13813Released August 26, 2022 ( 2022 Week 16 )

The final WEEKLY UPDATE of the 2022 growing season is here!

Thank you to the many people who performed and supported insect pest monitoring in field crops this year! The Prairie Pest Monitoring Network brings together a unique array of incredible cooperators and collaborators at federal, provincial, regional, post-secondary, and industry levels across western Canada! Thanks to these many individuals! The PPMN also thanks our many contributors to the Weekly Updates and Insect of the Week who stand as co-authors at the top of each Post. Last but not least, a small number of key individuals ensure 16 weeks of pertinent content are available through the growing season on behalf of the PPMN – thank you to Ross Weiss, Tamara Rounce, Serge Trudel, Cynthia Schock, Meghan Vankosky, and Jennifer Otani.

Vital insect pest data originates from in-field observations – that’s THE FOUNDATION – and now, more than ever, researchers need support and permission to continue to collect and build the many integral data sets needed to enable improvements in the detection, monitoring, and management of pest risk in field crops grown across the Canadian prairies! Please, this winter, if you’re a producer, connect with a field researcher and give permission for pests to be monitored in your field. If you’re able to monitor, connect with a field researcher to find out how to help. It’s vital that fields ALL ACROSS the prairies represent Canadian agriculture!

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Lygus bug monitoring
• Predicted wheat stem sawfly growth
• Pre-harvest intervals (PHI)
• West nile virus risk
• Provincial insect pest report links
• Crop report links
• Previous posts
….and review the 2022 Insect of the Week lineup – 16 in total!

Wishing everyone good 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.

13811Weather synopsis ( 2022 Week 16 )

TEMPERATURE: Though average temperatures for the 2022 growing season continue to be similar to long-term average values, August temperatures have been much warmer than normal. This past week (August 15-21, 2022) the average daily temperature for the prairie region was 1.5 °C warmer than the previous week and almost 5 °C warmer than climate normal temperatures for the region. Last week recorded the warmest weekly average temperature of the 2022 growing season so far. The warmest temperatures were observed across southwestern Saskatchewan and southeastern Alberta (Fig. 1).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of August 15-21, 2022.

The prairie-wide average 30-day temperature (July 23 – August 21, 2022) was 2 °C warmer than the long-term average value for the same period. Average 30-day temperatures continue to be warmest across southern Alberta and southwestern Saskatchewan (Fig. 2). The average growing season (April 1-August 14, 2022) temperature for the prairies has been similar to climate normal values. The growing season has been coolest in a region extending from Edmonton to the Peace River region (Fig. 3).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of July 23 to August 21, 2022.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to August 21, 2022.

PRECIPITATION: This week (August 15-21, 2022), minimal amounts of rain were reported for Alberta and Saskatchewan. The greatest weekly precipitation amounts occurred across southern Manitoba (Fig. 4). The 30-day (July 23-August 21, 2022) rainfall amounts continue to be greatest across eastern Manitoba while dry conditions persist across the southern and central regions of Alberta and Saskatchewan (Fig. 5). Rainfall amounts across southern Alberta and southwestern Saskatchewan have been 40% less than climate normal values.

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 15-21, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (July 23 to August 21, 2022).

Growing season rainfall for the prairies (April 1 – August 21, 2022) has been near normal for Alberta and above normal across southeastern Saskatchewan and Manitoba. Total rainfall continues to be greatest across Manitoba and eastern Saskatchewan and least across central and south-central Saskatchewan (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to August 21, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 22, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (August 16-22, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <26 to >34 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13816Predicted grasshopper development ( 2022 Week 16 )

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.

Model simulations were used to estimate grasshopper development as of August 21, 2022. Potential risk continues to be greatest across central and southern regions of Saskatchewan and southeastern Alberta. Simulations indicate that prairie populations are in the adult stage and that females are laying eggs in the soil. Since last week, model simulations indicate that oviposition is now occurring across all of the prairies (Fig. 1). 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 – August 21) predict that oviposition rates have been greatest across a large region that extends from east of Lethbridge to Regina and north to Saskatoon (Fig. 1).

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 21, 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.

13818Predicted diamondback moth development ( 2022 Week 16 )

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.

Recent warm conditions have resulted in the rapid development of diamondback moth populations. Model simulations to August 14, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater in 2022 than expected based on long-term average values (Fig. 2).

Warm conditions during August resulted in rapid development of diamondback moth populations. Model simulations to August 21, 2022, indicate that the fourth 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 than 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 21, 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 21, based on climate normal data.

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

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

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

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Figure 4. Diamondback moth pupa within silken cocoon.
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!

13822Lygus bug monitoring ( 2022 Week 16 )

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 continues 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.

13820Predicted wheat stem sawfly growth ( 2022 Week 16 )

Warm, dry weather is conducive to wheat stem sawfly (Cephus cinctus) population growth where they are present. Risk of damage to sawfly host crops is greatest when weather conditions are warmer and drier than normal. Risk associated with wheat stem sawfly can be predicted by calculating growth index values, where the growth index describes the potential for wheat stem sawfly population growth. Where growth risk index values are moderate to high, crop damage is more likely than in areas where growth risk index values are low to moderate. Scouting in moderate and high risk areas this fall (especially where wheat stem sawfly populations are known to be present) will provide valuable information about potential crop yield losses this year and about the risk of wheat stem sawfly population damage in next growing season.

Based on growing season weather in 2022 (April 1 to August 22), predicted wheat stem sawfly growth index values are low to moderate across most of the prairies (Fig. 1). This is due to average (in parts of Alberta) to above-average (in parts Manitoba and southeastern Saskatchewan) precipitation during the current growing season. Growth index values, based on 2022 growing season weather are predicted to be greatest in a region that extends from Swift Current to Saskatoon (Fig. 1). This area has been warmer and drier than the rest of the prairies.

