Weather synopsis

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

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! 

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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

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

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

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.  

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Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
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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). 

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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. 

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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

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

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

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

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

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

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.

Weekly Update

Greetings!

Lucky Week 13 and another busy week of in-field monitoring, data collection, and field tour events for all our Staff!  Please bookmark the Blog or subscribe to receive the latest growing season information!

This week, special thanks to all those field cooperators who continue to check and report their weekly in-field data!  Your efforts support agriculture in your province and ultimately the Prairie Pest Monitoring Network pulls the combined prairie-wide effort into the Annual Risk and Forecast Maps.  These are important research and grower resources so Thank you!!

Please access the complete Weekly Update either as a series of Posts for Week 13 (July 5, 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

Prairie temperatures continue to be cooler than average. Though temperatures this week were approximately 1 °C warmer than last week, temperatures were cooler than normal (Fig. 1).  The warmest temperatures were observed across MB while temperatures were cooler in western SK and across AB.

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

Across the prairies, 30-day average temperatures were approximately 1 °C cooler than normal (Fig. 2). Average 30-day temperatures were warmest across southern MB and SK. Cooler temperatures were reported across eastern and northern AB. The mean temperature differences from normal (June 1 – 30, 2019) were zero to two degrees Celsius cooler than for AB and  western SK while temperatures in eastern SK and MB have been zero to two degrees Celsius warmer than normal (Fig. 3). 

Figure 2. Average temperature (°C) across the Canadian prairies the past 30 days (June 2-July 1, 2019).
Figure 3. Mean temperature difference from Normal across the Canadian prairies over the past 30 days (June 1-30, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (04Jul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Growing season temperatures (April 1-July 1, 2019) have been warmest across the southern prairies. Across the prairies, the average growing season temperature has been 1.2 °C below normal (Fig. 4).

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

This past week significant rainfall amounts were reported for southern SK and the Peace River region. Minimal rainfall was reported across MB and southern AB (Fig. 5). 

Figure 5. Cumulative precipitation observed the past seven days across the Canadian prairies (June 24-July 1, 2019).

Across the prairies, rainfall amounts for the past 30 days have been near normal (Fig. 6). The Edmonton AB region has been the wettest. Growing season rainfall amounts have been below average for most of the prairies, particularly across southern regions of AB and eastern MB (Fig. 7). 

Figure 6. Cumulative precipitation observed the past 30 days across the Canadian prairies (June 2-July 1, 2019).
Figure 7. Cumulative precipitation observed for the growing season (April 1-July 1, 2019) across the Canadian prairies.

Based on modelled soil moisture, recent rains have improved soil moisture values across a large area of SK. Predicted soil moisture continues to be low across large regions of eastern MB and southern AB. 

Figure 8. Modeled soil moisture (%) across the Canadian prairies as of July 1, 2019.

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

Figure 9. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-July 1, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (04Jul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

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

Figure 10. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-July 1, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (04Jul2019).  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 at least 13 to at least 0 °C in the map below (Fig. 11).

Figure 11. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to July 1, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (04Jul2019).  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 less than 14 to at least 30 °C in the map below (Fig. 12).

Figure 12. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to July 1, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (04Jul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

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

Predicted grasshopper development

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

Recent cool conditions have resulted in reduced grasshopper development rates. Based on model runs, approximately 22% (33% last week) of the population is in the first instar, 29% (26% last week) is predicted to be in the second instar, and 27% (11% last week) in the third instar, 8.2% (1.5% last week) are predicted to be in the fourth instar and less than 1% may be in the fifth instar (Fig. 1).  Grasshopper development this season has been similar to long term average development. The following map indicates that grasshopper populations across the southern prairie are mostly in the second instar with some areas having populations that are mostly third instars.

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

Wheat midge

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 wheat midge emergence. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic  if rainfall did not exceed  20-30 mm  during May. Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model indicates that dry conditions may result in:

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

The wheat midge model indicates that 54% (70% last week) of the population are in the larval  cocoon stage and 42% (29% last week) of the population is predicted to have moved to the soil surface. This week 3.4% (less than 1% last week) is predicted to be in the pupal stage. Adults may begin to emerge later this week, or earlier next week.  

