Category: Week 13

2023 Week 13 (Released August 3, 2023)

Insect scouting season continues! Development of many pest insects (and of their host crops) is ahead of schedule this year, thanks to warmer than average weather during this growing season.

Between fieldwork and summer vacations, this Weekly Update is a short one. Thankfully, Shelley Barkley (Alberta Agriculture and Irrigation), James Tansey (Saskatchewan Ministry of Agriculture) and John Gavloski (Manitoba Agriculture) have kindly shared information about what they are seeing for insect pests in their respective prairie provinces.

Adult grasshoppers are now in flight and are expected to be busy reproducing across the prairie region. Scouting individual fields is important to best estimate crop risk. Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture. 

Adult (brown with fully developed wings) and immature (green with wing ‘nubs’). Picture by Meghan Vankosky, AAFC-Saskatoon.

Diamondback moth, if present, should now be well into their fourth generation across the prairies. As warm temperatures prevail, remember that diamondback moth develop from eggs to adults quickly and the population increases with each generation. Scout canola fields for diamondback moth larvae. To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

Watch out for Invasive and Migrating Insects! If you suspect that you have found any of the insects on the Prairie Region Poster, please let us know using the form linked to the QR code on the poster. Note: many of us entomologists on the prairies are members of the Insect Surveillance Community of Practice!

On the topic of invasive insects, August is Tree Check Month! The Prairie Region Poster (and posters for BC, Ontario & Quebec, and Atlantic Canada) include invasive insect pests that could affect our forests in Canada.

Remember: 1) there are many resources available to help with planning for late-season insecticide applications to ensure Pre-Harvest Interval requirements are met, and 2) insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification are available from the Prairie Pest Monitoring Network.

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Questions or problems accessing the contents of this Weekly Update? Please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca) to get connected to our information. Past Weekly Updates, full of information and helpful links, can be accessed on our Weekly Update page.

Provincial Insect Updates

In Alberta, grasshopper population densities are high in the southeast and southcentral municipalities and the Agricultural Fieldmen are now starting to survey for adult grasshopper populations. There have been reports of wheat head armyworm in the central Peace River region, but there have also been Cotesia parasitoid cocoons in those fields, which is a good sign in terms of natural control of the armyworm population. Tiger moth caterpillars have also been reported in the central Peace River region; these are not typically pests but are interesting as they have been feeding on wild buckwheat.

Visit the Alberta Insect Pest Monitoring Network and Crop Insects pages for information about insects and monitoring in Alberta, including links for live maps from the 2023 monitoring season for diamondback moth, bertha armyworm, cutworms, and cabbage seedpod weevil.

Grasshopper densities are high in many parts of the prairies this year, especially now that adult grasshoppers are able to fly to disperse. With adults present, egg laying is likely to be underway. Picture by Jonathon Williams, AAFC-Saskatoon.

In Saskatchewan, grasshopper population densities are particularly high in the southern and central regions. Ripening canola crops are currently playing host to crickets (reported consuming pods), crucifer flea beetles, diamondback moth and Lygus bugs. Densities of diamondback moth and Lyugs have been economically significant in some regions, so scouting is important. Pea aphid and cereal aphid numbers appear to be increasing in some parts of the province, so scouting for these pests in their respective host crops is also important as the growing season winds down. There have been four reports of Hessian fly in Saskatchewan this summer.

Saskatchewan Crop Production News issues are now online! There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

A diamondback moth larva on a canola leaf. Population densities are high in some fields and scouting is needed to avoid unpleasant surprises. Picture by Jonathon Williams, AAFC-Saskatoon.