Figure 1. Predicted risk for wheat stem sawfly (Cephus cinctus) across the Canadian prairies as of August 21, 2022.

Access these resources for more information:
• Wheat stem sawfly was the Insect of the Week in 2021 for Week 12.
• Biological and monitoring information (including tips for scouting and economic thresholds) related to wheat stem sawfly is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.
• Refer to the wheat stem sawfly page 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 historical survey data for wheat stem sawfly.

13824Pre-Harvest Intervals (PHI) ( 2022 Week 16 )

One last time….. 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 Keep 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 has 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.

13828West nile virus risk ( 2022 Week 16 )

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 21, 2022 and where present, C. tarsalis development has progressed. Remember, areas highlighted yellow have accumulated sufficient heat units for the second generation of C. tarsalis to fly. Many areas of the prairies well exceed the 250-300 DD of base 14.3 °C (e.g., areas orange red any any shade of pink) represented in Figure 1. Outdoor enthusiasts falling within areas highlighted yellow, orange, red or pink should wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are at increased risk for WNV from late July but typically peaks over the long weekend in August.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 21, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP was approximately 12-14 days in areas highlighted mauve and approximately 22-24 days in areas highlighted light green.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a C. tarsalis female as of August 21, 2022.

The above maps should be compared with historical confirmed cases of WNV. 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 August 13, 2022; retrieved August 26, 2022) and provided below.

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 25Aug2022).

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.

13832Provincial insect pest report links ( 2022 Week 16 )

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 August 24, 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!
• Aphids in soybeans and sunflower, Lygus bugs, grasshoppers, and crickets were described in the August 24 issue.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #6 (URL retrieved August 25, 2022) and find an update on Diamondback moth. Bookmark their insect pest homepage to access important information!

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.

13834Crop report links ( 2022 Week 16 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the August 23, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the August 16-22, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the August 9, 2022 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 22, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 23, 2022 edition).
• The USDA’s Weekly International Weather and Crop Highlights (access a PDF copy of the August 20, 2022 edition).

13830Previous posts ( 2022 Week 16 )

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)
Aphids in field crops (Wk14)
Bertha armyworm – predicted development (Wk07)
Cabbage seedpod weevil monitoring (Wk12)
Cereal leaf beetle – predicted development (Wk06)
Crop protection guides (Wk02)
Cutworms (Wk02)
European corn borer – Canadian standardized assessment 2.0 (Wk02)
Extension survey for Albertans (Wk12)
Field heroes (Wk08)
Field guides – New webpage to access (Wk02)
Flea beetles (Wk01; IOTW)
iNaturalist.ca (Wk02)
Invasive insect species – Early detection (Wk02)
Pea leaf weevil monitoring (Wk12)
Scouting charts – canola and flax (Wk03)
Ticks and Lyme disease (Wk02)
Wheat midge – predicted development (Wk12)
Wind trajectory reports (Wk09)

13723Released August 19, 2022 ( 2022 Week 15 )

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Lygus bug monitoring
• Pre-harvest intervals (PHI)
• West nile virus risk
• Provincial insect pest report links
• Crop report links
• Previous posts
….and Monday’s Insect of the Week for Week 15 – it’s rusty grain beetle (Cryptolestes ferrugineus)!

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.

13725Weather synopsis ( 2022 Week 15 )

TEMPERATURE: Average temperatures for the 2022 growing season continue to be similar to long-term average values. This past week (August 8-14, 2022), the average daily temperature for the prairies was 2 °C warmer than the previous week and 2.5 °C warmer than climate normals. The warmest temperatures were observed across southwestern Saskatchewan and the southern and central regions of Alberta (Fig. 1). The prairie-wide average 30-day temperature (July 16 – August 14, 2022) was 1.5 °C warmer than the long-term average 30-day temperature. Average temperatures have been warmest across southern Alberta and southwestern Saskatchewan (Fig. 2).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of August 8-14, 2022.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of July 16 to August 14, 2022.

The average growing season (April 1-August 14, 2022) temperature for the prairies has been similar to observed climate normal values. The growing season has been coolest across the Peace River region (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to August 14, 2022.

PRECIPITATION: The greatest weekly precipitation amounts occurred across eastern Saskatchewan last week (August 8-14, 2022) (Fig. 4). 30-day (July 16-August 14, 2022) rainfall amounts continue to be greatest across southeastern Manitoba while dry conditions persist across southern Alberta and southwestern Saskatchewan (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 8-14, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (July 16 to August 14, 2022).

Growing season rainfall for the prairies (April 1 – August 14, 2022) has been near normal for Alberta and above normal in Manitoba. Total rainfall continues to be greatest across Manitoba and eastern Saskatchewan and least across central and south-central Saskatchewan (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to August 14, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 15, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (August 9-15, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >11 °C while the highest temperatures observed ranged from <25 to >36 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13727Predicted grasshopper development ( 2022 Week 15 )

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.

Model simulations were used to estimate grasshopper development as of August 14, 2022. Potential risk continues to be greatest across central and southern regions of Saskatchewan and southeastern Alberta. Simulations indicate that prairie populations are in the adult stage and females are beginning to lay eggs in the soil. 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 – August 14) predicted that ovipositon rates so far in 2022 have been greatest across southern Saskatchewan and southeastern Alberta (Fig. 1).

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 14, 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.

13729Predicted diamondback moth development ( 2022 Week 15 )

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.

Recent warm conditions have resulted in the rapid development of diamondback moth populations. Model simulations to August 14, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern 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 14, 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 14, based on climate normal data.

In-Field Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 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).

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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!

13788Lygus bug monitoring ( 2022 Week 15 )

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 continues 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.

