2023 Week 14 (Released August 10, 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.

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. At this time of year, we start to look forward to next season. Insect surveyors are now working to estimate grasshopper populations in ditches/roadsides and may be collecting samples of adult grasshoppers for species identification.

Diamondback moth, if present, are into the fourth non-migrant generation across most of the prairies now. Keep in mind that diamondback moth develop quickly in warm weather which could lead to rapidly increasing populations over the summer.

Use the links in the Provincial Insect Updates post to learn more about what is happening with insect pest (and beneficial insect) populations in your province.

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.

Finally, due to the long weekend and my departure for southern Saskatchewan early on Tuesday morning (to help with the aforementioned grasshopper survey), I wasn’t able to post the Insect of the Week until today. This week, we feature Aphidius spp. parasitoids, an important natural enemy of aphids.

To receive Weekly Updates automatically, please subscribe to the website!

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.

Weather Synopsis

Warm, dry conditions continue to persist across most of the prairies. This past week (July 31 – August 6, 2023), the prairie average daily temperature was almost 2°C warmer than climate normals. The coolest temperatures occurred across central and northern Alberta (Fig 1). The warmest weekly average temperatures occurred across Saskatchewan and Manitoba (Fig. 1). 

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of July 31 – August 6, 2023. 

Average temperatures over the past 30 days (July 8 – August 6, 2023) have been 1°C above normal; many locations in the Peace River region have reported 30-day average temperatures that were 2°C warmer than average. The warmest temperatures were reported across southern regions of Alberta and Saskatchewan (Fig. 2).

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 8 to August 6, 2023. 

Precipitation for the period of July 31 – August 6, 2023 was minimal across most of the prairies (Fig. 3).

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 31 – August 6, 2023. 

In both the last 7 days and in the last 30 days, northern Alberta has had the most rainfall (Fig. 4). The average cumulative precipitation across the prairies from July 8 to August 6, 2023 was 39 mm, which is about 74% of the cumulative precipitation expected for the same period based on long-term average weather data.

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 8 -August 6, 2023. 

In the 2023 current growing season, the warmest and driest area of the prairies continues to be across southern Alberta and the western half of Saskatchewan. 

Predicted Grasshopper Development

As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of normal in 2023. This year, adults have occurred much earlier than normal (middle of June in some locations!) and simulations also indicate that adult females have begun laying eggs much earlier than normal. As of August 6, 2023, grasshopper models predict that grasshoppers oviposition is now occurring across most of the prairies (Fig. 1), assuming grasshoppers are present. Using an oviposition index, the model indicates the greatest potential for grasshopper oviposition in southern Alberta, southern Saskatchewan, and southern Manitoba.

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of Augst 6, 2023. Higher ovipositional index values indicate greater potential for oviposition. 

Compared to a ‘normal’ year (based on 30-year long-term average weather data), the potential for grasshopper oviposition in 2023 in early August is very high. In a ‘normal’ year, the grasshopper development model predicts that oviposition would be underway in early August, but only in the southern region of the prairies, and with a lower average oviposition index (Fig. 2) than predicted for 2023 (Fig. 1).

Figure 2. The predicted oviposition index for grasshoppers (Melanoplus sanguinipes) across the Canadian prairies as of August 6, predicted using long-term average (i.e., climate normals) weather data. Higher ovipositional index values indicate greater potential for oviposition. 

Geospatial maps are a tool to help time in-field scouting on a regional scale but grasshopper development and population densities can vary from place to place. Scouting is required to accurately assess the stage of grasshopper development and to estimate grasshopper densities.

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 IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

Predicted Diamondback Moth Development

After arriving in western Canada in the spring, migrant diamondback moths begin to reproduce. In western Canada, there are usually up to four non-migrant generations of diamondback moth produced in ‘local populations’ during the growing season.

Due to warm weather in 2023, development of diamondback moth populations is well ahead of average development. Model simulations to August 6, 2023, indicate that the fourth generation of non-migrant adults (based on early May arrival dates) are currently occurring across the Canadian prairies (Fig. 1).

Figure 1.  Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 6, 2023. 

In a ‘normal year’ based on climate normals data (e.g., 30-year averages), we would expect only the third generation of non-migrant diamondback moth to be occurring at this time of the year.

Figure 2. The predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 6, based on climate normals data.

Some areas of the prairies might be at risk of damage from diamondback moth this summer, based both on pheromone trap results for adult moths this spring and on the presence of high numbers of larvae in canola samples. Pheromone traps with cumulative counts greater than 25 male moths were located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan and in all regions of Manitoba (see the July 5 and July 19 editions of the Crop Pest Report). In Alberta, Shelley Barkley has found high numbers of diamondback moth larvae in canola samples from Yellowhead county, Parkland county, Lac St. Anne county, the Barrhead area, the Leduc area, and the Bonnyville area (so far).  

Because diamondback moth can have multiple generations in a single growing season and because the generation time is shorter when temperatures are warm, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises at the end of this summer.

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.

Provincial Insect Updates

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.

Saskatchewan Crop Production News issues are now online! Issue 4 is now online, as is a crop report up to the end of July, 2023 (available here). There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

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). The August 9 issue provides an update on Lygus bugs, diamondback moth, flea beetles, grasshoppers and aphids. It also has great pictures of beneficial insects!

Pre-Harvest Intervals

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 AlbertaSaskatchewan, and Manitoba.

Aphidius Parasitoid Wasps 

Aphidius spp. parasitoid wasps (Hymenoptera: Aphidiidae) are important natural enemies of aphids. Their hosts include over 40 aphid species! Female parasitoids lay individual eggs inside aphid nymphs. After hatching, the parasitoid larva consumes its host, eventually killing it. The parasitoid pupates inside the dead or mummified aphid before a new adult parasitoid emerges. New generation adult parasitoids chew a hole in the mummified aphid to exit and immediately search for new aphid hosts. 

Aphid mummies are the result of parasitism by Aphidius spp. parasitoids. Picture by Jennifer Otani, AAFC-Beaverlodge Research Farm.

Aphid mummies look bloated and discoloured compared to healthy adult aphids. Parasitism rates can be estimated by counting the number of aphid mummies on five host plants at five locations within a field. 

For more information about the predators and parasitoids of aphids, visit 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).   

To learn more about some of the natural enemies fighting insect pests in background visit www.fieldheroes.ca or follow @FieldHeroes on Twitter. 

Released August 12, 2022

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Lygus bug monitoring
• Aphids in field crops
• Pre-harvest intervals (PHI)
• Provincial insect pest report links
• Crop report links
• Previous posts
….and Monday’s Insect of the Week for Week 14 – it’s foreign grain beetle (Ahasverus advena)!

Wishing everyone good SCOUTING and harvesting weather!