The first map indicates the percent of the population that is in the larval stage, at the soil surface.  The second map indicates that pupae may be present in some fields in southern AB and MB. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.

Figure 1. Percent of larval population at the soil surface (as of July 1, 2019) across the Canadian prairies.
Figure 2. Percent of  population AT PUPAL STAGE (as of June 24, 2019) across the Canadian prairies.

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

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

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

Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage. 

Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10).  Check that post for help with in-field scouting for this economic pest of wheat!  The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11).  Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.

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.

Bertha armyworm monitoring

Bertha armyworm (Lepidoptera: Mamestra configurata– Last week (Fig. 1), bertha armyworm adults were emerging across the prairies and oviposition began across most of the southern prairie regions of SK, AB and MB.  That means it’s time to start check the undersides of canola leaves for egg masses and newly hatched larvae!

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

Here’s where bertha armyworm moths were intercepted last year (Fig. 2) so areas previously highlighted in yellow, gold, orange or red should be on the lookout in 2019 for larvae.  Also watch your provincial monitoring networks who are weekly recording cumulative pheromone-baited traps in Alberta, Saskatchewan (table on Left of webpage), and Manitoba (pg 7).

Figure 2.  Cumulative moth counts from pheromone-baited unitraps deployed during the 2018 growing season.

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. 3) to help identify moths from the by-catch that will be retained in phermone-baited unitraps.

Figure 3. 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!

Timely IOTW to review

A few past Insect of the Week (IOTW) segments to aid your in-field scouting at this time of year – see if you recognize them!

Aphidius wasps

Blister beetle

Bruner grasshopper

Canola flower midge

Cereal aphids

Cereal leaf beetle

Crab spider

Ground beetles

Ladybird beetle larva

Natural enemies of pea aphid

Pea aphid

Pteristichus melanarius

Red clover casebearer

Red turnip beetle

Rove beetle

Soybean aphid

Spotted wing drosphila

Tetrastichus julis

Provincial Insect Pest Report Links

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

Manitoba‘s Crop Pest Updates for 2019 are posted here. Access Issue #6 posted July 3, 2019 which includes grasshopper, and a link to an excellent fact sheet for thistle caterpillars with great photos of each life stage.

Saskatchewan‘s Crops Blog Posts includes a segment on “Economic thresholds” by Kaeley Kindrachuk posted in May 2019. Also access the Crop Production News with Issues:

•  Alberta Agriculture and Forestry’s Agri-News includes an insect-related item in the July 2, 2019 edition with an important reminder regarding bertha armyworm pheromone trap monitoring.

Crop report links

Crop reports are produced by:

The following crop reports are also available:

Field Events – Speak to an entomologist

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

•  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.

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 04Jul2019) but follow the hyperlink to check the interactive map.  They are moving west and near Yorkton, 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. 

Previous Posts

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Alfalfa weevil – Week 11

Bertha armyworm (predicted development) – Week 12

Cabbage seedpod weevil – Week 11
Cereal aphid manager APP – Week 12
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
Prairie Crop Disease Monitoring Network – Week 11

Ticks and Lyme disease – Week 4

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Review Page for list of PDFs for Weeks 1-12

Insect of the Week – Doppelgangers: Cereal leaf beetle vs. Collops beetles

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 cereal leaf beetle versus Collops beetles: 

Cereal leaf beetle, Boris Loboda

Cereal leaf beetles (Oulema melanopus), both adults and larva, feed on leaves (oat, barley, wheat, corn, etc), but it is the larval damage that can reduce yield and quality, especially if the flag leaf is stripped. Adults are 6-8 millimeters (.25-.31 inches) long with reddish legs and thorax (middle section between head and abdomen) and metallic bluish-black head and elytra (wing coverings).

Collops beetle, cc-by-nd-nc 1.0 Ashley Bradford

They may be confused with beneficial beetles belonging to the Collops genus (adults feed on aphids, stink bug eggs, moth eggs, small caterpillars, spider mites, whiteflies). Roughly the same size, they may have a red or orange thorax with/without red markings on their elytra, depending on the species. One consistent feature that will help distinguish between the two species is that the cereal leaf beetle elytra are smooth and shiny whereas the Collops’ elytra are covered in hairs.