13784Pre-Harvest Intervals (PHI) ( 2022 Week 15 )

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 Keep 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 has 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.

13609West nile virus risk ( 2022 Week 15 )

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 14, 2022 and where present, C. tarsalis development has progressed. Remember, areas highlighted yellow have accumulated sufficient heat units for the second generation of C. tarsalis to fly. Many areas of the prairies well exceed the 250-300 DD of base 14.3 °C (e.g., areas orange red any any shade of pink) represented in Figure 1. Outdoor enthusiasts falling within areas highlighted yellow, orange, red or pink should wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are at increased risk for WNV from late July but typically peaks over the long weekend in August.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 14, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP was approximately 12-15 days in areas highlighted mauve and approximately 22-24 days in areas highlighted light green.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a C. tarsalis female as of August 14, 2022.

The above maps should be compared with historical confirmed cases of WNV. 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 July 30, 2022; retrieved August 18, 2022) and provided below.

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 18Aug2022).

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.

13777Provincial insect pest report links ( 2022 Week 15 )

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 August 17, 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!
• Aphids in soybeans and small grains, Lygus bugs, grasshoppers, crickets, and diamondback moth were described in the August 17 issue.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #6 (URL retrieved August 18, 2022) and find an update on Diamondback moth. Bookmark their insect pest homepage to access important information!

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.

13762Crop report links ( 2022 Week 15 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the August 16, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the August 9-15, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the August 9, 2022 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 15, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 16, 2022 edition).
• The USDA’s Weekly International Weather and Crop Highlights (access a PDF copy of the August 13, 2022 edition).

13757Previous posts ( 2022 Week 15 )

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)
Aphids in field crops (Wk14)
Bertha armyworm – predicted development (Wk07)
Cabbage seedpod weevil monitoring (Wk12)
Cereal leaf beetle – predicted development (Wk06)
Crop protection guides (Wk02)
Cutworms (Wk02)
European corn borer – Canadian standardized assessment 2.0 (Wk02)
Extension survey for Albertans (Wk12)
Field heroes (Wk08)
Field guides – New webpage to access (Wk02)
Flea beetles (Wk01; IOTW)
iNaturalist.ca (Wk02)
Invasive insect species – Early detection (Wk02)
Pea leaf weevil monitoring (Wk12)
Scouting charts – canola and flax (Wk03)
Ticks and Lyme disease (Wk02)
Wheat midge – predicted development (Wk12)
Wind trajectory reports (Wk09)

13604Released August 12, 2022 ( 2022 Week 14 )

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.

13526Weather synopsis ( 2022 Week 14 )

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.

13515Predicted grasshopper development ( 2022 Week 14 )

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.

13537Predicted diamondback moth development ( 2022 Week 14 )

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).

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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!

13557Lygus bug monitoring ( 2022 Week 14 )

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.

13613Aphids in field crops ( 2022 Week 14 )

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)

13588Pre-Harvest Intervals (PHI) ( 2022 Week 14 )

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.

13575Provincial insect pest report links ( 2022 Week 14 )

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.

13456Previous posts ( 2022 Week 14 )

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)

13602Released August 5, 2022 ( 2022 Week 13 )

This week includes…..

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

Wishing everyone good SCOUTING weather!

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.

13524Weather synopsis ( 2022 Week 13 )

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

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

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

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

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

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

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

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

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

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

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

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

13513Predicted grasshopper development ( 2022 Week 13 )

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

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

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

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

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

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource 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.

13535Predicted diamondback moth development ( 2022 Week 13 )

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

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

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

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

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

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (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” (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!

13555Lygus bug monitoring ( 2022 Week 13 )

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

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect 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.

13612Aphids in field crops ( 2022 Week 13 )

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)

13586Pre-Harvest Intervals (PHI) ( 2022 Week 13 )

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

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

13573Provincial insect pest report links ( 2022 Week 13 )

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

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

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

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

13454Previous posts ( 2022 Week 13 )

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

13449Released July 29, 2022 ( 2022 Week 12 )

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Predicted wheat midge development
• Aphids in field crops
• Lygus bug monitoring
• Cabbage seedpod weevil monitoring
• Pea leaf weevil monitoring
• West Nile virus risk
• Extension survey for Albertans
• Pre-harvest intervals (PHI)
• Provincial insect pest report links
• Crop report links
• Previous posts
….and Monday’s Insect of the Week for Week 12 – it’s Western bean cutworm (Striacosta albicosta)!

Wishing everyone good SCOUTING 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.

13467Weather synopsis ( 2022 Week 12 )

TEMPERATURE: Though temperatures over the past 30 days have been warmer than normal, the 2022 growing season across the prairies has been quite similar to that of a ‘normal’ or long-term average season. This past week (July 18-24, 2022), the average daily temperature on the prairies was 2 °C cooler than the average daily temperature of the previous week and 1 °C warmer than the long-term normal temperature. The coolest temperatures were observed across central and northern Alberta (Fig. 1).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of July 18-24, 2022.

The prairie-wide average 30-day temperature (June 25 – July 24, 2022) was 0.5 °C warmer than the long-term average value. Average temperatures have been warmest across the southern prairies (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 25-July 24, 2022.

The average growing season (April 1-July 24, 2022) temperature for the prairies has been 0.2 °C cooler than the climate normal values. The growing season has been warmest across the southern prairies (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 24, 2022.

PRECIPITATION: Weekly rainfall accumulation for July 18 to 24 varied across the prairies. Very little precipitation has fallen across the northern prairies (Fig. 4). Observed rainfall amounts across central and northern Alberta were generally less than 5 mm. 30-day (June 25 – July 24, 2022) rainfall amounts have been well below average for the northern prairies and near normal across the southern prairies (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 18-24, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (June 25-July 24, 2022).