To receive free Weekly Updates automatically, please subscribe to the website!

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 values. This past week (August 1-7, 2022), the average daily temperature across the prairies was 2°C cooler than the previous week and 1°C  warmer than the long-term normal (climate normal). The warmest temperatures were observed for the southern prairies (Fig. 1).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of August 1-7, 2022.

The prairie-wide average 30-day temperature (July 9 – August 7, 2022) was 1.5°C warmer than long-term average values. Average temperatures have been warmest across southeastern Alberta and southwestern Saskatchewan (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of July 9 to August 7, 2022.

The average growing season (April 1 – August 7, 2022) temperature for the prairies has been similar to that expected based on 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 August 7, 2022.

PRECIPITATION: The lowest weekly (August 1 to 7) precipitation accumulation occurred across southern and central regions of all three prairie provinces (Fig. 4). 30-day (July 9 – August 7, 2022) rainfall amounts have been well below average for northern and western Alberta and near normal across the central and southern regions of Alberta and Saskatchewan (Fig. 5). Precipitation has been above normal in southeastern Saskatchewan and eastern Manitoba.

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 1-7, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (July 9 to August 7, 2022).

Average growing season rainfall for the prairies (April 1 – August 7, 2022) has been approximately 160% of normal. Total rainfall continues to be greatest across Manitoba and eastern Saskatchewan. Cumulative rainfall amounts have been near normal for Saskatchewan and Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to August 7, 2022.

Growing degree day (GDD) maps can be accessed 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 August 7, 2022. Potential risk continues to be greatest across central and southern regions of Saskatchewan and southeastern Alberta. Adults should now be occurring across central and southern regions of all three prairie provinces. Females are beginning to lay eggs in the soil. Development of grasshopper populations near Moose Jaw, Saskatchewan suggests that local populations are in the adult stage and that oviposition is progressing (Fig. 1). Model output indicates that populations are transitioning to the egg stage (Fig. 2). Potential risk continues to be greatest across the central and southern regions of Saskatchewan.

Figure 1. Predicted development of the migratory grasshopper (Melanoplus sanguinipes) population near Moose Jaw, Saskatchewan as of August 7, 2022.
Figure 2. Percentage of the migratory grasshopper (Melanoplus sanguinipes) population expected to be in the egg stage across the Canadian prairies as of August 7, 2022.

Earlier oviposition can result in above average production of eggs and increased overwintering survival of eggs. The oviposition index provides a method to assess where egg production is greatest; higher oviposition index values indicate where egg production is greatest. Model runs for the 2022 growing season (April 1 to August 7, 2022) predict that oviposition rates should be greatest near Winnipeg, Manitoba, Moose Jaw, Saskatchewan and Medicine Hat, Alberta (Fig. 3).

Figure 3. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 7, 2022 . Higher ovipositional index values indicate greater potential for oviposition.

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 DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (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 August 7, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across most of the prairies (Fig. 1). DBM development is predicted to be marginally greater in 2022 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 August 7, 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 August 7, based on climate normal data.

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

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. 2) 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  (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).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Adult diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan 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)

Remember your 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 a PDF copy of the latest report on their website. July 27, 2022 issue here. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more!

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, AAF’s Agri-News occasionally includes insect-related information. Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Wheat midge pheromone monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.
Cabbage seedpod weevil monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.
Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.

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.
• 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)
Wheat midge – predicted development (Wk12)
Wind trajectory reports (Wk09)

THE FOREIGN GRAIN BEETLE

The foreign grain beetle (Ahasverus advena) is one of the most commonly encountered insect species in farm-stored grain in Canada. Because it often is found in stored grain, it was thought to be a grain pest, but research has shown that the foreign grain beetle is instead chiefly a mould feeder. Its presence in stored grain tells much about the state of the grain.

Because it feeds on mould, the presence of foreign grain beetles in a grain bin is a telltale sign that grain is likely going out of condition somewhere in the bin. For example, if the grain hasn’t been appropriately aerated it could be that a hot spot is forming in the centre or top of the pile, or, if snow has blown into the bin, the mouldy grain may be restricted to the top of the pile. In many instances, when we encounter foreign grain beetles we cannot readily see mouldy grain, but measuring the grain temperature and moisture content at the very centre of the top of the pile (top of the cone) should show that the condition of the grain is beyond that recommended for safe storage (see link below text) and that grain quality has likely started to deteriorate.

Foreign Grain Beetle on a kernel of wheat. Photo: Vincent Hervet, AAFC

To learn more about current storage practices, storage issues, and to understand the main insect issues in stored grains across the Canadian prairies, Dr. Vincent Hervet with Agriculture and Agri-Food Canada (vincent.hervet@agr.gc.ca) is currently surveying insects in farm grain bins across the Prairie Provinces of Canada. Preliminary results collected over the last two years in Manitoba, predominantly from stored wheat, showed grain insects were present in most bins. To our surprise, most of the insects collected were chiefly mould feeders (61 % of all insects collected in 2020 were mould feeders and 99 % of all insects collected in 2021 were mould feeders), and these mould feeders were present in 72 % of the bins sampled. The most commonly collected insect species was by far the foreign grain beetle.

Different reasons can explain these results, such as precipitations during harvest or weather conditions that did not allow for quick drying and cooling of the grain after harvest, but there may also be a lack of awareness of best storage management techniques. Therefore, we need to continue this research over the next few years to obtain meaningful data. To this end, volunteer growers in Alberta, Saskatchewan, and Manitoba are sought to participate in this survey so we can better understand issues in farm-stored grain and how to address them.

HOW YOU CAN HELP: If you wish to participate in this survey, or if you wish to have more details about the survey, please contact Dr. Vincent Hervet (vincent.hervet@agr.gc.ca; 204-915-6918).

Access these valuable resources provided by the Canadian Grain Commission:
• Review or bookmark these Safe Storage Charts.
• Find more information on the Management of Stored Grain.

Weekly Update

Week 14 and it’s been another hot week for most of the prairies! This week review the weather synopsis and the historic above-average values for temperature. Once again, notice both the number of days various areas of the prairies have experienced >25 °C or >30 °C but ALSO the number of consecutive days of >25 °C or >30 °C!

Be sure to catch the Insect of the Weekit’s the migratory grasshopper!

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 past week (July 26 – August 1, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. The warmest temperatures were observed across the southern and central regions of Alberta and Saskatchewan (Fig. 1).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of July 26 – August 1, 2021.

Across the prairies, the average 30-day (July 3 – August 1, 2021) temperature was 2.5 °C warmer than climate-normal values. The warmest temperatures were observed across the southern prairies (Table 1; Fig. 2). Temperature anomalies for July indicated that the entire Canadian prairies were warmer than normal (Fig. 3). The Peace River region, Edmonton area, and southern Manitoba experienced average temperatures most similar to climate-normal values. July average temperatures for southern Alberta and Saskatchewan (southwest and northeast) were 3-4 °C warmer than normal. Lethbridge and Swift Current average temperatures were 3.1 °C warmer than climate-normals.