Specific information on the cereal leaf beetle can be found in the updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide.

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

Insect of the Week – Wheat stem sawfly (Cephus cinctus, Hymenoptera: Cephidae)

This week’s Insect of the Week is the wheat stem sawfly (Cephus cinctus). Adults are 8-13mm long and have a shiny, black, wasp-like body and yellow legs. When at rest on plant stems, they point their heads downwards.

Mature larvae overwinter in the base of stems in infested fields. In June, females emerge and fly to nearby wheat crops, where they can lay up to 50 eggs each on stems.

The wheat stem sawfly feeds primarily on spring and durum wheat, though winter wheat, rye, grain corn, barley, and some native grasses can support sawfly development. It cannot develop on oats.

Larvae feed on the pith of host plants stems which can cause a reduction in crop yield and quality. When plants mature, larvae move to the bottom of the stem to overwinter.

For more information about the wheat stem sawfly, head over to our Insect of the Week page!

Wheat stem sawfly – adult
(Alberta Agriculture and Rural Development)
Wheat stem sawfly – egg, larva, adult, damage
(Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org)

Weather synopsis

Weather synopsis – This past week (July 23 – 30, 2018) the average temperature (14.8 °C) was marginally cooler than long term average values (Fig. 1). The warmest weekly temperatures occurred across southern and central Alberta and eastern Manitoba. The 30-day (June 30 – July 30) average temperature (15.7 °C) was similar to the long term average (Fig. 2).  

Figure 1. Weekly (July 23 – 30, 2018) average temperature (°C).
Figure 2. The 30-day (June 30 – July 30, 2018) average temperature (°C).  

Weekly total precipitation was below average and 30-day total precipitation was marginally above average (Figs. 3 and 4).  The wettest region (30-day cumulative precipitation) was across eastern areas in Saskatchewan and southern Manitoba while central Saskatchewan and most of Alberta continue to be dry. Growing season precipitation is below average across large areas of Alberta, Saskatchewan and Manitoba. Average precipitation has been reported across the Peace River region, eastern Saskatchewan, and the Parkland region. 

Figure 3.  Weekly (July 23 – 30, 2018) cumulative precipitation (mm).
Figure 4. 30-day (June 30 – July 30, 2018) cumulative precipitation (mm).

The map below reflects the Highest Temperatures occurring over the past 7 days (July 24-30, 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 24-30, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (31Jul2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

The map below reflects the Highest Temperatures occurring over the past 7 days (July 24-30, 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 24-30, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (31Jul2018).  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 29, 2018) is below:

The growing degree day map (GDD) (Base 5ºC, March 1 – July 29, 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).  

Grasshopper populations were predicted to be in the adult stage (Fig. 1A). Development during this growing season is well ahead of average (Fig. 1B).  Development is predicted to be more advanced across the southern prairies than in the Peace River region. 

Figure 1.  Grasshopper development (percent of population) based on model output for the current growing season (A) and for long term normal climate data (B).

This week, adults are predicted to be appearing across the Peace River region (Fig. 2C). 

Figure 2. Predicted grasshopper phenology at Saskatoon (A), Lethbridge (B), and Grande Prairie (C); based on model output for the current growing season (April 1 – July 30, 2018).

Oviposition is ahead, and is predicted to occur across most of the southern prairies (Fig. 3).

Figure 3.  Predicted grasshopper phenology at Saskatoon (A), Lethbridge (B), and Grande Prairie (C); based on model simulations for long term climate normals (April 1 – July 30).
Figure 4.  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.

Weekly Update

Greetings!

In-field scouting remains critical as we move into August!  Access the complete Weekly Update either as a series of Posts for Week 13 (August 2, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 13!

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!

Bertha armyworm

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

Review your province’s 2018 bertha armyworm pheromone trapping results towards the end of this Post.

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 31Jul2018 for reference):

Saskatchewan growers can check the 2018 bertha armyworm map (screenshot below retrieved 31Jul2018 for reference):

Manitoban growers can find bertha armyworm updates in that province’s Insect and Disease Updates.  A screen shot of that summary is pasted 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.

