147812023 Week 16 (Released August 25, 2023) ( 2023 Week 16 )

Harvest is now well underway and the risk of insect damage to crops is declining as crops mature and are being harvested. This will be the last Weekly Update of 2023. The Prairie Pest Monitoring Network sincerely thanks everyone who has contributed to the 2023 Weekly Updates.

We wish everyone a safe and insect-free harvest season and fall insect scouting season – remember that the annual grasshopper survey is happening now across the prairies and that the wheat midge and wheat stem sawfly surveys will start after harvest is completed.

In 2023, development of many pest insects occurred earlier than normal, thanks to warmer than average weather during this growing season. In particular, we observed adult grasshoppers in mid-June for the first time in more than 30 years (if ever!). Adult grasshoppers will be busy reproducing now, and in looking to next year, insect surveyors are working to estimate grasshopper populations in ditches/roadsides and may be collecting samples of adult grasshoppers for species identification.

Diamondback moth, if present, are into the fifth non-migrant generation across the southern prairies now, with the fourth generation occurring in the more northern parts of the prairies. Diamondback moths could pose a threat to crucifer vegetables right now, as well as any canola that is late to mature.

This week, the Prairie Research post highlights studies being done at the University of Saskatchewan to learn more about the ability of ground beetles to contribute to weed seed management.

Use the links in the Provincial Insect Updates post to learn more about what is happening with populations of insect pests (and beneficial insects) in your province. In Manitoba, Dr. John Gavloski notes that grasshoppers remain a concern, that flea beetles are being found in high numbers on the pods in some canola fields and that some bertha armyworm larvae have been found in some canola fields. Dr. Gavloski also noted that there have been a lot of cabbage white and checkered white butterflies active in Manitoba late this summer. Dr. Vankosky observed high numbers of both butterflies in southeast Saskatchewan too. As in Manitoba, Dr. James Tansey reports that high grasshopper densities are a particular problem in central and southern Saskatchewan.

Remember:

1) There are many resources available to help with planning for late-season insecticide applications to ensure Pre-Harvest Interval requirements are met.

2) Insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification are available from the Prairie Pest Monitoring Network.

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

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

14773Weather Synopsis ( 2023 Week 16 )

This past week (August 14-20, 2023) the southern prairies experienced warmer temperatures and minimal rain. In contrast, cooler, wetter conditions continued to persist across most of the Parkland region.

The seven day average daily temperature was 1.5 °C warmer than average in the last week. The coolest temperatures occurred across the central and western areas of the Parkland region (Fig 1).

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of August 14-20, 2023. 

Growing season (April 1, 2023 to August 20, 2023) average temperatures were warmest across Alberta, southern Saskatchewan and southeastern Manitoba (Fig. 2).

Figure 2. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 20, 2023. 

In comparing the 2023 growing season temperature to the long-term average temperature for the same period (Fig. 3), growing season temperatures were 2°C warmer than average across Alberta in 2023. In Saskatchewan and Manitoba, the growing season average temperature was 1°C warmer than normal (Fig. 3).

Figure 3. Temperature (°C) anomaly (based on difference of average temperature between observed and climate normals) during the growing season (April 1 – August 20, 2023). 

Precipitation for the period of August 14-20, 2023 was greatest across the Parkland regions of Alberta and Saskatchewan (Fig. 4). Rainfall amounts were negligible for the Peace River region as well as south and central regions of the prairies. A more widespread rainfall event on the prairies occurred between August 21 and 24, bringing precipitation to many parts of the prairies.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 14-20, 2023. 

Growing season cumulative rainfall amounts were greatest in a region that extended from Red Deer to Grande Prairie (Fig. 5).

Figure 5. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 20, 2023. 

Rainfall amounts for central and southern regions of the prairies have been well below average (Fig. 6) in 2023. Areas around and including Lethbridge, Alberta, for example, received 40-70% of the precipitation expected in a ‘normal’ year, based on comparing 2023 to 30-year average weather datasets.

Figure 6. Percent of normal precipitation received during the 2023 growing season (April 1 – August 20, 2023), based on a comparison of cumulative rainfall in 2023 to the climate normal cumulative rainfall (mm).  

14769Predicted Grasshopper Development ( 2023 Week 16 )

As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of normal in 2023. This year, adults have occurred much earlier than normal (middle of June in some locations!) and simulations also indicate that adult females have begun laying eggs much earlier than normal.

The oviposition index provides a relative comparison of grasshopper oviposition rates across the prairies. The oviposition index predicts that oviposition should be occurring across the prairies, and that egg production should be greatest across southern regions of Alberta (Fig. 1), as of August 20, 2023. Egg production should also be high in areas of southern Saskatchewan and southern Manitoba, assuming that grasshoppers are present.

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of Augst 20, 2023. Higher ovipositional index values indicate greater potential for oviposition (egg-laying). 

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

Figure 2. Long-term average predicted grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 20 (based on climate normals). Higher ovipositional index values indicate greater potential for oviposition. 

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

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14764Predicted Diamondback Moth Development ( 2023 Week 16 )

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

Due to warm weather in 2023, development of diamondback moth populations is well ahead of average development. Model simulations to August 20, 2023, indicate that the fourth and fifth generations of non-migrant adults (based on early May arrival dates) are currently occurring across the Canadian prairies (Fig. 1). Fourth generation diamondback moths, if present, are occurring farther north on the prairies compared to fifth generation diamondback moths.

Figure 1.  Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 20, 2023.  

In a ‘normal year’ based on climate normals data (e.g., 30-year averages), we would expect the third generation of non-migrant diamondback moth to be occurring across the northern prairie region at this time of year, with the fourth generation occurring across the southern regions of the prairies (Fig. 2).

Figure 2. The predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 20, based on climate normals data.

Considering advanced canola development, risk across the southern and central regions of the prairies associated with the development of a fifth generation of diamondback moth should be minimal. In regions where broccoli, rutabaga, and other brassica vegetables are grown and where crops are late to mature, these crops could still be at risk of damage from diamondback moth. Keep scouting for diamondback moth where crops are still green and could provide a desirable food source for developing diamondback moth larvae.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14762Provincial Insect Updates ( 2023 Week 16 )

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

Saskatchewan Crop Production News issues are now online! Issue 5 is available now and though it focuses mostly on plant pathogens and weed management, there is an updated Crop Report for the period of August 15-21. The crop report notes that grasshoppers and gophers are causing some late season damage to crops, as well as winds, localized flooding, and drought. Aster yellows has been observed in crops. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year). The August 23 issue provides an update on grasshoppers, flea beetles, and bertha armyworm. It also has features insect pests that are often found in storage bins that could affect grain quality and a quiz for identifying butterflies!

14757Prairie Research: Carabid Beetles that help Manage Weeds ( 2023 Week 16 )

*Text for this post prepared by Daniella Canon-Rubio and Christian Willenborg, University of Saskatchewan.

At the University of Saskatchewan, Christian Willenborg, Khaldoun Ali, and Daniella Canon-Rubio are studying the role of carabid beetles in the biological control of weeds. These remarkable beetles have gained acclaim for their vital ecological role across diverse agroecosystems, including as predators of pest insects and for contributing to weed management by actively reducing the population of weed seeds in agricultural fields.

Stereoscope image of an adult of Pterostichus melanarius. Picture provided by Daniella Canon-Rubio, University of Saskatchewan.

The seed selection process in carabid beetles is a multifaceted phenomenon, subject to the influence of various ecological factors. The objective of Daniella’s study is to examine the effects of imbibition on the preferential tendencies exhibited by Pterostichus melanarius and Amara littoralis carabid beetles towards the seeds of Bassia scoparia (kochia) and Thlaspi arvense (stinkweed).

Stereoscope image of Thlaspi arvense seed eaten by P. melanarius next to an intact seed. Picture provided by Daniella Canon-Rubio, University of Saskatchewan.

Their research will involve conducting field experiments to trap live adult insects using pitfall traps. In the laboratory at the University of Saskatchewan, studies in controlled feeding environments will be conducted with varying imbibition length times to allow for the evaluation of seed preferability and consumption. Seed imbibition occurs when dry seeds take up water. Concurrently, we will utilize an olfactometer to evaluate how the odor emitted by Bassia scoparia and Thlaspi arvense seeds, treated with various imbibition times, influences the seed selection and favorability of Pterostichus melanarius and Amara littoralis. To integrate and analyze the behavioral data obtained from this experiment, we will employ Ethovision, a sophisticated software platform, to track the subjects through video analysis, perform movement analysis, and accurately identify specific behaviors exhibited by the beetles.

Through the implementation of this research on biological control in conservation, our objective is to significantly expand and enrich the knowledge base concerning carabid beetles and their feeding behavior in relation to diverse weed seed characteristics. By fostering a comprehensive understanding, we seek to promote awareness among farmers and fellow researchers about the valuable role carabid beetles play as beneficial organisms in North America. Furthermore, we aim to encourage the utilization of carabid beetles as an alternative approach to weed management.

14755Pre-Harvest Intervals ( 2023 Week 16 )

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

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

147402023 Week 15 (Released August 17, 2023) ( 2023 Week 15 )

Insect scouting season continues, even though harvest has already started in some regions! Development of many pest insects has been ahead of schedule all year in most parts of the prairies, thanks to warmer than average weather during this growing season.

Adult grasshoppers are now in flight and will be laying eggs across the prairie region. Scouting individual fields is the best way to estimate crop risk. At this time of year, we start to look forward to next season. Insect surveyors are working to estimate grasshopper populations in ditches/roadsides and may be collecting samples of adult grasshoppers for species identification.

Aside from grasshoppers, fall surveys for wheat midge and wheat stem sawfly will begin as harvest is completed in Alberta and Saskatchewan. This week, the Insect of the Week post features wheat stem sawfly, including information about how to estimate their population densities in the fall.

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

On the topic of diamondback moths, Dr. Maya Evenden’s lab at the University of Alberta is conducting research on diamondback moth, flea beetles, and alfalfa weevil. Learn more about Maya’s research program in this week’s Prairie Research post.

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

Remember:

1) There are many resources available to help with planning for late-season insecticide applications to ensure Pre-Harvest Interval requirements are met.

2) Insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification are available from the Prairie Pest Monitoring Network.

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

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

14735Weather Synopsis ( 2023 Week 15 )

The Parkland region of Alberta, Manitoba, and Saskatchewan experienced cooler temperatures and rain in the past week, but warm, dry conditions continue to persist across most of the southern prairies. This past week (August 7-13, 2023), the prairie average daily temperature was slightly cooler than the long-term average. The coolest temperatures occurred across the central and eastern areas of the Parkland region (Fig 1). In comparison to the Parkland region, temperatures were much warmer across southern Alberta and southwest Saskatchewan.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of August 7 to 13, 2023. 

Precipitation for the period of August 7-13, 2023 was highest for a large region northeast of Edmonton in Alberta, east of Saskatoon and north of Regina in Saskatchewan, and in most of Manitoba (Fig. 2). Southern Alberta has been extremely dry all of summer 2023 and that trend continued in the last week (Fig. 2). Similarly, it has continued to be dry in southwestern Saskatchewan.

Figure 2. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 7-13, 2023. 

This year, we used scatterplots for growing season average temperature and total rainfall to provide relative comparisons of site specific growing conditions across the prairies. Growing season temperature and precipitation has varied significantly across the prairies in 2023. Lethbridge has had less than 100 mm of rain, for example, while Grande Prairie has reported 250 mm. Growing season average temperatures have ranged from 12.3°C to 15.4°C. Northwestern Alberta locations are categorized as relatively cool and wet in 2023 (Fig. 5). In contrast, most locations in the southern prairies can be characterized as warm and dry.  

Figure 3. Site-specific comparison of growing season average temperature (°C) and cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 13, 2023. The red line indicates the average temperature and the blue line represents the average rainfall. 

14731Predicted Diamondback Moth Development ( 2023 Week 15 )

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

Due to warm weather in 2023, development of diamondback moth populations is well ahead of average development. Model simulations to August 13, 2023, indicate that the fourth generation of non-migrant adults (based on early May arrival dates) are currently occurring across the Canadian prairies (Fig. 1) and that fifth generation non-migrant adults could also be occurring in some localized areas of the southern prairies.

Figure 1.  Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 13, 2023.  

In a ‘normal year’ based on climate normals data (e.g., 30-year averages), we would expect only the third generation of non-migrant diamondback moth to be occurring across the northern prairie region at this time of year, with the fourth generation occurring across the extreme southern region of the prairies (Fig. 2).

Figure 2. The predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 13, based on climate normals data.