In Manitoba, aphid population densities have been high enough to warrant control in small grain cereal crops in some regions, especially where crops were planted late and crops are still in vulnerable stages. Where there are a lot of aphids in fields, there have also been lots of lady beetle larvae and aphid mummies (resulting from aphids being attacked by parasitoids). A few fields in the Cypress River/Balder area of Manitoba have been sprayed for bertha armyworm. Some canola fields have been sprayed for diamondback moth and Lygus bugs in the Eastern region, and for diamondback moth in the Interlake region. Like in Saskatchewan, crucifer flea beetles are now active again, and are feeding on green canola.  A soybean field in the Central region of Manitoba was treated for spider mites. Some insecticide applications for banded sunflower moth have occurred in the Eastern region. Grasshoppers are numerous in crops in some areas, and pastures in some areas have been sprayed for grasshoppers. John spotted some dead grasshoppers clinging to the upper leaves of plants that were infected with the pathogen Entomophaga grylii, but the incidence of infection has been low so far this year. Scout for aphids in cereal crops and for a variety of insects in canola fields.

Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year).

Prairie Research

*This text was prepared by Kanishka Seneveirathna, Natalie LaForest, and Boyd Mori from the University of Alberta

Under the supervision of Dr. Boyd Mori at the University of Alberta, the ecological and agricultural entomology lab employs diverse molecular methods to tackle pest-related problems and develop integrated pest management approaches. Here we highlight research conducted by two graduate students: Kanishka Seneveirathna and Natalie LaForest.

Kanishka’s research uses population genetics to detect and monitor invasive insects in the prairie ecosystem. His research focuses on reconstructing the invasion routes of wheat midge (Sitodiplosis mosellana) and diamondback moth (Plutella xylostella), two devastating pests, by determining their origins in North America. To understand their invasion patterns, Kanishka employs a genomic approach (RADSeq), which allows for genome-wide population structure analysis.

A pheromone trap (left) used to collect adult wheat midge for population genetic analyses. The adult midge are trapped on a sticky card (right). Pictures by Kanishka Seneveirathna, University of Alberta.

By reconstructing the invasion routes of these pests, Kanishka aims to identify their origins and determine the genetic diversity and structure of different populations. This comprehensive understanding will facilitate the development of integrated pest management strategies, including forecasting systems and insecticide resistance management strategies. Initial findings indicate multiple independent invasion events for wheat midge across North America.

Moving forward, Kanishka and the Mori Lab team will work with members of the PPMN to collect a larger number of samples across the Prairies, ensuring comprehensive coverage. Collaboration with international research groups is also on the agenda, enabling the validation of findings and broader knowledge exchange. The goal is to develop effective management strategies to mitigate the damage caused by these invasive pests and enhance the productivity and quality of canola and wheat crops in the Canadian Prairies.

Pheromone traps (A) are used to collect adult diamondback moths in canola fields. Once trapped, the moths are removed from the sticky cards that are placed on the floor of the pheromone trap (B). To collect diamondback moth larvae for population genetic analyses, canola is sampled using sweep nets (C). Pictures by Kanishka Seneveirathna, University of Alberta.

Natalie’s research focuses on integrated pest management, more specifically the ecosystem service of weed seed predation performed by ground beetles (Coleoptera: Carabidae). Previous research on determining the species of weeds consumed by this group of beneficial insects have used seed cards in the field or cafeteria choice tests in the laboratory. Natalie’s work uses a multiplex-PCR approach, where she uses the DNA found within the gut of field captured ground beetles to determine what the ground beetles are consuming in the field. She is designing species-specific primers of agronomic significant weeds to decipher this significant predator-prey interaction. 

Throughout the 2021 and 2022 seasons, the most abundant ground beetle species collected has been Pterostichus melanarius, which is an introduced, opportunist generalist predator. Natalie is focusing on ground beetles in wheat and industrial hemp, but there are other members in the Mori lab looking at the prey items of ground beetles in canola and pulses. Identifying species specific predator-prey interactions will development more sustainable pest management strategies for producers.

A pitfall trap full of adult ground beetles (Coleoptera: Carabidae); pitfall traps are used to collect ground beetles and other insects during the growing season. Picture by Natalie LaForest, University of Alberta.

Pre-Harvest Intervals (PHI)

As harvest gets started, it is necessary to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.

