Category: Week 11

2023 Week 11 (Released July 20, 2023)

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

Adult grasshoppers are 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.

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

Weather Synopsis

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.**

Predicted Grasshopper Development

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 Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture.

Predicted Wheat Midge Development

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.

Predicted Diamondback Moth Development

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.

Canola Flower Midge Scouting

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.

Watch Out for Invasive Insects

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)

Provincial Insect Updates

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

Saskatchewan Crop Production News issues are now online! 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).

DIAMONDBACK MOTH

The diamondback moth (Plutella xylostella) is an invasive species that migrates northward to the Canadian Prairies on wind currents from infested regions in the USA. Upon arrival, migrant diamondback moths begin to reproduce, resulting in non-migrant populations that may have three or four generations on the prairies during the growing season. The time required for diamondback moth to complete a generation gets shorter when temperatures are warm. In warmer years, diamondback moth populations can build up relatively quickly, increasing their chances of causing economic damage to crops where populations are present. Host plants of diamondback moth include canola, mustard and other cruciferous vegetables and weeds.

Diamondback moths lay their eggs on leaves. Hatchling larvae emerge and tunnel into the leaves, later moving to the surface to feed. Damage first appears as shot holes but eventually expands until the leaves are skeletonized, leaving only the leaf veins. Larvae also feed on flowers and strip the surface of developing pods and stems. Larval damage lowers seed quality and crop yield of canola and can affect the marketability of crucifer vegetables.

The lifecycle of diamondback moth: A) eggs, B) early instar larva with damage typical of this life stage, C) late instar larva on a skeletonized leaf, D) pupa, and E) adult moth. All pictures taken by Jonathon Williams, AAFC-Saskatoon.

Adult moths measure 12 millimeters long with an 18-20 millimeter wingspan. At rest, their forewings form a diamond-shaped pattern along the mid-line. Mature larvae are 8-millimetre-long green caterpillars. Their terminal prolegs extend backwards, resembling a fork. When disturbed, caterpillars drop towards the ground on a silken thread to avoid harm.

Biological and monitoring information related to diamondback moths in field crops can be found on our Monitoring page as well as on provincial Agriculture Ministry pages (Manitoba, Saskatchewan and Alberta). For more information, visit the diamondback moth page in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français: Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien).

Released July 22, 2022

This week includes…..

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

Wishing everyone good SCOUTING weather!

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

Weather synopsis

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

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

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

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

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

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

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

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

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

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

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

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

Predicted wheat midge development

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

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

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

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

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

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

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Regina, Saskatchewan** as of July 17, 2022.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Yorkton, Saskatchewan** as of July 17, 2022.

Figure 6. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Grande Prairie, Alberta,** as of July 17, 2022.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

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

Figure 5. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

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

**Figure** 6. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.

Economic Thresholds for Wheat Midge:
a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and larval damage.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

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

Predicted grasshopper development

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

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

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

Figure 1. Predicted migratory grasshopper (*Melanoplus sanguinipes*) development, presented as **average instar**, across the Canadian prairies **as of July 17, 2022**.

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

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

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network. Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. Review the historical grasshopper maps based on late-summer in-field counts of adults performed across the prairies.

Predicted diamondback moth development

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

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

Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to have occurred across the Canadian prairies **as of July 17**, **based on climate normal data**.

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

In-Field Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

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

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg — Figure 3. Diamondback moth pupa within silken cocoon.

This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png — Figure 4. Diamondback moth.

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

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

West nile virus risk

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

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

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

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

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

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date November 18, 2021; retrieved July 20, 2022). The screenshot below (retrieved 20Jul2022) serves as a background reference of what was reported in 2021.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 20Jul2022).

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

Pre-Harvest Intervals (PHI)

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

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

Provincial insect pest report links

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

MANITOBA’S Crop Pest Updates for 2022 are up and running! Access a PDF copy of the July 20, 2022 issue here. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more!
• Grasshoppers and pea aphids in MB were emphasized in the July 20 issue.
• Bertha armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 20, 2022) of cumulative weekly counts.
• Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of July 12, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

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

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information. Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
• Wheat midge pheromone monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.
• Cabbage seedpod weevil monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.
• Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available on this Live Map.

Crop report links

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

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

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

EUROPEAN CORN BORER: A GENERALIST PEST OF CROPS

Despite its common name, the European corn borer (Ostrinia nubilalis) feeds on many crop and non-crop plants including beans, potato, quinoa, millet, hemp, wheat, many vegetables and some flowers. European corn borer is occasionally an economic pest of crops such as corn and potatoes in Manitoba, where there is one generation per year. In parts of Ontario and eastern Canada, there are univoltine (one generation per year) and bivoltine (two generations per year) strains. How prevalent and damaging European corn borer is to many of its host crops is still not clear.

European Corn Borer larva in millet. Photo credit: John Gavloski, Manitoba Agriculture

European corn borer has traditionally been monitored in corn fields, and more recently in potato fields. However, a new harmonized protocol can be used to monitor for European corn borer in multiple crops. Anyone participating in insect monitoring on any potential host crop can access the harmonized protocol online or using the Survey123 app.

The protocol can be used to report the presence of European corn borer eggs, larvae, and crop damage. Anyone monitoring populations or encountering noticeable levels of European corn borer or their injury to any crop is highly encouraged to add this data. For more information about the harmonized protocol and to submit monitoring data, please click here to access all needed links. Information collected from across Canada will be used to better understand the distribution, feeding habits, and abundance of this pest.

European Corn Borer egg masses. Photo credit: John Gavloski, Manitoba Agriculture

Access these resources to find more information:
• Review the European corn borer page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) also accessible as a free downloadable PDF in either English or French on our new Field Guides page.
• Review the Manitoba Agriculture fact sheet for the European corn borer.
• Review the Ontario Ministry of Agriculture, Food, and Rural Affairs fact sheet for European corn borer.

Weekly Update

Week 11 and our staff are again busy surveying! In fact, it’s appropriate that we take this moment to thank the MANY people who are busy checking traps, doing sweeps, and processing samples! It’s a massive undertaking that happens across the Canadian prairies and begins with dedicated individuals.

Western Canada has one of the most expansive and historically deep data collections in agricultural entomology with grasshopper surveys extending over 100 years and many of our “recent” pests have data sets extending at least 5-40 yrs or more. That amazing data is used in so many ways but it directly supports the development of bioclimatic models for Canada’s most important economic agricultural insect pests and Canadians benefit with predictive model outputs that help growers time and prioritize in-field scouting. It also incrementally improves the ability to estimate insect pest risk from year to year. THANK YOU to everyone who contributes – just “see” how many sites were monitored in 2020!

Be sure to catch the Insect of the Week – it’s swede midge and the canola flower midge: Doppelganger pests!

Stay safe and good scouting to you!

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

Weather synopsis

TEMPERATURE: This past week (July 5 – 11, 2021), the prairies continued to experience record-setting temperatures and extremely dry conditions. The warmest temperatures were observed across southern Alberta and Saskatchewan (Fig. 1). Across the prairies, the average 30-day temperature (June 12 – July 11, 2021) was almost 3 °C warmer than climate normal values. The warmest temperatures were observed across southern Alberta and western Saskatchewan (Fig. 2). Southern and western areas of the Peace River region have been 4-5 °C warmer than average.

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of July 5 – 11, 2021.

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 12 – July 11, 2021.

The 2021 growing season (April 1 – July 4, 2021) has been 1.5 °C warmer than average. The warmest temperatures have occurred across southeastern Manitoba, west-central Saskatchewan and southern Alberta (Fig. 3).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 11, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-July 12, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (July 6-12, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -1 to >10 °C while the highest temperatures observed ranged from <26 to >36 °C. With the incredible heat experienced so far, check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-July 12, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This past week, significant rainfall was reported across southern and central Saskatchewan and Alberta (Fig. 4). Rainfall amounts for the period of June 12 – July 11 (30-day accumulation) have been well below average with most of the prairies receiving less than 40% average (Fig. 5). Growing season (April 1 – July 11) precipitation has been less than average across most of the prairies. Western Saskatchewan and most of Alberta have received less than 100 mm of rain (Fig. 6).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 5 – 11, 2021.