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 3 – August 1, 2021.
Figure 3. Temperature anomalies (difference from climate-normal values) for average temperature (°C) observed across the Canadian prairies for the period of July 3 – August 1, 2021.

The 2021 growing season (April 1 – August 1, 2021) has been 1.5 °C warmer than average (Table 2; Fig. 4). Growing season temperature anomalies indicate that Parkland and Peace River regions have been 2-3 °C warmer than climate-normals (Fig. 5).

Figure 4. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 1, 2021.
Figure 5. Temperature anomalies (difference from climate-normal values) for average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 1, 2021.

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 26-August 1, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >13 °C while the highest temperatures observed ranged from <25 to >37 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 1, 2021). At this point in the growing season, review the astonishing consecutive number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 1, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: Weekly (July 26 – August 1, 2021) rainfall amounts were generally less than 5 mm (Fig. 6). Rainfall amounts for the period of July 3 – August 1 (30-day accumulation) have been well below average with most of the prairies receiving less than 40 % of the average amount for this time period (Fig. 7). Accumulated rainfall varied significantly. Grande Prairie and Swift Current reported near-normal rainfall while Saskatoon (13.5 % of normal) and Winnipeg (21.6 % of normal) received minimal rainfall during July (Table 1).

Figure 6. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 26 – August 1, 2021.
Figure 7. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 3 – August 1, 2021.

Growing season precipitation has been below average across most of the prairies. A region extending from Regina to the USA border is the only region that has reported near-normal rainfall for the period of April 1 – August 1, 2021, whereas a region extending from Lethbridge to northeastern Saskatchewan has received less than 100 mm of rain (Table 2; Fig. 8).

Figure 8. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 1, 2021.

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.

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 August 1, 2021, indicate that the third and fourth generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Compared to long-term average data (climate normal) sufficient heat units have accumulated to produce a predicted an additional generation for the current growing season (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 1, 2021.
Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 1 (based on climate normals data).

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  (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).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted grasshopper development

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of August 1, 2021. Compared to average growing season temperatures, above-average temperatures during June and July continue to result in a noticeable increase in the rate of grasshopper development. Based on climate-normals, grasshopper populations near Saskatoon should have been in the fifth instar and adult stages on July 31 (Fig. 1).

Figure 1. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021, based on climate normals data).

Oviposition generally begins in early August. This year, the average July temperature at Saskatoon was 2.8 °C warmer than normal, resulting in advanced development of grasshopper populations. Based on a survey conducted across central, southern, and western regions of Saskatchewan, adults were observed during the first week of July. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July (Fig. 2).

Figure 2. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021.

The onset of oviposition earlier in a growing season can result in above-average production of eggs leading to higher risk of grasshopper issues the following growing season (e.g., 2022). Climate data suggests that, as of August 1, oviposition would be expected to occur in localized areas across the prairies (Fig. 3). Model runs for the 2021 growing season (April 1 – August 1) predicted, as a result of above-normal temperatures, that oviposition should now be occurring across most of the prairies (Fig. 4)

Figure 3. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021 (based on climate normals data).
Figure 4. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021.

Grasshopper Scouting Steps:
Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● 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 endpoint, 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.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

Reminder – Calls for survey help

This season, a number of research projects are seeking help with in-field monitoring. Please review the list below and follow the links, if there’s a possibility of participating by please providing samples:
Prairie-wide survey of stored grain pests in grain bins (Wk13)
Pestiforous slugs and their parasites (Wk04)
Fuzzy white intact Cotesia pupal cases (in wheat or barley) (Wk13)

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 August 1, 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 August 1) 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 August 1, 2021).
Figure 2. Predicted days for virulence of West Nile Virus to develop within Culex tarsalis, if present within a region (as of August 1, 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 August 4, 2021). The screenshot below (retrieved 04Aug2021) 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 04Aug2021).

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.

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.

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 August 4, 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 is 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 August 3 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 27, 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 August 2, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 3, 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)

MIGRATORY GRASSHOPPER: THESE OPPORTUNISTIC EATERS CAN CAUSE CONSIDERABLE DAMAGE

Migratory grasshopper (Joseph Berger, bugwood)

Adapted to all ecoregions in the Canadian grasslands, the migratory grasshopper is a versatile insect demonstrating variable colouration and a range of adult sizes. While a common pest in the Prairie region, the migratory grasshopper has a range that extends southward into Florida. These insects will consume almost all crops, including (but not limited to) forage legumes and grasses, pulses, oilseeds, cereals, and vegetables. Despite their name, migratory grasshoppers overwinter in the Prairie region.

As a mixed feeder, the migratory grasshopper thrives in many agricultural environments, including grain fields, cultivated pastures and rangeland. Feeding damage includes leaf notching and stripping. More extensive damage is caused when stems are severed below the heads of mature and maturing crops. The migratory grasshopper will also feed on dried plant material when accessible. The migratory grasshopper is one of a few species of grasshopper that can cause economic yield loss to prairie crops.

Migratory grasshopper adults grow up to 23-28 mm long, with bodies that range from brown to gray. A small black stripe runs across the head, while the hind legs are marked with a series of black bands. Nymphs are a mottled gray and like the adults, have a black stripe running across the head.

Migratory grasshopper nymphs and adults, albino and normal (AAFC)

Biological and monitoring information related to migratory grasshoppers in field crops can be found on our Monitoring page as well as on provincial Agriculture Ministry pages (Manitoba, SaskatchewanandAlberta). For more information, visit the grasshopper 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).

Weather synopsis

An abbreviated synopsis of the past week is provided below. Recent warm weather across the Canadian prairies helped crop development this past week

The growing degree day map (GDD) (Base 5 ºC, April 1-July 27, 2020) is below (Fig. 1) while the growing degree day map (GDD) (Base 10 ºC, April 1-July 27, 2020) is shown in Figure 2.

Figure 1. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-July 27, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 2. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-July 27, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). 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 <22 to >34 °C (Fig. 3). So far this growing season (up to July 29, 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. 4).

Figure 3. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-July 29, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 4. Number of days above 25 °C observed across the Canadian prairies this growing season (April 1-July 29, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Cumulative rainfall for the past 7 days was lowest across southern regions of Alberta, Saskatchewan, and Manitoba with the exception of around Regina south to the American border, and southwest Manitoba west into the southeast corner of Saskatchewan (Fig. 5). Cumulative 30-day (Fig. 6) and rainfall for the growing season (April 1-July 29, 2020; Fig. 7) are below.

