares the predicted phenology near Saskatoon of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge. The parasitoid wasp seeks out and lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 4). Taken together, this information can be used as a guide to determine when fields should be monitored.

Figure 3. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Saskatoon SK as of July 19, 2020.
Figure 4. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and its parasitoid, Macroglenes penetrans, at Saskatoon SK as of July 19, 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

Jennifer Otani, Ross Weiss, Owen Olfert and Meghan Vankosky
Categories
Week 13

As of July 19, 2020, the grasshopper model estimates that development of first instar nymphs is complete across most of the prairies and that adult grasshoppers may be beginning to emerge in southern Manitoba and Saskatchewan (Fig. 1; Table 1). Based on model simulations, development has been slowest in the Peace River region where average nymph development ranges between the 2nd and 3rd instar stages (Fig. 1; Table 1). Across the southern prairies, the majority of the nymph population is predicted to be in the 4th and 5th instar stages, with adults predicted to occur across southern Manitoba and Saskatchewan, where grasshopper populations are active (Fig. 1; Table 1).

Figure 1. Predicted average development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 19, 2020).

Table 1 indicates that predicted development at Brandon and Winnipeg is well ahead of Lacombe and Grande Prairie. The two graphs below compare grasshopper development at Lacombe (Fig. 2) and Brandon (Fig. 3). Near Lacombe, grasshopper populations are expected to be mainly in the 3rd and 4th instar (Fig. 2). Around Brandon, adult emergence is expected to be well underway, with some lingering 3rd, 4th, and 5th instar individuals remaining in the population (Fig. 3).

Figure 2. Predicted grasshopper (Melanoplus sanguinipes) phenology at Lacombe AB. Values are based on model simulations (April 1-July 19, 2020).
Figure 3. Predicted grasshopper (Melanoplus sanguinipes) phenology at Brandon MB. Values are based on model simulations (April 1-July 19, 2020).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Lygus bug monitoring

Jennifer Otani
Categories
Week 13

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

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

This image has an empty alt attribute; its file name is 2019_Lygus_lineolaris_AAFC-Sask.png
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
This image has an empty alt attribute; its file name is 2019_Lygus_nymph_AAFC-Sask.png
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

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

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

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

This image has an empty alt attribute; its file name is 1998_SequentialSampling_WiseAndLamb.png
Figure 3. Sequential sampling for lygus bugs at late flowering stage in canola.

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

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

This image has an empty alt attribute; its file name is 1998_EconomicThreshold_LateFlower-EarlyPod_Captions-1024x488.png
This image has an empty alt attribute; its file name is 1998_EconomicThreshold_Pod_Captions-1024x461.png

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

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

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

Field heroes

Jennifer Otani
Categories
Week 13

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

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

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

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

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

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

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

• NEW – Access Episode 6Plentiful parasitoids

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

West nile virus risk

Jennifer Otani, David Giffen and Owen Olfert
Categories
Week 13

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; retrieved July 23, 2020). The screenshot below (retrieved July 23, 2020) serves reference but access that information here.

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

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas).  As of July 19, 2020, areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge.  Plan to protect yourself by wearing DEET!  

Figure 1. Predicted development of Culex tarsalis, across the Canadian prairies (as of July 19, 2020).

Provincial insect pest report links

Jennifer Otani
Categories
Week 13

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 22, 2020 report. The summary indicates that, “Grasshoppers and armyworms continue to be the insects of greatest concern. Twostriped grasshopper is mainly into the later nymph stages with some adults present; clearwinged grasshopper adults are present. Lots of reports of Cotesia pupal clusters in some of the cereals, resulting from parasitized armyworm populations. Armyworms seem to be turning to pupae and levels dropping in some areas. Jack pine budworm, a moth whose larvae feed on pines trees, is very abundant this year, and agronomists are noticing the moths around farmyards are enquiring regarding what it is and what it feeds on.”

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

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

Crop report links

Jennifer Otani
Categories
Week 13

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 21, 2020 report.

• Saskatchewan Agriculture  or access a PDF of July 14-20, 2020 report.

• Alberta Agriculture and Forestry or access a PDF of July 14, 2020 report.

The following crop reports are also available:

• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the July 20, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the July 21, 2020 edition). 