Considering advanced canola development, risk across the southern and central regions of the prairies associated with the development of a fifth generation of diamondback moth should be minimal. However, in regions where broccoli, rutabaga, and other brassica vegetables are grown and where crops are late to mature, these crops could still be at risk. Keep scouting for diamondback moth where crops are still green and could provide a desirable food source for developing diamondback moth larvae.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14726Prairie Research: The Evenden Lab ( 2023 Week 15 )

*Text for this post prepared by Priyatha Sundaran, Sharavari Kulkarni and Maya Evenden, from the University of Alberta.

Dr. Maya Evenden’s lab in the Department of Biological Sciences at the University of Alberta researches insect behaviour, chemical ecology and integrated pest management. They study how insects orient and maneuver in their environment and exploit that knowledge for the development of IPM tactics. This summer the Evenden lab has multiple agriculture-based projects targeting diamondback moth, flea beetles, pea leaf weevil and alfalfa weevil. Here we highlight the work of an MSc student, Priyatha Sundaran, and a postdoctoral fellow, Dr. Sharavari Kulkarni.

Priyatha’s research focuses on the presence and distribution of alfalfa weevil (Hypera postica), in alfalfa grown for seed in southern Alberta. The study also assesses the diversity of Sitona spp. in sampled alfalfa fields. In three field seasons, alfalfa weevils have been sampled with soil and sweep samples, and emergence and pit fall traps. Soil samples at the beginning and end of each crop season estimate the density of alfalfa weevils in the soil over the winter. Sweep net samples can collect both larvae and adults to monitor alfalfa weevil density in the field for timely use of insecticides. Pitfall trap capture can indicate weevil movement in and out of the field over the course of the growing season. Emergence cages assessed the overwintering locations of weevils inside and outside the field. Initial results reinforce the effectiveness of sweep net sampling to monitor alfalfa weevil populations with peak larval activity in June-July. Alfalfa weevils were captured in equal numbers in pitfall traps placed at the edge and in the interior of the field suggesting that alfalfa weevils remain within alfalfa fields, unlike in other parts of their range. Sitona spp. bycatch consisted mostly of alfalfa curculio (Sitona lineellus) and pea leaf weevil (Sitona lineatus).

Alfalfa weevil sampling methods used in alfalfa fields grown for seed: A) Emergence cages were located inside and outside the field to reveal the overwintering sites of alfalfa weevils. B) Two hundred sweep samples were collected from four locations in each field throughout the growing season in three seasons. C) Directional pitfall traps were employed in the 2023 season to measure the direction of movement of alfalfa weevils in the field. Pictures by Priyatha Sundaran, University of Alberta.

Sharavari’s research focuses on developing weather-based stage-structured predictive models for two important canola pests, striped flea beetles, (Phyllotreta striolata (Fab.)) and crucifer flea beetles (Phyllotreta cruciferae (Goeze)). Flea beetles are oligophagous species feeding mainly on canola (Brassica napus L. and Brassica rapa L.) and mustard (Brassica juncea L.). Sharavari used field surveys to assess local phenology and laboratory bioassays to study the effect of temperature on beetle development and interspecific competition between the two species. The flea beetle surveys were conducted in the spring (pre-seeding) and fall of 2021, 2022 and 2023 across 20+ canola fields throughout Alberta.  Season-long, site-specific weather data was collected for modeling and validation. None of the available monitoring methods provides accurate forecasting for flea beetles, and weather-based phenology models can help producers make informed decisions on timing and the need to apply foliar insecticides for flea beetle management.  Lab assays showed a dramatic effect of temperature on the time and success of egg hatch and development time from egg to adult.  On-going lab work is testing for plant-mediated interactions between the two species to understand if P. cruciferae prefers to feed and oviposit on plants previously damaged by P. striolata and to determine if inter-species interactions have fitness costs.

Flea beetle monitoring in commercial canola fields with yellow sticky cards at sites with weather stations for site-specific temperature measurements. Pictures by Sharavari Kulkarni, University of Alberta.

14724Provincial Insect Updates ( 2023 Week 15 )

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

Saskatchewan Crop Production News issues are now online! Issue 4 is available now, as well as a Crop Report covering the period of August 1 to August 7. The crop report notes that grasshoppers and flea beetles are causing some late season damage to crops. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year). The August 16 issue provides an update on Lygus bugs, diamondback moth, flea beetles, grasshoppers and aphids. It also has great pictures to help identify insect pests!

14722Pre-Harvest Intervals (PHI) ( 2023 Week 15 )

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

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

147052023 Week 14 (Released August 10, 2023) ( 2023 Week 14 )

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

Adult grasshoppers are now in flight and are expected to be busy reproducing across the prairie region. Scouting individual fields is important to best estimate crop risk. At this time of year, we start to look forward to next season. Insect surveyors are now working to estimate grasshopper populations in ditches/roadsides and may be collecting samples of adult grasshoppers for species identification.

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

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

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

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

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

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

14698Weather Synopsis ( 2023 Week 14 )

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

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

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

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

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

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

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

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

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

14696Predicted Grasshopper Development ( 2023 Week 14 )

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

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

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

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

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

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14694Predicted Diamondback Moth Development ( 2023 Week 14 )

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

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

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

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

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

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

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

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14688Provincial Insect Updates ( 2023 Week 14 )

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

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

Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year). The August 9 issue provides an update on Lygus bugs, diamondback moth, flea beetles, grasshoppers and aphids. It also has great pictures of beneficial insects!

14686Pre-Harvest Intervals ( 2023 Week 14 )

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

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

146742023 Week 13 (Released August 3, 2023) ( 2023 Week 13 )

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

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

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

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

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

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

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

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

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

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

14659Provincial Insect Updates ( 2023 Week 13 )

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

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

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

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

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

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

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

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

14667Prairie Research ( 2023 Week 13 )

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

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

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

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

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

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

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

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

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

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

14672Pre-Harvest Intervals (PHI) ( 2023 Week 13 )

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

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

146412023 Week 12 (Released July 27, 2023) ( 2023 Week 12 )

It sounds like harvest has started in some parts of the prairies in the past week, but crop development and insect pest issues are variable across the prairie region. Insect scouting season continues! Development of many pest insects (and of their host crops) is ahead of schedule this year, thanks to warmer than average weather during this growing season.

Adult grasshoppers are becoming more and more common across the prairies. The stage of grasshopper development and grasshopper population densities can vary between fields, thus scouting individual fields is important to best estimate crop risk. Now that adult grasshoppers are active, egg laying has begun.

Diamondback moth, if present, are into the fourth non-migrant generation in some parts of the prairies now. Keep in mind that diamondback moth develop quickly in warm weather which could lead to rapidly increasing populations over the summer. Scout canola fields for diamondback moth larvae and use the links in the Provincial Insect Updates post to learn about diamondback moth risk in your region. Parasitoids of diamondback moth are highlighted in the Week 12 Insect of the Week!

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

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

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

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

14630Weather Synopsis ( 2023 Week 12 )

During the week of July 17-23, 2023, the prairie average daily temperature was 1°C warmer than the climate normal average daily temperature for the same period. The coolest temperatures were observed across eastern Saskatchewan, western Manitoba, and the Peace River region. The warmest weekly average temperatures occurred across southern Alberta and southwestern Saskatchewan (Fig. 1). 

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of July 17-23, 2023. 

Average prairie daily temperatures over the past 30 days (June 24 – July 23, 2023) have been 1°C above normal. Many locations in the Peace River region have reported 30-day average temperatures that were 4°C warmer than average, so it was no surprise that the warmest temperatures in the last 30 days were reported across most of the southern prairies and the Peace River region (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 24 to July 23, 2023. 

Growing season (April 1 – July 23, 2023) temperatures continue to be warmer than normal by 1.7°C. For the growing season so far, the warmest temperatures have occurred across the southern regions of all three prairie provinces (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 23, 2023. 

Precipitation for the week of July 17-23, 2023 was minimal across most of the prairies; only the Parkland region had rainfall amounts that were greater than 20mm (Fig. 4).

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 17-23, 2023. 

In the last 30 days (June 24 to July 23), the average cumulative prairie precipitation was 35 mm, which is only 62% of the precipitation we would normally receive in the same period of the growing season. Cumulative rainfall in the past 30 days was greatest in the Edmonton  and Winnipeg regions and the lowest rainfall totals continue to be those recorded across most of Saskatchewan and southern Alberta (Fig. 5). 

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 24 – July 23, 2023. 

Since April 1, conditions have generally been dry across the prairies, with some notable exceptions. Most of the prairie region has now received approximately 90% of total rainfall we would expect to receive based on long-term climate normals. Below normal precipitation has occurred across most of Saskatchewan and southern Alberta (Fig. 6). During the current growing season, the warmest and driest area of the prairies continues to be southern Alberta and the western half of Saskatchewan. 

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 23, 2023. 

14626Predicted Grasshopper Development ( 2023 Week 12 )

Grasshopper risk may be significant for large areas of Alberta, Saskatchewan, and southern Manitoba. In 2023, grasshoppers developed to the adult stage earlier than normal (by nearly 2 weeks!) and high densities of grasshoppers have been observed in many regions. Grasshoppers are exacerbating crop yield losses in drought-affected areas.

Model simulations were used to estimate the developmental stage of grasshoppers as of July 23, 2023. Simulations indicate that 54% of the prairie population should be in the adult stage (51% last week). Grasshopper development continues to be well ahead of average in 2023. For example, in an average year, based on long-term average weather, we would expect only 10% of the population to be in the adult stage at the end of July.

Following early development to the adult stage, grasshopper reproduction is now expected to be underway. Our grasshopper model indicates that oviposition has begun across most of the prairies (Fig. 1).

Figure 1. Proportion (%) of the migratory grasshopper (Melanoplus sanguinipes) population expected to be in the egg stage across the Canadian prairies as of July 23, 2023. 

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

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14620Predicted Diamondback Moth Development ( 2023 Week 12 )

A fourth generation of non-migrant adult diamondback moths could be flying right now in southern Manitoba and in southeastern Alberta (Fig. 1). This prediction is based on model simulations to July 23, 2023 using early May arrival dates for diamondback moth adults that migrated into western Canada in the spring.

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred (or be occurring) across the Canadian prairies as of July 23, 2023.  

Compared to past years, warm weather in 2023 has sped up the development of diamondback moth. Using long-term average weather data (also known as climate normal data), model simulations to July 23 indicate that a second or third non-migrant generation of diamondback moth should be occurring right now (Fig. 2). In 2023, we could already be seeing a fourth generation!

Figure 2. The number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 23, based on climate normal data. 

Some areas of the prairies might be at risk of damage from diamondback moth this summer. Pheromone traps with cumulative counts greater than 25 male moths were located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan and in all regions of Manitoba (see the July 5 and July 19 editions of the Crop Pest Report). In Alberta, Shelley Barkley is finding diamondback moth larvae in canola samples from Yellowhead county, Parkland county, the Leduc area, and the Bonnyville area.  

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

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14618Watch Out for Invasive Insects ( 2023 Week 12 )

Invasive insects are a threat to agriculture and forestry in Canada. The Insect Surveillance Community of Practice is asking anyone monitoring, photographing, or observing insects to be on the lookout for invasive insects across Canada. They have developed posters for four regions of Canada, including the Prairies, with pictures and information about potentially invasive insects of concern to each region.

Early detection is critical for slowing the spread of invasive insects. Please view the poster for your region using the links below to learn more about insects to watch out for. Use the QR code on the poster to report your detections/observations.

A sample of the first page of the Prairie Region poster of invasive and migratory insects to watch for.

Prairie Region (French version here)

British Columbia (French version here)

Ontario & Quebec (French version here)

Atlantic Canada (French version here)

This initiative is a collaborative project developed by the Insect Surveillance Community of Practice of the Canadian Plant Health Council, a multi-partner body that coordinates action for the protection of plant health in Canada. 

14616Pre-harvest Intervals (PHI) ( 2023 Week 12 )

As harvest is nearing (if not already begun), it is necessary to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.

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

14614Provincial Insect Updates ( 2023 Week 12 )

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

Saskatchewan Crop Production News issues are now online! Use this link to read Issue #3. Issue #3 for 2023 includes information about grasshoppers and Lauxanid flies, as well as about plant diseases and some notes about plant development across Saskatchewan. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

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

145992023 Week 11 (Released July 20, 2023) ( 2023 Week 11 )

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

Adult grasshoppers are becoming more and more common across the prairies. Although grasshoppers are more widespread this year than in the past few years, the stage of grasshopper development and grasshopper population densities can vary between even relatively close locations. Scouting individual fields is important to best estimate crop risk.

Diamondback moth, if present, are into the third non-migrant generation across most of the prairies. Keep in mind that diamondback moth develop quickly in warm weather which could lead to rapidly increasing populations over the summer. Scout when you can and use the links in the Provincial Insect Updates post to learn about diamondback moth and bertha armyworm risk in your region. Diamondback moth was also the Week 11 Insect of the Week!