Figure 5. Observed cumulative precipitation across the Canadian prairies the past seven days (as of July 29, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 6. Observed cumulative precipitation across the Canadian prairies the past 30 days (as of July 29, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 7. Observed cumulative precipitation across the Canadian prairies for the growing season (as of July 29, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30Jul2020). 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.

Wheat midge

Click to link to last week’s information posted for Wk 13 (released 23Jul2020) to review the predictive model outputs for this insect pest.

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 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 1). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 1. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads 
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 2), 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.

Figure 2. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long.  (Photo: AAFC-Beav-S. Dufton).

Economic Thresholds for Wheat Midge:

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

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

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

Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week in 2019 (for Wk11).  Review that post for descriptions and photos to help with in-field scouting for this economic pest of wheat!  Additionally, the differences between midges and parasitoid wasps were featured as the current Insect of the Week in 2019 (for Wk12).  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.  

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.

Bertha armyworm

Click to link to last week’s information posted for Wk 13 (released 23Jul2020) to review the predictive model outputs for this insect pest. As larvae now begin to develop and feed in fields, emphasis is now placed on in-field scouting in areas where high moth counts are being intercepted by provincial networks highlighted below.

Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies.  Click each province name to access moth reporting numbers observed in AlbertaSaskatchewan and Manitoba. 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 available maps or data from Alberta, Saskatchewan, and Manitoba are below.

This image has an empty alt attribute; its file name is 2020Jul15_BAW_SK-791x1024.png
This image has an empty alt attribute; its file name is 2020Jul22_BAW_MB.png

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

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

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

Diamondback moth

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

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

This image has an empty alt attribute; its file name is DBM_Larva_AAFC.jpg
Figure 1. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.
This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 2. Diamondback moth pupa within silken cocoon.

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

This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 3. Diamondback moth.

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

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

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). 

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

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

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

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

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

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

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

Field heroes

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 6Plentiful 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 humanmosquitobird and horse surveillance.  Link here to access the most current weekly update (July 5-11, 2020; retrieved July 30, 2020). The screenshot below (retrieved July 30, 2020) serves reference but access that information here.

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

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas).  As of July 30, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge.  Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!  

Figure 1. Predicted development of Culex tarsalis, across the Canadian prairies (as of July 30, 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 29, 2020 report. The summary indicates that, “Grasshoppers are the insect of greatest concern to field crops in Manitoba currently. Some populations of diamondback moth above economic threshold have been found in eastern Manitoba recently.”

Saskatchewan‘s Crop Production News (for Issue 6). 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 28, 2020 report.

• Saskatchewan Agriculture  or access a PDF of July 21-27, 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 27, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the July 28, 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)

    • Predictive model updates: Bertha armyworm, Grasshoppers, Wheat midge (Wk13).

    • Scouting charts – canola and flax (Wk02)

    • Ticks and Lyme Disease (Wk06)

    • Wind trajectories (Wk09)

Sweet Clover Pests / Feature Entomologist: Sean Prager

This week’s Insect of the Week featured crop is sweet clover: a soil-building, weed suppressing legume. Our feature entomologist this week is Sean Prager.

Sweet clover
cc by 2.0 Phil Gayton

Native to Turkey, Canadian sweet clover includes plants developed from Spanish and Siberian sources. Tolerant to cold, drought and various soil textures, sweet clover is a robust crop that is grown across the Prairies. Sweet clover has a taproot that can grow as deep as 1. 5 metres (5 feet) by the end of spring, adding nitrogen and organic matter to soil. As a forage grazed by livestock, it achieves maximum palatability and feed quality between 25 and 35 centimetres (10-14 inches) in height, as it reaches the bud stage. As sweet clover matures, it loses its palatability. Sweet clover contains a unique chemical called coumarin. When sweet clover is exposed to mold growth, coumarin is converted into the anticoagulant dicoumarol, which poses a risk to livestock consuming contaminated hay or silage. For this reason, proper harvesting of sweet clover for hay or silage is essential.

Sweet clover is vulnerable to several pests. 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.

Sweet clover plant
cc by 2.0 Des Blenkinsopp
Sweet clover pests
  • Alfalfa caterpillar
  • Army cutworm
  • Beet webworm
  • Blister beetle
  • Clover root weevil
  • Grasshoppers
  • Mormon crickets
  • Sweet clover weevil
  • Variegated cutworm
Sweetclover weevil – AAFC

Entomologist of the Week: Sean Prager

Name: Sean Michael Prager
Affiliation: Department of Plant Sciences, University of Saskatchewan
Contact Information:
sean.prager@usask.ca
306-361-8525
Agriculture Building, 51 Campus Drive, Saskatoon, SK S7N 5A8

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

I coordinate the Lygus surveys in faba bean as part of the provincial monitoring and survey efforts in Saskatchewan. Our lab also occasionally conducts other studies that result in pest information for crops in the prairies.

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

The first insects I worked on were mosquitoes. Because of that experience, I have always been really interested in disease vectors. On the Prairies, Aster Leafhoppers are a vector and pest that have some pretty neat aspects to their biology. They can be a major problem in canola; although the events are rare. Finally, they are also really useful for many of the ecological questions our lab asks.

What is your favourite beneficial insect?

As a postdoc, I studied a small parasitoid wasp called Aphelinus rhamni. It is a species that parasitizes aphids, especially soybean aphid. It was collected in Asia and has potential as a classical biological control agent.

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

I think the work we are doing to develop thresholds for aphids in pulse crops will be very useful on the Prairies and is quite interesting. Similarly, the work we have been doing on Lesser clover leaf weevils in red clover has been interesting as well and will hopefully be important to industry.

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

We use many of the standard tools. My lab has a website (www.pragerlab.ca), a twitter account (@USaskENt), and Instagram. We are more active in some places than others. In addition to that, members of my lab often attend field days and grower meetings.

Weekly Update

Greetings!

Week 14 and it’s again filled with 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!

Please access the complete Weekly Update either as a series of Posts for Week 14 (July 11, 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. Temperatures this week were approximately 1 °C cooler than last week (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 (July 2-July 8, 2019).

Across the prairies, 30-day average temperatures have been approximately 1.5 °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. 

Figure 2. Average temperature (°C) across the Canadian prairies the past 30 days (June  8- July 8, 2019).

Growing season temperatures (April 1-July 1, 2019) have been 1 °C cooler than average; the warmest temperatures were observed across the southern prairies (Fig. 3). 

Figure 3. Average temperature (°C) across the Canadian prairies for the growing season (April 1-July 8, 2019).