Growing season rainfall for April 1 – July 24, 2022, continues to be greatest across Manitoba and eastern Saskatchewan; cumulative rainfall amounts have been much lower for the central and western regions of Saskatchewan and Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 24, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 25, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (July 12-18, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <23 to >32 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13445Predicted grasshopper development ( 2022 Week 12 )

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

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

Model simulations were used to estimate grasshopper development as of July 24, 2022. As a result of above-normal temperatures, grasshopper development has rapidly progressed over the past few weeks. Last week, adults were just beginning to appear. Based on estimates of average development, populations should consist of 4th (25%) and 5th (34%) instar nymphs and adults (19%) across the southern regions of all three prairie provinces (Fig. 1). Adults should now be occurring across the southern regions of all three prairie provinces (Fig. 2). Potential risk continues to be greatest across the central and southern regions of Saskatchewan.

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 24, 2022.
Figure 2. Long-term average predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent adults, across the Canadian prairies as of July 17, 2022.

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

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource 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.

13528Predicted diamondback moth development ( 2022 Week 12 )

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

Model simulations to July 24, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater than long-term average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 24, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 24, 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 2. 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 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. 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!

13497Predicted wheat midge development ( 2022 Week 12 )

The following maps represent predicted regional estimates of wheat midge development. Remember – field level populations are assessed only through in-field scouting.

As of July 24, 2022, where wheat midge is present, model simulations predict that Albertan populations should be primarily in the egg stage, while populations across Manitoba and eastern Saskatchewan should consist of larvae developing in wheat heads (Fig. 1).

Figure 1. Wheat midge larvae (AAFC)

Regional differences in wheat midge development can be attributed to rainfall differences that occurred in May and June. Optimal rainfall in May and June across Saskatchewan and Manitoba has resulted in faster rates of wheat midge development rates than in Alberta. As a result, some adult wheat midge may still be active in Alberta (Fig. 2), while adult populations should have peaked and should be declining across Saskatchewan and Manitoba. Populations in the Peace River region are predicted to be primarily in the egg stage (Fig. 3). Across Manitoba and Saskatchewan, populations are predicted to be transitioning from the egg stage to the larval stage (Fig. 4). Wheat midge developmental rates near Regina, Saskatchewan are predicted to be greater than for Grande Prairie, Alberta.

Figure 2. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the adult stage, across western Canada, as of July 24, 2022.
Figure. 3. Percent of wheat midge population (Sitodiplosis mosellana) that is in the egg stage across western Canada, as of July 24, 2022.
Figure 4. Percent of wheat midge population (Sitodiplosis mosellana) that is in the larval stage (in wheat heads), across western Canada, as of July 24, 2022.

Model simulations indicate that egg development is complete and populations are primarily in the larval stage (>90%) for populations near Regina (Fig. 5) while Grande Prairie populations are predicted be in both egg (31%) and larval stages (61%) (Fig. 6). Potential risk continues to be greatest across eastern Saskatchewan and Manitoba.

Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of July 24, 2022.
Figure 6. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Grande Prairie, Alberta, as of July 24, 2022.

In-Field Monitoring: The window for scouting and application of the economic threshold for wheat midge (i.e., during the synchrony between wheat anthesis and midge flight period) has now drawn to a close for 2022. 

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  Wheat midge was featured as the Insect of the Week in 2021 (for Wk07).

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

13461Aphids in field crops ( 2022 Week 12 )

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)
Syrphid flies (Insect of the Week; 2015 Wk16)

13459Lygus bug monitoring ( 2022 Week 12 )

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.

13463Cabbage seedpod weevil monitoring ( 2022 Week 12 )

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

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.

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.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 2022Jul28).

CSPW was the Insect of the Week for Wk08 in 2021!

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

13465Pea leaf weevil monitoring ( 2022 Week 12 )

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

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

Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge (Fig. 2).  Females lay their eggs in the soil either near or on developing pea or faba bean plants from May to June.

Figure 2. Examples of adult pea leaf weevil damage on field pea seedlings, (A) seedling with notches on all nodes, (B) stereotypical crescent shaped notches on the leaf margin, (C) clam or terminal leaf of the pea seedling with arrows indicating the feeding notches.
All photos courtesy of Dr. L. Dosdall.

Larvae develop under the soil and are “C” shaped and milky-white with a dark-brown head capsule ranging in length from 3.5-5.5 mm (Figure 3).  Larvae develop through five instar stages.  After hatching, larvae seek and enter the roots of a pea plant.  Larvae will enter and consume the contents of the nodules of the legume host plant. It is the nodules that are responsible for nitrogen-fixation which affect yield plus the plant’s ability to input nitrogen into the soil. Consumption of or damage to the nodules (Figure 4) results in partial or complete inhibition of nitrogen fixation by the plant and results in poor plant growth and low seed yields.

Figure 3. Larva of pea leaf weevil in soil (Photo: L. Dosdall).
Figure 4. Damaged pea nodules (Photo: L. Dosdall).

Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol. Also access the Pea leaf weevil page from 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).

13443West nile virus risk ( 2022 Week 12 )

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

As of July 24, 2022, C. tarsalis development is now on the verge of the second generation of adults beginning to fly in areas highlighted yellow (i.e., 250-300 DD of base 14.3 °C) represented below in Figure 1. Outdoor enthusiasts falling within areas highlighted orange or yellow should begin to wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are now in a period of increased risk for WNV that typically peaks over the long weekend in August.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 24, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP is approximately 17 days in areas highlighted red and approximately 15 days in areas highlighted pink.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a C. tarsalis female as of July 24, 2022.

The above maps should be compared with historical confirmed cases of WNV. 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 November 18, 2021; retrieved July 28, 2022). The screenshot below (retrieved 28Jul2022) serves as a background reference of what was reported in 2021.