Thrips

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

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

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

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

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

Curled pods of canola caused by thrips feeding damage (Photos: AAFC-Saskatoon, Olfert et al. 1998)

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

Lygus in canola

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

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

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

Scouting tips to keep in mind:

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

Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.

Sampling becomes more representative IF repeated at multiple spots within a field.  For lygus bug monitoring, sampling is most accurate when repeated at a total of 15 spots within the field.  Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). 

If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.

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

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

Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

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

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

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

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

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

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

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 31Jul2018).

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

Ladybird beetles

While scouting, you may encounter these fascinating organisms…..

Figure 1. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)
Figure 2. Ladybird beetle pupa (Left) and larva (Right) (photo credit: AAFC-Beaverlodge)
Figure 3. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge)
Figure 4. Ladybird beetle (Coccinella septempunctata) (photo credit: AAFC-Beaverlodge)
Figure 5. Aphids nestled on wheat head (photo credit: AAFC-Beaverlodge)
Figure 6. An aphid “mummy” adhered to a wheat awn.  Mummy is the aphid host converted to enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge)

Ladybird beetle larvae (Fig. 1-2), pupae (Fig. 2-3), and adults (Fig. 4) can all be found in fields at this time of year.  Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes!  Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids (Fig. 5).  

Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) – By this point in the season, pupae and newly emerged adults will be present in fields.  

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.

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). 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 shelter belts, deciduous and conifer forests. They will emerge in the spring once temperature reaches 10-15 ºC.

Figure 1. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

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”.

Pea leaf weevil

Pea Leaf Weevil (Sitona lineatus– Over the past ten days newly emerged adult pea leaf weevils are predicted to be emerging from pea crops (Fig. 1).  

Figure 1. Predicted pea leaf weevil phenology at Saskatoon (A) and Lethbridge (B). Values are based on model simulations for the current growing season (April 1 – July 30, 2018).

Pea leaf weevil larvae develop under the soil over a period of 30 to 60 days. They are “C” shaped with a dark brown head capsule. The rest of the body is a milky-white color (Fig. 2 A). Larvae develop through five instar stages. In the 5th instar, larvae range in length from 3.5 – 5.5 mm. First instar larvae bury into the soil after hatching, and search out root nodules on field pea and faba bean plants. Larvae enter and consume the microbial contents of the root nodules (Fig. 2 B). These root nodules are responsible for nitrogen-fixation, thus pea leaf weevil larval feeding can affect plant yield and the plant’s ability to input nitrogen into the soil. 

Figure 2.  Pea leaf weevil larva in soil (A) and field pea root nodules damaged by larval feeding (B).  Photos: 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.  A review of this insect was published in 2011 in Prairie Soils and Crops by Carcamo and Vankosky.

Pre-Harvest Intervals

Pre-Harvest Interval (PHI) – Growers with late-season insect pest problems will need to remember to factor in the PHI which is the minimum number of days between a pesticide application and swathing or straight combining of a crop.  

The PHI recommends sufficient time for a pesticide to break down and a PHI-value is both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

An excellent summary of PHI for various pesticides in their various crops was posted by Saskatchewan Agriculture’s Danielle Stephens in 2016 within their Crop Production News.

In 2013, the Canola Council of Canada created and circulated their “Spray to Swath Interval Calculator” to help canola growers accurately estimate their PHI.  Other PHI are described in your provincial crop protection guides and remember that specific crop x pesticide combinations will mean different PHIs.  

Finally, work towards “Keeping It Clean” so your grain is ready for export!  More information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean site. 

Provincial Insect Pest Reports

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

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

Saskatchewan‘s Crop Production News for 2018 is posted with Issue #5 now available. This issue includes a description of cereal leaf beetle in Saskatchewan. Growers can review articles on how to scout for cutworms, how to assess plant stand densities in flax or canola, and for flea beetles, pea leaf weevils, and results from 2018 diamondback moth pheromone trapping. NEW – review the 2018 bertha armyworm pheromone trapping results!

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 26, 2018) includes a brief description of the new canola flower midge and the current survey underway in Alberta, that bertha armyworm monitoring should be focusing on in-field monitoring to establish larval densities, presence of english grain aphid showing up in a few fields in low numbers, and some reports of ladybird beetle larvae and pupae active on cereal heads feeding on aphids and other insect pests.