This past week, significant rainfall amounts were reported central AB (Fig. 4). Minimal rainfall was reported across MB and southern AB. Across the prairies, rainfall amounts for the past 30 days have been highly variable (Fig. 5). Dry conditions persisted across much of MB and southern AB. Rainfall was well above average in SK.  Growing season rainfall amounts have been below average for most of the prairies, particularly across southern regions of AB and eastern MB (Fig. 6). 

Figure 4. Cumulative precipitation observed the past seven days across the Canadian prairies (July 2-8, 2019).
Figure 5. Cumulative precipitation observed the past 30 days across the Canadian prairies (June 8-July 8, 2019).
Figure 6. Cumulative precipitation observed over the growing season across the Canadian prairies (April 1-July 8, 2019).

Based on modeled soil moisture (Fig. 7), 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 7. Modeled soil moisture (%) across the Canadian prairies as of July 8, 2019.

The growing degree day map (GDD) (Base 5 ºC, April 1-July 7, 2019) is below (Fig. 8):

Figure 8. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-July 7, 2019).

The growing degree day map (GDD) (Base 10 ºC, April 1-July 7, 2019) is below (Fig. 9):

Figure 9. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-July 7, 2019).

The lowest temperatures (°C) observed the past seven days ranged from at least 13 to at least 1 °C in the map below (Fig. 10).

Figure 10. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to July 11, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (011Jul2019).  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 15 to at least 30 °C in the map below (Fig. 11).

Figure 11. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to July 11, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (011Jul2019).  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.

Bertha armyworm monitoring

Bertha armyworm (Lepidoptera: Mamestra configurata– Early instar bertha armyworm are predicted to begin appearing across the prairies.  A model run for Saskatoon SK indicates that the hatch should be complete (Fig.1) and that BAW should be in the early instar (Fig. 2).

Figure 1.  Predicted status of bertha armyworm (Mamestra configurata) populations as of July 8, 2019.
Figure 2. Predicted percent of bertha armyworm (Mamestra configurata)  populations at LARVAL STAGE across the Canadian prairies as of July 8 2019. 

Important – Watch your provincial monitoring networks who are weekly recording cumulative pheromone-baited traps in AlbertaSaskatchewan, and Manitoba (pg 8).

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

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 3) to help identify egg masses and the economically important larvae in canola.

Figure 3. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Now is the time to do in-field scouting for this insect pest.  Review the Insect of the Week which features bertha armyworm and its doppelganger, the clover cutworm!

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).

Cool temperatures continue to result in reduced grasshopper development rates. Populations are developing into third and fourth instars. Based on model runs, approximately 13% of the population is in the first instar, 23%  is predicted to be in the second instar, and 32% is in the third instar, 21%  are predicted to be in the fourth instar and l4% may be in the fifth instar. Grasshopper development this season has been similar to long term average development. The following map (Fig. 1) indicates that grasshopper populations across the southern prairie are mostly in the third instar. Compared to last week development has increased across southern regions of the prairies. Grasshopper development has been greatest near Winnipeg MB.

Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 8, 2019). 

This week, the Insect of the Week’s Doppelganger features GRASSHOPPERS!!!  Check out the excellent nymph photos to help your in-field scouting!

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

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – Where wheat midge are present, cool, dry conditions have resulted in delayed emergence of adults. Wheat midge larvae have moved to the soil surface and pupae are appearing.  In some locations adults should be beginning to emerge. The wheat midge model predicts that 45% (54% last week) of the population are in the larval  cocoon stage and 47% (42% last week) of the population is predicted to have moved to the soil surface. This week 7% (3.4% last week) is predicted to be in the pupal stage. Adults have begun to emerge in localized areas in southern AB and MB. 

The first map indicates the percent of the population that is in the larval stage, at the soil surface.  Midge development in SK was reduced due to dry soil moisture conditions. 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 8, 2019) across the Canadian prairies.
Figure 2. Percent of  population AT PUPAL STAGE (as of July 8, 2019) across the Canadian prairies.
Figure 3. Percent of  population AT ADULT STAGE (as of July 8, 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.

Diamondback moth

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

Monitoring:

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

Figure 1. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.
Figure 2. Diamondback moth pupa within silken cocoon.

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

Figure 3. Diamondback moth.

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

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

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 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, Shelby Dufton, Amanda Jorgensen, Boyd Mori.

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

West Nile Virus and Culex tarsalis

West Nile Virus Risk –  In 2018, there were 426 human clinical cases of West Nile virus (WNV) in Canada (Fig. 1). 

Figure 1. Geographic distribution of WNV human clinical cases and asymptomatic infections in Canada, 2018.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jul2019).  Access the full map at https://www.canada.ca/en/public-health/services/publications/diseases-conditions/west-nile-virus-surveillance/2018/november-11-december-15-week-46-50.html

Health Canada posts information related to West Nile Virus in Canada.  Health Canada also tracks WNV through humanmosquitobird and horse surveillance.  Link here to access the most current weekly update (June 29, 2019). The screenshot below was retrieved 11Jul2019 as reference but access that information here.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds.  Take note of the provincial distribution of positive WNV birds in 2018 (table posted below as reference).

The following is offered to predict when Culex tarsalis will begin to fly (Fig. 2) across the Canadian prairies. Protect yourself by wearing DEET!  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  Areas highlighted lime green in the map below (Fig. 2) are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge soon.  

Figure 2. Predicted development of Culex tarsalis, across the Canadian prairies (as of July 7, 2019).

Once the adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – as quickly as 20-22 days, given the current environmental conditions in the highlighted areas of the map below (Figure 3).

Crop report links

Crop reports are produced by:

The following crop reports are also available:

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 #8 posted July 10, 2019 which includes more thistle caterpillar information, updated bertha armyworm pheromone trap information, the presence of low numbers of green cloverworm in some pulse crop fields, grasshopper presence, andsome higher numbers of diamondback moth larvae in some canola.

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 8, 2019 edition with an important reminder that field scouting in July can lead to a more successful crop.

Preparing and protecting grains for market

A few helpful tools to keep at your finger tips:

Since May we have posted our prairie provinces’ searchable PDFs of Crop Production Guides.

Keeping It Clean has information to help prepare and protect your grains for market.  Check out their site to find important information.  Learn more about avoiding malathion in bins storing canola, access their spray to swath calculator, and access a pre-harvest glyphosate staging guide

The Canadian Grain Commission has information to help you manage stored grain.  Read tips to prepare your bins to prevent insect infestations.  If there are insects in your grain, use their online diagnostic tools to help identify the problem species.  If pest species are confirmed, there are control options – read more to make the right choice for your grain storage system and your specific grain.

Interested in signing up for Canadian Grain Commission’s Harvest Sample Program?