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 28Jul2022).

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.

13542Extension survey for Albertans ( 2022 Week 12 )

Prompted by recent discussions at Results Driven Agriculture Research (RDAR) meetings, a survey has been initiated as part of an M.Sc. research project in the Faculty of Science at the University of Alberta to assess the effectiveness and producer preferences for entomological extension in agriculture in Alberta. The project is funded by RDAR and the Alberta Pulse Growers.

Albertans can read the description of the survey or opt to complete the 20-minute online survey.

More information about this survey can be gained by contacting Ilan Domnich (domnich@ualberta.ca) or Dr. Maya Evenden (mevenden@ualberta.ca).

13584Pre-Harvest Intervals (PHI) ( 2022 Week 12 )

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

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

13447Provincial insect pest report links ( 2022 Week 12 )

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 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!
• Pea aphids, aphids in small grains, grasshoppers and armyworm larvae in MB were emphasized in the July 27 issue.
Bertha armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 26, 2022) of cumulative weekly counts.
Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 12, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

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 and note this link for July’s Crop Diagnostic School.

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.

13566Crop report links ( 2022 Week 12 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the July 26, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the July 19-25, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the July 12, 2022 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 25, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 26, 2022 edition).

13452Previous posts ( 2022 Week 12 )

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

13405Released July 22, 2022 ( 2022 Week 11 )

This week includes…..

• Weather synopsis
• Predicted wheat midge development
• Predicted grasshopper development
• Predicted diamondback development
• West Nile virus risk
• Pre-harvest intervals (PHI)
• Provincial entomologist updates
• Links to crop reports
• Previous posts
….and Monday’s Insect of the Week for Week 11 – it’s European corn borer (Ostrinia nubilalis)!

Wishing everyone good SCOUTING 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.

13352Weather synopsis ( 2022 Week 11 )

TEMPERATURE: Though recent temperatures have been warmer than normal, the 2022 growing season across the prairies continues to be marginally cooler than average. This past week (July 11-17, 2022) the average daily temperature (prairies) was 2.5 °C warmer than last week. Coolest temperatures were observed across Alberta (Fig. 1). The prairie-wide average 30-day temperature (June 18 – July 17, 2022) was 1.5 °C warmer than the long-term average value. Average temperatures have been warmest across the southern prairies, particularly across Saskatchewan and Manitoba (Fig. 2).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of July 11-17, 2022.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 18-July 17, 2022.

The average growing season (April 1-July 17, 2022) temperature for the prairies has been 0.3 °C cooler than climate normal values. The growing season has been warmest across the southern prairies (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 17, 2022.

PRECIPITATION: Weekly (July 11-17, 2022) rainfall varied across the prairies. Highest rainfall amounts were reported across southern Manitoba and southeastern Saskatchewan (Fig. 4). Observed rainfall events across Alberta were generally less than 5 mm. The 30-day (June 18 – July 17, 2022) rainfall amounts have been well below average for the Peace River region, average to above average for Alberta, below normal for Saskatchewan and near normal to above normal across Manitoba (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 11-17, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (June 18-July 17, 2022).

Growing season rainfall for April 1 – July 17, 2022, continues to be greatest across Manitoba and eastern Saskatchewan; cumulative rainfall amounts have been much lower for central and western regions of Saskatchewan and Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 17, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 18 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (July 12-18, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 2 to >14 °C while the highest temperatures observed ranged from <25 to >37 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13348Predicted wheat midge development ( 2022 Week 11 )

The following maps represent predicted regional estimates of wheat midge development. Remember – the rate of development and density varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds!

As of July 17, 2022, where wheat midge are present, model simulations predict that eggs and larvae (in heads) are the two prevalent stages occurring across the prairies. Differences in wheat midge development are attributed to rainfall differences across the prairies. Optimal rain events in May and June across Saskatchewan and Manitoba have contributed towards and advanced development rates of WM populations whereas populations in southern and central Alberta remain largely in the adult stage (Fig. 1). Adult populations in Saskatchewan and Manitoba are predicted to have peaked and are declining. Populations in the Peace River region are predicted to be primarily in the egg stage (Fig. 2). Across Manitoba and Saskatchewan, populations are predicted to be transitioning from the egg stage to the larval stage (Fig. 3).

Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada, as of July 17, 2022.
Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the egg stage across western Canada, as of July 17, 2022.
Figure 3. Percent of wheat midge population (Sitodiplosis mosellana) that is in the larval stage (in wheat heads), across western Canada, as of July 17, 2022.

Wheat midge development can be very site specific. For example, (as of July 17, 2022) developmental rates near Regina, Saskatchewan were predicted to be greater than for Yorkton, Saskatchewan, and Grande Prairie, Alberta. Model simulations indicate that populations near Regina were predominantly in the larval stage (Fig. 4) while Yorkton and Grande Prairie populations were predicted to be predominantly eggs (Figs. 5 and 6).

Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of July 17, 2022.
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Yorkton, Saskatchewan as of July 17, 2022.
Figure 6. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Grande Prairie, Alberta, as of July 17, 2022.

In-Field Monitoring: When scouting 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. 5). 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 5. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 6), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 6. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain 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 larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – 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 OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

13350Predicted grasshopper development ( 2022 Week 11 )

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 but local development can vary and is only accurately assessed through in-field scouting.

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

Model simulations were used to estimate grasshopper development as of July 17, 2022. Based on estimates of average nymphal development, populations should consist of primarily in the 4th and 5th instar and adults across southern regions of all three prairie provinces (Fig. 1). Adults should now be occurring across southern regions of all three prairie provinces (Fig. 2).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 17, 2022.
Figure 2. Long-term average predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent adults, across the Canadian prairies as of July 17, based on climate normal data.

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.