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 12 – July 11, 2021

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – July 11, 2021.

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

Predicted wheat midge development

The continued warm temperatures have resulted in the rapid development of wheat midge populations. Where present, wheat midge populations are predicted to be predominantly in the egg stage across most of the prairies (Fig. 1). This is a substantial change from last week where only 12 % of the population was predicted to be in the egg stage. The initial appearance of larvae (in wheat heads) is predicted to be occurring (Fig. 2).

Figure 1. Percent of wheat midge (*Sitodiplosis mosellana*) population that is **in the egg stage**, across the Canadian prairies **as of July 11, 2021**.

Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) population that is **in the larval stage (in wheat heads)**, across the Canadian prairies **as of July 11, 2021**.

The model was projected to July 27 to determine potential development at Regina (Fig. 3), Lacombe (Fig. 4), and Grande Prairie (Fig. 5) over the next two weeks. The model output suggests that oviposition will continue to increase over the next 5-7 days and should peak sometime this week. Larvae (Sm L1-2) are expected to complete development by the end of July. Macroglenes penetrans, a parasitoid of wheat midge, is active in wheat fields when wheat midge adults are present. Simulation runs indicate that the parasitoid has begun to appear in wheat crops in fields near Regina.

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Regina, Saskatchewan **as of July 11, 2021 (projected to July 27, 2021)**.

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Lacombe, Alberta **as of July 11, 2021 (projected to July 27, 2021)**.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Grande Prairie, Alberta as of July 11, 2021 (projected to July 27, 2021).

If not already underway, scout for wheat midge adults this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

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

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

**Figure** 7. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on the wheat heads
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

**Figure** 8. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beav-S. Dufton).

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

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

Predicted grasshopper development

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 11, 2021. Above-average temperatures in late June and early July have resulted in a noticeable increase in grasshopper development. Grasshopper development should be greatest across southern Manitoba where the majority of the population will be in the adult stage (Fig. 1). Adults should be present across all three provinces; more than 13.5 % of the population should be adults.

Figure 1. Predicted grasshopper (*Melanoplus sanguinipes*) development across the Canadian prairies **as of July 11, 2021**.

Figure 2. Percent of grasshopper (*Melanoplus sanguinipes*) population in the adult stage across the Canadian prairies **as of July 11, 2021**.

The long-term average value for this week of the growing season is less than 1% of the population in the adult stage. Development, as of July 11, 2021, is well ahead of long-term average values (Fig. 3).

Figure 3. Long-term average predicted grasshopper (*Melanoplus sanguinipes*) development, presented as the average instar, across the Canadian prairies **as of July 11, based on climate normals data**.

Grasshopper Scouting Steps:
● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
● Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

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

Predicted diamondback moth development

Model simulations to July 11, 2021, indicate that the second generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). A third generation is predicted for southern Manitoba. Based on climate normal inputs, development is well ahead of long-term average values (Figure 2). Based on current weather, the mean number of generations that have occurred is 2.1 compared to model runs, based on climate normals, predict that the number of generations should be 1.4.

Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth *(Plutella xylostella*) expected to have occurred across the Canadian prairies as of July 13 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

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

Bertha armyworm

Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta. So far, interception counts remain mainly in the “low risk” categories across the Canadian prairies. Review the 2020 pheromone trapping cumulative moth counts here to identify potential high risk areas to target for scouting for larvae now!

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 1) to help identify the various stages. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png — **Figure 6**. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

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

Midges in canola

The Insect of the Week features Swede midge and the canola flower midge as doppelganger pests this week!

Two species of midges (Diptera: Cecidmyiidae) are known to infest canola in Canada. Since 2000, swede midge (Contarinia nasturtii) has been established in southern Ontario with serious levels of damage observed in several species of Brassicaceae, including canola by 2003. Swede midge is also established in Quebec, Nova Scotia, and Prince Edward Island. Across the prairie region of Canada, a separate canola flower midge (Contarinia brassicola Sinclair) was identified initially as larvae feeding within the developing flower that caused the formation of a “pop-bottle”-shaped gall (Fig. 1). To date, this is the only damage associated with the canola flower midge, and it has been minimal across the prairies.

Figure. 1. “Pop-bottle”-shaped galls created by the canola flower midge.
(c) 2016 Boyd Mori, AAFC

Because of the serious threat that swede midge poses to canola production, it is vital that monitoring for swede midge continues across the Prairies. Monitoring is underway for 2021.

Tips for scouting canola for midges:
• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.

Access more information about midges in canola via these links:
• Swede midge and canola flower midge: Doppelganger pests (2021; Wk 11)
• New canola flower midge (2018; Wk 11)
• Natural enemies of the canola flower midge (2018; WK 12)
• Ontario’s swede midge fact sheet produced by Baute et al. 2016.
• Canola Council of Canada’s Canola Encyclopedia – Swede midge

West nile virus risk

As of July 11, 2021 (Fig. 1), C. tarsalis development continues to be most advanced in Manitoba, southern Alberta, and in a small pocket in southern Saskatchewan. The map will change very quickly to red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Areas highlighted yellow or orange in the map below (as of July 11) should start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 12 days for adults to become fully infective with the current warm weather.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 4, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 13, 2021). The screenshot below (retrieved 13Jul2021) serves as a reference.

Provincial insect pest report links

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

MANITOBA’S Crop Pest Updates for 2021 are now available – access the July 14, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
• Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. The initial counts are categorized as “low risk” so far (i.e., 0-300 moths).
• Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 65 traps intercepted moths and the highest cumulative count was 171 moths near Selkirk. Access the summary (as of June 30, 2021). At this point, in-field scouting for larvae remains important.

SASKATCHEWAN’S Crop Production News are available. Access Issue #2 online which includes information on cabbage seedpod weevil, grasshoppers in Saskatchewan, and wheat midge. Be sure to bookmark their insect pest homepage to access important information!
• Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data is now available here.
• Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
• Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. Some sites in central Alberta are beginning to report “high risk” adult counts so synchrony with anthesis will need to be carefully monitored(08Jul2021).
• Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map. Some sites in southern Alberta are reporting densities at or above the economic threshold in canola (08Jul2021).
• Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. Cumulative counts throughout the province report “low risk” numbers of moths so far (08Jul2021).
• Diamondback moth pheromone trap monitoring update for AB – Trapping has drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<50 province-wide as of 01Jul2021). At this point, in-field scouting for larvae remains important.
• Cutworm reporting tool – Refer to the Live Map which now reports seven sites with cutworms (as of 01Jul2021).

Crop report links

Click the provincial name below to link to online crop reports produced by:
• Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the July 13 2021 report).
• Saskatchewan Agriculture (or access a PDF copy of the July 6-1 2 , 2021 report).
• Alberta Agriculture and Forestry (or access a PDF copy of the June 28, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the July 12, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the July 13, 2021 edition).

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

SWEDE MIDGE AND CANOLA FLOWER MIDGE: DOPPLEGANGER PESTS

In 2016, entomologists on the Canadian Prairies identified a previously unknown species of midge while conducting field experiments in northeastern Saskatchewan. The new midge was described in 2019 and is named Contarinia brassicola Sinclair (Diptera: Cecidomyiidae). It is known unofficially as the canola flower midge, although its host range includes mustard varieties.

The full extent of the host range of canola flower midge has yet to be studied. Field surveys conducted between 2017 and 2019 found that the canola flower midge is widely distributed in Alberta, Saskatchewan, and Manitoba, with some pockets of higher population densities (i.e., northeastern Saskatchewan). The canola flower midge is morphologically similar to the swede midge: a doppelganger insect that damages the same field crops that canola flower midge does, as well as a variety of cruciferous vegetables (e.g., cabbage, cauliflower, Brussels sprouts) and Brassica weeds. Both species have much in common, but differences in the type of plant damage they inflect can help distinguish between the two.

Neither insect poses a threat to crops in their adult form, but both species have larvae that cause damage to their host plants. Canola flower midge larvae consume individual canola buds, resulting in characteristic galled flowers. In comparison, swede midge larvae are known to attack and consume plant material at any growing point on their host plants, affecting normal plant development.