There is now a monitoring protocol for canola flower midge! As canola flowering finishes, it can be easy to see the galled flowers that result from infestation by canola flower midge, so the time to scout could be now. A three-year survey completed in 2019 found that canola flower midge is quite widely distributed across the prairies, but in relatively low densities and probably doesn’t cause economic yield losses. If you scout for canola flower midge this year and are willing to share your results please send them to meghan.vankosky@agr.gc.ca. If we get enough information, we will map the results!

This is a busy time for our field research programs across western Canada and with upcoming field days, we are even busier. A list of events can be found on the Prairie Pest Monitoring Network homepage and in the Week 10 update

Watch out for Invasive and Migrating Insects! The Insect Surveillance Community Practice has created posters for the Prairie Region, BC, Ontario & Quebec, and Atlantic Canada to raise awareness of potentially invasive insects to each region. If you suspect that you have found any of the insects on the Prairie Region Poster, please let us know using the form linked to the QR code on the poster. Note: many of us entomologists on the prairies are members of the Insect Surveillance Community of Practice!

Remember: insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification are available from the Prairie Pest Monitoring Network.

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

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

14585Weather Synopsis ( 2023 Week 11 )

The average daily temperature across the prairies was 0.5°C cooler than climate normals during the week of July 10 to July 16, 2023. However, specific locations remained warmer than normal, including Fort St. Jean, British Columbia, where it was 4°C warmer than normal; the warmest weekly average temperatures occurred across most of the Peace River region, southern Alberta, and southwestern Saskatchewan (Fig. 1). The coolest temperatures occurred across eastern Saskatchewan and western Manitoba with many locations having weekly average temperatures that were 2-4°C cooler than average.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of July 10-16, 2023. 

Average temperatures over the past 30 days (June 17 – July 16, 2023) have been almost 1°C above normal; many locations in the Peace River region have reported 30 day average temperatures that were 3°C warmer than average. The warmest 30-day temperatures were reported across most of the southern prairies, particularly southern Manitoba (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 17 to July 16, 2023. 

Precipitation during the week of July 10 to July 16, 2023 was minimal across most of the prairies (Fig. 3). Precipitation amounts ranged from 0.1mm at Lloydminster, Alberta/Saskatchewan to 34mm at Red Deer, Alberta. Average prairie precipitation (44 mm) for June 17-July 16, 2023) is 71% of normal. Unfortunately, much of the rain since July 10 has been accompanied by hail in some areas.

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 10-16, 2023. 

Cumulative rainfall for the past 30 days was greatest in the Edmonton region; the lowest rainfall amounts continue to be observed across most of Saskatchewan and southern Alberta (Fig. 4). Rain totals in the last 30 days ranged considerably from location to location. Mayerthorpe, Alberta had 131 mm in the last 30 days (167% of normal). In contrast, Taber, Alberta had only 6mm of rain (16% of normal) in the same period.

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 17 -July 16, 2023. 

Since April 1, conditions across the prairies have generally been quite dry. Precipitation accumulation has been below normal across most of Saskatchewan and southern Alberta (Fig. 5). Most of the prairie region has had less than 88% of normal or expected precipitation so far in 2023. However, some areas have received more rainfall than normal, especially locations around Edmonton, Alberta.

Figure 5. Growing season cumulative rainfall, expressed as the percent of normal/expected rainfall, observed across the Canadian prairies for the period of April 1 to July 16, 2023. 

14582Predicted Grasshopper Development ( 2023 Week 11 )

Based on earlier than normal appearance of adults, high densities and drought conditions, grasshopper risk continues to increase and may be significant for large areas of Alberta, Saskatchewan, and southern Manitoba. Model simulations were used to estimate development of grasshoppers as of July 16, 2023. As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of average. Simulations indicate that 51% of the prairie population should now be in the adult stage (Fig. 1).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percentage of the population in the adult stage, across the Canadian prairies as of July 16, 2023. 

In contrast, in a ‘normal’ year we would expect that 60% of the population would be in the fourth or fifth instar, with less than 5% of the population in the adult stage in mid-July (Fig. 2).

Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percentage of the population in the adult stage, across the Canadian prairies as of July 16 in a ‘normal’ year, based on long-term average weather data. 

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

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14578Predicted Wheat Midge Development ( 2023 Week 11 )

Wheat midge (Sitodiplosis mosellana) emergence is reduced when soil moisture is insufficient to terminate spring diapause. Dry conditions in southcentral Manitoba as well as central and southern regions of Alberta have likely resulted in reduced emergence of larvae from the soil.

In regions where rainfall was sufficient to trigger the end of wheat midge diapause and the completeion of wheat midge development, we expect that eggs and larvae should be the most abundant life stages (Figs. 1 and 2).

Figure 1. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the egg stage in western Canada, as of July 16, 2023. 
Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the larval stage in western Canada, as of July 16, 2023. 

Simulated development at Regina, Saskatchewan and Grande Prairie, Alberta indicates that adult emergence has peaked (Fig. 3). Development in the Peace River region is approximately 1 week behind development of wheat midge in eastern Saskatchewan. 

Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan and in the Peace River region as of July 16, 2023. Note, Sm L1-2 in the legend refers to wheat midge larvae that are feeding in wheat heads. The model used to simulate wheat midge development was developed by Olfert et al. (figure by Ross Weiss, 2023).

It may still be important to be scouting for adult wheat midge in some areas of the prairies. For more information about scouting and economic thresholds for wheat midge, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14567Predicted Diamondback Moth Development ( 2023 Week 11 )

In summer 2023, diamondback moth development is well ahead of average. Model simulations to July 16, 2023, indicate that the third generation of non-migrant adults (based on early May arrival dates) is currently occurring across the Canadian prairies (Fig. 1).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 16, 2023.

When we ran the model using long term average weather data (based on climate normals), the model output showed that the second generation of diamondback moth would be occurring at this date in a ‘normal’ year (Fig. 2). Above normal temperatures in 2023 have increased the rate of diamondback moth development, resulting in three generations in the time it usually takes for the development of two generations!

Figure 2. The number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 16, based on climate normal data. 

Some areas of the prairies might be at risk of damage from diamondback moth this summer. Pheromone traps with cumulative counts greater than 25 male moths were located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in all regions of Manitoba (data in the July 5 Crop Pest Update). According to the July 19 edition of the Manitoba Crop Pest Update, canola fields in the Plum Coulee, St. Joseph and Dominion City areas of Manitoba had high levels of diamondback moth larvae in the last week.  Because diamondback moth can have multiple generations in a single growing season and because the generation time is shorter when temperatures are warm, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises at the end of this summer.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14564Canola Flower Midge Scouting ( 2023 Week 11 )

Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.

Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.

Check out the Canola Flower Midge Scouting post from Week 10 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.

14556Watch Out for Invasive Insects ( 2023 Week 11 )

From the Insect Surveillance Community of Practice:

Do you spend time monitoring, photographing or observing insects? If so, your help is needed to watch for and report invasive and migratory insect pests that harm plants, causing damage to Canada’s environment, farm lands, forests, parks and other natural areas. Early detection is critical for slowing the spread of these insect pests. 

View the poster for your region (links below) to learn more about priority insect pests to watch out for. Use the QR codes on the posters to report your detections!

A sample from the Priority Invasive and Migratory Insects to Report poster for the Prairie Region. Use the links below to view and download the full version of the Prairie Region poster, as well as posters for other regions in Canada.

This initiative is a collaborative project developed by the Insect Surveillance Community of Practice of the Canadian Plant Health Council, a multi-partner body that coordinates action for the protection of plant health in Canada. 

Prairie Region (French version here)

British Columbia (French version here)

Ontario & Quebec (French version here)

Atlantic Canada (French version here)

14554Provincial Insect Updates ( 2023 Week 11 )

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

Saskatchewan Crop Production News issues are now online! Use this link to read Issue #2 and watch for future issues. Issue #2 for 2023 includes information plant diseases and plant staging for pesticide applications. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter.

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

145382023 WEEK 10 (Released July 12, 2023) ( 2023 Week 10 )

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

Adult grasshoppers are becoming more common across the prairies now. Although grasshoppers are more widespread this year than in the past few years, the stage of grasshopper development and grasshopper population densities can vary between even relatively close locations. Scouting individual fields is important to best estimate crop risk.

The first adult wheat midge of 2023 were reported in Saskatchewan in late June. Adult flight may have peaked in some areas, but scouting remains important in wetter areas of the prairies.

Diamondback moth could be entering into the third non-migrant generation in some areas this week (if present). Check back next week for a more in-depth update on diamondback moth development but keep in mind that diamondback moth develop quickly in warm weather which could lead to rapidly increasing populations over the summer. Use the links in the Provincial Insect Updates post to learn about diamondback moth and bertha armyworm risk in your region and scout accordingly.

There is now a monitoring protocol for canola flower midge! As canola flowering finishes, it can be easy to see the galled flowers that result from infestation by canola flower midge, so the time to scout could be now or coming soon. A three-year survey completed in 2019 found that canola flower midge is quite widely distributed across the prairies, but in relatively low densities and probably doesn’t cause economic yield losses. If you scout for canola flower midge this year and are willing to share your results please send them to meghan.vankosky@agr.gc.ca. If we get enough information, we will map the results!

This is a busy time for our field research programs across western Canada and with upcoming field days, we are even busier. A list of events can be found on the Prairie Pest Monitoring Network homepage and in this weekly update. Read about the AAFC display planned for Ag in Motion in the latest edition of Science News from the Prairies – find a link to the newsletter in the Prairie Research post where we also feature a new research project focused on the lesser clover leaf weevil.

This week, the Insect of the Week featured Macroglenes penetrans, a parasitoid that attacks wheat midge. Diamondback moth is on our schedule for next week!

Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.

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

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

14503Weather Synopsis ( 2023 Week 10 )

During the week of July 3-9, 2023, the warmest weekly average temperatures occurred across most of the Peace River region, southern Alberta and southwestern Saskatchewan (Fig. 1). The coolest temperatures during the same week occurred across the Parkland region of Manitoba and Saskatchewan. The prairie average daily temperature was similar to that expected based on climate normals. In fact, a number of locations reported temperatures that were cooler than normal; in northeastern Saskatchewan, for example, some locations had weekly average temperatures that were 2°C cooler than normal.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of July 3-9, 2023. 

Average temperatures over the past 30 days (June 10 – July 9, 2023) have been almost 2°C above normal; many locations in the Peace River region have reported 30 day average temperatures that were 3°C warmer than average. The warmest 30-day average temperatures were reported across most of the southern prairies, particularly southern Manitoba (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 10 to July 9, 2023. 

Precipitation for the period of July 3-10, 2023 was minimal across most of the prairies (Fig. 3).

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 3-9, 2023. 

Cumulative rainfall for the past 30 days has been greatest in the Edmonton region (Fig. 4). The lowest rainfall amounts continue to be those reported across most of Saskatchewan and southern Alberta. Conditions continue to be dry across most of the prairies.

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 10 to July 9, 2023. 

Prairie rain amounts for June 10-July 9 have been 72% of normal on average across the prairies. Most of Saskatchewan has had less than 40% of normal rainfall (Fig. 5). Southern Alberta and most of Manitoba have had rainfall amounts that are less 60% of normal (Fig. 5). 

Figure 5. The percent of normal precipitation (based on cumulative rainfall, in mm) over the last 30 days (June 10 to July 9, 2023) observed across the Canadian prairies.

14515Predicted Grasshopper Development ( 2023 Week 10 )

Model simulations were used to estimate the status of grasshopper development as of July 9, 2023. As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of average. As of July 9. 2023, the average predicted instar for grasshopper populations across the prairies is 4.9, which is significantly greater than the long term average of 3.1 for this time of year. Simulations indicate that 70% of the prairie population should be in the fifth instar or adult stage (Fig. 1).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 9, 2023. 

In a ‘normal’ year, we would expect that 57% of the grasshopper population would be in the third or fourth instar in early July (Fig. 2).

Figure 2. In an average year (based on 30-year average weather or climate normals), we expect that about 57% of the grasshopper population would be in the third or fourth instar in early July, as pictured here on the map. In contrast, in 2023, warm weather has significantly sped up the rate of grasshopper development (Fig. 1). 

Reports from across the prairies indicate that adult grasshoppers are now occurring. This is much earlier than normal, but agrees with our model simulations, which predict that adult grasshoppers are now occurring across most of the prairies (Fig. 3). Based on earlier than normal appearance of adults, high densities and drought conditions, grasshopper risk may be significant for large areas of Alberta and Saskatchewan as well as southern Manitoba. 