Helpful resources include:
• The Keep It Clean website, with information about PHI and Maximum Residue Limits (MRL)
• The Pest Management Regulatory Agency fact sheet, “Understanding Preharvest Intervals for Pesticides”, with a free copy available to download
• Keep It Clean’s “Pre-Harvest Interval Calculator” that will help to accurately estimate PHI for a variety of crops
• The Pre-Harvest Glyphosate Stage Guide
• The provincial crop protection guides include the PHI for every pesticide by crop combination. The 2023 Crop Protection Guides are available as FREE downloadable PDFs for Alberta, Saskatchewan, and Manitoba.

English Grain Aphid

The English grain aphid (Sitobion avenae) is a pest that infests wheat, barley, oat, rye, timothy, and canaryseed. Adults are 1.5 to 2 mm in size and yellow-green to reddish-brown with black antennae, leg joints, and cornicles. Nymphs are similar in appearance, but smaller in size. 

Adults and nymphs of the English grain aphid. Picture credit: Jennifer Otani, AAFC-Beaverlodge.

Aphids are typically found on the heads of cereal crops, where they feed on the ripening kernels. Feeding damage results in shriveled kernels and leaf discoloration. Severe infestations result in large visible bronze or brown patches in the field. English grain aphids produce honeydew, a sugary liquid waste, that can promote the infestation and growth of saprophytic and pathogenic fungi on cereal heads. This aphid is also a vector for barley dwarf virus, which can severely stunt plants and prevent heading. 

English grain aphids on a cereal head. Picture credit: Jennifer Otani, AAFC-Beaverlodge.

The economic threshold for English grain aphids in spring wheat in western Canada is 12-15 aphids per head prior to the soft dough stage. The number of aphids per head should be recorded on 20 tillers at five different spots scattered throughout the field to ensure an accurate estimate of their population density. Scouting should occur from June until the soft-dough stage is reached. Early seeding may allow crops to move past susceptible stages before aphid populations reach damaging thresholds and reduce risk for barley yellow dwarf virus.  

More information related to English grain aphid and other aphid species can be found on provincial the Manitoba Agriculture page. For more information, check out the English grain aphid page in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien).  

Released August 5, 2022

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Aphids in field crops
• Lygus bug monitoring
• Pre-harvest intervals (PHI)
• Provincial insect pest report links
• Crop report links
• Previous posts
….and Monday’s Insect of the Week for Week 13 – it’s spotted wing drosophila (Drosophila suzukii)!

Wishing everyone good SCOUTING weather!

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

Weather synopsis

TEMPERATURE: Average temperatures for the 2022 growing season have been similar to long-term average temperature values. This past week (July 25-31, 2022), the average daily temperature on the prairies was 1 °C cooler than the average daily temperature of the previous week and 1.5 °C warmer than the long-term normal temperature. The coolest temperatures were observed across Manitoba and eastern Saskatchewan (Fig. 1).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of July 25-31, 2022.

The prairie-wide average 30-day temperature (July 2 – July 31, 2022) was 1.5 °C warmer than the long-term average value. Average temperatures have been warmest across a region that extends south from Lethbridge to Saskatoon to Winnipeg (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of July 02 to July 31, 2022.

The average growing season (April 1-July 31, 2022) temperature for the prairies has been similar to climate normal values. The growing season has been coolest across the Parkland and Peace River regions (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 31, 2022.

PRECIPITATION: Last week (July 25 to 31), southern Alberta and southwestern Saskatchewan received the lowest amounts of rain of locations across the prairies (Fig. 4). Over the last 30 days (July 2 – July 31, 2022), rainfall amounts have been well below average for northern Alberta and near normal across the central and southern regions of Alberta and Saskatchewan (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 25-31, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (July 02 – July 31, 2022).