Both midge species are quite similar in their physical characteristics. Adults are delicate, 2–5 mm long flies ranging in colour from light brown to grey. These insects have long legs, long beaded antennae and sparse venation on their wings. Larvae grow between 3–4 mm long. Young larvae are semi-translucent when they hatch and turn yellow as they mature.

Biological and monitoring information related to the swede midge in field crops can be found on our Monitoring page. For more information, visit the swede midge page in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien). For more information on the canola flower midge, check out this publication from the Alberta Department of Agriculture and Forestry, and previous postson the Prairie Pest Monitoring Network website.

Weather synopsis

This week, June 29-July 5, 2020, prairie temperatures were warmest in Manitoba and eastern Saskatchewan and seven day cumulative rainfall varied across the prairies (Table 1). Average 7-day temperatures continue to be warmest across Manitoba and eastern Saskatchewan and coolest across most of Alberta (Fig. 1). The weekly average temperature at Winnipeg (24.5 °C) was 6.6 °C warmer than the long term average value and was 10.9 °C warmer than the 7-day observed temperature at Grande Prairie (Table 1; Fig. 1). The average weekly temperature for Lethbridge was 13.8 °C and 2.3 °C cooler than normal (Table 1).

**Figure 1.** Observed average temperatures across the Canadian prairies the past seven days (June 29-July 5, 2020).

Average 30-day (June 6-July 5, 2020) temperatures continue to be cooler in Alberta than southern Saskatchewan and Manitoba (Table 2). The average 30-day temperature at Winnipeg and Brandon continued to be greater than locations in Alberta and Saskatchewan (Table 2; Fig. 2). June temperature anomalies indicate that temperatures have been below normal across most of Alberta and Saskatchewan and were 0 to 2 °C warmer than average across southeastern Saskatchewan and southern Manitoba (Table 2; Fig. 3). Based on growing season temperatures (April 1 – July 5, 2020), conditions were warmest for southern locations (Table 3).

**Figure 2.** Observed average temperatures across the Canadian prairies the past 30 days (June 6-July 5, 2020).

**Figure 3**. Mean temperature difference from Normal for the month of June 2020.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (05Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Cumulative rainfall for the past 7 days was lowest across western regions of Saskatchewan (Table 1; Fig. 4). Lethbridge reported 69.4 mm. Cumulative 30-day rainfall continued to be greatest across central regions of Alberta (Table 2; Fig. 5). Rainfall amounts were lowest across the most of Saskatchewan.

**Figure** 4. Observed cumulative precipitation across the Canadian prairies the past seven days (June 29-July 5, 2020).

Total 30-day rainfall at Saskatoon, Lethbridge, Lacombe and Grande Prairie exceeded 100 mm (Table 2; Fig. 5). Saskatoon has reported 156.6 mm (277% of normal) in the past 30 days (Table 2). Growing season rainfall (percent of average) is below normal southern Saskatchewan and most of Manitoba. Rainfall amounts are above average across central regions of Saskatchewan and across Alberta.

**Figure 5**. Observed cumulative precipitation across the Canadian prairies the past 30 days (June 6-July 5, 2020).

**Figure 6.** Percent of average precipitation for the growing season (April 1-July 5, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (05Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-July 6, 2020) is below (Fig. 7):

**Figure 7**. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-July 6, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (09Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The highest temperatures (°C) observed the past seven days ranged from <15 to >33 °C in the map below (Fig. 8).

**Figure 8**. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-July 8, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (09Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

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

Predicted wheat midge development

Wheat midge overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impact on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larval to the sol surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model (Olfert et al. 2020) indicates that dry conditions may result in: (a) Delayed adult emergence and oviposition, (b) Reduced numbers of adults and eggs.

Wheat midge model runs indicate that, where wheat midge are present, pupation is occurring across Alberta, northwest Saskatchewan and southern Manitoba (Fig. 1). Simulations suggest that, though still less than 15%, adult emergence has begun, most notably across Alberta (Fig. 1). Females lay eggs on developing wheat heads. This typically occurs in evenings when winds are calm. Wheat midge monitoring protocol suggests that wheat fields should be inspected for adults in late June and early July as wheat heads are emerging. The next three weeks are very important for monitoring wheat midge populations for the purpose of making management decisions.

**Figure 1**. Predicted percent of population of wheat midge (*Sitodiplosis mosellana*) at adult stage across the Canadian prairies (as of July 5, 2020).

Simulations were run to July 21 to assess population development over the next two weeks (Figs. 2-4). The first graph illustrates development of wheat midge populations near Saskatoon (Fig. 2). Adult emergence has begun and should peak next week, suggesting that monitoring fields for adults should begin in the next few days. Oviposition has just started and larvae will occur soon after.

**Figure 2**. Predicted wheat midge (*Sitodiplosis mosellana*) phenology at Saskatoon SK *projected to July 21, 2020*.

The second graph compares synchrony between wheat midge and wheat for fields near Lacombe (Fig. 3). The graph indicates that adult emergence and oviposition may occur this year when the crop is most susceptible.

**Figure 3**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and wheat at Lacombe AB projected to July 21, 2020.

The last graph compares phenology of wheat midge adults near Saskatoon with the phenology of Macroglenes penetrans, a parasitoid of wheat midge (Fig. 4). The parasitioid wasp lays is eggs inside wheat midge eggs. The graph shows that the timing of emergence and oviposition of wheat midge adults is similar to the emergence and oviposition timing of M. penetrans. All of this information can be used as a guide to determine when fields should be monitored.

**Figure 4**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and its parasitoid, *Macroglenes penetrans*, at Saskatoon SK *projected to July 21, 2020*.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

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

Predicted grasshopper development

As of July 5, 2020, the grasshopper model estimates that hatch is essentially complete. Development is slowest in the Peace River region where the simulation indicates that approximately 30% of the population is still in the egg stage (Fig. 1). Across the prairies, the majority of the nymphal population is predicted to be in the second to fourth instar stages (Table 1; Fig. 1). Development in Manitoba is predicted to be well ahead of most locations across Alberta (Table 1; Fig. 1). Recent warm temperatures in eastern Saskatchewan and Manitoba have resulted in higher rates of grasshopper development. This week, adults are predicted to occur at locations across southern Manitoba and southeastern Saskatchewan (Table 1; Fig. 1). Across the prairies, populations are predicted to be 11, 9, 25, 25, 22, 8 and less than 1% in egg, first, second, third, fourth, fifth and adult stages, respectively (Table 1).

**Figure 1**. Predicted average instar stages of grasshopper (*Melanoplus sanguinipes*) populations across the Canadian prairies (as of July 5, 2020).

The two graphs compare predicted development for Saskatoon (Fig. 2) and Winnipeg (Fig. 3). Grasshopper populations near Saskatoon are expected to be predominantly in the third and fourth instars (Fig. 2) while populations near Winnipeg are expected to be primarily in the fifth instar with some adults beginning to appear (Fig. 3).

**Figure 2**. Predicted grasshopper (*Melanoplus sanguinipes*) phenology at Saskatoon SK. Values are based on model simulations (April 1-July 5, 2020).

**Figure** 3. Predicted grasshopper (*Melanoplus sanguinipes*) phenology at Winnipeg MB. Values are based on model simulations (April 1-July 5, 2020).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network. Also refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Predicted bertha armyworm development

Model simulations for July 5, 2020, indicate that 5 % of the population is in the pupal stage (26 % last week), 43 % is in the adult stage (52 % last week), and 37 % of the population is in the egg stage (20 % last week). In southern Manitoba and southeastern Saskatchewan, larval stages are predicted to increase this week (14 % compared to 2 % last week). Across the Parkland and Peace River regions, BAW populations are predicted to be mostly adults with oviposition occurring in these areas (Fig. 1). Operation of BAW traps in these areas should continue until adult emergence is complete. Populations across southern regions are primarily in the larval stage (Fig. 2).