Figure 3. The proportion (%) of the migratory grasshopper (Melanoplus sanguinipes) population expected to be in the adult stage across the Canadian prairies as of July 9, 2023. 

Models and geospatial maps are tools to help time in-field scouting on a regional scale but grasshopper development and population densities can vary even between relatively close locations. Thus, grasshopper populations are best assessed through scouting. Monitor roadsides and field margins to assess the developmental stage and densities of local grasshopper populations.  

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring NetworkAlberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture and in the Field Crop and Forage Pests guide.

14501Predicted Wheat Midge Development ( 2023 Week 10 )

Wheat midge (Sitodiplosis mosellana) emergence is limited when soil moisture is lacking. Dry conditions in southcentral Manitoba as well as central and southern regions of Alberta have likely resulted in reduced emergence of larvae from the soil. The wheat midge development model indicates that peak emergence of adults is now occurring. Oviposition is predicted to have begun across most of the prairies and eggs should be the most abundant lifestage (Fig. 1).

Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the egg stage in western Canada, as of July 9, 2023. Note that wheat midge may not be active in all parts of the prairies, for example in regions where populations were absent last year or in regions where it did not rain in May and June.

In fields across Saskatchewan and western Manitoba, if wheat midge are present, model simulations indicate that egg development is progressing and larvae should be present (Fig. 2).

Figure 2. Percent of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the larval stage (in wheat heads) in western Canada, as of July 9, 2023. 

The wheat midge model, run for Regina, Saskatchewan indicates that adult emergence has peaked (Fig. 3) in that area. Oviposition should peak later this week. Larval populations (in wheat heads) should reach peak populations later next week.  

Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan as of July 9, 2023. 

Based on the occurrence of wheat midge adults, field monitoring should begin now, if it has not started already. In order to assess wheat midge populations and to take the appropriate action for management, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads. 

For more information about scouting and economic thresholds, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14517Canola Flower Midge Scouting ( 2023 Week 10 )

Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.

A canola raceme with galled flowers containing canola flower midge larvae; these galled flowers will not produce pods. Picture credit: Boyd Mori, University of Alberta.

From 2017-2019, entomologists and volunteers across the prairies conducted a survey to determine the range of canola flower midge (Fig. 1). There has not been a formal survey conducted since 2019.

Figure 1. Density of canola flower midge, based on the number of galled flowers per raceme across the prairie region observed during a survey conducted in 2017, 2018, and 2019. Map credit: Shane Hladun; map modified from Vankosky et al. (2022).

Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used from 2017-2019 is now available online so that everyone can scout for canola flower midge.

*If you cannot follow the link to the protocol, please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca).

14495Upcoming Events ( 2023 Week 10 )

Several field days are coming up! Entomologists, weed scientists, and plant pathologists from across western Canada will be attending various events over the next few weeks. Please look for us – we love to talk about insects, weeds, and plant diseases! A partial list of upcoming events (in no particular order and with no endorsement intended) includes:

Ag in Motion, July 18-20, 2023 at Langham, Saskatchewan.

2023 Lacombe Field Day, July 26, 2023 from 8:00 am to 4:30 pm MDT. Use this link to register.

Saskatchewan Crop Diagnostic School, July 25 or July 26, 2023 at Indian Head, Saskatchewan. It looks like registration for July 25 is maxed out, but spots are still available on July 26.

North Peace Applied Research Association Tour on July 27, 2023 in the Peace River region.

14488Prairie Research ( 2023 Week 10 )

Science News from the Prairies

A new issue of the newsletter, Science News from the Prairies is now available! This issue highlights the Agriculture and Agri-Food Canada information booth that can be found at Ag in Motion (July 18-20, 2023), new publications arising from prairie research, and upcoming events.

Developing Economic Thresholds for Lesser Clover Leaf Weevil

*This text was prepared by Jeremy Irvine and Sean Prager from the University of Saskatchewan.

Red clover (Trifolium pratense) is a short-lived perennial crop grown for seed production. Red clover seed is an important commodity in the Canadian Prairies, providing upwards of $2 million annually to the Saskatchewan economy. The production of red clover seed can be affected by the lesser clover leaf weevil (Hypera nigrirostris; LCLW). Yield losses of up to 50% have been recorded with high infestations of the LCLW. The weevil larvae feed on the developing shoots, flower heads, and seeds of red clover plants. Larvae cause the worst damage but secondary feeding damage can occur once LCLW larvae become adults.

Lesser clover leaf weevil damage, resulting when larvae exit the stem of the host plant. Picture credit: Jeremy Irvine, University of Saskatchewan.

Lesser clover leaf weevils are traditionally controlled using insecticides, but these can have negative impacts on  non-target insect species, notably bees. Managed bee species are used by red clover seed growers to ensure fields receive adequate pollination, high seed set, and subsequent yield.

There are currently no established economic thresholds for control of LCLW and insecticides can be applied when they are not needed, which increases the cost of clover production, negatively affects pollinators, and could contribute to the development of insecticide resistance in the LCLW population. The threat of insecticide resistance is significant because there is only one registered active ingredient for LCLW.  

A field trial near Carrot River, Saskatchewan is set up in second-year red clover to study the lesser clover leaf weevil. Picture by Jeremy Irvine, University of Saskatchewan.

The primary purpose of this research, which began in May 2023, is to develop an economic thresholds for LCLW in red clover crops. The project will also study the development of LCLW in varying weather conditions so that seasonal development can be incorporated into the economic thresholds. Finally, the project will generate a sequential sampling plan, meant to assist with the decision-making process to optimize management of LCLW. To conduct this research, we will work with farmers to conduct on-farm field trials where LCLW population densities will be manipulated and red clover yield will be quantified to determine the relationship between weevil density, injury level, and yield loss.

The overall goal of our project is to develop new tools that can be used to manage LCLW and protect red clover seed yields. Financial support for this study was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Government of Saskatchewan Agriculture Development Fund (ADF) and the Saskatchewan Forage Seed Development Commission (SFSDC).

14484Provincial Insect Updates ( 2023 Week 10 )

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

Saskatchewan Crop Production News issues are now online! Use this link to read Issue #2 and watch for future issues. Issue #2 for 2023 includes information plant diseases and plant staging for pesticide applications. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter.

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

144752023 WEEK 9 (Released July 7, 2023) ( 2023 Week 9 )

Insect scouting season is in full swing after the long weekend! The Prairie Pest Monitoring Network is busy with the annual cabbage seedpod weevil survey right now. Grasshoppers, wheat midge, and moths remain on our radar though, with development of many insect pests ahead of schedule this year thanks to warmer than average weather.

The first adult wheat midge of 2023 were reported in Saskatchewan in late June. Although not all areas had enough rainfall at the right time for wheat midge development, but scouting for wheat midge will be important in wetter areas. Models suggest that pupal development is well underway and that adults are flying and laying eggs in some areas. This could be an interesting year for wheat midge.

Adult grasshoppers are becoming more common across the prairies now. Diamondback moth could be entering into the third non-migrant generation in some areas (if present), and the peak flight of adult bertha armyworm should now be finished. Where present, bertha armyworm populations should mostly consist of larvae. Use information from this Weekly Update and updates from our provincial partners to learn more about risk in your area and to plan scouting activities.

This is a busy time for our field research programs across western Canada. In particular, the annual cabbage seedpod weevil survey is well underway. For farmers in Alberta, watch the map for near-real-time monitoring results from the cabbage seedpod weevil survey! It looks like some fields in southern Alberta have high numbers of cabbage seedpod weevils. The PPMN monitoring protocol for cabbage seedpod weevil is available on the Monitoring Protocol page.

This week, the Insect of the Week featured Tetrastichus julis, a parasitoid that attacks cereal leaf beetle. Next week, look for our post about natural enemies of wheat midge.

Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.

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

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

14455Weather Synopsis ( 2023 Week 9 )

During the week of June 26 – July 2, 2023, the average daily temperature was 3°C warmer than normal on the prairies. The weekly average temperature in Dawson Creek, British Columbia was 17.8 °C, a whopping 5°C warmer than normal. The warmest temperatures were observed across the southern prairies last week (Fig. 1). The weekly average temperature at Carman, Manitoba was 22°C (4.4°C warmer than normal). The coolest temperatures occurred across northwestern Alberta.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of June 26 to July 2, 2023. 

Average temperatures over the past 30 days (June 3 – July 2, 2023) have been 3°C above normal with the warmest values reported across Manitoba and eastern Saskatchewan (Fig. 2). Relative to climate normals, many Manitoba locations have been 4°C  warmer than normal over the last 30 days of 2023. Though warmer than normal, temperatures continue to be coolest in the Peace River and Edmonton regions.

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of June 3 to July 2, 2023. 

Since April 1, warmest temperatures have been reported across the southern prairies (Fig. 3). The coolest temperatures have been observed across eastern Saskatchewan.

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to July 2, 2023.  

Between June 26 and July 3, 2023 only small amounts of rainfall were recorded across most of Alberta and Saskatchewan. The exception was the Parkland region of both provinces, where more than 15 mm of rain was recorded (Fig. 4). Seven-day cumulative rainfall was greatest in Manitoba, where many locations reported rain amounts greater than 20 mm.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 26 to July 2, 2023. 

The greatest 30 day (June 3 – July 2, 2023) rainfall totals (100-160mm) were reported from a region near Edmonton, Alberta where rainfall totals are 200% of normal (Fig. 5). Rainfall amounts continue to be low across the southern prairies, particularly southern Alberta.

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 3 to July 2, 2023. 

Since April 1, prairie rainfall has generally been below normal (Fig. 6). The driest region is southern Alberta where rainfall received so far in 2023 is only 40% of the average rainfall for the region. A region extending from Oyen to Taber has had less than 60 mm rain in 2023 (Fig. 6). Over the same time period, this region has also been one of the warmest regions of the prairies (Figs. 3). 

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to July 2, 2023.  

14453Predicted Wheat Midge Development ( 2023 Week 9 )

Wheat midge (Sitodiplosis mosellana) development is ahead of normal in 2023. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant lifestage (Fig. 1).

Figure 1. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is expected to be in the pupal stage in western Canada, as of July 2, 2023. 

First emergence of adults was reported last week and the model indicates that peak emergence has not yet occurred. Model simulations indicate that eggs and larvae should be occurring in fields across Saskatchewan and western Manitoba (Fig. 2). 

Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is expected to be in the egg stage in western Canada, as of July 2, 2023. 

Based on the occurrence of wheat midge adults, field monitoring should begin now, if it has not started already. In order to assess wheat midge populations and to take the appropriate action for management, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads. 

For more information about scouting and economic thresholds, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14451Grasshoppers ( 2023 Week 9 )

Development of the pest grasshoppers continues to be ahead of schedule in 2023, as compared to past years. The first adult two-striped grasshoppers (Melonplus bivittatus) were collected on June 15 (Alberta) and June 19-20 (Saskatchewan). No one that we’ve spoken to remembers finding adult two-striped grasshoppers in June before. Especially in the southern prairies, densities are quite high and crop damage is being reported, as well as spraying to protect crops.

Model simulations were used to estimate development of grasshoppers as of July 2, 2023 and indicate that about 75% of the prairie grasshopper population should be in the 4th or 5th instar (Fig. 1). In an average year, we would expect 52% of the prairie grasshopper population to be in the 2nd or 3rd instar in early July (Fig. 2).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of July 2, 2023. 
Figure 2. In an average year (based on 30-year average weather or climate normals), about 50% of the grasshopper population would be expected to be in the second or third instar in early July as pictured here on the map. In contrast, in 2023, warm weather has significantly sped up the rate of grasshopper development.

Reports of adult occurrence suggest that adults are occurring much earlier than normal. The grasshopper model, developed for pest grasshoppers, indicates that adult grasshoppers should now be occurring across most of the southern prairies (Fig. 3).  

Figure 3. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population that now in the adult stage, across the Canadian prairies as of July 2, 2023. 

Geospatial maps are a tool to help time in-field scouting on a regional scale but grasshopper development can vary and is only accurately assessed through scouting. In Saskatchewan, grasshoppers have be observed in field crops. Monitor roadsides and field margins to assess the development and densities of local grasshopper populations.  

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14447Diamondback Moth ( 2023 Week 9 )

Diamondback moths are a migratory invasive species; in 2023, the first migratory adults were found in pheromone traps in early May. Thanks to the above average warm weather across most of the prairie region this year, diamondback moth development is well ahead of average. Based on development models and weather to July 2, a third generation of non-migrant adults is expected to be occurring in some parts of the prairies (Fig. 1), with the second generation occurring in nearly all other areas of the prairies (Fig. 1).

Figure 1.  Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 2, 2023.  