Previous posts

Jennifer Otani
Categories
Week 13

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

    • 2019-2020 Risk and forecast maps

    • Alfalfa weevil (Wk08)

    • Aster leafhopper (Wk05)

    • Beetle data please! (Wk03)

    • Cereal aphid APP (Wk11)

    • Crop protection guides (Wk02)

    • Cutworms (Wk02)

    • Diamondback moth (Wk11)

    • Flea beetles (Wk02)

    • John Doane (Wk10)

    • Monarch migration (Wk10)

    • Pea leaf weevil (Wk11)

    • Pea leaf weevil – predicted development (Wk09)

    • Prairie provincial insect webpages (Wk02)

    • Scouting charts – canola and flax (Wk02)

    • Ticks and Lyme Disease (Wk06)

    • Wind trajectories (Wk09)

Clover Pests / Feature Entomologist: Vincent Hervet

Finch Van Baal
Categories
Week 13

This week’s Insect of the Week featured crop is clover: a plant used both as a cover crop and in pasture blends. Our feature entomologist this week is Vincent Hervet.

Red clover
cc by 2.0 George Hodan

While there are numerous clover species, we will be looking at three clovers that are common across the Prairie region: red clover, white clover, and alsike clover. All are short-lived perennial legumes used for pasture and hay production, with red and white clover also used for silage (in mixture with grasses). All three species are cold-tolerant, though each clover is best suited to its own peak soil conditions. All three clovers are palatable and digestible to livestock, though it’s recommended that clover content in a pasture mix never exceed 30% to avoid bloating in cattle and other livestock. In addition to all this, all three species provide pollen and nectar, and attract insects like the bumblebee.  

Certain pests target clover. 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.

White clover
cc by 2.0 Trish Steele
Clover Pests
  • Alfalfa caterpillar
  • Alfalfa looper
  • Alfalfa weevil
  • Black cutworm
  • Clover cutworm
  • Clover leaf weevil
  • Grasshoppers
  • Green cloverworm
  • Less clover weevil
  • Pea aphid
  • Pea leaf weevil
  • Potato aphid
  • Potato leafhopper
  • Red clover casebearer moth
  • Saltmarsh caterpillar
  • Variegated cutworm
Clover cutworm – AAFC

Entomologist of the Week: Vincent Hervet

Name: Vincent Hervet
Affiliation: Agriculture and Agri-Food Canada
Contact Information: Email: vincent.hervet@canada.ca; Tel: 204-915-6918

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

I was previously involved with the monitoring of cereal leaf beetle, diamondback moth, and cutworms in southern Alberta. I am currently planning a monitoring program for pests of stored seeds across the Canadian Prairies.

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

We can find that all species, pests and non-pests, are fascinating if we look close enough. For example, the cereal leaf beetle belongs in the family commonly known as “leaf beetles” and scientifically known as “Chrysomelidae” (from the Greek word “Chrysos” = gold, an allusion to the shininess of most species). Cereal leaf beetles neatly eat the soft parenchyma tissue between the parallel longitudinal veins of cereal leaves and other grasses. Larvae cover themselves with their own feces and a moist secretion, which is often referred to as the “fecal coat”. It provides them protection and camouflage. Ironically, this fecal coat also attracts the parasitoid Tetrastichus julis, the arch nemesis of the cereal leaf beetle in North America.

What is your favourite beneficial insect?

Rather than a single species my favourite beneficial insect is a group of species: parasitoids. Inconspicuous little critters, they are ubiquitous and represent about 10% of all known insect species on Earth. From Tetrastichus julis that keeps the cereal leaf beetle in check in North America, Bracon cephi that keeps wheat stem sawfly in check on the prairies, Macroglenes penetrans that keeps wheat midge in check where it is established, Cotesia glomerata that keeps imported cabbageworm in check in North America, Diolcogaster claritibia that seems to be keeping diamondback moth for the most part in check in southern Alberta since at least 2010, to an undescribed species of Cotesia that appears to keep the alfalfa looper in check (a system that has not been studied because the alfalfa looper is not a big deal―likely thanks to this unknown parasitoid species), and many more, parasitoids are the true silver bullets against insect pests. Insect pest problems could be brought to an end if we could have one effective parasitoid species for each insect pest species and preserve them.

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

I am currently working on the detection and control of the bean weevil in stored beans. The bean weevil is a quarantine species for India, our main importer of beans, and bean prices would increase if we could ensure no bean weevils in shipments. I am currently looking for live bean weevils for research. Please contact me if you encounter any!

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

I most frequently rely on email and telephone.


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