Crop reports

Crop reports are produced by:

The following crop reports are also 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 (July 7, 2018) on 2018 testing (screenshot retrieved 25Jul2018 provided below for reference only).

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, 872 birds were examined and nine have tested positive for West Nile virus. View a screen shot of the summary of those results below:

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 12 
Cabbage root maggot – Week 11 
Cereal aphid manager (CAM) – Week 2
Cereal leaf beetle larvae request – Week 8
Crop protection guides – Week 2
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

PMRA Pesticide Label Mobile App – Week 4

Scouting charts (canola and flax) – Week 3

Ticks and Lyme Disease – Week 4

Weather radar – Week 3
Wheat midge – Week 12

White grubs in fields – Week 8

Wind trajectories – Week 6
Wireworm distribution maps – Week 6

Weekly Update

Hello!

A technical glitch this week: The Blog failed to send subscribers the Weekly Update Wednesday morning!  Follow the links to the Posts for Week 13 (August 2, 2018):

Access the complete Weekly Update either as a series of Posts for Week 13 (August 2, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 13!

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

Subscribe to the Blog by following these three steps!

Insect of the Week – Soybean aphid

This week’s Insect of the Week is the soybean aphid. This pest overwinters in the US and is blown into Canada, where winged females migrate to soybeans and produce several generations over the summer.

In 2016, 2.5 million acres of soybeans were planted in Alberta, Saskatchewan, and Manitoba. This amount is expected to rise in coming years. Thus, it is important to know how to scout for and manage soybean aphids.

For more information on soybean aphids, visit our Insect of the Week page.

Soybean aphid – adult (Robert J. O’Neil, Purdue University (wiki))



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

BONUS Insect of the Week – Wheat stem maggot

The Wheat Stem Maggot, Meromyza americana (Diptera) is minor pest that causes eye-catching damage in wheat, rye, barley, oat, millet, timothy, brome, crested wheatgrass and bluegrass. This is a timely insect of the week, because the larval damage (dead white heads in an otherwise green field) started to appear in the last few weeks and is now highly visible in many fields.

Your eyes are naturally drawn to these white heads and can cause you to overestimate the actual amount of damage to your fields. However, the damage is usually limited to 1-5% of the crop. To identify if the wheat stem maggot is the culprit, gently pull on the white head to see if it easily separates from the flag leaf sheath and shows evidence of feeding damage at the base of the culm.

By the time you see damage, the greenish-white larva has exited and is off to begin a second generation that will overwinter in volunteer cereals. There are no registered chemicals or resistant varieties so your best management practices are rotate to non-cereals/non-grassses, destroy infested stubble, and control volunteer hosts and grassy weeds. Delayed seeding, where/when possible may also limit damage.

For more information on the Wheat Stem Maggot, see our Insect of the Week page.

Wheat stem maggot damage (Tyler Wist – AAFC)


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

Weekly Update – Weather Synopsis

Weather synopsis – This week’s temperatures were similar to last week, both the seven-day (Fig. 1) and 30-day average temperatures (Fig. 2) were similar to long term averages (Fig. 3). Compared to 30-day average temperatures, Alberta was above normal, whereas Saskatchewan and Manitoba were slightly below normal (Fig. 2).

Figure 1.  Accumulated precipitation the past  7 days (from July 17-24, 2017) across the Canadian prairies.


Figure 2.  Accumulated precipitation the past 30 days (from June 24-July 24, 2017) across the Canadian prairies.


Figure 3.  Long Term Normal (LTN) average temperatures over 30 days
 (from June 24-July 24) across the Canadian prairies.





Seven-day rainfall accumulations were low across the prairies ( Fig. 4). Total 30-day rainfall accumulations indicate that conditions are normal to dryer than normal for most of the prairies (Fig. 5). Growing season (April 1 – July 23, 2017) percent of average precipitation continues to be average for most of Alberta and below average for most of Saskatchewan and Manitoba.

Figure 4. Accumulated precipitation the past seven days (July 17-24, 2017) across the Canadian prairies.


Figure 5. Accumulated precipitation the past 30 days (June 24-July 24, 2017) across the Canadian prairies.