**Figure 1**. Predicted percent of bertha armyworm (*Mamestra configurata*) population ***in the adult stage*** as of July 5, 2020.

**Figure 2**. Predicted percent of bertha armyworm (*Mamestra configurata*) population ***in the larval stage*** as of July 5, 2020.

The two graphs demonstrate that larval development near Brandon (Fig. 3) is predicted to be ahead of fields near Lethbridge (Fig. 4).

**Figure 3**. Predicted bertha armyworm (*Mamestra configurata*) phenology at Brandon MB as of July 5, 2020.

**Figure 4**. Predicted bertha armyworm (*Mamestra configurata*) phenology at Lethbridge AB as of July 5, 2020.

**Figure 5**. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Click each province name to access moth reporting numbers observed in Alberta, Saskatchewan and Manitoba (as they become available). Check these sites to assess cumulative counts and relative risk in your geographic region but remember in-field scouting is how the economic threshold is applied to manage this pest.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images above (Fig. 5) to help identify the economically important larvae. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

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

Diamondback moth

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

Wind Trajectory Updates – Completed for 2020 growing season as of Week 09 (released June 22, 2020).

Weekly Pheromone-baited Trapping Results – Early season detection of diamondback moth is improved through the use of pheromone-baited delta traps deployed in fields across the Canadian prairies. Click each province to access moth reporting numbers observed in Alberta, Saskatchewan and Manitoba as they become available. Check these sites to assess cumulative counts and relative risk in your geographic region.

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

Figure 1. Diamondback larva measuring ~8 mm long.Note brown head capsule and forked appearance of prolegs on posterior.

Figure 2. Diamondback moth pupa within silken cocoon.

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

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

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

Pea leaf weevil

Models runs predicting spring adult activity, oviposition and larval development for this pest are completed as of Week 9 (June 21, 2020). Use the following information to aid in-field scouting for larvae.

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

**Figure 1**. Comparison images and descriptions of four *Sitona* species adults including pea leaf weevil (Left).

Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.

Larvae develop under the soil and are “C” shaped and milky-white with a dark-brown head capsule ranging in length from 3.5-5.5 mm (Figure 2). Larvae develop through five instar stages. After hatching, larvae seek and enter the roots of a pea plant. Larvae will enter and consume the contents of the nodules of the legume host plant. It is the nodules that are responsible for nitrogen-fixation which affect yield plus the plant’s ability to input nitrogen into the soil. Consumption of or damage to the nodules (Figure 3) results in partial or complete inhibition of nitrogen fixation by the plant and results in poor plant growth and low seed yields.

**Figure 2**. Larva of pea leaf weevil in soil (Photo: L. Dosdall).

**Figure 3**. Damaged pea nodules (Photo: L. Dosdall).

Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.

Also refer to the pea leaf weevil page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Cereal Aphid Manager

Aphids can cause significant damage to fields and increase crop losses but low densities in a grain field sometimes have little economic impact on production. This is especially true if the aphid’s natural enemies (beneficial insects) are present in the field because they can keep the aphids under control.

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:

the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

Frequent in-field scouting, supported by the app’s dynamic threshold, allows growers to weigh the above factors and the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

To learn more and to download, go to AAFC’s CAM webpage.

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 4, 2020). The screenshot below was retrieved 09Jul2020 as reference but access that information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below. As of July 8, 2020, areas highlighted yellow are approaching sufficient heat accumulation for mosquitoes to emerge. Plan to protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of July 8, 2020).

Scouting charts for canola and flax

Reminder – Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.

We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:

1. CANOLA INSECT SCOUTING CHART

2018_ScoutingChart_Canola

2. FLAX INSECT SCOUTING CHART

2018_ScoutingChart_Flax

These charts feature hyperlinks directing growers to downloadable PDF pages with photos within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“.

Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.

Field heroes

The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!

Real Agriculture went live in 2020 with a Pest and Predators podcast series!

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

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

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

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

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

Access ALL the Field Heroes links here and be sure to follow @FieldHeroes!

Provincial insect pest report links

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

• Manitoba‘s Crop Pest Updates for 2020 are available. Access the July 8, 2020 report. The summary indicates that, “Armyworms are being found at high levels in many cereal and forage grass fields in the Eastern, Interlake, Central, and Southwest regions. High levels of grasshoppers continue to be found and controlled in some areas.”

• Saskatchewan‘s Crop Production News and read Issue 4 which includes articles on Pest Scouting 101: Mid-Summer, and The Wheat Midge.

• Alberta Agriculture and Forestry’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.

Crop reports

Click the provincial name below to link to online crop reports produced by:

• Manitoba Agriculture and Rural Initiatives – Other viewing options include subscribing to receive or access a PDF of July 7 , 2020 report.

• Saskatchewan Agriculture or access a PDF of June 30-July 6, 2020 report.

• Alberta Agriculture and Forestry or access a PDF of June 29, 2020 report.

The following crop reports are also available:

• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the July 6, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the July 7, 2020 edition).

Click to review these earlier 2020 Posts (organized alphabetically):

• 2019-2020 Risk and forecast maps

• Alfalfa weevil (Wk08)

• Aster leafhopper (Wk05)

• Beetle data please! (Wk03)

• Crop protection guides (Wk02)

• Cutworms (Wk02)

• Flea beetles (Wk02)

• John Doane (Wk10)

• Monarch migration (Wk10)

• Pea leaf weevil – predicted development (Wk09)

• Prairie provincial insect webpages (Wk02)

• Scouting charts – canola and flax (Wk02)

• Ticks and Lyme Disease (Wk06)

• Wind trajectories (Wk09)

Forage Grass Pests / Feature Entomologist: Chrystel Olivier

This week’s Insect of the Week feature crop is forage grasses: common Prairie plants know to be robust, adaptive, and tolerant to grazing. Our feature entomologist this week is Chrystel Olivier.

The total cattle population in the Prairie region is 7.7 million animals: over three times the combined population of Atlantic Canada, according to the 2016 census. In order to feed millions of cattle and other livestock, forage is an important component to Prairie agriculture. Forage grasses include native and nonnative grass species grown for grazing, as well as hay and silage production. Sometimes doubling as cover crops in order to prevent soil erosion and nutrient loss, forage grasses are resilient, multi-purpose crops used to sustain livestock: either as a nutritional source in-pasture or as hay and silage used to supplement or replace grazing during the off-season. Common species include timothy grass, crested wheatgrass, and orchard grass.

A number of pests target forage grasses. Monitoring and scouting protocols as well as economic thresholds (when available) are found in Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management and the Cutworm Pests of Crops on the Canadian Prairies: Identification and Management Field Guide. Additional monitoring protocols exist to control certain pests.

Forage Grass Pests

Army cutworm
Armyworm
Aster leafhopper
Black grass bugs
Cereal leaf beetle
Chinch bug
Corn leaf aphid
Dingy cutworm
Fall armyworm
Glassy cutworm
Grasshoppers
Green grass bugs
Greenbug
Hessian fly
Mormon cricket
Rice leaf bug
Russian wheat aphid
Variegated cutworm
Wheat head armyworm
Wheat stem maggot

Entomologist of the Week: Chrystel Olivier

Name: Chrystel Olivier
Affiliation: AAFC-Saskatoon
Contact Information: Chrystel.olivier@agr.gc.ca

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

We are monitoring the aster leafhopper (Macrosteles quadrilineatus) that vectors aster yellow (AY) diseases and two species of flea beetles, the crucifer flea beetle (Phyllotreta cruciferae) and the striped flea beetle (Phyllotreta striolata) that feed on canola seedlings. We monitor for these species throughout SK using sweep nets and sticky cards. We record the emergence dates of the flea beetles in spring and their abundance in spring and fall. We also note when migratory aster leafhoppers arrive in the spring and their rate of AY infection.

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

The most interesting field crop pest is the aster leafhopper. It is a small insect (about 4 mm long) that migrates from the southern US states to the Canadian prairies, carried by the wind. It is an efficient vector of the economically important aster yellow disease. Aster yellow phytoplasma infect over 300 plant species, including canola, cereals and many vegetables grown in Canada. Phytoplasma are fascinating because they modify the feeding and reproduction behavior of their insect vectors to their own advantage. For example, AY-infected aster leafhoppers live longer, lay more eggs and can feed on plants they usually don’t feed on, all to increase spread of the pathogen.