Precipitation has been above normal in Manitoba. The average growing season rainfall for the prairies (April 1 – July 31, 2022) has been approximately 150% of normal. Total rainfall continues to be greatest across Manitoba and eastern Saskatchewan; cumulative rainfall amounts have been much lower for the central and western regions of Saskatchewan and Alberta. Cumulative rainfall amounts have been near normal for the remainder of Saskatchewan and in Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 31, 2022.

Growing degree day (GDD) maps for the prairies can be accessed by using the AAFC Maps of Historic Agroclimate Conditions interface.

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

Predicted grasshopper development

The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Model outputs provided below as geospatial maps are a tool to help time in-field scouting on a regional scale yet local development can vary and is only accurately assessed through in-field scouting.

Some areas of the Canadian prairies are presently experiencing high densities of economically important species. Review lifecycle and damage information for this pest to support in-field scouting.

Model simulations were used to estimate grasshopper development as of July 31, 2022. Grasshopper development has progressed rapidly over the past few weeks and development rates are more advanced this year than expected based on long-term climate normal values. Based on estimates of average development, populations should consist of 4th (18%) and 5th (37%) instar nymphs and adults (33%) across the southern regions of all three prairie provinces (Fig. 1). Adults should now be occurring across the southern regions of all three prairie provinces (Fig. 1). Model output indicates that oviposition (egg-laying) is now occurring across the southern prairies (Fig. 2). Potential risk continues to be greatest across the central and southern regions of Saskatchewan.

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 31, 2022.
Figure 2. Percent of the migratory grasshopper (Melanoplus sanguinipes) predicted to be in the egg stage across the Canadian prairies as of July 31, 2022.

Grasshopper Scouting Tips:
● Review grasshopper diversity and photos of nymphs, adults, and non-grasshopper species to aid in-field scouting from egg hatch and onwards.
● Access the PPMN’s Grasshopper Monitoring Protocol as a guide to help implement in-field monitoring.
● Review grasshopper lifecycle, damage and scouting and economic thresholds to support sound management decisions enabling the preservation of beneficial arthropods and mitigation of economic losses.

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta 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” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. Review the historical grasshopper maps based on late-summer in-field counts of adults performed across the prairies.

Predicted diamondback moth development

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

Model simulations to July 31, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) is currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater this year than expected based on long-term average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 31, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 31, based on climate normal data.

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

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

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

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Figure 4. Diamondback moth pupa within silken cocoon.
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Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

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 that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

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

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

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

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

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

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

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.

Aphids in field crops

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

• Aphidius wasp (Insect of the Week; 2015 Wk15)
• Aphids in canola (Insect of the Week; 2016 Wk13)
• Aphids in cereals (Insect of the Week; 2017 Wk09)
• Cereal aphid manager APP (Weekly Update; 2021 Wk07)
• Ladybird larva vs. lacewing larva (Insect of the Week; 2019 Wk18)
• Ladybird beetles and mummies (Weekly Update; 2020 Wk15)
• Lygus bug nymphs vs. aphids (Insect of the Week; 2019 Wk16)
• Hoverflies vs. bees vs. yellow jacket wasps (Insect of the Week; 2019 Wk19)
• Soybean aphids and aphid annihilating allies (Insect of the Week; 2022 Wk07)
• Syrphid flies (Insect of the Week; 2015 Wk16)

Pre-Harvest Intervals (PHI)

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

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keep It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keeping It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop’s already been sprayed.
◦ To find a pesticide to suit your timeline.
• Access the Pre-Harvest Glyphosate Stage Guide.
• And remember Provincial crop protection guides include the PHI for every pesticide x crop combination. The 2022 Crop Production Guides are available as a FREE downloadable PDF for Alberta, Saskatchewan, and Manitoba.

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 2022 are up and running! Access the August 3 issue as a PDF on their website. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more!
• Pests of greatest concern in Manitoba from July 28 to August 3 were armyworms, aphids and grasshoppers. The August 3 update has great information on scouting and monitoring for these pests!