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

Monarch migration – Week 13

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

Ticks and Lyme disease – Week 4
Timely IOTW to review – Week 13

Weather Radar – Week 6
Wildfires – Week 8

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

Doppelgangers: Grasshoppers

Bruner grasshopper (Melanoplus bruneri) adult. 
Photo credit: S. Barkley, Alberta Agriculture and Forestry.

The case of the prairie grasshoppers: There are 80 grasshopper species on the prairies but only a few that are considered pests. These include Packard (Melanopus packardii), clearwinged (Camnula pellucida), migatory (Melanopus sanguinipes), two-striped (Melanopus bivittatus) and Bruner Melanoplus bruneri) grasshoppers. They are recognizable as grasshoppers (similar body shape and distinctive large rear legs) and, depending on the species, range in size from 21 to 40 centimetres (8.25 to 15.75 inches). Most of these pest species can be distinguished by colouring and size. However, the Bruner and migratory grasshoppers are difficult to tell apart, needing to rely on examining the male genitalia (see Insect of the Week post from July , 2018).

For more information about grasshopper pests, see our Insect of the Week page!

Packard grasshopper – egg, nymph, adult
AAFC
Clearwinged grasshopper – egg, nymph, adult
AAFC
Migratory grasshopper – adult
Joseph Berger, Bugwood.org
Two-striped grasshopper – adult
John Gavloski, Manitoba Agriculture,
Food and Rural Development

More information related to the Bruner grasshopper:

See also:

Predicted grasshopper development (July 5, 2019)

Specific information about these grasshoppers, other pests and natural enemies can be found in the updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide.

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.

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

Weekly Update

Hello!

We’re doing a bit of catch-up with the Weekly Update….

Please view the Weekly Update FOR WEEK 14 (August 9, 2018) which is available only as a PDF.  Also review the Insect of Week for Week 14 featuring both the Natural enemies of wheat stem sawfly plus the English grain aphid.

The Weekly Update FOR WEEK 15 (August 16, 2018) is available as either as a series of Posts  OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 15!

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

Subscribe to the Blog by following these three steps!

Insect of the Week – Natural Enemies of the wheat stem sawfly

This week’s Insects of the Week are the natural enemies (@FieldHeroes) of the wheat stem sawfly, namely Bracon cephi (Gahan) and B. lissogaster (Hymenoptera: Braconidae).

Nine species of parasitic wasps are known to attack wheat stem sawfly but Bracon cephi and B. lissogaster are the main species that help regulate this pest in North America.  These closely related wasp species are described as idiobiont ectoparasitoids meaning the parasitoid larva, after hatching from an egg laid on the surface of the sawfly larva, feeds on the exterior of the host. Normally, both Bracon species will complete their development (i.e., pupates) inside the wheat stem within the integument of the sawfly larva or just beside the consumed host.  There are two generations of B. cephi and B. lissogaster per year.  The first generation normally completes its lifecycle then escapes from the wheat stem to locate a new sawfly larva to parasitize.  The second generation of these wasps will overwinter within the wheat stem.

These wasps are 2-15 mm long and are usually brown in colour. They have a narrow waist connecting the abdomen to the thorax and the combined length of head plus thorax is equal to the length of the abdomen.  These parastiod wasps have long antennae and two pairs of transparent wings. Females have a noticeable ovipositor protruding from the end of the abdomen.

For more information about the natural enemies of the wheat stem sawfly, check out our Insect of the Week page!

Bracon cephi (Gahan) (H. Goulet)

Extra Insect of the Week – English grain aphid (Hemiptera: Aphididae)

The English grain aphid (Sitobion avenae) has started to appear across the Prairies in various cereal crops this past week so the time to scout is now. Look for this aphid infesting wheat heads (favourite host) as well as barley, oat, rye, Timothy and canaryseed.

This aphid can also be a vector for barley yellow dwarf virus. You might see the green, red colour morph or both morphs in fields this year (Fig. 1). You will probably also see ladybeetle (@FieldHeroes) adults and larvae hunting the aphids (Fig. 2). The economic threshold for aphids in spring wheat in Western Canada is 12-15 aphids per head prior to the soft dough stage. 

Agriculture and Agri-Food Canada, with funding from the Pest Management Centre, has developed a smartphone app called Cereal Aphid Manager (CAM) to facilitate scouting for aphids in cereals that also allows you to record the beneficial insects in the field that can keep aphid populations below the economic threshold – available at Apple iTunes and Google Play app stores. CAM information and download links.

For more information on the English grain aphid, check out our Insect of the Week page!

Submitted by Dr. Tyler Wist (Tyler.Wist@agr.gc.ca).

Fig. 1 Green and red morph English grain aphid
(Tyler Wist, AAFC)
Fig. 2 Seven-spotted lady bird larva hunting aphids
(Tyler Wist, AAFC)

Cabbage seedpod weevil

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




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


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

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


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

Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has posted a live CSPW map and online reporting tool for growers.  A screenshot (retrieved 03Aug2017) is included below.

Provincial Insect Pest Reports

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


● Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and read Issue #11 (posted August 2, 2017) noting diamondback moth exceeding economic thresholds in some fields, higher numbers of soybean aphids but the appearance of natural enemies in response to their prey (so growers may refer to the Soybean Aphid App to help monitor and manage that pest), and high levels of bertha armyworm larvae have been scouted in Holland and Austin areas.

● 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.  A reminder to watch for the final bertha armyworm pheromone trap counts update on the 2017 map.

● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (August 3, 2017) provided by Scott Meers. This week diamondback moth numbers have exploded in southern Alberta so canola growers need to be scouting right up to swathing but be aware of Pre-harvest intervals! The annual grasshopper survey begins the first week of August for that province’s Agricultural Fieldmen. In central Alberta,
Red turnip beetle are now starting to feed, mate and lay eggs that overwinter. Painted lady butterfly – the 2nd generation is starting to fly and lay eggs now so sunflower, soybean and borage growers need to continue to monitor.

Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (July 31, 2017)
• Saskatchewan Agriculture Crop Report (July 24-31, 2017)

• Alberta Agriculture and Forestry Crop Report (July 25, 2017)


West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of July 30, 2017areas highlighted in red on the map below have accumulated sufficient heat for C. tarsalis to fly.  Areas highlighted in red, orange and even yellow 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 and two cases of viral West Nile have been reported so far (as of July 22, 2017).  Both cases were reported from Ontario (in Timiskaming and Windsor-Essex).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds.  As of August 3, 2017, 964 birds were examined and 23 have tested positive for West Nile virus; two from Manitoba, eight from Ontario, and 13 from Quebec.