13346Predicted diamondback moth development ( 2022 Week 11 )

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

Model simulations to July 17, 2022, indicate that the second generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the Canadian prairies (Fig. 1). This week, development of the second generation has expanded across most of the Peace River region and the third generation is predicted to occur in a localized region of southern Manitoba. DBM development is predicted to be similar to average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 17, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 17, 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 2. 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).

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Figure 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. 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!

13374West nile virus risk ( 2022 Week 11 )

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

As of July 17, 2022, C. tarsalis development is now on the verge of the second generation of adults beginning to fly in areas highlighted yellow (i.e., 250-300 DD of base 14.3 °C) represented below in Figure 1. Outdoor enthusiasts falling within areas highlighted orange or yellow should begin to wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are now entering a period of increased risk for WNV that typically peaks over the long weekend in August.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of July 17, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP is approximately 14 days in areas highlighted red.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a C. tarsalis female as of July 17, 2022.

The above maps should be compared with historical confirmed cases of WNV. 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 November 18, 2021; retrieved July 20, 2022). The screenshot below (retrieved 20Jul2022) serves as a background reference of what was reported in 2021.

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 20Jul2022).

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.

13383Pre-Harvest Intervals (PHI) ( 2022 Week 11 )

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

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

13344Provincial insect pest report links ( 2022 Week 11 )

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 July 20, 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!
Grasshoppers and pea aphids in MB were emphasized in the July 20 issue.
Bertha armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 20, 2022) of cumulative weekly counts.
Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 12, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #4 (July 14, 2022) here and find updates linking to information for Wheat stem sawfly. Bookmark their insect pest homepage to access important information! Crops Blog Posts are updated through the growing season and note this link for July’s Crop Diagnostic School.

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.

13342Crop report links ( 2022 Week 11 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the July 19, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the July 5-11, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the July 12, 2022 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 18, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 19, 2022 edition).

13340Previous posts ( 2022 Week 11 )

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

13260Released July 15, 2022 ( 2022 Week 10 )

This week includes…..

• Weather synopsis
• Predicted wheat midge development
• Predicted grasshopper development
• Predicted diamondback development
• Provincial entomologist updates
• Links to crop reports
• Previous posts
….and Monday’s Insect of the Week for Week 10 – it’s cereal thrips (various species) and European skipper (Thymelicus lineola)!

Wishing everyone good SCOUTING 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.

13258Weather synopsis ( 2022 Week 10 )

TEMPERATURE: Though recent temperatures have been warmer than normal, the 2022 growing season across the prairies continues to be cooler than average. This past week (July 4-10, 2022) the average daily temperature for the prairie region was 2.5 °C warmer than last week. The warmest temperatures were observed across the southern prairies, particularly southeastern Saskatchewan and Manitoba (Fig. 1). The prairie-wide average 30-day temperature (June 11 – July 10, 2022) was 1 °C warmer than the long-term average value. Average temperatures have been warmest across the southern prairies, particularly in Saskatchewan and Manitoba (Fig. 2).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of July 4-10, 2022.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 11-July 10, 2022.

The average growing season (April 1-July 10, 2022) temperature for the prairies has been 0.5 °C cooler than climate normal values. The growing season has been warmest across a region than extends from Lethbridge to Regina and Saskatoon as well as southern Manitoba (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 10, 2022.

PRECIPITATION: Weekly (July 4-10, 2022) rainfall varied across the prairies. The highest rainfall amounts were reported across central Alberta and southern Saskatchewan (Fig. 4). The Peace River region and central Saskatchewan reported rainfall amounts that were generally less than 10 mm. The 30-day (June 11 – July 10, 2022) rainfall accumulation amounts have been well above average for Alberta, near normal to above normal across Manitoba, and well below normal for Saskatchewan (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 4-10, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (June 11-July 10, 2022).

Growing season rainfall for April 1 – July 10, 2022, continues to be greatest across Manitoba and eastern Saskatchewan; cumulative rainfall amounts have been lower for central and western regions of Saskatchewan and Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 10, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 11, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (July 5-11, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < -2 to >14 °C while the highest temperatures observed ranged from <23 to >33 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13266Predicted wheat midge development ( 2022 Week 10 )

Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface.

The following maps represent predicted regional estimates of wheat midge development. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds!

As of July 10, 2022 and where wheat midge is present, model simulations predict that pupae, adults, and eggs are present in wheat fields across the prairies. Differences in wheat midge development are attributed to rainfall differences across the prairies. Due to drier conditions in May and June, wheat midge development was delayed across most of Alberta. Alberta populations should be predominantly in the pupal stage (Fig. 1).

Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada, as of July 10, 2022.

The appearance of adults is predicted to increase across all three provinces (Fig. 2). Optimal rain in May and June across Saskatchewan and Manitoba has resulted in development rates that are greater than those predicted for Alberta. The simulation indicates that oviposition has begun across eastern Saskatchewan, Manitoba, the Peace River region and north-western Alberta (Fig. 3). Larvae may be in wheat heads in a region south of Winnipeg.

Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the adult stage across western Canada, as of July 10, 2022.
Figure 3. Percent of wheat midge population (Sitodiplosis mosellana) that is in the egg stage, across western Canada, as of July 10, 2022.

Adults may be occurring when wheat is most susceptible. Adults and eggs (top panel) are predicted to occur when wheat is heading (bottom panel) for fields near Regina, Saskatchewan (Fig. 3). Phenology simulations suggest that wheat may be susceptible for the next two weeks.

Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of July 10, 2022.

In-Field Monitoring: When scouting 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. 5). 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 5. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 6), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 6. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain 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 larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – 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 OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

13264Predicted grasshopper development ( 2022 Week 10 )

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 but local development can vary and is only accurately assessed through in-field scouting.