Diamondback moth typically have 4 full generations during prairie summers. In an average year, we would expect that the second generation of non-migrant diamondback moth would we widespread right now, NOT the third non-migrant generation (Fig. 2).

Figure 2. Number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the prairie region by early July in a ‘normal’ year (based on 30-year average or long-term normal weather data).

Some areas of the prairies might be at risk of damage from diamondback moth. Pheromone traps with cumulative counts greater than 25 male moths so far in 2023 are located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in all regions of Manitoba (see the July 5 Manitoba Crop Pest Update). In Manitoba, the highest counts of diamondback moths in pheromone traps exceed 200 total moths in the Central and Eastern regions. Because diamondback moth can have multiple generations in a single growing season and because the generation time is shorter when temperatures are warm, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises later this summer.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14433Bertha Armyworm ( 2023 Week 9 )

Based on model simulations, bertha armyworm development continues to be 7-10 days ahead of normal. Where present, populations of bertha armyworm will largely be in the larval stage (Fig. 1).

Figure 1. The proportion (%) of the bertha armyworm (Mamestra configurata) population that is expected to be in the larval stage across the Canadian prairies as of July 2, 2023. Note that bertha armyworm may not be present at all locations.

The larvae of this generalist moth could be found in canola fields, but also in other crops.

The lifestages of bertha armyworm: A) eggs, B) larva, C) pupa, and D) adult. All pictures taken by Jonathon Williams, AAFC-Saskatoon (please include a photo credit if these pictures are reproduced elsewhere).

The network of pheromone traps across the prairies is reporting low numbers of adults (less than 300 cumulative catch over the last 6 weeks) so far in 2023, including in Manitoba (check out the July 5 Manitoba Crop Pest Update), Saskatchewan, and Alberta. Only one monitoring location (in Manitoba) has caught more than 300 bertha armyworm adults so far this year, suggesting relatively low risk across the prairies. Risk to yield from bertha armyworm increases when cumulative trap catches exceed 300 (300-900 = medium risk, >900 = high risk). Although the pheromone trap network suggests low risk of economic damage from bertha armyworm, it is still important to scout for larvae. For information about scouting, check out the PPMN protocol and the Alberta Agriculture and Irrigation pages.

14431Provincial Insect Updates ( 2023 Week 9 )

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

The first Saskatchewan Crop Production News issue is now online! Use the link to read Issue #1 and watch for future issues. Issue #1 for 2023 includes information about springtails and wheat midge. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter.

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

143832023 WEEK 8 (Released June 29, 2023) ( 2023 Week 8 )

Watch out for Wheat Midge!

The first adult wheat midge of 2023 were reported in Saskatchewan last week. This year could be an interesting year for wheat midge. Some areas have had sufficient rain to trigger the end of diapause and the completion of larval and pupal development. If adult emergence coincides with susceptible crop stages, damage could result. Scouting for wheat midge right now is very important!

This is a busy week for our field research programs across western Canada. In particular, the annual cabbage seedpod weevil survey has begun. For farmers in Alberta, watch the map for near-real-time monitoring results from the cabbage seedpod weevil survey! It looks like some fields in southern Alberta have high numbers of cabbage seedpod weevils. The PPMN monitoring protocol for cabbage seedpod weevil is available on the Monitoring Protocol page.

Because we are so busy in the field, this Weekly Update is shorter than usual. We decided to focus on wheat midge due to adult emergence reported last week, but do not forget about grasshoppers, diamondback moths, or bertha armyworm. This Weekly Update includes a short post with important links for all three of these species.

This week, the Insect of the Week also featured the wheat midge, a pest of cereal crops. In the next two weeks, we will feature the parasitoid of cereal leaf beetle and natural enemies of wheat midge.

Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.

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

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

14399Weather Synopsis ( 2023 Week 8 )

During the week of June 19-25, the prairie average daily temperature was 1°C warmer than normal (Fig. 1). The warmest temperatures were observed across Manitoba, with Dauphin, Manitoba recording temperatures 4.5°C warmer than normal. The coolest temperatures occurred across eastern Alberta. Calgary, Alberta, for example was 2°C cooler than normal.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of June 19-25, 2023.

Average temperatures over the past 30 days (May 27 to June 25, 2023) have been 3.5°C above normal with the warmest values being reported across Manitoba and Saskatchewan (Fig. 2). Relative to climate normals, Dauphin, Manitoba was 5.5°C  warmer than normal. In the last 30 days, temperatures have been coolest in the Peace River region; Grande Prairie, Alberta was only 1°C warmer than normal.

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 27 to June 25, 2023. 

Seven-day cumulative rainfall was greatest in a region around Edmonton, Alberta (Fig. 3). Precipitation amounts were minimal for southern Alberta and a large area of Saskatchewan.

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 19 – 25, 2023. 

The greatest 30 day rainfall totals (100-160mm) were reported from a region near Edmonton, Alberta (Fig. 4); rainfall totals in some of those areas have been 200% of normal. Rainfall amounts continue to be low across the southern prairies and near Saskatoon, Saskatchewan. For example, at Carman, Manitoba rainfall has been only 26% of normal and Brooks, Alberta has received only 49% of the precipitation expected in an average year.  

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 27 to June 25, 2023. 

14381Predicted wheat midge development ( 2023 Week 8 )

Wheat midge (Sitodiplosis mosellana) development is ahead of normal. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant life-stage (Fig. 1). Recent rainfall in the Peace River region and Edmonton regions may have resulted movement of larvae to the soil surface and subsequent occurrence of pupae. First emergence of adults was reported last week.

Figure 1. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the pupal stage in western Canada, as of June 25, 2023. 

Model simulations indicate that adults may be occurring in fields near Saskatoon, Regina, Estevan and Melita (Fig. 2). It is expected that adult populations may peak later next week. Oviposition is predicted to begin over the next few days. 

Figure 2. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the adult stage in western Canada, as of June 25, 2023. 

Based on the occurrence of wheat midge adults, field monitoring should begin now. In order to assess wheat midge populations and to take the appropriate action, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads. 

For more information about scouting, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14378Grasshoppers, bertha armyworm, and diamondback moth ( 2023 Week 8 )

Grasshoppers

Development of the pest grasshoppers continues to be ahead of schedule in 2023, as compared to past years. The first adult two-striped grasshoppers (Melonplus bivittatus) were collected on June 15 (Alberta) and June 19-20 (Saskatchewan). No one that we’ve spoken to remembers finding adult two-striped grasshoppers in June before. Especially in the south, densities are quite high and crop damage is being reported, as well as spraying to protect crops.

Model simulations for grasshopper development indicate that grasshoppers should range from first to fifth instars with some adults now present at many locations across the prairies, as of June 25. Based on average instar, development is most advanced across the southern prairies where 65% of the population is predicted to be fourth and 5th instar, with some adults also present (Fig. 1). In an ‘average year’, the majority of the grasshopper population (60%) would typically be in the first, second, and third instars in late June.

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 25, 2023. 

Based on occurrence of fifth instar grasshoppers, development is most advanced across southern Manitoba (Fig. 2).

Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population in the fifth instar, across the Canadian prairies as of June 25, 2023. 

Adult two-striped grasshoppers (Melanoplus bivittatus) and migratory grasshoppers (M. sanguinipes) have been observed across the southern prairies.   

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

Bertha armyworm

Last week, models predicted that first instar bertha armyworm larvae might be present in some areas of the prairies. Bertha armyworm larvae could also be developing quickly, thanks to warm weather. The network of pheromone traps across the prairies is reporting low numbers of adults (less than 300 cumulative catch), including in Manitoba (check out the June 21 Manitoba Crop Pest Update) and Alberta. Risk to yield from bertha armyworm increases when cumulative trap catches exceed 300 (300-900 = medium risk, >900 = high risk). For information about scouting, check out the PPMN protocol and the Alberta Agriculture and Irrigation pages.

Diamondback moth

Some areas of the prairies might be at risk of damage from diamondback moth; pheromone traps with cumulative counts greater than 25 male moths so far in 2023 are located around Rosetown and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in the Central, Eastern, and Interlake regions in Manitoba (see the June 21 Manitoba Crop Pest Update). Like grasshoppers and bertha armyworm, diamond back moth development occurs quickly in warm weather. Last week, we predicted that diamondback moths had reached the second non-migrant generation and we heard of some sightings of larvae in some areas of the prairies. Because diamondback moth can have multiple generations in a single growing season, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises later this summer.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14385Prairie Research ( 2023 Week 8 )

Developing tools for the management of Lygus bugs in faba bean

*The text of this post was written by Teresa Aguiar-Cordero and Sean Prager.

This research project, led by Sean Prager and Teresa Aguiar-Cordero, focuses on studying insects in the genus Lygus and their impact on faba bean crops in the province of Saskatchewan. Faba beans are a significant legume crop in the region, but they face threats from various insect pests, including Lygus species. Lygus bugs feed on faba beans by injecting salivary enzymes into the plant, resulting in damage such as hull perforations, seed coat discoloration, and tissue wilting which reduces yield. Damage to seed lowers the quality and grade of faba beans below that for human consumption with substantial economic consequences.

Microscope image of an adult Lygus bug. Picture provided by Teresa Aguiar-Cordero, University of Saskatchewan.

The project aims to address crucial knowledge gaps regarding Lygus bugs in faba beans. By conducting a survey across Saskatchewan, the study aims to determine the optimal timing and methods for effective Lygus sampling. In addition to the survey, a series of no-choice bioassay are currently being performed to quantify the relationship between Lygus bug numbers and the resulting damage to faba bean pods, which can help develop action thresholds.

Faba bean pods with damage resulting from Lygus bug feeding activity. Picture provided by Teresa Aguiar-Cordero, University of Saskatchewan.

As part of the future directions, the researchers plan to incorporate the electrical penetration graph technique (EPG) to gain a better understanding of the feeding behavior of Lygus bugs in faba beans. This technique will provide valuable insights into the precise feeding patterns employed by Lygus bugs.

In addition, a series of choice bioassays will be conducted to analyze and determine the preferences of Lygus when given a choice of different crop and plant species. This will help establish which crops Lygus may migrate into faba bean from. By studying the preferences of Lygus bugs for different crops, the researchers aim to identify potential trap crops that can attract Lygus populations as part of a management program to reduce the impact of Lygus bugs on faba bean crops.

The project’s outcomes will contribute important information and management tools for growers, enabling them to mitigate the impact of Lygus insects on faba bean crops. By understanding the associations between Lygus numbers and damage, and exploring innovative strategies such as trap crops, the project strives to minimize damage and decrease losses for growers.

Teresa Aguiar-Cordero is a graduate student at the University of Saskatchewan, working with Dr. Sean Prager to study Lygus bugs.

14376Provincial Insect Updates ( 2023 Week 8 )

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

New issues of the Saskatchewan Crop Production News are coming soon in 2023. Use the link to browse the articles from 2022 or subscribe to receive new issues of the newsletter as they are published online.

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

143422023 WEEK 7 (RELEASED JUNE 22, 2023) ( 2023 Week 7 )

It’s officially summer!

Grasshoppers thrive in warm, dry conditions. The first adult two-striped grasshoppers of 2023 were reported in southern Alberta and Saskatchewan in the last 5 days, although the majority the grasshopper population are still nymphs. Signs of damage in the roadsides and field edges are being reported. Now is the time to scout for grasshoppers in your fields.  

Diamondback moths develop rapidly when it is warm and their population densities can build up quickly with each generation. Like other insects, bertha armyworm development is also well ahead of schedule. Other green caterpillars, like clover cutworm and alfalfa looper, might also be found in canola crops at this time of year. Correctly identifying green caterpillars is important to ensure the correct economic thresholds (where available) and management tactics are used.

This year could be an interesting year for wheat midge. Some areas have had sufficient rain to trigger the end of diapause and the completion of larval and pupal development, but crop staging is also widely variable. Scouting for wheat midge will be important in the next few weeks.

This week, the Insect of the Week featured the cereal leaf beetle, a pest of cereal crops. Next week, we will feature a very important natural enemy of cereal leaf beetle, the parasitoid Tetrastichus julis.

Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.

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

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

14328Weather Synopsis ( 2023 Week 7 )

This past week (June 12-18, 2023), the prairie average daily temperature was 1.8°C warmer than normal (Fig. 1). The warmest temperatures were observed across southern Manitoba and Saskatchewan and the coolest temperatures occurred across the Peace River region of British Columbia and Alberta.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of June 12-18, 2023. 

Average temperatures over the past 30 days (May 20 to June 18, 2023) have been 4°C above normal with the warmest temperatures being reported across Manitoba and Saskatchewan (Fig. 2).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 20 to June 18, 2023. 