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #5 (URL retrieved July 28, 2022) and find updates linking to information for Beneficial insects, and Managing grasshoppers. Bookmark their insect pest homepage to access important information! Crops Blog Posts are updated through the growing season.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember that Agri-News occasionally includes insect-related information. Twitter users can connect to #ABBugChat Wednesdays at 10:00 am MDT.

Crop report links

Click the provincial name below to link to online crop reports produced by:
• Manitoba Agriculture and Resource Development
• Saskatchewan Agriculture
• Alberta Agriculture, Forestry, and Rural Economic Development

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (link to August 1 report on right of the page)
• The USDA’s Weekly Weather and Crop Bulletin

Previous posts

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2022 Posts (organized alphabetically):
• 2021 Risk and forecast maps
• Alfalfa weevil – predicted development (Wk06)
• Bertha armyworm – predicted development (Wk07)
• Cereal leaf beetle – predicted development (Wk06)
• Crop protection guides (Wk02)
• Cutworms (Wk02)
• European corn borer – Canadian standardized assessment 2.0 (Wk02)
• Field heroes (Wk08)
• Field guides – New webpage to access (Wk02)
• Flea beetles (Wk01; IOTW)
• iNaturalist.ca (Wk02)
• Invasive insect species – Early detection (Wk02)
• Scouting charts – canola and flax (Wk03)
• Ticks and Lyme disease (Wk02)
• Wind trajectory reports released in 2

Spotted Wing Drosophila

With the 2022 growing season well underway, we decided to feature an insect that is becoming a growing problem on the Canadian Prairies: Spotted Wing Drosophila (SWD), Drosophila suzukii.

This invasive insect is thought to have originated in southeast Asia. The first record of SWD is from Japan in 1916. SWD is now established in small and stone fruit production areas throughout North America. SWD has been reported in British Columbia since 2009, and was first reported in Alberta in 2010. Occurrence in Alberta, and low levels in southern Manitoba in 2019 suggested that SK infestations were likely imminent. Monitoring for this pest conducted by the Saskatchewan Ministry of Agriculture began in 2019. Populations were detected throughout the province that year, spurring continued monitoring. Data from 2021 and 2022 indicate continued widespread distribution throughout the province. Early season detection of significant numbers suggests overwintering populations on the prairies.

SWD is an economic pest of many soft fruits, including raspberries, strawberries, cherries, blueberries and plums. Saskatoon berry has been documented as a host. Haskap is also considered to be susceptible but may escape major damage, as SWD populations typically do not increase until after harvest. However, Ontario haskap growers have seen economic losses when a mild winter is coupled with factors that lead to delayed ripening. SWD adults are 3-4 mm, yellow-brown with red eyes. Males have a conspicuous spot on the leading edge of each wing (Figure 1).

Figure 1. Spotted Wing Drosophila, male. Photo Credit: Encyclopedia of Life; Martin Cooper; University of Nebraska-Lincoln Dept. of Entomology

Females lack the spots but have a characteristic large, serrated ovipositor (Figure 2).

Figure 2. Spotted Wing Drosophila, female. Photo Credit: Encyclopedia of Life; Martin Cooper, University of Nebraska-Lincoln Dept. of Entomology

SWD overwinter as adults. These become active in the spring, mate and seek egg-laying sites. Female SWD lay as many as 16 eggs per day for up to two months. An average of 384 eggs are produced by each female. With their serrated ovipositor, female SWD deposit eggs under the skin of healthy, ripening fruit. Oviposition sites look like pin-holes in the skin (Figure 3). These can also serve as avenues of entry to pathogens like brown rot and botrytis.

Figure 3: SWD-damaged cherry showing oviposition scars. Photo Credit: Martin Hauser, California Department of Food and Agriculture

Several larvae can occur per fruit (Figure 4). Larval feeding causes fruit to become prematurely soft and unmarketable. Larvae mature in 3-13 days and pupate most commonly in the fruit. The pupal stage lasts another 3-15 days. Multiple generations per year are common.