What is your favourite beneficial insect?

My favourite beneficial insects are dragonflies. They are sky acrobats, and can fly in every direction, even backwards.

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

An important project I am working on right now investigates if hairy lines of brassicas can be used to protect seedlings from feeding and oviposition of flea beetles, diamond-back moths and aster leafhopper. This project is funded by the Canola Agronomic Research Program (CARP). Trichomes (hairs) are known to deter herbivorous insects and have been used as a deterrent with success in several crops. Recently, natural lines of Brassica napus, and the related Brassica villosa species, that exhibited high level of hairs were identified as potential sources of natural resistance towards flea beetles, diamond-back moths and aster leafhoppers. This project involves both field trials and laboratory-based bioassays.

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

Communication is mostly via peer-reviewed publications, written reports to the funding agencies, and oral presentations during grower/agronomist meetings and conferences. I often speak about insects to groups of all ages at parks and other community events across Saskatchewan.

Weekly Update

Greetings!

Another busy week of in-field monitoring, data collection, and field tour events for all our Staff! A reminder that, from now until mid-July, the Weekly Update may need to be posted in multiple segments (i.e., at any point from Wednesday-Saturday). Please bookmark the Blog or subscribe to receive the latest growing season information!

This week, special thanks to Ross Weiss (AAFC-Saskatoon) – entomologist and the integral modeler who works to generate all the weekly wind trajectory, meteorological, and predictive model updates supporting the Prairie Pest Monitoring Network.

Please access the complete Weekly Update either as a series of Posts for Week 12 (June 27, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week – the rest of the growing season features doppelgangers to aid in-field scouting!

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

Subscribe to the Blog by following these easy steps!

Weather synopsis

Temperatures this week, June 11-17 2019, were similar to last week and near normal (Fig. 1). The warmest temperatures were observed across AB while temperatures were cooler in eastern SK and across MB. Average 30-day temperatures were warmest across southern MB and SK from Estevan to Saskatoon and west to Kindersley (Fig. 2). Cooler temperatures were reported across the Parkland region, and western areas in AB (Fig. 2).

Seven-day cumulative rainfall indicated that minimal rain was observed across most of the prairies (Fig. 3). Many locations reported less than 10 mm. Higher rainfall amounts were reported for eastern SK and western MB.

Across the prairies, rainfall amounts for the past 30 days (May 19 – June 17, 2019; Fig. 4) have been approximately 56 % of normal (Fig. 5). Western SK and eastern AB continue to be dry.

Figure 5. Percent of Average precipitation across the Canadian prairies for the past 30 days (to June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Growing season rainfall (April 1 – June 17) amounts have been well below average for most of the prairies, particularly in west central SK and eastern regions of AB (Fig. 6). Almost all of the prairies has had growing season rainfall that is 4 percent, or less, than average. Soil moisture values are low across most of the prairies.

Figure 6. Accumulated precipitation (mm) across the Canadian prairies for the growing season (April 1 to June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The growing degree day map (GDD) (Base 5 ºC, April 1-June 17, 2019) is below (Fig. 7):

Figure 7. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-June 17 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The growing degree day map (GDD) (Base 10 ºC, April 1-June 17, 2019) is below (Fig. 8):

Figure 8. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The lowest temperatures (°C) observed the past seven days ranged from about 8 to -2 °C in the map below (Fig. 9).

Figure 9. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The highest temperatures (°C) observed the past seven days ranged from about 18 to at least 31 °C in the map below (Fig. 10).

Figure 10. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to June 17, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jun2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

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

Monarch migration

We continue to track the migration of the Monarch butterflies as they move north by checking the 2019 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 18Jun2019) but follow the hyperlink to check the interactive map. They are moving west in Manitoba and getting closer to Saskatchewan this week!

Access this Post to help you differentiate between Monarchs and Painted Lady Butterflies!

Visit the Journey North website to learn more about migration events in North America and visit their monarch butterfly website for more information related to this amazing insect.

Weekly Update

Hello!

Our field research programs are now in full field research mode with in-field monitoring, data collection, and field tour events. This means that, from now until mid-July, the Weekly Update may need to be posted in multiple segments (i.e., at any point from Wednesday-Saturday). Please bookmark the Blog or subscribe to receive the latest growing season information!

Please access the complete Weekly Update either as a series of Posts for Week 11 (June 20, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week – the rest of the growing season features doppelgangers to aid in-field scouting!

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

Subscribe to the Blog by following these easy steps!

Field Events – Speak to an entomologist

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

• June 20, 2019: Solstice Forage and Crops Field Tour to be held at the Beaverlodge Research Farm (Beaverlodge AB). View event info/registration details. Entomologists tentatively participating: Jennifer Otani, Keith Uloth

• June 26, 2019: 2019 CanolaPALOOZA to be held at the Lacombe Research and Development Centre (Lacombe AB). View event info/registration details. Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Meghan Vankosky, Scott Meers, Shelley Barkley, Patty Reid, Sunil Shivananjappa, Hector Carcamo, Julie Soroka, Mark Cutts, Jim Tansey, Sherrie Benson and the Junior Entomologists.

•  July 9-12, July 16-18, 2019: Crop Diagnostic School. Held at the University of Manitoba Research Farm at Carman, Manitoba. An 2-week diagnostic school will complete units on entomology, plant pathology, weed science, soil fertility, pulse crop production, and oilseed production. View registration and event information. Entomologists participating: John Gavloski and Jordan Bannerman.

•  July 9, 2019: CanolaPALOOZA Saskatoon, to be held at the SRDC Llewellyn Farm. Read more about this event.  Entomologists presenting: Tyler Wist, James Tansey, Greg Sekulic, Meghan Vankosky

•  July 22, 2019: Pulse grower gathering held near Three Hills AB. Check Alberta Pulse Growers Event Page for more information. Entomologists presenting: Graduate students from Dr. Maya Evenden’s (U of A) working on pea leaf weevil.

•  July 23-24, 2019: Crop Diagnostic School, Scott Saskatchewan. Read more about this event.  Entomologists presenting: Meghan Vankosky, Tyler Wist.

•  July 24, 2019: Crops-a-Palooza. Held at Canada-Manitoba Crop Diversification Centre (CMCDC), Carberry, Manitoba. Read more about this event. Entomologist participating: John Gavloski, Vincent Hervet, Tharshi Nagalingam, Bryan Cassone.

•  August 8, 2019: 2019 Wheatstalk to be held at Teepee Creek AB.  View event info/registration details. Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Boyd Mori.

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

Provincial Insect Pest Reports

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

• Manitoba‘s Insect and Disease Updates for 2019 are posted here and includes an update posted June 5, 2019.

• Saskatchewan‘s Crops Blog Posts includes a segment on “Early season scouting of cutworms” by Sara Doerksen posted in April 2019 and “Economic thresholds” by Kaeley Kindrachuk posted in May 2019. Also access the Crop Production News with Issues #1, #2, and #3 now available and containing insect pest information for 2019.

• Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Mr. Scott Meers. The most recent Call of the Land was posted March 18-22, 2019 but did not include an insect update.

Crop report links

Crop reports are produced by:

Manitoba Agriculture (June 11, 2019 or access the current online report)
Saskatchewan Agriculture (June 4-10, 2019) or access the current online report).
Alberta Agriculture and Forestry Crop Report (June 11, 2019 or access the current online report)

The following crop reports are also available:

The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the June 17, 2019 edition).
The USDA’s Weekly Weather and Crop Bulletin (read the June 9-15, 2019 edition).

