Category: Week 9

2023 WEEK 9 (Released July 7, 2023)

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

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

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

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

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

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

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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

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

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

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

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

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

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

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

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

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

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

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

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

Predicted Wheat Midge Development

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

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

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

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

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

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

Grasshoppers

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

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

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

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

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

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

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

Diamondback Moth

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

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

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

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

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

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

Bertha Armyworm

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

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

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

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

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

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.

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

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

TETRASTICHUS JULIS

The cereal leaf beetle larvae you see in wheat fields may be full of this week’s Insect of the Week, Tetrastichus julis. This parasitoid wasp is an important natural enemy of cereal leaf beetle. Adult T. julis lay their eggs inside cereal leaf beetle larvae, leaving about five eggs to consume the beetle from the inside out. Adult parasitoids feed on nectar and aphid honeydew.  

A Tetrastichus julis female in the process of parasitizing a cereal leaf beetle larva, sitting on a wheat leaf with cereal leaf beetle feeding damage. Picture credit: Emily Lemke and Karen Shamash, AAFC-Lethbridge.

Mature T. julis larvae overwinter in infested cereal leaf beetle cocoons and emerge in spring to lay more eggs in cereal leaf beetle larvae. Where T. julis has become established, it can reduce cereal leaf beetle populations by 40 – 90%, preventing yield loss without using pesticides. See also the factsheet, Biological Control at its Best, Using the T. julis Wasp to Control the Cereal Leaf Beetle (en français).  

AAFC researchers have assisted T. julis in establishing and spreading to help control cereal leaf beetle populations in the Canadian prairies! Reducing the use of insecticides (if possible), leaving refuge areas, and reducing tillage can all help protect populations of this valuable parasitoid in areas where they are already established in a field.  

Biological information related to T. julis and cereal leaf beetle in field crops is available online. For more information, visit the cereal leaf beetle page from the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien).  

Released July 8, 2022

This week includes…..

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

Wishing everyone good weather!

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

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

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

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

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

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

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

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

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

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

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 nymphs and economically important species are present. Review lifecycle and damage information for this pest to support in-field scouting.

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

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

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

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

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

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

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

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

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

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

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

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

Figure 5. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long.  Photo: AAFC-Beav-S. Dufton.

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

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

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

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

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.

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

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 3, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of July 3, based on climate normal data.

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

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

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

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

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Figure 3. Diamondback moth pupa within silken cocoon.
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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!

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 6, 2022 issue here. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more!
• Pea aphids, barley thrips and blister beetles in MB were new additions to the July 6 issue.
• Diamondback moth pheromone trap monitoring update for MB – Traps will come down at the end of this week. Review the detailed summary of cumulative trap counts from 52 sites deployed across the province (as of June 28, 2022).
• Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of June 28, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.

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

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

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 5, 2022 report).
• Saskatchewan Agriculture (or access a PDF copy of the June 28-July 4, 2022 report).
• Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the June 27, 2022 report).

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

Review INSECT OF THE WEEK for 2022 scouting help!

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

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

2022
2021
2020
2019 – Doppelgangers series
2018
2017

Previous posts

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

BE ON THE LOOKOUT FOR SPOTTED LANTERNFLY!

The Canadian Food Inspection Agency (CFIA) and entomologists are on the lookout for Spotted Lanternfly (Lycorma delicatula), a new invasive species in the United States that could move north into Canada. This very distinctive bug has tan-coloured forewings with black spots and can be quite large as adults (about 2.5 cm long by 1 cm wide). The underwing of the adults has bright red or pink highlights.

Spotted Lanternfly. Photo credit: Dr. Bryan Brunet, AAFC Ottawa

Spotted Lanternfly is native to Asia but was detected in Pennsylvania, United States of America, in 2014. Since then, it has been found in many states in the northeast of the United States, including Connecticut, Delaware, Maryland, New Jersey, New York, Ohio, Virginia, and West Virginia. It can disperse short distances as an adult or nymph by walking or flying, but eggs can be moved long distances by humans, especially if they are laid on vehicles, packing materials, or other items that are moved by humans. It is very important to inspect vehicles for egg masses if you are traveling back to Canada from areas where spotted lanternfly is established.