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

Warm, dry conditions across southern and central regions of the prairies have advanced grasshopper development. Model simulations were used to estimate grasshopper development as of July 10, 2022. Based on estimates of average nymphal development, populations are predicted to consist of primarily 4th and 5th instar stages across all three prairie provinces (Fig. 1). Across most of the prairies, grasshopper development is predicted to be similar to average values; development is delayed across southern Manitoba (Fig. 2).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 10, 2022.
Figure 2. Long-term average predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 10, based on climate normal data.

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.

13268Predicted diamondback moth development ( 2022 Week 10 )

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

Model simulations to July 10, 2022, indicate the second generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the Canadian prairies (Fig. 1). DBM development is predicted to be similar to long-term average development for this time of the growing season (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 10, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 10, 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 2. 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).

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Figure 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. 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!

13270Provincial insect pest report links ( 2022 Week 10 )

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 July 13, 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!
Pea aphids in MB were emphasized in the July 13 issue.
Bertha armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 11, 2022) of cumulative weekly counts.
Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of June 28, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #4 (July 14, 2022) here and find updates linking to information for Wheat stem sawfly. Bookmark their insect pest homepage to access important information! Crops Blog Posts are updated through the growing season and note this link for July’s Crop Diagnostic School.

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.

13272Crop report links ( 2022 Week 10 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the July 12, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the July 5-11, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the June 27, 2022 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 11, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 12, 2022 edition).

13274Previous posts ( 2022 Week 10 )

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

13181Released July 8, 2022 ( 2022 Week 9 )

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted wheat midge development
• Predicted diamondback development
• Provincial entomologist updates
• Links to crop reports
• Review Insect of the Week for 2022 scouting help
• Previous posts
….and Monday’s Insect of the Week for Week 9 – it’s the spotted lanternfly, Lycorma delicatula!

Wishing everyone good 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.

13146Weather synopsis ( 2022 Week 9 )

TEMPERATURE: The 2022 growing season continues to be cooler while rainfall amounts have been highly variable across the prairies. This past week (June 27 – July 3, 2022) the average daily temperature (prairies) was 1 °C cooler than the previous week and 0.5 °C cooler than normal. The warmest temperatures were observed across the southern prairies (Fig. 1). The prairie-wide average 30-day temperature (June 4 – July 3, 2022) was 1 °C cooler than the long-term average value. Average temperatures have been warmest across the southern prairies, particularly for Saskatchewan and Manitoba (Fig. 2).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of June 27-July 3, 2022.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 4-July 3, 2022.

The average growing season (April 1-July 3, 2022) temperature for the prairies has been 0.7 °C cooler than climate normal values. The growing season has been warmest across a region than extends from Lethbridge to Regina and Saskatoon (Fig. 3).

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

PRECIPITATION: Weekly (June 27 – July 3) rainfall varied across the prairies. The highest rainfall amounts were reported for central Alberta and the Peace River region. Eastern Saskatchewan and Manitoba reported rainfall amounts that were generally less than 10 mm (Fig. 4). 30-day accumulation amounts have been well above average for Alberta, near normal to above normal across Manitoba, and well below normal for Saskatchewan (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 27-July 3, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (June 4-July 3, 2022).

Growing season rainfall for April 1 – July 3, 2022, continues to be greatest across Manitoba and eastern Saskatchewan; cumulative rainfall amounts have been lower for central and western regions of Saskatchewan and Alberta (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 3, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 6, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (June 30-July 6, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <20 to >32 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more 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.

13157Predicted grasshopper development ( 2022 Week 9 )

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 but local development can vary and is only accurately assessed through in-field scouting.

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

Compared with the previous week, warm, dry conditions have advanced grasshopper development, particularly across central and southern regions of the prairies. Model simulations were used to estimate grasshopper development as of July 3, 2022. Based on estimates of average nymphal development, first to fifth instar nymphs should be occurring across southern and central regions of all three prairie provinces (Fig. 1). Across most of the prairies, grasshopper development is predicted to be similar to average values; development is delayed across southern Manitoba (Fig. 2).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 3, 2022.
Figure 2. Long-term average predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 3, based on climate normal data.

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.

13151Predicted wheat midge development ( 2022 Week 9 )

Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface.

The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds.

As of July 3, 2022, model simulations predict that larvae (surface) and pupae are present with increased occurrence of adults. Larvae are completing development and transitioning to the pupal stage. Compared to last week, pupal populations are predicted to increase across the Parkland and Peace River regions (Fig. 1). Appearance of adults is predicted to increase across eastern Saskatchewan and southern Manitoba (Fig. 2). Occurrence of adults may be occurring when wheat is most susceptible. Occurrence of adults and eggs (top panel) are predicted to occur when wheat is heading (bottom panel) for fields near Regina, Saskatchewan (Fig. 3). Phenology simulations suggest that wheat may be susceptible for the next 10-12 days.

Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada, as of July 3, 2022.
Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the adult stage, across western Canada, as of July 3, 2022.
Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of July 3, 2022.

In-Field Monitoring: When scouting 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. 4). 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 4. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 5), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 5. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain 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 larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – 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 OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

13161Predicted diamondback moth development ( 2022 Week 9 )

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.

Recent warm conditions should result in the development of DBM populations. Model simulations to July 3, 2022, indicate that the first generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the Canadian prairies and that the second generation is emerging across Manitoba and Saskatchewan (Fig. 1). DBM development is predicted to be similar to average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 3, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 3, 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 2. 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 3. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. 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!