Figure 6.  Percent of average precipitation  for the across the Canadian prairies for
the growing season (April 1-July 24, 2017).

The lowest temperatures across the prairies over the past seven days (July 18-24, 2017) are mapped below.  

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



The growing degree day map (GDD) (Base 10ºC, March 1 – July 23, 2017) is below:


The growing degree day map (GDD) (Base 5ºC, March 1 – July 23, 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 – Greetings!

Greetings!

Please access the Weekly Update for July 27, 2017 (Week 13), as either a series of Posts  or a downloadable PDF.   


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

Subscribe to the Blog by following these three steps!

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 26Jul2017) is included below.

Weekly Update – Predicted Grasshopper Development

Grasshopper Simulation Model Output – Based on model output, grasshopper development is slightly ahead of long term averages. The greatest development was predicted to be across southern regions in all three provinces, particularly southern Alberta. Grasshoppers should be predominantly in the fourth and fifth instar stages with adults present across most of the region. 


  

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.

● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. 

● Grasshoppers that jump/fly through the field of view within a one meter width in front of the observer are counted. 

● A meter stick can be carried as a visual tool to give perspective for a one meter width.  However, after a few stops one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. 

● At the end point the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. 
● Compare counts to the following damage levels associated with pest species of grasshoppers:

0-2  per m² – None to very light damage
2-4  per m² – Very light damage
4-8  per m² – Light damage
8-12 per m² – Action threshold in cereals and canola


12-24 per m² – Severe damage 
>24 per m² – Very severe damage


* For lentils at flowering and pod stages, >2 per m² will cause yield loss.
* For flax at boll stages, >2 per m² will cause yield loss.



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

Weekly Update – Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) – Throughout April and May, both forward and backward wind trajectory data was compiled weekly to identify potential DBM arrival events from southerly source areas including Mexico and southwest USA or the Pacific Northwest.  This week, two biofix dates were selected as “starting points” used to apply the DBM model based on Harcourt (1954).  By selecting and presenting mapped model outputs for both a biofix date of May 1 (Fig. 1) AND May 21 (Fig. 3), the predicted number of generations of DBM can be estimated across the Canadian prairies as of July 24, 2017. The following maps indicate that potentially two generations have been completed across most of the prairies for both biofix dates (Fig. 1 and 3). 

Using Biofix of May 1Based on the biofix date of May 1, 2017, the model predicts two generations of DBM (e.g., areas highlighted in yellow) whereas southern Alberta populations are potentially in the third generation (Fig. 1).  The second map (Fig. 2), showing predicted results for Long Term Normal (LTN) data, indicates that populations in southern Alberta and the Peace River region are ahead of normal development (based on May 1 introductions)

Figure 1.  Predicted number of generations of Diamondback moth based on a biofix date of May 1, 2017.
Figure 2.  Predicted number of generations of Diamondback moth based on a biofix date of
May 1, 2017, but using Long Term Normal (LTN) data.

Using Biofix of May 21 – In the following scenario using biofix date of May 21, 2017 (Fig. 3), the number of generations of DBM are marginally behind the early May introduction presented above in Figure 1.

Figure 3.  Predicted number of generations of Diamondback moth based on a biofix date of May 21, 2017.


REMINDER – Once diamondback moth is present in the area, it is important to monitor individual canola fields for larvae.  Remove the plants in an area measuring 0.1 m² (about 12″ square), beat them on to a clean surface and count the number of larvae (Fig. 4) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.  The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1  (approximately 1-2 larvae per plant).


Figure 4. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.


Figure 5. Diamondback moth pupa within silken cocoon.



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

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


Figure 6. Diamondback moth.


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

● Low numbers of moths have been reported across Saskatchewan for the 2017 pheromone monitoring.  
● Manitoba Agriculture and Rural Initiatives posted low DBM counts which can be reviewed here.  
● Alberta Agriculture and Forestry has a live 2016 map reporting Diamondback moth pheromone trap interceptions.  A copy of the map (retrieved July 20, 2017) is below for reference.

Weekly Update – Bertha Armyworm

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

Manitoba counts as of July 26, 2017





Saskatchewan map as of July 19, 2017



Alberta map as of July 26, 2017



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 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.