Spotted Lanternfly Egg Mass. Photo credit: Holly Raguza, Pennsylvania Department of Agriculture, Bugwood.org

Adults and nymphs of the spotted lanternfly feed on their host plants by sucking sap from leaves and stems. Their preferred host plant is tree-of-heaven, a plant introduced to North America. However, spotted lanternfly also feeds on grapes, apples, plums, cherries, peaches, nectarines, apricots, oak, walnut, and poplar trees. Thus, this insect could be a significant threat to the orchard and forestry industries in Canada.

Spotted lanternfly is on the CFIA regulated pest list, thus, it is our responsibility to report sightings. Early detection of this invasive insect is the best way to eradicate it and prevent it from becoming established in Canada. If you think you have seen or found a spotted lanternfly, report it to the CFIA Canadian Food Inspection Agency / Agence canadienne d’inspection des aliments. Refer to this PDF copy of an expanded description of this invasive species.

You can also upload sightings to iNaturalist.ca and tag @cfia-acia in the comment section of your observation to reach the CFIA experts.

References:

This article is an edited version of Dave Holden’s earlier article on the same subject. The article can be seen at this link: Spotted lanternfly (Lycorma delicatula) – Fact sheet – Canadian Food Inspection Agency (canada.ca) , or on the CFIA facebook page: Have you seen the… – Canadian Food Inspection Agency | Facebook

Weekly Update

Week 9 and the unusually hot weather stretching over the Canadian prairies is making it difficult for plants to tolerate insect pest pressure! Scouting is critical under these conditions! Be sure to catch the Insect of the Week – it’s lygus bugs! This week find updates to predictive model outputs for wheat midge, grasshoppers, bertha armyworm, and diamondback moth plus a lot more to help prepare for in-field scouting!

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 (June 21-27, 2021), weekly temperatures were warmer than normal and rainfall amounts were generally less than 5 mm. The warmest temperatures were observed across Alberta (Fig. 1).

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of June 21- 27, 2021.

Across the prairies, the average 30-day (May 29 – June 27) temperature was almost 3 °C warmer than climate normal values. The warmest temperatures continue to be observed across southern Manitoba and southeastern Saskatchewan (Fig. 2). The 2021 growing season (April 1 – June 27, 2021) has been characterized by near-normal temperatures. The warmest temperatures have occurred across southern and central regions of the three prairie provinces (Fig. 3).

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of May 29 – June 27, 2021.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – June 27, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-Jun 28, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (June 22-28, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -32 to >7 °C while the highest temperatures observed ranged from <22 to >36 °C. Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: This week, the highest rainfall amounts were reported across central Alberta, southeastern Saskatchewan and southwestern Manitoba. Minimal rainfall was reported across most of central Alberta and northwestern Saskatchewan (Fig. 4).

Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 21 -27, 2021.

Rainfall amounts for the period of May 29-June 27 (30-day accumulation) were near normal. Rainfall amounts have been below normal across Alberta and large areas of Saskatchewan. Eastern Saskatchewan and western Manitoba have continued to receive the greatest amount of rainfall (Fig. 4).

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 29 – June 27, 2021

Average growing season (April 1 – June 27) precipitation was 103 % of normal with greatest precipitation occurring across eastern Saskatchewan, including Regina. Below normal rainfall has been reported across western Saskatchewan, southern Alberta and the Peace River region (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-June 27, 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.

Weekly Wind Trajectory Report for June 28

Access background information for how and why wind trajectories are monitored in this post.

1. REVERSE TRAJECTORIES (RT)
Since June 16, 2021, a decreasing number of reverse trajectories have moved north from the Pacific Northwest (Idaho, Oregon and Washington), Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Though these US regions can be a source of diamondback moths (DBM), the ECCC models predict air movement, not actual occurrence of diamondback moths. Fields (and DBM traps) should be monitored for DBM adults and larvae.

Figure 1. The average number (based on a 5 day running average) of reverse trajectories that have crossed the prairies for the period of May 28 – June 28, 2021.

a. Pacific Northwest (Idaho, Oregon, Washington) – This week (June 22-28, 2021) there were 3 trajectories that crossed Alberta, Manitoba and Saskatchewan that originated in the Pacific Northwest.

b. Mexico and southwest USA (Texas, California) – This week (June 22-28, 2021) there were 0 trajectories that originated in Mexico or the southwest USA that crossed the prairies.

c. Oklahoma and Texas – This week (June 22-28, 2021) there were 0 trajectories originating in Oklahoma or Texas that passed over the prairies.

d. Kansas and Nebraska – This week (June 22-28, 2021) there were 0 trajectories that originated in Kansas or Nebraska that passed over the prairies.