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Alfalfa weevil – Week 10

Bertha armyworm – Week 10

Cabbage seedpod weevil – Week 10
Cereal aphid APP – Week 10
Cereal leaf beetle – Week 9
Crop protection guides – Week 6
Cutworms – Week 5

Field heroes – Week 6
Flea beetles – Week 5

Grasshoppers – Week 10

Insect scouting chart for Canola – Week 5
Insect scouting chart for Flax – Week 5

Painted lady butterfly – Week 8
Pea leaf weevil – Week 10

Ticks and Lyme disease – Week 4

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Review Page for list of PDFs

Predicted grasshopper development

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

Across the prairies, the grasshopper hatch is well underway this week with most locations having approximately 51% hatch (30% last week). Based on model runs, (i) approximately 30% (21% last week) of the population is in the first instar, (ii) 14.5% (7% last week) is predicted to be in the second instar, and (iii) 4.3% (1% last week) in the third instar.

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

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015). Models predicting the development of Alfalfa weevil (AAW) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae.

Alfalfa weevil larval populations are developing into later instars (Fig. 1). Second instar development is nearing completion and this week there larvae should be in the third instar stage. This week larvae are mostly second (26%, 52% last week) and third instars (52%, 22% last week; Fig. 1). Model output indicates that fourth instar larvae are beginning to occur in southern SK and isolated areas in southern AB and MB.

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhanced or French-enhanced version.

Predicted bertha armyworm development

Bertha armyworm (Lepidoptera: Mamestra configurata) – Pupal development is progressing and this week adults should be occurring across most of southern SK and localized areas in AB. Most of the population is predicted to be in the pupal stage (89%). The BAW model indicates that 10% of the population is in the adult stage .

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

Again, thanks to John Gavloski (Manitoba Agriculture) who helped update the PPMN Bertha armyworm monitoring protocol. Use the images below (Fig. 2) to help identify moths from the by-catch that will be retained in phermone-baited unitraps.

Figure 2. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Also be sure to review the Insect of the Week which features bertha armyworm and its doppelganger, the clover cutworm!

Predicted wheat midge development

Wheat Midge (Sitodiplosis mosellana) – Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on midge emergence. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic, if rainfall did not exceed 20-30 mm during May.

Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Two simulations were run to demonstrate the impact of rainfall and temperature on adult emergence and oviposition. The first graph illustrates adult emergence and oviposition based on long term (climate) data for Saskatoon (Fig. 1). The model indicates that emergence should begin in early July with oviposition beginning a few days later.

The second graph (Fig. 2) shows how DRYER, COOLER conditions would result in:

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

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

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

Figure 3. Adult wheat midge (*Sitodoplosis mosellana*) active on wheat head at anthesis stage
(Photo: AAFC-Beaverlodge; S. Dufton and A. Jorgensen).

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

Figure 4. The tiny parasitoid wasp, *Macroglenes penetrans*, is synchronized to emerge when wheat midge adults are present and the wasp seeks and oviposits on wheat midge eggs (Photo: AAFC-Beaverlodge; S. Dufton).

Economic Thresholds for Wheat Midge:

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

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

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

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture, Alberta Agriculture & Forestry) or access the Prairie Pest Monitoring Network’s monitoring protocol recently updated by Wist et al. 2019. A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has also released a YouTube video describing in-field monitoring for wheat midge this week.

Cabbage seedpod weevil

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

Monitoring:

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

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

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

Albertan growers can report and check the online map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 02Jul2019).

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

Doppelgangers: Wheat midge vs. Lauxanid

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

The case of the wheat midge vs. Lauxanid fly:Wheat midge larvae, in high enough numbers, can significantly reduce yield and quality of a wheat crop. The time to control this pest is at the adult stage. The key to determining whether adult numbers exceed the economic threshold for control is to follow the recommended insect pest monitoring protocol.

One hiccup is that it can be easy to mistake lauxanid flies for wheat midge adults when doing in-field scouting. But their size, general body shape and colour differences will help enable a person to tell them apart.

Wheat midge:

Thinner “mosquito-like” body (Image 1, left)
Long, thin legs
Between 1.5- 2 mm long
Dark, vibrant orange when alive
Large, black eyes that proportionally make up approximately 9/10’s of head

Lauxanid fly:

Bulkier body (Image 1, right)
Shorter, compact legs
Between 2 and 4 mm long
Paler, less vibrant orange colour
Smaller eyes that may be black, brown or red. Eyes proportionally make up approximately ½ of head

Image 1: Wheat midge (left) and Lauxanid (right).
Photo Credit: Bob Elliott (ret.), AAFC

Wheat midge larvae (Image 2) will feed on developing wheat kernels and can be found inside the wheat head. Lauxaniid larvae are not recorded as pests of any field crop and tend to be found in decaying leaf litter. Wheat midge larvae can be identified by their bright orange colour, and presence of spatula structure (Fig. 2; y-shaped structure circled below).

Image 2: Wheat midge larvae
Photo credit: AAFC-Jorgensen

Image 3: Wheat midge laying eggs on wheat head.
Photo credit: AAFC-Dufton

More information on wheat midge, other crop pests and their natural enemies, is available by accessing the updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide. Also refer to https://MidgeTolerantWheat.ca for the latest information on fighting wheat midge using tolerant wheat varieties.

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

Post contributed by Amanda Jorgensen.

Wind Trajectories

Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.

In a continuing effort to produce timely information, the wind trajectory reports are available in two forms:

DAILY REPORTS, as they can be generated, are accessible as a downloadable PDF file on this page.
WEEKLY REPORTS can be retrieved by clicking this hyperlink with the most recent version available here.

Prairie Crop Disease Monitoring Network

The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of our prairie pathologists who work together to support in-field disease management in field crops.

In 2019, the PCDMN will release a series of weekly Cereal Rust Risk Reports throughout May and June. Information related to trajectory events based on forecast and diagnostic wind fields and cereal rust risk is experimental, and is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY.

Background: Agriculture and AgriFood Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s. Trajectory models are used to deliver an early-warning system for the origin and destination of migratory invasive species, such as diamondback moth. In addition, plant pathologists have shown that trajectories can assist with the prediction of plant disease infestations and are also beginning to utilize these same data. An introduction will be presented of efforts to identify wind trajectory events that may bring rust urediniospores into Western Canada from epidemic areas in the central and Pacific northwest (PNW) regions of the USA. Identification of potential events as well as an assessment of epidemic severity from source locations, and prairie weather conditions, will be used to assess the need for prompt targeted crop scouting for at-risk regions of the Canadian Prairies.

Two documents are available from the PCDMN:

Summary of wind trajectory and cereal rust risk assessment and the need for in-crop scouting in the Prairie region, June 11-17, 2019:

1. Pacific Northwest – Currently there is limited stripe rust development in the PNW, a low number of recent wind trajectories from the PNW, and relatively dry Prairie weather conditions, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage. Thus, as of June 17, 2019, the risk of stripe rust appearance from the PNW is relatively low and scouting for this disease is not urgent.

2. Texas-Oklahoma corridor – In general, crops are advancing towards maturity, while in many areas of Texas harvesting has been completed, and thus winter wheat crops in these areas will become less of a source of rust inoculum. There has been a limited number of recent wind trajectories from this area, relatively dry Prairie weather conditions, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage. Thus, as of June 17, 2019, the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is low and scouting for these diseases is not urgent.

3. Kansas-Nebraska corridor – Leaf and stripe rust development in winter wheat continues in Kansas, although the winter crop is starting to turn colour in many regions. Although rusts have only been recently reported in Nebraska, levels are on the rise, and thus over the next few weeks this region could act as a significant source of rust inoculum for the Prairie region. From June 11-17, 2019 there has been a low number of wind trajectories from this area. In general, weather conditions have been relatively dry across the Prairies, while winter wheat is progressing into heading and beyond, and spring wheat is moving into the stem elongation stage. Thus, as of June 17, 2019, the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is relatively low and scouting for these diseases is not urgent; however, further development of rust Nebraska may increase the risk.

4. Where farmers or consultants noticed stripe rust development on winter wheat in the fall of 2018 it is recommended to scout winter wheat fields this spring. Scouting is especially critical where the variety being grown is susceptible to stripe rust. Currently, there are no reports of stripe rust in commercial fields of winter or spring wheat across the Prairie region.