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.

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 #10 (posted July 26, 2017) noting diamondback moth exceeding economic thresholds in some fields within the southwest and Gladstone areas, cereal aphids and soybean aphids plus the appearance of green cloverworm in some eastern Manitoba soybean fields.


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

Additionally, Danielle Stephens with Sask Ag reported that bertha moth counts in pheromone traps appears to have peaked over most areas of Saskatchewan during the week of July 17th. Cooperators operating BAW traps are asked to take down their traps the week of August 2nd and to submit their counts but also thanked for their ongoing support which makes the 2017 map possible.

● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (July 27, 2017) provided by Scott Meers. That reports notes surveying is underway targeting a ‘new’ midge in canola, continued scouting needed for diamondback moth with larval populations exceeding thresholds in a few canola fields at early pod stages in southern Alberta, appearance of low numbers of wheat leaf miner which is typically an occasional pest but seems to be accompanied by its parasitoid by K. Fry this year.

Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (July 24, 2017)
• Saskatchewan Agriculture Crop Report (July 18-24, 2017)

• Alberta Agriculture and Forestry Crop Report (July 18, 2017)


Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of July 23, 2017areas highlighted in yellow on the map below have accumulated sufficient heat for the initial C. tarsalis to begin to fly.  Areas highlighted in orange will have C. tarsalis flying so wear your DEET to stay protected!




The Public Health Agency of Canada posts information related to West Nile Virus in Canada.  In 2016, 104 human clinical cases of West Nile Virus were reported.  The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 15, 2017).  

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

Weekly Update – Active Wildfires

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

Update from the field….

Canola growers at the far south of Alberta will want to note this preliminary update kindly provided by Dr. H. Carcamo (AAFC-Lethbridge) on July 20, 2017 related to flea beetles in canola…..


“We just collected sticky cards from a canola field just east of Stirling that is part of a collaborative study led by Dr. Alejandro Costamagna. I noticed an unusual dominance by striped flea beetles in this field. 15 years ago only 1 out of a 1000 flea beetles would have been striped and the rest crucifer, however, the two fields we sampled today near Stirling AB were unusual.  Approximately 48% of the flea beetle population trapped on sticky cards in the one field were striped flea beetles and a second canola field had ~71% striped flea beetles.”


Dr. Carcamo goes on to caution that the above observation was based on only a single week of sticky card monitoring.  Stay tuned because the entire seasonal data set from these two sites will warrant careful scrutiny!  Even so, this update is an excellent example of the importance of in-field scouting and the value of ongoing data collection!


Review previously posted information about flea beetles in canola here.

Weekly Update – Previous Posts

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

Alfalfa Weevil (Week 11)

Brood X Cicadas


Cabbage seedpod weevil (Week 12)

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

Wheat midge
White grubs in fields (Week 9)

Wind trajectories

Weekly Update

Greetings!

A downloadable PDF version of the complete Weekly Update for Week 13 (July 27, 2016) can be accessed here.  

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

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



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

Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata– Reporting sites across the prairies have generally reported lower cumulative interceptions but moderate numbers have been intercepted a few sites within Manitoba and Saskatchewan.  Cumulative counts from pheromone traps are summarized and mapped by provincial staff in ManitobaSaskatchewan and Alberta.  Screen shots of the three maps are provided below:


Manitoba map (screenshot retrieved July 27, 2016):




Saskatchewan map (screenshot retrieved July 13, 2016):



Alberta map (screenshot retrieved July 27, 2016):





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





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

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


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

Cabbage seedpod weevil

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

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

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


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


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

Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has released a new live CSPW map and online reporting tool for growers.  A screenshot (retrieved 27 July 2016) is included below.


Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of July 24, 2016areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!




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




The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus.  As of July 27, 2016, 27 birds were submitted for testing yet none have tested positive for West Nile virus. 

Provincial Insect Pest Reports

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

– Manitoba’s Insect and Disease Update which includes lygus in canola, wheat midge, and a few sites showing moderate risk levels for bertha armyworm based on phermone trap interceptions (July 27, 2016, prepared by John Gavloski and Pratisara Bajracharya).