2. FORWARD TRAJECTORIES (FT)
a. Since June 9, 2021 there has been a steady decrease in the number of forward trajectories that are predicted to cross the prairies (Fig. 2). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line).

Figure 2. The average number (based on a 5 day running average) of forward trajectories that were predicted to cross the prairies for the period of May 28-June 28, 2021.

Predicted wheat midge development

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. 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. The Olfert et al. (2020) model indicated that dry conditions may result in:
a. Delayed adult emergence and oviposition
b. Reduced numbers of adults and eggs

This week, wheat midge model simulations indicate that the majority of the larval population has moved to the soil surface (Figure 1). Dry conditions in the Peace River region have resulted in delayed development of larval cocoon populations. Pupae should now be occurring across most of the prairies (Figure 2). First appearance of adults is predicted across Manitoba and most of Saskatchewan (Figure 3).

Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) larval population that has moved to the soil surface across the Canadian prairies as of June 27, 2021.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the pupal stage, across the Canadian prairies as of June 27, 2021.
Figure 3. Percent of wheat midge (Sitodiplosis mosellana) population that is in the adult stage, across the Canadian prairies as of June 27, 2021.

The model was projected to July 13 to determine potential development at Regina (Fig. 4), Lacombe (Fig. 5), and Grande Prairie (Fig. 6) over the next two weeks.

Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Regina, Saskatchewan as of June 27, 2021 (projected to July 13, 2021).
Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Lacombe, Alberta as of June 27, 2021 (projected to July 13, 2021).
Figure 6. Predicted development of wheat midge (Sitodiplosis mosellana) and wheat development near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).

Compared to Lacombe and Grande Prairie, Regina has been warmer and wetter for the period of May 1 – June 27, 2021, resulting in advanced development of larvae and pupae (Fig. 4). In the Regina and Lacombe areas, initial oviposition is predicted to occur this week (Figs. 4 and 5). Emergence patterns for southern Manitoba are predicted to be similar to Regina. Cooler and dryer conditions in the Peace River region are expected to have impacted the movement of larvae to the soil surface, resulting in reduced adult emergence and later appearance of adults. Oviposition in the southern Peace River region is predicted to occur during the first week of July (Figure 6). Wheat crops near all three locations may be susceptible for the next 14-17 days.

If not already underway, scouting for wheat midge adults should begin 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).

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

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

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

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

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

Predicted grasshopper development

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 27, 2021. The development of grasshopper nymphs, based on average instar, should be most advanced across southern Manitoba and southeastern Saskatchewan (Figure 1). Grasshopper populations south of Winnipeg are predicted to be mostly in the 4th and 5th instar stages. Across the prairies, nymph development, as of June 27, 2021 is well ahead of long term average values (Figure 2).

Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, 2021.
Figure 2. Long term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, based on climate normals data.

The model was projected to July 13 to determine potential development at Saskatoon and Grande Prairie over the next two weeks. Results suggest that by July 13, Saskatoon populations will primarily be in the fourth and fifth instars with first appearance of adults (Figure 3). Development near Grande Prairie is predicted to be slower, with populations being mostly in the third and fourth instars (Figure 4). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.

Figure 3. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan as of June 27, 2021 (projected to July 13, 2021).
Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).

Grasshopper Scouting Steps:
● Review grasshopper diversity and scouting information including photos of both 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 bertha armyworm development

Model simulations to June 27, 2021 indicate that development of bertha armyworm (BAW) (Mamestra configurata) populations is transitioning to egg and larval stages. Model simulations indicate that BAW oviposition is occurring across most of the prairies with occurrence of larvae across southern regions of all three provinces (Figs. 1 and 2).

Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the egg stage (% of population) across the Canadian prairies as of June 27, 2021.
Figure 2. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the larval stage (% of population) across the Canadian prairies as of June 27, 2021.

BAW populations in southern Manitoba are predicted to be predominantly in the larval stage by early July whereas BAW populations near Grande Prairie will be in the adult and egg stages. Model projections to July 13 predict that development near Brandon will be more advanced than development near Lacombe (Figs. 3 and 4). Over the next few days adult populations should be declining in southern Manitoba. In central Alberta adults should continue to lay eggs over the next 10 days. Above average temperatures will result in rapid development of larval populations.