5. Access the full downloadable report.

Insect of the Week – The new canola flower midge (Contarinia brassicola, Diptera: Cecidomyiidae)

This week’s Insect of the week is a new find on the prairies, tentatively called the canola flower midge, Contarinia brassicola (Diptera: Cecidomyiidae). The canola flower midge has been found throughout central Alberta, Saskatchewan, and the Swan River Valley in Manitoba. The female lays eggs on developing canola flower buds. Upon hatching, the larvae feed within the developing flower and cause the formation of a “pop-bottle”-shaped gall. To date, this is the only damage associated with the midge, and it has been minimal across the prairies.

Adult canola flower midges appear similar to swede midge (Contarinia nasturtii). They are tiny, delicate flies, 2-5 mm in size. They can be differentiated from swede midge based on the appearance of the female antennae, the damage symptoms they produce and genetically.

Many thanks to Scott Meers and Shelley Barkley (Alberta Agriculture and Forestry) for organizing the Alberta surveys for the canola flower midge.

Submitted by Dr. Boyd Mori and Dr. Meghan Vankosky

Find out more about the insect pests that plague your crops and the natural enemies that keep them in check at the Insect of the Week page!

“Pop-bottle”-shaped galls created by the canola flower midge.
(c) 2016 Boyd Mori, AAFC

Weekly Update

Greetings!

Field crop entomologists across the prairies are on the move with surveying and at field events. Access the complete Weekly Update either as a series of Posts for Week 11 (July 19, 2018) OR a downloadable PDF version. Also review the “Insect of the Week” for Week 11!

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

Subscribe to the Blog by following these three steps!

Weather synopsis

Weather synopsis – This past week (July 9 – 16, 2018), the average temperature (16.7 °C) was almost 2 °C warmer than last week and marginally warmer than long term average values (Fig. 1). Once again, the warmest weekly temperatures occurred across MB. The 30-day (June 16 – July 16, 2018) average temperature (15.8 °C) was just slightly above long term average temperatures.

Weekly and 30-day total precipitation was less than average (Figs. 2 and 3). The wettest region (30-day cumulative precipitation) was across eastern areas in Saskatchewan and southern Manitoba while western Saskatchewan and most of Alberta continue to be dry.

The map below reflects the Highest Temperatures occurring over the past 7 days (July 11-17, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 4).

Figure 4. Highest temperature across the Canadian prairies the past seven days (July 11-17, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jul2018). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

The map below reflects the Lowest Temperatures occurring over the past 7 days (July 11-17, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 5).

Figure 5. Lowest temperature across the Canadian prairies the past seven days (July 11-17, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18Jul2018). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

The growing degree day map (GDD) (Base 10ºC, March 1 – July 15, 2018) is below:

The growing degree day map (GDD) (Base 5ºC, March 1 – July 15, 2018) is below:

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

Predicted grasshopper development

As of July 16, 2018, the model output indicated that the average instar stage was 4.9, with populations being primarily comprised of fifth instar stage (37%) or adults (33%) (Fig. 1).

Development is predicted to be more advanced across the southern prairies; primarily fifth instar stages and adults near Lethbridge AB and Saskatoon SK than in the Peace River region where they are predicted to be mainly fourth and fifth instar stages (Fig. 2).

Figure 3. Clearwinged grasshopper stages including egg, first to fifth instar stages and adult (left to right).

Grasshopper Scouting Steps:

Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
Starting at one end in either the field or the roadside and walk toward the other end of the 50 m making some disturbance with your feet to encourage any grasshoppers to jump.
Grasshoppers that jump/fly through the field of view within a one meter width in front of the observer are counted.
A meter stick can be carried as a visual tool to give perspective for a one meter width. However, after a few stops one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
At the end point the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.

● Compare counts to the following damage levels associated with pest species of grasshoppers:

0-2 per m² – None to very light damage

2-4 per m² – Very light damage

4-8 per m² – Light damage

8-12 per m² – Action threshold in cereals and canola

12-24 per m² – Severe damage

>24 per m² – Very severe damage

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

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

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

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – The warm, moist conditions in Manitoba are predicted to be favourable for emergence of adults (Fig. 1) while dry conditions in Alberta and Saskatchewan should result in reduced emergence (Fig. 2).

In Manitoba and eastern Saskatchewan, populations should be primarily in the early larval stage (80%). Model runs for Saskatoon indicate the midge development, as a result of dryer conditions in June, is slower than predicted emergence at Brandon and Edmonton (Fig. 3).

Monitoring:

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

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

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

Economic Thresholds for Wheat Midge:

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

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

Click here to review the 2018 wheat midge forecast map.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Lygus in canola

Lygus bugs (Lygus spp.) – As of July 16, 2018, the model output indicates that Lygus populations range from first instar stage to adults with most populations being comprised mainly of fifth instar stage and adult stages (Fig. 1).

Warmer temperatures have resulted in more rapid development in southern Manitoba and southeast Saskatchewan. Model runs were conducted for Saskatoon, Lethbridge and Grande Prairie to compare site specific development. The Lygus model output suggests that populations in Lethbridge and Saskatoon should be primarily comprised of fifth instar and adult stages while populations near Grande Prairie are predicted to be comprised of fourth and fifth instar stages with adults beginning to appear (Fig. 2)

Remember – The economic threshold for Lygus in canola is applied at late flower and early pod stages.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Bertha armyworm

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

Monitoring:

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

Scouting tips:

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

Albertans can access the online reporting map (screenshot below retrieved 18Jul2018 for reference):

Saskatchewan growers can check the 2018 bertha armyworm map (screenshot below retrieved 18Jul2018 for reference):

Manitoban growers can find bertha armyworm updates in that province’s Insect and Disease Updates. The July 11th update summarized that, “out of the 99 traps, 93 currently have cumulative counts in the low risk category (less than 300), and six traps are in the uncertain risk category. Most of the highest cumulative counts so far are in the western part of Manitoba. Trap counts in eastern Manitoba and the Interlake have generally been quite low.”

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

Cabbage seedpod weevil

Monitoring:

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

Albertan growers can report and check the online map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 18Jul2018).

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

Cabbage root maggot

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

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

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

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted yellow then orange are approaching sufficient heat accumulation for mosquitoes to emerge while mosquitoes will be flying in areas in red so wear DEET to stay protected!

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (June 30, 2018) on 2018 testing (screenshot retrieved 18Jul2018 provided below for reference only).

Reminder – The 2017 WNV surveillance map for human cases is available here but a screenshot is posted below for reference.

Figure 1. As of surveillance week 49, ending December 9, 2017, the preliminary data indicated 197 human cases of WNV in Canada; twenty-five from Québec, 159 from Ontario, five from Manitoba, seven from Alberta, and one from British Columbia.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of June 28, 2018, 642 birds were examined and zero have tested positive for West Nile virus.

Provincial Insect Pest Reports

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

Manitoba‘s Insect and Disease Updates for 2018 can be accessed here. Issue #7 (posted July 11, 2018) notes monitoring is underway for grasshoppers, armyworms in some cereal fields but no soybean aphids reported yet. Also find a summary of cumulative bertha armyworm counts from pheromone traps for 2018.

Saskatchewan‘s Crop Production News for 2018 is posted with Issue #4 now available. This issue includes a report from the Crop Protection Lab summarizing disease and insect samples submitted this growing season. Notable insects submitted so far include Enchytraeids, barley thrips, and red bugs identified as soft-winged flower beetles (Collops sp.) and white-margined burrower bugs (Sehirus cinctus). Growers can review articles on how to scout for cutworms, how to assess plant stand densities in flax or canola, and for flea beetles, pea leaf weevils. Also note the following diamondback moth pheromone trap interception counts from across the regions (updated June 27, 2018):

Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Scott Meers. The most recent Call of the Land (posted July 12, 2018) identified that SOME bertha armyworm pheromone traps over a wide geographic range have started to intercept higher numbers of moths. This means in-field scouting will be critical in 10-14 days (as larvae move up from leaves to feed among canola pods). Processing of canola survey samples has begun; initial samples suggest lower diamondback moth and Lygus bug numbers so far compared to 2017 but higher numbers of small parasitoid wasps associated with diamondback moths, and a pocket of grasshoppers (clearwinged) near Carmangay AB.