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

– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on July 21, 2016) and noted pea aphid risk in relation to pea and lentil seed maturity, froghoppers in ditches, leafminers in wheat, and reporting the occurrence of aphids in wheat in order to help researchers developing an action threshold.

Insect of the Week – Trichomalus lucidus

Cabbage seedpod weevil parasitoids


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

Early in the season, cabbage seedpod weevil adults can cause canola flower budblasting as they feed on developing flowers and later in the season, they will feed on pods. However it’s the larvae that cause most of the damage by feeding on developing seeds; infested pods are also more prone to shattering and may have a higher incidence of fungal infections. To the rescue are tiny wasp parasitoids that attack the adults (e.g. Microtonus melanopus) and larvae (e.g. Trichomalus lucidus).

For more information about these natural enemies, 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).


Trichomalus lucidus, a cabbage seedpod weevil parasitoid.
CC 3.0 BY-NC-SA CNC/BIO Photography Group, Biodiversity Institute of Ontario

Weekly Update – Weather Synopsis

Across prairies, the 7-day average cumulative rainfall also brought some strong storms with rain, wind and worse.


The following map reflects the number of days above 25°C across the prairies for the growing season as of July 18, 2016.



The accumulated precipitation for the growing season (April 1-July 24, 2016) is mapped below.




The map below shows the Lowest Temperatures the Past 7 Days (July 20-26, 2016) across the prairies:



The map below shows the Highest Temperatures the Past 7 Days (July 20-26, 2016):



The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 24, 2016) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – July 24, 2016) 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
Saskatchewan’s Cumulative Precipitation Map
Environment Canada’s Historical Data Interface

Weekly Update – Thrips

Thrips in canola (Thynsanoptera) – While surveying for swede midge this week in Saskatchewan, lots of thrips and curled pods were observed.  

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



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


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


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

Curled pods of canola caused by thrips feeding damage (Photos: AAFC-Saskatoon, Olfert et al. 1998)


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


Weekly Update – Aphids in canola

If you encounter aphids in canola, know that it could be one of several species!  The following was kindly offered by Dr. Julie Soroka (Research Scientist Emeritus with AAFC-Saskatoon):


A small survey was conducted in canola in central Saskatchewan in 2014 and 2015 and a few fields were observed with aphids.  When found, over 90% of the aphid colonies were turnip aphid (Lipaphis erysimi).  Of the remainder, more of the generalist feeder, the green peach aphid (Myzus persicae), was found than cabbage aphid (Brevicoryne brassicae).  Interestingly, several of the aphid colonies were infested with the parasitic wasp, Dieretiella rapae!

Weekly Update – Lygus

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

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

Fifth instar lygus bug nymph (3-4 mm long) (photo:  AAFC-Saskatoon).


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

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

Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.

Repeat the sampling in another 14 locations. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.

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


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

Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

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


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

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


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

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



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

Weekly Update – Cabbage root maggot

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


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

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

Weekly Update – Wheat midge

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


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

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



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




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

b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage. 



Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps.  A screen shot of the map is provided below (retrieved 27Jul2016).


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) – Descriptions related to the biology, monitoring and management of this insect can be reviewed on Week 12’s Post.  


For the week of July 27, 2016, the following map predicts that sufficient heat units have accumulated across the prairies for alfalfa weevils to be present. 



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


Reminder – 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 25, 2016)
– Saskatchewan Agriculture Crop Report (July 18, 2016)

– Alberta Agriculture and Forestry (for July 19, 2016)

Weekly Update – Previous Posts

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


Bertha armyworm development and flight

Bertha armyworm monitoring


Canola scouting chart
Cereal leaf beetle
Crop protection guides
Cutworms


Diamondback moth


Environment Canada’s radar maps to follow precipitation events


Flea beetles in canola


Grasshoppers


Iceburg reports
Insects in our diet


Monarch migration

Multitude of mayflies



Pea leaf weevil monitoring

Predicted cereal leaf beetle development

Predicted lygus bug development
Predicted wheat midge development


Swede midge


Weather Synopsis (Week 12)
Wind trajectories

Insect of the Week – Alfalfa looper

This week’s Insect of the Week is the alfalfa looper (Autographa californica Speyer) (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).