Figure 3. Predicted development of bertha armyworm (Mamestra configurata) populations near Brandon, Manitoba as of June 27, 2021 (projected to July 13, 2021).
Figure 4. Predicted development of bertha armyworm (Mamestra configurata) populations near Lacombe, Alberta as of June 27, 2021 (projected to July 13, 2021).

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.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 6) to help identify the various stages.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

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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.

Cabbage seedpod weevil monitoring

Monitoring is already underway for cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) in southern areas of the prairies – it was the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

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 live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

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 refer to the cabbage seedpod weevil pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

Lygus bug monitoring

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally. The Insect of the Week featured lygus bugs for Wk 09 – be sure to take a look!

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

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

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

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

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

Figure 3. Sequential sampling for lygus bugs at late flowering stage in canola.

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

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

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

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

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

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 June 27, 2021, indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies and that the start of the second generation is occurring in southern Manitoba and southeastern Saskatchewan (Figure 1).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) that are expected to have occurred across the Canadian prairies as of June 27, 2021.

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).

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Figure 3. Diamondback moth pupa within silken cocoon.
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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” (accessible in either English-enhanced or French-enhanced versions).

Aphids in field crops

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

• Cereal aphids (Insect of the Week; 2017 Wk09)

• Aphids in canola (Insect of the Week; 2016 Wk13)

• Lygus bug nymphs vs. aphids (Insect of the Week; 2019 Wk16)

• Cereal aphid manager APP (Weekly Update; 2021 Wk07)

• Ladybird beetles and mummies (Weekly Update; 2020 Wk15)

• Ladybird larva vs. lacewing larva (Insect of the Week; 2019 Wk18)

• Aphidius wasp (Insect of the Week; 2015 Wk15)

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

• Hoverflies vs. bees vs. yellow jacket wasps (Insect of the Week; 2019 Wk19)

West nile virus risk

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 1, 2021). The screenshot below (retrieved 01Jul2021) serves as a reference.

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 (retried 01Jul2021).

The following is offered to help 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 Figure 1 but the current unusual heat across the prairies will accelerate mosquito development! As of June 27, 2021 (Fig. 1), C. tarsalis development is most advanced in Manitoba and within small pockets in southeastern Alberta. Stay tuned because this map will change quickly to yellow and more imminently orange then red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Prepare yourself by having DEET on hand for the weeks to come!

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of June 27, 2021).

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.

Monarch migration

Track the migration of the Monarch butterflies as they move north by checking the 2021 Monarch Migration Map!  A screenshot of the map has been placed below as an example (retrieved 01Jul2021) but follow the hyperlink to check the interactive map.  They’ve reached more sites in Manitoba and Saskatchewan compared to last 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. 

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 June 30, 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 very low so far.
• 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 have begun to roll out for 2021 and are accessible now! Access Issue #1 online which includes a crop protection laboratory update including how to submit samples, information on curculios on fruit crops, and information for scouting flea beetles and assessing damage. 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 will be available here shortly.
• Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <65 moths have been intercepted (2021Jun28 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
• Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.
• Cabbage seedpod weevil sweep-net monitoring update for AB – In-field counts can be entered here to populate the Live Map.
• Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map.
• 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 01Jl2021). 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 June 29 2021 report).
• Saskatchewan Agriculture (or access a PDF copy of the June 22-28, 2021 report).
• Alberta Agriculture and Forestry (or access a PDF copy of the June 22, 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 June 28, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the Jun 29, 2021 edition).

Previous posts

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
• 2020-2021 Risk and forecast maps
• Alfalfa weevil – predicted development (Wk07)
• 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)
• LGrasshopper diversity and scouting photos (Wk08)
• Ladybird beetles (Wk03)
• 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)
• Wireworms (Wk02)

LYGUS BUGS: SEVERAL SPECIES CAUSING PROBLEMS ON THE PRAIRIES

Tarnished plant bug (Lygus lineolaris).
Photo: Winston Beck, cc-by-nc 3.0

On the Canadian prairies, there are several native lygus bug species that cause crop damage including Lygus borealis, L. keltoni, pale legume bug (L. elisus), tarnished plant bug (L. lineolaris) and western tarnished plant bug (L. hesperus). The species vary by preferred host plants, region, and seasonally. These insects feed on both cultivated and wild plants such as canola, alfalfa, soybeans, sunflowers, other crop plants and weeds.