The Public Health Agency of Canada also monitors and posts updates on the status of WNV in Mosquitoes.  As of July 22, 2017, Quebec, Ontario, Manitoba and Saskatchewan have reports of positive mosquito pools of West Nile Virus.  A total of 47 positive mosquito pools have been found: 

  • 33 from Ontario [Peel Regional (5), Toronto (6), Halton(5), Haliburton-Kwartha-Pine Ridge District(1), Simcoe Muskoka District (1), Windsor-Essex County (6), Eastern Ontario (1), Durham Reginal (1), Hamilton (1), Haliburton-Kawarta-Pine Ridge district (1), Hastings and Prince Edward Countries (2), and York Regional (3)];  
  • 11 from Manitoba [(Winnipeg (3), Southern (2), Interlake eastern (1), and Prairie Mountain(5)]; 
  • 2 from Quebec [Montérégie (1), Laval (1)], and 
  • 1 from Saskatchewan. 

Insect of the Week – Red clover casebearer moth

This week’s Insect of the Week is the red clover casebearer moth. As it’s name suggests, its primary host is red clover, but larvae also reportedly feed on alsike, stone, white and zig-zag clover. The mature larvae are contained within portable cases made of withered flower petals and silk and they feed from the front end of the case on developing seed in the floret. They can consume up to three seeds per day. In areas with high numbers of these moths, such as the Peace River region in BC and AB, red clover stands should only be grown for one year in rotation.

For more information on the red clover casebearer moth, visit our Insect of the Week page.

Red clover case bearer moth – adult (Tim Haye)
Red clover casebearer moth – sealed overwintering larval cases (Boyd Mori)



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

Weekly Update – Greetings!

Greetings!

Please access the Weekly Update for August 3, 2017 (Week 14), 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!

Weekly Update – Weather Synopsis

Weather synopsis – This past week’s temperatures were above normal in many locations on the prairies, especially south and central Alberta and Saskatchewan (Fig. 1).  

Figure 1. Highest temperatures across the Canadian prairies the 
past seven days (July 25-31, 2017).



Seven-day rainfall accumulations were low across the prairies. Total 30-day rainfall accumulations indicate that conditions are normal to dryer-than-normal for most of the prairies (Fig. 2). 

Figure 2.  Percent of average precipitation across the Canadian prairies the 
past 30 days (July 2-31, 2017). 



Growing season (April 1 – July 31, 2017) percent of average precipitation continues to be average for some areas of Alberta, but below average for most of Saskatchewan and Manitoba.

Figure 3.  Percent of average precipitation across the Canadian prairies over 
the growing season (April 1-July 31, 2017).




The growing degree day map (GDD) (Base 10ºC, March 1 – July 30, 2017) is below:








The growing degree day map (GDD) (Base 5ºC, March 1 – July 30, 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 – Pre-Harvest Intervals (PHI)

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” which was intended 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.  More information about PHI and Maximum Residue Limits (MRL) is available on the Canola Council of Canada’s website.

Weekly Update – Crop protection guides

Crop Protection Guides – If you don’t have a copy of your province’s Crop Protection Guide, please make use of these links to access:
• Saskatchewan’s Crop Protection Guide
• Manitoba’s Guide to Crop Protection Guide 
• Alberta’s Crop Protection or Blue Book 
• Western Committee on Crop Pests Guidelines for the Control of Crop Pests




Recall earlier this spring that Health Canada’s Pest Management Regulatory Agency launched a new mobile app to access pesticide labels registered for use in Canada. The App helps homeowners, farmers, industry, provincial and federal organizations access details for pest control products from a smartphone or tablet.  Download it as either:

Weekly Update – Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) – Last week, biofix dates were used to predict the number of generations of DBM as of July 24, 2017.  That data predicted the completion of two generations of DBM across the Canadian prairies.  The number of generations, combined with the recent heat, has resulted in densities of DBM above threshold in some fields this week!  In-field scouting is critical and necessary to protect developing pods since DBM larvae will feed on the exterior which can render pods prone to shattering even in high temperatures and high winds or during swathing and direct-harvesting.  

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


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


Figure 5. Diamondback moth pupa within silken cocoon.


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

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


Figure 6. Diamondback moth.


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

● Low numbers of moths have been reported across Saskatchewan for the 2017 pheromone monitoring.  
● Manitoba Agriculture and Rural Initiatives posted low DBM counts which can be reviewed here.  
● Alberta Agriculture and Forestry has a live 2017 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– REMINDER – Reporting sites across the prairies have generally reported lower cumulative interceptions and cumulative counts are summarized by provincial staff in ManitobaSaskatchewan and Alberta.

Manitoba counts as of July 26, 2017



Saskatchewan map as of July 19, 2017



Alberta map as of July 26, 2017


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





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

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


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

Weekly Update – Lygus in canola

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

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

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


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

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

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

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

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


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

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

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


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

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


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

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


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

Update from the field….

Many prairie growers have a cutworm or armyworm story of woe but this time around growers on Vancouver Island near Port Alberni contended with an unusual pest – True armyworm (Mythimna unipuncta) in high densities were eating up hay fields and pasture!  Thanks to Tracy Hueppelsheuser with the BC Ministry of Agriculture who shared this CTV news clip.


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

Weekly Update – Time of Swathing for Canola

The Canola Council of Canada created a guide to help growers estimate swathing time in canola.  A screen shot of the downloadable Canola Swathing Guide has been included below for reference.





Weekly Update – Insects as food

Earlier this summer a link was posted taking readers to an article about unique popcorn toppings.  While novel, the cricket topping for popcorn will surely be followed by other insect-based food items in the future. In 2013, a FAO report entitled, “Edible insects: future prospects for food and feed security” was published.  The document noted a predicted global population of 9 billion by 2050, the increasing need for more sustainable means to produce food and the feasibility of insects as means to do 


Last week, the Financial Post printed a follow-up article describing Canadian entrepreneurs and their efforts to mainstream insects as food for humans, livestock and pets.

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
Cutworms

Diamondback moth


Flax scouting chart

Flea beetles


Grasshoppers (Week 13)

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)
Wildfires (Week 13)

Wind trajectories

Insect of the Week – Natural Predators

The importance of non-crop areas as habitat for beneficial insects



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] 
Natural enemies don’t just appear from nowhere – they rely on nearby
non-crop and (semi-)natural sites for shelter, food, overwintering sites and
alternate hosts for when crop pests are either not present or in low numbers.
How you manage these sites can have a huge impact on natural enemies’ capacity
to supress pests when you need them to. These same sites are also essential
habitats for pollinators, important for maximizing yield of non-cereal seed
crops (e.g. oil seed crop). A recent publication, ‘Agricultural practices that
promote crop pest suppression by natural predators’, describes the role of
non-crop areas and management practices to nurture natural enemy populations.
Go to the Insect of the Week page for download links for
this publication. There you will also find more information about natural
enemies, the pests they control and details about important crop and forage
pest insects by downloading the new Field Crop and Forage Pests and their
Natural Enemies in Western Canada – Identification and Management Field Guide.