Rainfall events were observed across the prairie region in the last week. The 7-day cumulative rainfall was 80-95mm in a region around Edmonton, Alberta (Fig. 3). Areas west of Edmonton that were evacuated due to forest fires are now flooded.

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 12 – 18, 2023. 

The greatest 30-day rainfall totals (90-140mm) were reported from Red Deer to Grande Prairie, Alberta for the period from May 20 to June 18, 2023 (Fig. 4). Rainfall totals continue to be lowest across the southern prairies.  

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 20 to June 18, 2023. 

Over the past 30 days, different parts of the prairies have been characterized by warm/dry, warm/wet, cool/dry, and cool/wet conditions, as represented in the scatter plot (Fig. 5). Grande Prairie and Lacombe, Alberta have generally been cooler and wetter than most other locations across the prairies, while locations in Manitoba have experienced mostly warm and dry weather so far in 2023.  

Figure 5. Site-specific comparison of 30-day average temperature (°C) and cumulative rainfall (mm) observed across the Canadian prairies for the period of May 20 to June 18, 2023. The red line indicates the average temperature and the blue line represents the average rainfall for the period of May 20 to June 18, 2023. 

14326Wind Trajectory Summary ( 2023 Week 7 )

‘Reverse trajectories’ refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date. Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating. If diamondback adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g., rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data. 

Mexico, California and Texas: This week (June 14 – 20, 2023), no reverse trajectories originating over Mexico, California, or Texas, were predicted to pass over the prairies. 

Pacific Northwest (Idaho, Oregon, Washington): This week, 90 reverse trajectories were predicted to cross the prairies. The majority of Pacific Northwest reverse trajectories were reported to pass over Alberta and western Saskatchewan (Fig. 1).   

Figure 1. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and June 20, 2023. 

Oklahoma and Texas: This week only one (1) reverse trajectory that originated over Texas and Oklahoma was predicted to pass through the prairies, near Selkirk, Manitoba (Fig. 2). 

Figure 2. The total number of dates with reverse trajectories originating over Oklahoma and Texas that have crossed the prairies between April 1 and June 20, 2023. 

Kansas and Nebraska: This week there were 9 reverse trajectories, originating over Kansas and Nebraska, that were predicted to pass over Saskatchewan and Manitoba (Fig. 3).  

Figure 3. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between April 1 and June 20, 2023. 

14321Predicted Grasshopper Development ( 2023 Week 7 )

Model simulations were used to estimate development of grasshoppers as of June 18, 2023. Warm temperatures continue to promote rapid grasshopper development. Model runs suggest that this spring’s hatch is 99% complete. As of June 18, grasshoppers should range from first to fourth instars. Based on average instar, development is most advanced across the southern prairies where 70% of the population is predicted to be third and fourth instars (Fig. 1). The model indicates that grasshopper development should be most advanced near Morden, Manitoba and Kindersley, Saskatchewan.

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 18, 2023. 

Entomologists across western Canada are closely watching the grasshopper situation. The first adult two-striped grasshopper was found in southern Alberta on June 15 (first reported on Twitter by Dr. Dan Johnson, University of Lethbridge) and in southern Saskatchewan on June 20 (reported by Taylor Dzikowski and Ross Weiss, both from AAFC-Saskatoon).

An adult two-striped grasshopper, Melanoplus bivittatus. Picture credit: Meghan Vankosky, AAFC-Saskatoon.

Geospatial maps, like that in Fig. 1, are tools to help time in-field scouting on a regional scale. However,  grasshopper development can vary from region to region and from field to field. To best assess local grasshopper development, scouting is required. In Saskatchewan, grasshoppers have already been observed in field crops in some regions and there have been reports of spraying for grasshoppers in some areas. Scout or monitor grasshopper populations in roadsides and field margins to assess the development and densities of local grasshopper populations. 

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture

14318Predicted Diamondback Moth Development ( 2023 Week 7 )

Diamondback moths (Plutella xylostella) were first found on pheromone traps across western Canada in early May in 2023. After the first migrant adults arrive, there can be multiple non-migrant populations of diamondback moth, with the population density potentially increasing with each generation. Average development, based on climate normals, suggests that diamondback moths should be in the first non-migrant generation. However, diamondback moth development can be rapid during periods of warm weather, such as we have experienced across most of western Canada so far this spring. As a result, model simulationsto June 18, 2023, indicate that prairie diamondback moth populations are now in the second non-migrant generation (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 18, 2023. 

Local scouting is needed to determine if diamondback moths pose a threat to crops. To scout, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

The life stages of diamondback moth: A) eggs, B) early instar larva, C) later instar larva, D) pupa, and E) adult. Picture credit: Jonathon Williams, AAFC-Saskatoon.

14310Predicted Bertha Armyworm Development ( 2023 Week 7 )

Based on model simulations, bertha armyworm development continues to be 7-10 days ahead of normal. Where present, females should have already begun to lay eggs (Fig. 1).

Figure 1. Proportion (% of total population) of the bertha armyworm (Mamestra configurata) population that is expected to be in the egg stage across the Canadian prairies as of June 18, 2023. 

In some areas, first instar larvae (caterpillars) may be present (Fig. 2).

Figure 2. Proportion (% of total population) of the bertha armyworm (Mamestra configurata) population that is expected to be in the larval stage across the Canadian prairies as of June 18, 2023.

This week there have been some reports of large green caterpillars on canola crops in Alberta and Saskatchewan. The green caterpillars are too advanced in their development to be bertha armyworm. These are more likely to be alfalfa looper or clover cutworm. This week, a Canola Watch quiz challenges us to identify ‘green worms‘ in oilseed crops and provides excellent information about how to tell the difference between bertha armyworm, alfalfa looper, diamondback moth, clover cutworm, and cabbageworm.

14308Predicted Wheat Midge Development ( 2023 Week 7 )

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June largely determine whether or not larvae exit cocoons to move to the soil surface to continue development (i.e., to pupate then emerge as adults this season). Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May and June.

Cumulative rainfall from May 1-June 18, 2023 across western Manitoba, most of Saskatchewan, and northwestern Alberta now exceeds the threshold (30 mm) required to terminate larval diapause. Though late, the rainfall event last week in the Edmonton region of Alberta may promote movement of larvae to the soil surface.

The wheat midge model indicates that, where wheat midge populations are present, larvae have begun to move to the soil surface (Fig. 1).

Figure 1. Proportion (%) of the larval population of wheat midge (Sitodiplosis mosellana) that is expected to have moved to the soil surface across western Canada, as of June 18, 2023. 

Pupae are expected to be in the soil in the Peace River region, localized areas of Saskatchewan, and southwestern Manitoba (Fig. 2).

Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the pupal stage in western Canada, as of June 18, 2023. 

Model output suggests that first adults may be appearing in fields in southeastern Saskatchewan and southwestern Manitoba this week. Dr. Tyler Wist reports that adult wheat midge have been found on sticky cards baited with pheromone lures, including at the AAFC research farm in Saskatoon.

Scouting for adult wheat midge should start now. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict the status of wheat midge development and will provide additional updates.

For information about scouting, check out the wheat midge monitoring protocol. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14306Provincial Insect Updates ( 2023 Week 7 )

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

New issues of the Saskatchewan Crop Production News are coming soon in 2023. Use the link to browse the articles from 2022 or subscribe to receive new issues of the newsletter as they are published online.

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

142832023 WEEK 6 (Released June 15, 2023) ( 2023 Week 6 )

This year it is as important as ever to scout and to monitor insect populations at the field-scale.

Grasshoppers thrive in warm, dry conditions. Some 5th instar nymphs were spotted in ditches in southwestern Saskatchewan in the past week, although there are many first, second, third, and fourth instar nymphs active as well. Signs of damage in the roadsides and field edges are being reported.  

Diamondback moths develop rapidly when it is warm and their population densities can build up quickly with each generation. Be ready to scout if pheromone traps in your area have detected diamondback moths this spring and watch the provincial websites and PPMN updates for pheromone trap results.  

Bertha armyworm development is also well ahead of schedule. Watch the provincial websites in Alberta, Saskatchewan, and Manitoba for reports on bertha armyworm pheromone trap captures for your area over the next few weeks; these provide an estimate of regional risk and are meant to guide in-field scouting.

This week, the Insect of the Week featured the strawberry blossom weevil. This is an invasive insect to Canada that is currently found in BC, but it is important to watch for it on the prairies in raspberry and strawberry patches.

Please read this week’s posts in the Weekly Update for more information about the insects listed above and for a sneak peak of wheat midge development!

Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.

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

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

14275Weather Synopsis ( 2023 Week 6 )

The week of June 5-11, 2023 was characterized by average prairie temperatures that continue to be well above average. The prairie average daily temperature was 3.5°C warmer than normal (Fig. 1). Like last week, the warmest temperatures were observed across Manitoba and eastern Saskatchewan. The coolest temperatures occurred across the Peace River region of British Columbia and Alberta.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of June 5 – 11, 2023. 

Average temperatures over the past 30 days (May 13 to June 11, 2023) have been 4°C above normal with the warmest values being reported across Manitoba and Saskatchewan (Fig. 2). Average 30-day temperatures ranged from 14.2°C at High Level, Alberta to 20°C at Morden, Manitoba.  

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 13 to June 11, 2023. 

Seven-day cumulative rainfall was nominal for most of Alberta and western Saskatchewan while significantly higher rainfall amounts were reported for eastern Saskatchewan and Manitoba (Fig. 3). Southern Alberta, including Lethbridge and Taber reported weekly rainfall totals that were greater than 25mm up to June 11. Winnipeg and Minnedosa, Manitoba reported more than 45mm.

Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 5-11, 2023. 

Eastern Saskatchewan has generally had the highest rainfall totals over the past 30 days. Rainfall amounts continue to be low across Alberta and Manitoba (central and eastern regions) (Fig. 4). In Alberta, a large region that extends from Lethbridge to Edmonton, is extremely dry – this area has received only 40% of the precipitation normally expected for this time of year in the last 30 days. Central and eastern regions of Manitoba have also had less than 40% of normal precipitation. A large region extending north from an area that extends from Brandon, Manitoba to North Battleford, Saskatchewan has had above normal precipitation.  

Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 13 to June 11, 2023. 

Over the past 30 days, different parts of the prairies have been characterized by warm/dry, warm/wet, cool/dry, and cool/wet conditions, as represented in the scatter plot (Fig. 5). Central and southern regions of Alberta are categorized as relatively cool/dry. The Peace River region has been cool and wet. Eastern Saskatchewan and a number of western Manitoba locations are now categorized as warmer and wetter. 

Figure 5. Site-specific comparison of 30-day average temperature (°C) and cumulative rainfall (mm) observed across the Canadian prairies for the period of May 13 to June 11, 2023. The red line indicates average temperature and the blue line represents average rainfall (for the period of May 13 to June 11, 2023). 

14273Wind Trajectory Summary ( 2023 Week 6 )

‘Reverse trajectories’ refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date.  Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating.  If diamondback adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g., rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data. 

There was a significant decrease in the number of reverse trajectories that entered the Canadian prairies during the week of June 7-13, 2023 as compared to the previous week (Fig. 1).   

Figure 1. The average number (based on a 5-day running average) of reverse trajectories (RT) that have crossed the prairies for the period of May 14 to June 13, 2023. 

Mexico, California and Texas: Only 5 reverse trajectories crossed into the prairies from Mexico, California, and Texas from June 7-13. These trajectories were expected to cross into southeastern Saskatchewan and Manitoba (Fig. 2).

Figure 2. Total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and June 13, 2023. 

Pacific Northwest (Idaho, Oregon, Washington): This week 40 reverse trajectories were predicted to cross the prairies from the Pacific Northwest. The majority of the reverse trajectories from the Pacific Northwest passed over Alberta and western Saskatchewan (Fig. 3).   

Figure 3. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and June 13, 2023. 

Oklahoma and Texas: There were 17 reverse trajectories that originated over Texas and Oklahoma and passed through the prairies in the past week. These reverse trajectories largely passed over Manitoba and southeastern Saskatchewan and (Fig. 4).  

Figure 4. The total number of dates with reverse trajectories originating over Oklahoma and Texas that have crossed the prairies between May 1 and June 13, 2023. 

Kansas and Nebraska: Since April 1, reverse trajectories originating in Kansas and Nebraska were reported to cross southeastern Saskatchewan and southern Manitoba (Fig. 5). This week (June 7-13), there were 46 reverse trajectories, originating over Kansas and Nebraska that were predicted to pass over Saskatchewan and Manitoba. 

Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between May 1 and June 13, 2023. 