Adult and nymph lygus bugs have mouthparts that allow them to pierce and suck liquids out of their plant hosts. Their desired meal usually includes new growth and reproductive parts such as buds, flowers and young seeds. Having punctured the plant, lygus bugs will inject digestive enzymes and suck out the plant juices. Crop damage includes buds and flowers falling off, incomplete seed pod maturation, misshapen fruit and seeds that collapse and shrink.

Adult lygus bugs are 6 millimetres (1/4 inch) long and vary in colour, ranging between pale green to reddish, brown to black, and uniform to mottled. A distinct triangular or V-shaped marking on the upper centre of their backs and wingtips is also present and can be used to distinguish them from other Hemiptera. Mature nymphs share similar colouration to adults, but with five black dots on their thorax and abdomen.

Biological and monitoring information related to lygus bugs in field crops is posted by the provinces of Manitoba and Alberta. The Prairie Pest Monitoring Network’s monitoring protocol is also available online. For more information, visit the lygus bug 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).

Tarnished plant bug nymph (Lygus lineolaris).
Photo: Scott Bauer cc-by 3.0

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.

The entire list of 2020 Wind Trajectory Reports is available here.

→ Read the WEEKLY Wind Trajectory Report for Wk10 (released June 22, 2020).

Weekly Update

Time to transition to more insects in field crops – add a few more to your scouting list!

Access information to support your in-field insect monitoring efforts in the complete Weekly Update either as a series of Posts for Week 9 OR a downloadable PDF.

Stay Safe!

Questions or problems accessing the contents of this Weekly Update? Please email Meghan.Vankosky@agr.gc.ca or Jennifer.Otani@agr.gc.ca. Past “Weekly Updates” can be accessed on our Weekly Update Blog Page.

Flax Pests / Feature Entomologist: Boyd Mori

This week’s Insect of the Week feature crop is flax, a crop that thrives in cooler environments. Our feature entomologist this week is Boyd Mori.

Flax Field
Ian Patterson cc by sa 2.0

Flax is a versatile crop grown across the Canadian Prairies, and is used in cooking, animal nutrition, and industrial production. Since 1994 Canada has been the largest flax producer and exporter in the world (Flax Council of Canada, 2020). In 2019 flax was grown on 375,700 hectares (928,500 acres) across the Prairies, producing 483,000 metric tonnes (532,400 US tons). Just under 80% of that total was grown in Saskatchewan.

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

Flax Pests:
  • Army cutworm
  • Aster leafhopper
  • Beet webworm
  • Bertha armyworm
  • Clover cutworm
  • Darksided cutworm
  • Dingy cutworm
  • Flax bollworm
  • Grasshoppers
  • Pale western cutworm
  • Potato aphid
  • Redbacked cutworm
Redbacked cutworm, larval stage – AAFC

Entomologist of the Week: Boyd Mori

Name: Boyd Mori
Affiliation: Department of Agricultural, Food and Nutritional Sciences, University of Alberta
Contact Information: bmori@ualberta.ca twitter: @BoydMori

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

I actively participate in the PPMN. In my position at the U of A, I help monitor bertha armyworm and wheat midge at sites in North-Central Alberta.Next year, my research group will have a project that will try to verify the source of diamondback moths captured in pheromone traps. We will also be re-evaluating the wheat midge pheromone monitoring system with Dr. Maya Evenden (U of A). In the past, my former research group (AAFC-Saskatoon) along with Dr. Meghan Vankosky ran the survey for the canola flower midge in SK and MB and I occasionally helped with the pea leaf weevil survey in SK. I have also been involved with verifying some of the monitoring protocols used by all members of the PPMN.

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

Probably not a surprise to most, but I am going to have to say the canola flower midge, an insect I helped to recently discover and describe. The canola flower midge was previously mistaken for the swede midge, a significant pest of canola and other cruciferous vegetable crops in Ontario. Luckily, the canola flower midge is not as damaging as the swede midge (at least so far), and we are still trying to determine its overall pest status. What makes it really interesting is that we don’t know where the canola flower midge came from. We don’t know if it is a native or invasive species, although we tend to think it is native to the Prairies. We hypothesize it may have switched hosts to canola as acreage increased over the last 40 years, but we don’t know what is its original host plant was. There is a lot of interesting research to come on this species!