Weekly Update

Greetings!

A downloadable PDF version of the complete Weekly Update for Week 14 (August 3, 2016) can be accessed here.  

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

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



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

Weekly Update – Weather Synopsis

The map below reflects the 7 Day cumulative precipitation map (July 26-August 1, 2016)


While the map below summarizes the cumulative precipitation for the growing season (April 1-August 1, 2016).



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



The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 31, 2016) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – July 31, 2016) is below:




The map below shows the Lowest Temperatures the Past 7 Days (July 26-August 1, 2016) across the prairies:



The map below shows the Highest Temperatures the Past 7 Days (July 26-August 1, 2016):



While the map below reflects the number of consecutive days above 25°C across the prairies for the growing season as of July 29, 2016.

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 – Pre-Harvest Intervals (PHI)

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 this week within their Crop Production News.


In 2013, the Canola Council of Canada created and circulated their “Spray to Swath Interval Calculator” which was intended 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.  More information about PHI and Maximum Residue Limits (MRL) is available on the Canola Council of Canada’s website.

Weekly Update – Lygus in canola

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

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

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


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

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

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

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

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


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

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

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


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

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


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

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


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

Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata– Reminder – Reporting sites across the prairies have generally reported lower cumulative interceptions but moderate numbers have been intercepted a few sites within Manitoba and Saskatchewan.  


Cumulative counts from pheromone traps are summarized and mapped by provincial staff in ManitobaSaskatchewan and Alberta.  Screen shots of the three maps are provided below:

Manitoba map (screenshot retrieved August 3, 2016):



Saskatchewan map (screenshot retrieved August 3, 2016):



Alberta map (screenshot retrieved August 3, 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 instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. 
● Larvae eat the outer green layer of the stems and pods exposing the white tissue. 
● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

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


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

Cabbage seedpod weevil

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

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

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


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


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

Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has released a new live CSPW map and online reporting tool for growers.  A screenshot (retrieved August 3, 2016) is included below.


Weekly Update – Time of Swathing for Canola

The Canola Council of Canada created a guide to help growers estimate swathing time in canola.  A screen shot of the downloadable Canola Swathing Guide has been included below for reference.

Weekly Update – Harvest Sample Program

The Canadian Grain Commission is ready and willing to grade grain samples harvested in 2016.  Samples are accepted up to November but send samples as soon a harvest is complete.


This is a FREE opportunity for growers to gain unofficial insight into the quality of their grain and to obtain valuable dockage information and details associated with damage or quality issues.  The data collected also helps Canada market its grain to the world!


More information on the Harvest Sample Program is available at the Canadian Grain Commission’s website where growers can register online to receive a kit to submit their grain.  


In exchange for your samples, the CGC assesses and provides the following unofficial results FOR FREE:
  • dockage assessment on canola
  • unofficial grade
  • protein content on barley, beans, chick peas, lentils, oats, peas and wheat
  • oil, protein and chlorophyll content for canola
  • oil and protein content and iodine value for flaxseed
  • oil and protein for mustard seed and soybeans
Many producers find having both grade and quality information on their samples before delivering their grain to be helpful.

Weekly Update – Previous Posts

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

Alfalfa weevil

Aphids in canola 


Bertha armyworm development and flight

Cabbage root maggot
Canola scouting chart
Cereal leaf beetle
Crop protection guides
Cutworms


Diamondback moth

Environment Canada’s radar maps to follow precipitation events


Flea beetles in canola


Grasshoppers

Iceburg reports

Insects in our diet

Monarch migration

Multitude of mayflies


Pea leaf weevil monitoring

Predicted cereal leaf beetle development

Predicted lygus bug development
Predicted wheat midge development

Swede midge



Thrips in canola

Weather Synopsis (Week 12)

Wind trajectories

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 pre-harvest intervals (PHI) for a long list of field crop pesticides in Issue 6prepared by Danielle Stephens.  As the report notes, “all pesticides have a PHI” specific for product and crop type.  The PHI prevents crops exceeding Maximum Residue Levels (MRL) that will affect the quality of seed in terms of export.

– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on July 28, 2016) noting completion of Bertha armyworm pheromone trap monitoring and lower numbers throughout Alberta, low numbers of the orange-morph of English grain aphids, and swede midge in the northeast of Alberta.

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 31, 2016areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!



The Public Health Agency of Canada posts information related to West Nile Virus in Canada.  The map of clinical cases of West Nile Virus in Canada in 2016 is posted (as of July 23, 2016) while a screen shot is provided below (retrieved August 3, 2016).



The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus.  As of August 3, 2016, 27 birds were submitted for testing yet none have tested positive for West Nile virus. 

Weekly Update – Crop reports

Crop reports are produced by:

– Manitoba Agriculture, Rural Development (August 2, 2016).
– Saskatchewan Agriculture Crop Report (July 25, 2016) which is also posted in a printer-friendly version.

– Alberta Agriculture and Forestry (for July 26, 2016).

This week, the USDA’s Crop Progress Report (posted August 1, 2016) which includes harvest and condition ratings for winter wheat, spring wheat, oat, barley, plus range and pasture conditions is available. 

The USDA also produces a World Agricultural Production Report (July 2016) which estimates production across the globe for corn, cotton, rapeseed, and wheat but also includes tabular data for other grains.

Weekly Update – Wheat midge

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


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

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


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




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

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

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



Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps.  A screen shot of the map is provided below (retrieved August 3, 2016).


Additional information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

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

Insect of the Week – Ladybird beetle larva

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] 

You can’t tell by looks whether an insect is a good bug (beneficial) or a bad bug (pest). And while you might recognize the adult, the immature form might appear quite alien. This is definitely the case with the ladybird beetle (aka lady beetle). This cute, orange, nearly round beetle with varying number of spots depending on species appears harmless but is a voracious eater, consuming up to 100 aphids a day (and other soft bodied insects). The larvae (slate blue, elongated body with varying black and yellow patterns) can be just as hungry.

One of the exciting projects at Agriculture Canada is looking at how natural enemies like ladybird beetles control cereal aphids in wheat, oat, barley and rye, preventing them from causing economic damage without you having to lift a finger (or hook up a sprayer). Of course, there are times when there aren’t enough free helpers/natural enemies and we’re developing an app that will help growers figure out if and when they need to control cereal aphids. (Refining and making accessible to growers a validated dynamic action threshold for cereal aphid control in cereal crops).

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).


Ladybird beetle larva eating aphids
Mike Dolinski, MikeDolinski@hotmail.com

Insect of the Week – Red turnip beetle

This week’s Insect of the Week is the red turnip beetle (Entomoscelis americana Brown) (from the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide – download links available on the Insect of the Week page).