14264Predicted Grasshopper Development ( 2023 Week 6 )

Model simulations were used to estimate development of grasshoppers as of June 11, 2023. Well above normal temperatures across the prairies continue to result in rapid grasshopper development. Model runs suggest that this spring’s hatch is almost complete. As of June 11, grasshopper nymphs should range from the first to fourth instar in many locations on the prairies. Based on average instar, development is most advanced across the southern prairies where populations should consist of mainly third and fourth instar nymphs (Fig. 1). 

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 11, 2023. 

At some locations between in central Saskatchewan (between Saskatoon and Swift Current), some fifth instar grasshopper nymphs have been captured in sweep net samples and the number of nymphs in the fourth instar has increased. Two-striped grasshoppers continue to be most prevalent in this region, but more first instar nymphs of the other primary pest species were observed in ditches in Saskatchewan this week. From the roadsides, there were some signs of grasshopper damage to crop plants, including canola, along field edges.

Models and geospatial maps are tools to help time in-field scouting on a regional scale but grasshopper development can vary and is only accurately assessed through scouting. Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations. Due to the small size, it may be difficult to visually observe first and second instar grasshoppers in roadside vegetation and field margins. If possible, grasshopper assessments should be conducted with sweep nets. This will permit assessment of grasshopper densities, stage and species present.  

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and IrrigationSaskatchewan Ministry of Agriculture, and Manitoba Agriculture.

14257Predicted Diamondback Moth Development ( 2023 Week 6 )

Diamondback moths (Plutella xylostella) are a migratory invasive species; after initial migration into the prairies, diamondback moths can have multiple non-migratory generations during the growing season. Typically, there are three to four non-migrant generations of diamondback moths on the prairies.

Diamondback moth development can be rapid during periods of warm weather. Model simulationsto June 11, 2023, indicate that the second generation of non-migrant adults (based on early-May arrival dates) is currently occurring across the southern prairies (Fig. 1).  

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of June 11, 2023. 

On the prairies, we use a network of pheromone traps to detect the first spring appearance of diamondback moths. In the June 7 and June 14 issues of the Manitoba Crop Pest Update, some diamondback moth trap locations in the central and eastern parts of the province reported catching between 100-200 adult moths. At least three sites in central and southern Alberta (use the link to see the live map) have also caught between 100-200 moths so far this year. Lower numbers have been recorded so far in Saskatchewan in 2023.

Now, local scouting is needed to determine if diamondback moths pose a threat to crops. To scout, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14254Predicted Bertha Armyworm Development ( 2023 Week 6 )

Based on model simulations, development of overwintered bertha armyworm (Mamestra configurata) continues to be 7-10 days ahead of normal. Where present, we expect the majority of the prairie population of bertha armyworm to now be in the adult stage (Fig. 1) and females have likely already begun to lay eggs (Fig. 2).

Figure 1. Proportion (%) of the bertha armyworm (Mamestra configurata) population that is expected to be in the adult stage across the Canadian prairies as of June 11, 2023. 

Figure 2. Proportion (%) of the bertha armyworm (Mamestra configurata) population that is expected to be in the egg stage across the Canadian prairies as of June 11, 2023. 

Bertha armyworm populations were very low in 2022. So far, trap catches in Alberta in 2023 have also been very low (most traps with less than 20 adult male moths). A few trap locations in Saskatchewan and at least one in Manitoba have reported more than 100 moths caught since the traps were set up in late May or early June.

Pheromone trap monitoring for bertha armyworm provides a regional picture of potential risk. Cumulative trap catches below 300 generally represent low risk. To know if a specific field is at risk of economic yield losses, scouting for larvae in that field is required. The PPMN protocol for bertha armyworm monitoring provides information about scouting for adult and larval bertha armyworm and about economic thresholds for this pest.

14251Predicted Wheat Midge Development ( 2023 Week 6 )

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Adequate rainfall in May and June is a signal to larval cocoons to end their diapause and move to the soil surface to pupate. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in delayed adult emergence, delayed oviposition by female wheat midge, fewer adults, and fewer eggs laid.

In the last few weeks, rainfall events over parts of the prairies may have provided the cue to end wheat midge larval diapause. Cumulative rainfall from May 1 to June 11 across western Manitoba, most of Saskatchewan and northwestern Alberta now exceeds the threshold of 30 mm of rain required to terminate the larval diapause of wheat midge (Fig. 1).

Figure 1. Areas in western Canada where cumulative rainfall from May 1 to June 11, 2023 is equal to or greater than 30 mm, which is the threshold required to promote movement of wheat midge (Sitodiplosis mosellana) larvae to the soil surface where they will pupate.  

The wheat midge model indicates that, where wheat midge populations are present, larvae have begun to move to the soil surface in some areas of the prairies (Fig. 2). 

Figure 2. Percent of the wheat midge larval population (Sitodiplosis mosellana) that has moved to the soil surface across western Canada, as of June 11, 2023. 

In contrast to the wet areas on the prairies, wheat midge adult emergence might be delayed in 2023 in areas that have not yet received much rain. It is also possible that the wheat midge larval cocoons will remain in a diapause state in the dry areas of the prairies until a future year when spring moisture is more suitable for wheat midge development.

Scouting for adult wheat midge usually starts in late June or early July. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict that status of wheat midge development and provide additional updates.

For information about scouting, check out the wheat midge monitoring protocol. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14249Provincial Insect Updates ( 2023 Week 6 )

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

Watch for new issues of the Saskatchewan Crop Production News coming soon in 2023 and browse the articles from 2022 for information from the past.

The latest Manitoba Crop Pest Update for 2023 was posted on June 14. Watch their website for new Crop Pest Updates as the season continues and check out the archives to read past Updates.

142162023 Week 5 (Released June 8, 2023) ( 2023 Week 5 )

Insect scouting and monitoring season is getting into full swing!

Weather patterns in May and so far in June have been perfect for the development of some insect pests, but suboptimal for others. However, it is hard to generalize, as some parts of the prairies have been wet and others dry. Similarly, some areas have been very warm, while others have been cooler. This year it will be very important to scout and to monitor insect populations at the field-scale.

Grasshoppers thrive in warm, dry conditions. This week, some 4th instar nymphs were spotted in ditches in southwestern Saskatchewan, although there are many first, second and some third instar nymphs as well. Signs of damage are starting to appear. Overall grasshopper development continues to be ahead of schedule and two-striped grasshoppers continue to be prevalent.  

Diamondback moths that arrived in early May have likely reproduced and adult moths found now could be from the first generation produced on the prairies. Diamondback moths develop rapidly when it is warm and their population densities can build up quickly with each generation. Be ready to scout if pheromone traps in your area have detected diamondback moths this spring.  

Bertha armyworm development is also well ahead of schedule – pupal development could be 90% complete in some areas and adult moths could already be flying around. Watch the provincial websites in Alberta, Saskatchewan, and Manitoba for reports on bertha armyworm pheromone trap captures for your area over the next few weeks.

This week, the Insect of the Week featured ground beetles and rove beetles! Both can prey on different life stages of the pea leaf weevil and on other insect pests (and slugs!).

 Please read this week’s posts in the Weekly Update for more information about the insects listed above and for a sneak peak of wheat midge development!

Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to plan for in-field scouting, and economic thresholds to help support in-field management decisions. All are available to read or download for free!

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

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

14203Weather synopsis ( 2023 Week 5 )

Average prairie temperatures continued to be well above average from May 29 to June 4. The prairie average daily temperature was 5°C warmer than normal (Fig. 1). The warmest temperatures were observed across southern Manitoba and southeastern Saskatchewan. The coolest temperatures occurred in the Peace River region where temperatures in northwestern Alberta and northeastern British Columbia were similar to climate normal temperatures.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of May 29 to June 4, 2023. 

Average temperatures over the past 30 days (May 6 to June 4, 2023) have been 4°C above normal with the warmest values being reported across Manitoba and Saskatchewan (Fig. 2). Average temperatures (30-day) ranged from 13.9°C at Grande Prairie, Alberta to 18.4°C at Morden, Manitoba.

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 6 to June 4, 2023. 

Since April 1, the 2023 growing season has been coolest across eastern Saskatchewan and western Manitoba (Fig. 3). Alberta temperatures continue to be above average. Relative to climate normals, temperatures continue to be above average in the Peace River region.  

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to June 4, 2023. 

Seven-day cumulative rainfall was nominal for most of Alberta and Manitoba from May 29 to June 4. Eastern Saskatchewan reported greater than 40 mm of rain in the last 7 days (Fig. 4). Coronach, Saskatchewan reported 74 mm and Canora, Saskatchewan had 51 mm in the last 7 days.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 29 to June 4, 2023. 

Saskatchewan has generally had more rainfall over the past 30 days than Alberta and Manitoba (Fig. 5). Saskatchewan has had 85-150% of normal rainfall. Central and southern Alberta and most of Manitoba have had 40-60% of normal rainfall in the last 30 days.

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 6 to June 4, 2023. 

Growing season rainfall has been lowest in southern Alberta and highest in Saskatchewan and the Peace River region (Fig. 6). Hanna, Alberta has reported only 21 mm of rain since April 1 and Brooks, Alberta has had only 25 mm. In contrast, Assiniboia, Saskatchewan has had 114 mm of rain since April 1, 2023 and Valley View, Alberta has recorded 110 mm.

Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to June 4, 2023. 

Over the past 30 days, different parts of the prairies have been characterized by warm/dry, warm/wet, cool/dry, and cool/wet conditions (Fig. 7). Thus far, locations in southern Manitoba have experienced the warmest and driest growing conditions. The Peace River region has been the coolest and the wettest. Southern Alberta has been the driest and coolest. Many locations in Saskatchewan have had average temperatures and rainfall, although Coronarch is an interesting outlier that has been about average in terms of temperature but also quite wet. 

Figure 7. A scatterplot of prairie locations based on 30-day total rain (y-axis) and temperature (x-axis) for site-specific comparison of weather conditions experienced during the last 30 days of the 2023 growing season (May 6 to June 4, 2023). Graph by Ross Weiss.

14201Wind trajectory summary ( 2023 Week 5 )

‘Reverse trajectories’ refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date.  Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating.  If diamondback adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g., rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data. 

Relative to the previous two weeks, there was a significant increase in the number of reverse trajectories that entered the Canadian prairies between May 31 and June 6, 2023 (Fig. 1). This week, most of the reverse trajectories that crossed the prairies originated from the Great Plains (Nebraska, Kansas, Texas, Oklahoma). In earlier weeks of this growing season, most of the reverse trajectories originated from the Pacific Northwest. The number of reverse trajectories originating from California and Mexico also significantly increased in the last week. These results may indicate potential introductions of diamondback moth and leafhoppers to the prairies. 

Figure 1. The average number (based on a 5-day running average) of reverse trajectories (RT) that have crossed the prairies for the period of May 8 to June 6, 2023. 

Mexico, California and Texas: This week, 63 reverse trajectories crossed into the prairies from Mexico and the US southwest. These trajectories were predicted to cross into southeastern Saskatchewan and Manitoba (Fig. 2)

Figure 2. Total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and June 6, 2023. 

Pacific Northwest (Idaho, Oregon, Washington): This week 104 reverse trajectories were predicted to cross the prairies, with the majority of Pacific Northwest reverse trajectories reported to pass over Alberta and western Saskatchewan (Fig. 3).   

Figure 3. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and June 6, 2023. 

Oklahoma and Texas: In the last week, 98 reverse trajectories that originated over Texas and Oklahoma passed through the prairies, particularly through Manitoba and southeastern Saskatchewan and (Fig. 4). 

Figure 4.  The total number of dates with reverse trajectories originating over Oklahoma and Texas that have crossed the prairies between May 1 and June 6, 2023. 

 Kansas and Nebraska: Between May 31 and June 6, 2023 there were 119 reverse trajectories have been reported that originated in Kansas and Nebraska and passed over southeastern Saskatchewan and southern Manitoba (Fig. 5).

Figure 5.  The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between May 1 and June 6, 2023. 

14199Predicted grasshopper development ( 2023 Week 5 )

Model simulations were used to estimate development of grasshoppers as of June 4, 2023. Compared with average spring temperatures, well above normal temperatures across the prairies continue to result in rapid grasshopper development. Model runs suggest that this spring’s hatch is still proceeding with 68% of the hatch now complete (Fig. 1). In an average year, only 6% of the grasshopper hatch would be completed by this time in June. Hatch is predicted to be well underway across Alberta, western regions of Saskatchewan and southern Manitoba (Fig. 1).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 4, 2023. 

As of June 4, 32% of the grasshopper population is predicted to be in the egg stage, 34% first instar, 21% second instar, 12% third instar and 0.5% in the fourth instar. Based on average instar, development is most advanced across Alberta and a large area of Saskatchewan (Fig. 2). Field observations from June 7, 2023 agree with the model predictions.

Figure 2. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 4, 2023. 