What is your favourite beneficial insect? 

I am partial to hover flies (Syrphids). The adult flies are often mistaken for bees due to their colouration, but they are harmless and actually help to pollinate many different plants. The larvae are active predators within crops, feeding on a variety of soft-bodied insects, especially aphids.

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

I am currently working on a project with Dr. Hector Carcamo (AAFC-Lethbridge) and Jennifer Otani (AAFC-Beaverlodge) investigating insecticide resistance in alfalfa weevil in southern Alberta. We have identified a few populations with resistance to synthetic pyrethroids and we now have a graduate student, Michelle Reid, whose project will map resistance and also the presence of parasitoids throughout southern Alberta. We don’t see much insecticide resistance on the Prairies compared to other regions of the world, so this is a unique project.

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

I enjoy giving presentations, speaking with farmers and actively participating in extension events (e.g., CanolaPalooza, WheatStalk, Crop walks, etc.) and AGMs each year. Results of our work is published by industry magazines, blogs and newsletters. You can also reach me directly via email or Twitter (@BoydMori). Hopefully my research group will have a functional website soon too.

Weekly Update

Hello – again!

We had an email glitch so the Weekly Update was released over June 6-7, 2019.  

Please access the complete Weekly Update either as a series of Posts for Week 09 (June 6, 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

Weather synopsis – The prairie wide average temperature for May was 2 °C cooler than average (Fig. 1) while rainfall was approximately 50% of average (Fig. 2). The coolest conditions have occurred across southern MB and SK. 

Figure 1. Average temperature (°C) across the Canadian prairies for the month of May (May 1-31, 2019).
Figure 2. Mean temperature differences from Normal across the Canadian prairies from May 1-31, 2019.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

This week (May 29 – June 4, 2019) weather conditions were warm and dry. Across the prairies, temperatures were 3-4 °C warmer than last week and 1-2 °C warmer than average (Fig. 3). The warmest temperatures were observed across a region that extended from Medicine Hat AB to Saskatoon SK and southwestern MB.  

Figure 3. Average temperature (°C) across the Canadian prairies the past seven days (May 29-June 4, 2019).

Average 30-day temperatures were warmest in AB and coolest in eastern SK and MB (Fig. 4). Northern locations within the Peace River region were warmer than average. 

Figure 4. Average temperature (°C) across the Canadian prairies the past 30 days (May 5-June 4, 2019).

Seven day cumulative rainfall indicated that minimal rain was observed across most of the prairies (Fig. 5). Most locations reported less than 5 mm.  Higher rainfall amounts were reported in southwestern AB, southeastern SK and an area near Dauphin MB. 

Figure 5. Cumulative precipitation observed the past seven days across the Canadian prairies (May 29-June 4, 2019).

Across the prairies, rainfall amounts for the past 30 days (May 5 – June 4, 2019) were approximately 48 % of normal (Fig. 7 and 8). Most of the prairies reported rainfall amounts less than 40 % of normal. 

Figure 6. Cumulative precipitation observed the past 30 days across the Canadian prairies (May 5-June 4, 2019).

Growing season rainfall (April 1 – June 4) amounts have been well below average for most of the prairies, particularly in west central SK and eastern regions of AB (Fig. 7). Almost all of the prairies has had growing season rainfall that is 85 percent, or less, than average. 

Figure 7. Cumulative precipitation observed for the growing season across the Canadian prairies (April 1-June 4, 2019).
Figure 8. Percent of Average precipitation across the Canadian prairies for the growing season (April 1-June 5, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Soil moisture values are low across most of the prairies (Fig. 9). 

Figure 9. Modeled soil moisture (%) across the Canadian prairies (up to June 4, 2019).

The growing degree day map (GDD) (Base 5 ºC, April 1-June 3, 2019) is below (Fig. 10):

Figure 10. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-June 3, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  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 3, 2019) is below (Fig. 11):

Figure 11. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-June 3, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  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 6 to at least -5 °C in the map below (Fig. 12).

Figure 12. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (May 30-June 5, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  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 14 to at least 32 °C in the map below (Fig. 14).