Figure 4. SWD larva inside raspberry. Photo: Bugwood.org, Hannah Burrack

Although SWD adults can be moved around by winds, movement of contaminated plant material is the major route for initial dispersal. Current management includes culling and destruction of soft fruit and the application of insecticides to limit populations. There are several products registered to control SWD. These can be found here: http://pr-rp.hc-sc.gc.ca/ls-re/index-eng.php. Use the search term ‘spotted wing drosophila’. Product updates occur periodically so check this site regularly.

Weekly Update

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

Be sure to catch the Insect of the Week – it’s wheat stem sawfly!

Stay safe and good scouting to you!

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

Weather synopsis

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

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

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

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

Prairie-wide survey of stored grain pests

Scientists are looking for volunteers to help conduct a survey of stored grain pests on the Canadian Prairies. The goals of this survey are to:
1) detect potentially new invasive grain pests to the area,
2) know the nature of the insect species currently occurring in farm grain bins,
3) determine the prevalence of those species, and 4) determine the conditions under which these species occur.
The data collected will help assess current and future threats to the grain supply on the Canadian Prairies and help focus research efforts. Producers willing to participate will be notified of the results obtained on their farm, as well as the results of the overall survey.

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

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

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

Fuzzy white “eggs” on wheat or barley heads?

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

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

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

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

Pre-Harvest Intervals (PHI)

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

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

West nile virus risk

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

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

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

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

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

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

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

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

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

Crop report links

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

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

Previous posts

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

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 Alberta, Saskatchewan 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 Manitoba, Saskatchewan, Alberta 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 Agriculture, Saskatchewan Agriculture, Alberta 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.  

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

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

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

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

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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. 

This image has an empty alt attribute; its file name is 1998_EconomicThreshold_LateFlower-EarlyPod_Captions-1024x488.png
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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 in 2020 with a Pest and Predators podcast series!

• Access Episode 1 – Do you know your field heroes? Jennifer Otani (Agriculture and Agri-Food Canada-Beaverlodge) and Shaun Haney (RealAg). Published online May 12, 2020.

• Access Episode 2 – An inside look at the Prairie Pest Monitoring Network. Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon) and Shaun Haney (RealAg). Published online May 26, 2020.

• Access Episode 3 – How much can one wasp save you? Haley Catton (Agriculture and Agri-Food Canada-Lethbridge) and Shaun Haney (RealAg). Published online June 9, 2020.

• Access Episode 4 – Eat and be eaten — grasshoppers as pests and food John Gavloski (Manitoba Agriculture and Resource Development) and Shaun Haney (RealAg). Published online June 23, 2020.

• Access Episode 5 – Killer wasp has only one target — wheat stem sawfly Scott Meers (Mayland Consulting) and Shaun Haney (RealAg). Published online July 7, 2020.

• Access Episode 6 – Plentiful parasitoids Tyler Wist ( Agriculture and Agri-Food Canada-Saskatoon) and Shaun Haney (RealAg). Published online July 21, 2020.

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 human, mosquito, bird 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.

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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@agr.gc.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 Agriculture, Saskatchewan Agriculture, Alberta 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 Manitoba, Saskatchewan, Alberta 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.

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

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. 

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)

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!

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 Agriculture, Saskatchewan Agriculture, Alberta 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.

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 Manitoba, Saskatchewan, Alberta 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 Forestry, Saskatchewan 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.

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 human, mosquito, bird 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:

Crop reports

Crop reports are produced by:

The following crop reports are also available:

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.

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 a 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 Forestry, Saskatchewan 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 Development, Saskatchewan Agriculture, Alberta 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 1 – Based 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 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).


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 Development, Saskatchewan Agriculture, Alberta 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 Manitoba, Saskatchewan 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 Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network.  Also refer to the bertha armyworm pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Weekly Update – 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.

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, 2017, areas 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. 

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 Manitoba, Saskatchewan 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 Manitoba, Saskatchewan, Alberta 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 Forestry, Saskatchewan 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, 2016, areas 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 5, prepared 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!