In contrast to 2023, in an average year, most of the grasshopper population would still be in the egg stage or in the first instar stage at this time in early June.

Geospatial maps and model predictions are tools to help time in-field scouting on a regional scale but grasshopper development can vary and is only accurately assessed through scouting. Monitor roadsides and field margins to assess the development and densities of local grasshopper populations. Due to their small size, it may be difficult to visually observe first and second instar grasshoppers in roadside vegetation and field margins. If possible, use a sweep net to sample grasshoppers in ditches and along the edges of crops. Sweep net sampling allows for easier assessments of grasshopper densities at this time of year. Using the grasshoppers collected in sweep nets, we can also determine which life stages are present (which nymphal instars) and the species that are present. Information about grasshoppers and monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture.

14197Predicted diamondback moth development ( 2023 Week 5 )

Diamondback moths (Plutella xylostella) are a migratory invasive species; after initial migration into the prairies, diamondback moths can have multiple non-migratory generations during the growing season. Diamondback moth development can be rapid during periods of warm weather. Model simulationsto June 4, 2023, indicate that the first generation of non-migrant adults (based on early-May arrival dates) is currently occurring across the Canadian prairies. If above-normal temperatures persist, then we may start to see some second-generation diamondback moths next week.

The life cycle of diamondback moth can rapidly progress from egg (A) to larvae (B and C), to pupae (D) to adults (E). Photo credit: Jonathon Williams, AAFC-Saskatoon.

On the prairies, we use a network of pheromone traps to detect the first spring appearance of diamondback moths. Now, local scouting is needed to determine if diamondback moth pose a threat to crops. To scout, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

14195Predicted bertha armyworm development ( 2023 Week 5 )

Based on model simulations, development of overwintered bertha armyworm (Mamestra configurata) pupae continues to be significantly ahead of normal for most of the prairies. Bertha armyworm pupae across the prairie region are expected to be at least 90% finished their larval development (Fig. 1); as a result, adults might already be emerging in some areas.

Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development (%) across the Canadian prairies as of June 4, 2023. 

The bertha armyworm model predicts that adults could already be present in a region between Lethbridge, Alberta and Swift Current, Saskatchewan (Fig. 2). Adult moths may also be flying near Edmonton, Alberta and in the northern limits of the Peace River region (Fig. 2).

Figure 2. The proportion of the bertha armyworm (Mamestra configurata) population that is predicted to be in the adult stage (% of total population) across the Canadian prairies as of June 4, 2023. 

14169Predicted wheat midge development ( 2023 Week 5 )

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Adequate rainfall in May and June is a signal to larval cocoons to end their diapause and move to the soil surface to pupate. where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in: 
a. Delayed adult emergence and oviposition 
b. Reduced numbers of adults and eggs

Figure 1. Areas in western Canada where cumulative rainfall (mm) from May 1 to June 4, 2023 is sufficient (greater than 30 mm) to promote movement of wheat midge (Sitodiplosis mosellana) larvae to the soil surface. 

In the last few weeks, rainfall events over parts of the prairies may have provided the cue to end wheat midge larval diapause. From May 1 to June 4, cumulative rainfall was normal or above normal in the Peace River region and parts of Saskatchewan (Fig. 1). Larvae, if present, are likely moving towards the soil surface in the Peace River region and in wet areas of Saskatchewan (Fig. 2).  

Figure 2. The proportion of the wheat midge (Sitodiplosis mosellana) larval population that has moved to the soil surface across western Canada, as of June 4, 2023.

In contrast to the wet areas on the prairies, wheat midge adult emergence might be delayed in dry areas 2023. It is also possible that the wheat midge larval cocoons will remain in a diapause state until a future year when spring moisture is more suitable for wheat midge development.

Scouting for adult wheat midge usually starts in late June or early July. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict that status of wheat midge development and provide additional updates.

For information about scouting, check out the wheat midge monitoring protocol. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

14167Prairie Research ( 2023 Week 5 )

The 2023 growing season is in full swing and researchers working with insects, weeds, plant pathogens, and crops are very busy across the prairie region! For something new this year, the Prairie Pest Monitoring Network will occasionally include Prairie Research Updates in the Weekly Update. This post will highlight the hard work of our colleagues at Agriculture and Agri-Food Canada (AAFC) research centers, at universities, and by other research organizations across western Canada. If you have ideas for a Prairie Research Update, please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca).

Science News from the Prairies is an AAFC newsletter that highlights work by scientists at AAFC research centres in Alberta, Saskatchewan, and Manitoba. The June 3, 2023 edition highlights the Plant Gene Resources of Canada, a plant gene bank at the AAFC Saskatoon Research and Development Centre. Plant gene banks serve to maintain the genetic diversity of plants by collecting, preserving, and rejuvenating plant reproductive material and sharing their resources to support plant breeding programs, education, and research. Read more about the Plant Gene Resources of Canada and other AAFC research projects in Science News from the Prairies.

To learn more about entomology research at the AAFC Saskatoon Research and Development Centre, please read “Pest Detective: How AAFC is using pest monitoring data to model climate change impacts” available in English and in French.

14165Provincial Insect Updates ( 2023 Week 5 )

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

Watch for new issues of the Saskatchewan Crop Production News coming soon in 2023 and browse the articles from 2022 for information from the past.

The latest Manitoba Crop Pest Update for 2023 was posted on June 7. Watch their website for new Crop Pest Updates as the season continues and check out the archives to read past Updates.

141382023 Week 4 (Released June 1, 2023) ( 2023 Week 4 )

Happy new month! Week 4 kicks off June 2023.

May was characterized by wonky weather – unseasonably warm days and very little rain. As a result, some prairie insect pests are developing faster than normal.

Grasshoppers thrive in warm, dry conditions and we continue to hear about high numbers of nymphs along roadsides and field edges. Last week, we also observed some third instar grasshopper nymphs, which normally do not appear in the population until mid-June. Diamondback moths that arrived in early May have likely reproduced and adult moths found now could be from the first generation produced on the prairies. Bertha armyworm development is also well ahead of schedule – pupal development could be 90% complete in some areas, so it is probably time to set up pheromone traps for bertha armyworm monitoring in most parts of the prairies. This week, we featured the pea leaf weevil in the Insect of the Week – the annual damage survey for pea leaf weevil is now underway! For more information, check out the posts in the Weekly Update!

Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to plan for in-field scouting, and even thresholds to help support in-field management decisions are all available for review or download.

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14136Weather Synopsis ( 2023 Week 4 )

***Special thanks to Mark Berry, AAFC-Geomatics, for providing up-to-date weather information for the prairies that is summarized here and used to predict insect development***

This past week (May 22-28, 2023), average prairie temperatures continued to be well above average. The prairie average daily temperature was 4°C warmer than normal (Fig. 1). The warmest temperatures were observed across southern regions of Manitoba and Saskatchewan. Even though temperatures have moderated across the Peace River region, temperatures were still 2-3°C warmer than normal for this time of year.

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of May 22-28, 2023. 

Average temperatures over the past 30 days (April 28 – May 28, 2023) have been 4°C above normal (Fig. 2), with the warmest temperatures reported for Alberta and western Saskatchewan.

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of April 29-May 28, 2023. 

Since April 1, the 2023 growing season has been coolest across eastern Saskatchewan and western Manitoba (Fig. 3). Temperatures have been below normal for many locations across western Manitoba. For example, the average temperature near Melita has been 1.3°C cooler than average. Alberta temperatures continue to be above average. Relative to climate normals temperatures, the warmest and most above average conditions continue to be those in the Peace River region. For example, the growing season temperature has been 5°C warmer than normal at Fort Vermillion, AB. 

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to May 28, 2023. 

Seven-day cumulative rainfall was nominal for most of Alberta and Manitoba last week (Fig. 4). Central Alberta and southern locations in the Peace River region received much need rain. Grande Prairie, Alberta reported 65 mm and Peace River, Alberta reported 59 mm. Saskatoon, Saskatchewan reported 41 mm.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 22-28, 2023. 

Rainfall over the past 30 days has been highly variable across the prairies (Fig. 5). Recent rainfall in the Peace River region has resulted in many locations in that region having rainfall amounts that are 200% of normal. Conversely eastern Alberta and western Saskatchewan have had rainfall amounts that are well below normal. Over the past 30 days rainfall totals are less than 60% of normal across most of Alberta, northwestern and eastern Saskatchewan and Manitoba.

Figure 5. 30-day average cumulative rainfall (mm) observed across the Canadian prairies for the period of April 29-May 28, 2023. 

Growing season rainfall has been greatest across southern Saskatchewan and southern areas of the Peace River region; rainfall amounts have been low for most of the southern and central regions of Alberta, western Saskatchewan, and most of Manitoba (Fig. 6). A large region, extending from Lethbridge, Alberta to Edmonton, Alberta and into western Saskatchewan (to about Saskatoon) continues to have well below normal rainfall accumulations. At Hanna, Alberta for example, the total rainfall this growing season is only 40% of what would normally have accumulated by this time of year.

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to May 28, 2023. 

14134Wind trajectory summary ( 2023 Week 4 )

‘Reverse trajectories’ refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date.  Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating.  If diamondback moth adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g., rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data. 

More reverse trajectories entered the Canadian prairies between May 25-31 than in the last two weeks (Fig. 1). With more reverse trajectories occurring, we may also see an increase in the introduction or migration of diamondback moths and aster leafhoppers to the prairies.

Figure 1. The average number (based on a 5-day running average) of reverse trajectories (RT) that have crossed the prairies for the period of May 1-31, 2023. 

Mexico, California and Texas: Last week no reverse trajectories that entered the prairies that originated from Mexico, California or Texas. In comparison, 37 reverse trajectories from Mexico, California, or Texas crossed into the prairies this week (May 25-31). These trajectories were predicted to cross into southeastern Saskatchewan and Manitoba (Fig. 2) 

Figure 2. Total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and May 31, 2023. 

Pacific Northwest (Idaho, Oregon, Washington): This week 55 reverse trajectories from the Pacific Northwest were predicted to cross the prairies, which is less than observed last week (n=79). The majority of Pacific Northwest reverse trajectories have been reported to pass over Alberta and western Saskatchewan (Fig. 3).  

Figure 3. Total number of dates with reverse trajectories originating over Idaho, Oregon, and Washington that have crossed the prairies between April 1 and May 31, 2023. 

Oklahoma and Texas: This past week there were 38 reverse trajectories that originated over Texas and Oklahoma and passed through the prairies, particularly southeastern Saskatchewan and Manitoba (Fig. 4).  

Figure 4.  The total number of dates with reverse trajectories originating over Oklahoma and Texas that have crossed the prairies between May 1 and May 31, 2023. 

Kansas and Nebraska: Since April 1, reverse trajectories originating in Kansas and Nebraska were reported to cross southeastern Saskatchewan and southern Manitoba (Fig. 5). Between May 25 and May 31, 2023 there were 95 reverse trajectories that were predicted to occur. This is a significant increase over the previous week (n=9). 

Figure 5.  The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between May 1 and May 31, 2023. 

14130Predicted grasshopper development ( 2023 Week 4 )

Over the past 5-7 days we have conducted a roadside survey for grasshoppers in west-central Saskatchewan. Numbers and development were higher than normal. First and second instar nymphs were found at all locations and many sites had low numbers of third instar grasshopper nymphs. We generally do not see third instars until mid-June! Many locations had high numbers of first instars suggesting that the hatch is still progressing. Melanoplus bivittatus, the two-striped grasshopper, was the most common species at all locations sampled in Saskatchewan in the last five days.   

An adult two-striped grasshopper, Melanoplus bivittatus. Photo credit: Meghan Vankosky, AAFC-Saskatoon.

Our observations in the field over the last week agree with the model simulation used to estimate the status of grasshopper development as of May 28, 2023. Grasshopper development is progressing rapidly where temperatures have been well above normal in Alberta and western Saskatchewan. Model runs for 2023 suggest that egg development is 87% complete, on average. At the end of May in an average year, we would expect egg development to be only 72% complete. Recent warm conditions across southern Manitoba have also resulted in faster development rates for eggs.

Grasshopper eggs are now hatching across Alberta and in western and central regions of Saskatchewan (Fig. 1). Hatch rates are well ahead of expected hatch rates based on long-term average weather conditions. In central and eastern regions and across most of Manitoba, hatch is predicted to be less than 15% but hatch rate is increasing (15-45%) in southern Manitoba after some warmer weather last week.

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of May 28, 2023. 

2023 is shaping up to be an interesting year for grasshoppers and prairie farmers should be prepared to scout for grasshoppers, especially if conditions remain warmer and drier than normal. For more information about grasshopper scouting, biology, and management in your province (Alberta, Saskatchewan, Manitoba), please check out their resources available online.