Figure 14. Highest temperatures (°C) observed across the Canadian prairies the past seven days (May 30-June 5, 2019).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (06Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

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

Predicted bertha armyworm development

Bertha armyworm (Lepidoptera: Mamestra configurata) – Based on BAW model runs, pupal development is nearing 80% in some areas of southern and central AB and SK (Fig. 1). BAW adults may begin to emerge within the next 10 days (Table 1).It is advisable to place pheromone traps in fields when pupal development is 80% to capture the full extent of adult flight activity. Based on this value, traps should be put out in SK and AB fields this week.

Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development acrossthe Canadian prairies as of June 3, 2019. 
Table 1. Predicted emergence date of bertha armyworm moths at select locations across the Canadian prairies in 2019.

Recent warm conditions have advanced bertha armyworm (BAW) pupal development. Compared to last week, development is 2-6 days faster and development is 2 days ahead of normal (based on climate normals).  Model outputs were run for bertha armyworm for Saskatoon SK (Fig. 2), Lethbridge AB (Fig. 3), and Edmonton AB (Fig. 4).

Figure 2. Predicted development of bertha armyworm populations near Saskatoon SK as of June 3, 2019. 
Figure 3. Predicted development of bertha armyworm populations near Lethbridge AB as of June 3, 2019. 
Figure 4. Predicted development of bertha armyworm populations near Edmonton AB as of June 3, 2019. 

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” as an English-enhanced or French-enhanced version.

Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) – The cereal leaf beetle model indicates hatch has begun (Fig. 1).  Models were projected to June 21, 2019 and run for Lethbridge AB (Fig. 2), Grande Prairie AB (Fig. 3), and Brandon MB (Fig. 4). 

Figure 1.  Percent of populations of cereal leaf beetle (Oulema melanopus) in the larval stage as of June 3, 2019, across the Canadian prairies. 
Figure 2. Predicted status of cereal leaf beetle populations near Lethbridge AB projected to June 21, 2019, generated using long term average temperatures.
Figure 3. Predicted status of cereal leaf beetle populations near Grande Prairie AB projected to June 21, 2019, generated using long term average temperatures.
Figure 4. Predicted status of cereal leaf beetle populations near Brandon MB projected to June 21, 2019, generated using long term average temperatures.

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 5). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  

Figure 5. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 6).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 6.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.

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).  

This week,  the grasshopper hatch is well underway across the prairies (Fig. 1 and 2) with most locations having approximately 15% hatch and some areas having 35% hatch. 

Figure 1. Predicted percent of grasshopper (Melanoplus sanguinipes) population at first instar stage across the Canadian prairies (as of June 4, 2019). 
Figure 2. Predicted percent of grasshopper (Melanoplus sanguinipes) population at second instar stage across the Canadian prairies (as of June 4, 2019). 

Model runs for Saskatoon SK (Fig. 3), Lethbridge AB (Fig. 4), and Grande Prairie AB (Fig. 5) were projected to June 30, 2019. Results for Lethbridge and Saskatoon indicated that populations are primarily in the first and second instars. A survey of roadsides south of Saskatoon indicated that melanoplines were primarily first an second instars. 

Figure 3. Predicted status of Melanoplus sanguinipes populations near Lethbridge  AB projected to June 30, 2019.  
Figure 4.  Predicted status of Melanoplus sanguinipes populations near Saskatoon SK projected to June 30, 2019.  
Figure 5.  Predicted status of Melanoplus sanguinipes populations near Grande Prairie AB projected to June 30, 2019.  

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the 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.

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. 

Weather conditions continue to be favourable for development of alfalfa weevil, if alfalfa weevil are present in your area. First instar development is nearing completion (Fig. 1) and the more individuals in the population should be in the second instar stage (Fig. 2). 

Figure 1. Percent of populations of alfalfa weevil (Hypera postica)  in the first instar stage across the Canadian prairies as of June 3, 2019. 
Figure 2. Percent of populations of alfalfa weevil (Hypera postica)  in the second instar stage across the Canadian prairies as of June 3, 2019.

Model runs for Brooks AB (Fig. 3)  and Swift Current SK (Fig. 4) were projected to June 21, 2019.  In alfalfa fields near Brooks AB larvae should start to reach the third instar stage late this week. At Swift Current SK third instar larvae will begin to appear approximately 5-7 days later.