13183Provincial insect pest report links ( 2022 Week 9 )

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 July 6, 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!
Pea aphids, barley thrips and blister beetles in MB were new additions to the July 6 issue.
Diamondback moth pheromone trap monitoring update for MB – Traps will come down at the end of this week. Review the detailed summary of cumulative trap counts from 52 sites deployed across the province (as of June 28, 2022).
Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of June 28, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #3 (June 2022) here and find updates linking to information for Grasshopers in pulse crops, and Diamondback moth. Bookmark their insect pest homepage to access important information! Crops Blog Posts are updated through the growing season and note this link for July’s Crop Diagnostic School.
Diamondback moth pheromone trap monitoring update for SK – Access this link to review counts summarized regionally (as of June 15, 2022).

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.
Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.
Cutworm live monitoring map for AB – Reports are mapped on this Live Map. Use this online form to report cutworms in Alberta.

13186Crop report links ( 2022 Week 9 )

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (or access a PDF copy of the July 5, 2022 report).
Saskatchewan Agriculture (or access a PDF copy of the June 28-July 4, 2022 report).
Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the June 27, 2022 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 5, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 6, 2022 edition).

13203Review INSECT OF THE WEEK for 2022 scouting help! ( 2022 Week 9 )

The Insect of the Week features species you may encounter while scouting in field crops. This popular feature began with the release of the 2015 insect field guide and carries on today.  Many thanks to all our contributors!

Need help finding information or a quick refresher when doing in-field scouting? Scroll the carousels to access the INSECT OF THE WEEK lineups for 2022 and the past 5 years:

2022
2021
2020
2019 – Doppelgangers series
2018
2017

13178Previous posts ( 2022 Week 9 )

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

13100Released July 1, 2022 ( 2022 Week 8 )

HAPPY CANADA DAY! This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted wheat midge development
• Predicted diamondback development
• Weekly wind trajectory report
• Field Heroes – access a NEW Pest & Predator podcast
• Provincial entomologist updates
• Links to crop reports
• Previous posts
….and Monday’s Insect of the Week for Week 8 – it’s the strawberry blossom weevil, Anthonomus rubi!

Wishing everyone good 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.

13028Weather synopsis ( 2022 Week 8 )

TEMPERATURE: This past week (June 20-26, 2022) the average daily temperature on the prairies was 1 °C warmer than the previous week and 1 °C warmer than normal (Fig. 1). Similar to last week, the warmest temperatures were observed across Manitoba and southeastern Saskatchewan. The prairie-wide average 30-day temperature (May 28 – June 26, 2022) was 0.5 °C cooler than the long-term average temperature. Average temperatures have been warmest across the southern prairies (Fig. 2).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of June 20-26, 2022.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 28-June 26, 2022.

The growing season (April 1 to June 26, 2022) temperature for the prairies has been 1 °C cooler than climate normal values. A review of specific prairie locations illustrates that Grande Prairie was 1.8 °C cooler than average (Table 1). The growing season has been warmest across western Saskatchewan and southern and central regions of Alberta (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to June 26, 2022.
Table 1. Growing season (April 1 – June 26, 2022) temperature and rainfall summary for specific locations across the Canadian prairies.

PRECIPITATION: Weekly (June 20-26) rainfall varied across the prairies. Significant rainfall was reported across southeastern Saskatchewan (Weyburn – 82mm) and from Edmonton (66 mm) to Meadow Lake, Saskatchewan (52 mm). The Peace River region and southwestern Saskatchewan reported rainfall amounts that were generally less than 10 mm (Fig. 4). 30-day rainfall accumulation totals have been well above average across Manitoba and Alberta while rainfall accumulation has been well below normal across Saskatchewan (Fig. 5).

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 20-26, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (May 28-June 26, 2022).

Growing season rainfall for April 1 – June 26, 2022 continues to be greatest across Manitoba and eastern Saskatchewan; growing season rainfall remains below normal across central Saskatchewan and near normal for Alberta (Fig. 6; Table 1).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to June 26, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-June 27, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (June 21-27, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < -1 to >10 °C while the highest temperatures observed ranged from <21 to >32 °C. Again this week, areas of the prairies hit warmer temperatures with a slight bump in the number of sites experiencing days at or above 25 °C across the prairies and a moderate increase in the sites recording days at or above 30 °C. Access these maps and more 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.

13041Predicted grasshopper development ( 2022 Week 8 )

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 but local development can vary and is only accurately assessed through in-field scouting.

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

Warm, dry conditions across central and southern regions of Saskatchewan have resulted in rapid grasshopper development. Model simulations were used to estimate grasshopper development as of June 26, 2022. The grasshopper hatch is nearly complete for the southern prairies (Fig. 1). Hatch is still progressing across the Parkland and Peace River regions. Based on estimates of average nymphal development, first to fifth instar nymphs should be occurring across southern and central regions of all three prairie provinces (Fig. 2).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 26, 2022.
Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 26, 2022.

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

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource 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.

13085Predicted wheat midge development ( 2022 Week 8 )

Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface.

The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds.

As of June 26, 2022, model simulations predict that larvae (surface) and pupae are present with limited occurrence of adults. In terms of occurrence of pupae, wheat midge development is most advanced across central Saskatchewan, Manitoba and the Peace River region (British Columbia) (Fig. 1). The first appearance of adults is predicted near Regina and across southern Manitoba (Fig. 2). Model projections for July 3, 2022, indicate that the first appearance of adults should begin across the central prairies and Peace River region over the weekend.

Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada, as of June 26, 2022.
Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the adult stage, across western Canada, as of June 26, 2022.

In-Field Monitoring: When scouting 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. 3). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 3. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Figure 4. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain 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 larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting!  Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12).  Remember – 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 OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

13071Predicted diamondback moth development ( 2022 Week 8 )

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 June 26, 2022, indicate that the first generation of non-migrant adults (based on mid May arrival dates) are currently occurring across the Canadian prairies and that the start of the second generation is emerging in southern Manitoba (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 June 26, 2022.

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