Crop reports

Crop reports are produced by:

Manitoba Agriculture (July 11, 2018)
Saskatchewan Agriculture (July 3-9, 2018)
Alberta Agriculture and Forestry Crop Report (July 10, 2018)

The following crop reports are also available:

The United States Department of Agriculture (USDA) produces a Crop Progress Report (view the July 16, 2018 edition).
The USDA’s Weekly Weather and Crop Bulletin (view the July 10, 2018 edition).

The following is a list of 2018 Posts – click to review:

Abundant parasitoids in canola – Week 10

Alfalfa weevil – Week 6

Cabbage seedpod weevil – Week 8
Cereal aphid manager (CAM) – Week 2
Cereal leaf beetle – Week 5
Cereal leaf beetle larvae request – Week 8
Crop protection guides – Week 2
Crop reports – Week 8
Cutworms – Week 4

Diamondback moth – Week 7
Download the field guide – Week 10

Field heroes – Week 8
Flea beetles – Week 4

Monarch migration – Week 8

Pea leaf weevil – Week 8
PMRA Pesticide Label Mobile App – Week 4

Scouting charts (canola and flax) – Week 3

Ticks and Lyme Disease – Week 4

Weather radar – Week 3
Wind trajectories – Week 6
Wireworm distribution maps – Week 6
White grubs in fields – Week 8

Insect of the Week – Cereal leaf beetle

This week’s Insect of the Week is the cereal leaf beetle. Wheat is their preferred host, but they also feed on oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Adults and larvae feed on the leaf tissue of host plants. Yield quality and quantity is decreased if the flag leaf is stripped. It is also interesting to note that larvae carry all of their own fecal waste with them as protection from predators.

For more information on the cereal leaf beetle, see our Insect of the Week page.

Cereal leaf beetle larva (cc-by 2.0 Christophe Quintin)

Cereal leaf beetle damage (cc-by-nc-sa 2.0 CIMMYT)

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

Weekly Update – Greetings!

Greetings!

Please access the Weekly Update for July 13, 2017 (Week 11), as either a series of Posts for Week 11 (Jul 13, 2017) or a downloadable PDF.

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

Subscribe to the Blog by following these three easy steps!

Weekly Update – Weather Synopsis

Weather synopsis – Although temperatures were warmer than last week, both the seven- and 30-day average temperatures were similar to long term averages.

Compared to 30-day average temperatures, Alberta was above normal, whereas Saskatchewan and Manitoba were slightly below normal.

Central and northern regions of all three provinces reported increased rainfall amounts. Total 30-day rainfall accumulations indicate that conditions are normal to dryer than normal for most of the prairies.

Growing season (April 1 – July 10, 2017) percent of average precipitation is average for most of Alberta and below average for most of Saskatchewan and Manitoba.

The lowest temperatures across the prairies over the past seven days (July 5-11, 2017) are mapped below.

In contrast, the highest temperatures recorded over the past seven days (July 5-11, 2017) are presented below.

The updated growing degree day map (GDD) (Base 5ºC, March 1 – July 9, 2017) is below:

While the growing degree day map (GDD) (Base 10ºC, March 1 – July 9, 2017) is below:

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

Weekly Update – Predicted Bertha Armyworm Development

Bertha armyworm (Lepidoptera: Mamestra configurata) – Bertha armyworm should be in the adult stage across the prairies this week. The map illustrates predicted appearance of adults (percent of the population) across the southern prairies.

For those monitoring BAW pheromone traps, compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture:

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

Weekly Update – Wheat midge

Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge!

Model output indicates that wheat midge adult emergence has begun across the prairies. Cooler, dryer conditions in 2017 have resulted in lower emergence than the same time last year. Elliott et al. (2009) reported that adult emergence was delayed by inadequate rainfall amounts (May and June). The model was parameterized to take rainfall into account. Model output indicates that midge emergence across most of SK has been limited by inadequate rainfall during June.

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

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

Economic Thresholds for Wheat Midge:

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

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

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

Cabbage seedpod weevil

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

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

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

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

Also watch provincial reports for updates on surveying underway now. Alberta Agriculture & Forestry has posted a live CSPW map and online reporting tool for growers. A screenshot (retrieved 13Jul2017) is included below.

Weekly Update – Predicted Grasshopper Development

Grasshopper Simulation Model Output – Compared to last week, grasshopper development has progressed by approximately one instar (Fig. 1). Based on model output, grasshopper development is slightly ahead of long term averages (Fig. 2).

Figure 1. Predicted Melanoplus sanguinipes development across
the Canadian prairies (July 4, 2017).

Figure 2. Predicted Melanoplus sanguinipes development prepared
using Long Term Normal (LTN) data.

Across the prairies, grasshoppers should be predominantly in the third and fourth instar stages with more rapid development across southern Alberta (Fig. 3 and 4). This is the first week where the model has predicted appearance of adults. The greatest development was predicted to be across southern regions in all three provinces, particularly southern Alberta. Current developmental rates are well behind last year.

Figure 3. Predicted percent of Melanoplus sanguinipes at fourth instar
development stage (July 10, 2017).

Figure 4. Predicted percent of Melanoplus sanguinipes at fifth instar
development stage (July 10, 2017).

Grasshopper Scouting Steps:

● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.

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

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

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

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

0-2 per m² – None to very light damage

2-4 per m² – Very light damage

4-8 per m² – Light damage

8-12 per m² – Action threshold in cereals and canola

12-24 per m² – Severe damage

>24 per m² – Very severe damage

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

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

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

Weekly Update – Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Across the prairies, the model indicates that 95% of the population should be in the pupal stage. This week adults should be appearing at most locations. Output indicates that adult emergence is well underway at many southern locations (Brooks, Estevan) , while adult emergence at many central locations (Saskatoon) has begun over the last five days.

In terms of degree-day heat units, the map below reflects the predicted development of alfalfa weevil across the Canadian prairies.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon) and additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). That guide is available in both a free English-enhanced or French-enhanced version.

Provincial Insect Pest Reports

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

● Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and read Issue #7 (posted July 5, 2017) noting the presence of thistle caterpillar (Vanessa cardui) and larval populations of diamondback moth reaching economically significant levels in the southwest of that province. Cumulative counts of bertha armyworm generated from weekly counts in Manitoba can be accessed here.

● Saskatchewan’s Crop Production News – 2017 – Issue #3 includes the insect update prepared by Scott Hartley and Danielle Stephens. That report includes an update on the red bugs in canola (also described in Week 8) and how to submit samples to that provincial lab, very low numbers of diamondback moth in pheromone traps across that province, initial low numbers of bertha armyworm in pheromone traps, and cabbage seedpod weevil.

● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (July 5, 2017) provided by Scott Meers. That report notes migration of painted lady butterflies which feed on thistles but also soybeans, sunflowers, and dry beans. Soybean and sunflower producers will need to carefully follow the development of a second generation of V. cardui as it could affect those crops by mid-July. Additionally, diamondback moth are more numerous than in previous seasons so careful scouting will be required during early pod stages in canola as that stage is the most susceptible to yield losses.

Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (July 10, 2017)
• Saskatchewan Agriculture Crop Report (June 27-July 3, 2017)

• Alberta Agriculture and Forestry Crop Report (July 4, 2017)

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 9, 2017, areas highlighted in yellow on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 1, 2017).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of July 6, 2017, 729 birds were examined and six have tested positive for West Nile virus in Ontario.

Weekly Update – Previous Posts

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

Brood X Cicadas

Cabbage seedpod weevil (Week 8)
Canola scouting chart
Cereal leaf beetle
Crickets with your popcorn
Crop protection guides
Cutworms

Diamondback moth

Flax scouting chart
Flea beetles

Iceberg reports

Lily leaf beetle

Monarch migration (Week 10)

Painted lady butterflies (Week 9)
Pea leaf weevil
PMRA Pesticide Label Mobile App

Nysius niger (Week 8)

Ticks and Lyme disease

Weather radar
White grubs in fields (Week 9)

Wind trajectories