Figure 3. Predicted status of alfalfa weevil populations near Brooks AB projected to June 21, 2019, using long term average temperatures.
Figure 4. Predicted status of alfalfa weevil populations near Swift Current SK projected to June 21, 2019, using long term average temperatures.

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.

Pea leaf weevil

Pea Leaf Weevil (Sitona lineatus) – Model runs for Red Deer and Saskatoon were projected to June 30, 2019. Results indicated that oviposition is well underway at both locations.  

Figure 1. Predicted status of pea leaf weevil populations near Red Deer AB projected to June 30, 2019, using long term average temperatures.
Figure 2.  Predicted status of pea leaf weevil populations near Saskatoon SK projected to June 30, 2019, using long term average temperatures.

This week, pea leaf weevil and its doppelgangers were featured as part of the INSECT OF THE WEEK.  

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.

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

Also refer to the pea leaf weevil page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.  A review of this insect was published in 2011 in Prairie Soils and Crops by Carcamo and Vankosky.

Cereal Aphid Manager (CAM)

Congratulations!  The Cereal Aphid Management (CAM) Mobile Application Team was recognized with an Agriculture and Agri-Food Canada Gold Harvest Award this month!  Team members included Ashraf Eid, Paul Faure, John Gavloski, François Jodoin, Elham Karimi, Eric Li, Jackson Macdonald, Nancy MacDonald, Owen Olfert, Chrystel Y. Olivier, 

Daniel Shen, Erl Svendsen, Gabriel Tobian, Tyler J. Wist.

“The app is a culmination of innovative thinking, extensive research, and most importantly collaboration in order to design a tool that met the needs of the farming community. The team’s ability to work together and build this application will result in economic savings, a greener environment, and increased crop quality in the food production industry.”

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) innovative 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.

By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

Available in iOS and Android.

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

Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.

CAM Homepage
CAM monitoring report and recommendation
CAM icon

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. 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.

•  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 4, 2019 or access the current online report)
• Saskatchewan Agriculture (May 28-June 3, 2019) or access the current online report).
• Alberta Agriculture and Forestry Crop Report (May 28, 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 3, 2019 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the June 4, 2019 edition). 

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 06Jun2019) but follow the hyperlink to check the interactive map.  They are in Manitoba!

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.  

Previous Posts

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Crop protection guides – Week 6
Cutworms – Week 5

Field heroes – Week 6
Flea beetles – Week 5

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

Painted lady butterfly – Week 8

Ticks and Lyme disease – Week 4

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Weeks 1-4

Doppelgangers: Pea leaf weevil and other Sitona species

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is a 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 monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  In some cases, doppelgangers are relatively harmless. In others, the doppelganger is a pest too yet behaviour, lifecycle and 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 pea weevil and other Sitona species doppelgangers

Weevils of the genus Sitona are broad-nosed weevils that are pests of various legume crops, including field pea, faba bean, alfalfa and sweet clover. Sitona larvae attack the roots of the host plant and usually consume the root nodules and the enclosed symbiotic bacteria that fix nitrogen. Adult Sitona weevils consume plant leaves resulting in ‘U’-shaped feeding notches. Sitona species  known to occur in Canada include:

• Sitona lineatus –  pea leaf weevil (Fig. 1), has two primary hosts: field pea and faba bean.
• Sitona cylindricollis – clover root weevil or sweet clover weevil (Fig. 4).
• Sitona hispidulus – clover root curculio* (Fig. 3), a clover pest.
• Sitona lineellus –  alfalfa curculio (Fig. 5), eats alfalfa, vetch and field pea.
• Sitona obsoletus (=S. flavescens = S. lepidus) – clover root curculio*, a clover pest (Fig. 6).

* Note that common names can be used to describe more than one species and can be confusing.

Figure 1. Pea leaf weevil (Sitona lineatus L.).
Photo: AAFC-Sasktoon-Williams.

The above five Sitona species found in Canada are doppelgangers of each other for several reasons:

1. Similar in size and appearance – Require a taxonomic key and microscope to accurately identify to species. Notable difference is Sitona hispidulus which has hairy elytra compared to the other four species which lack hair on their elytra (Fig. 2). 

2.  Sitona weevils share primary and secondary hosts – Pea leaf weevils must feed on primary hosts (i.e., field pea and faba bean) to attain sexual maturation AND the larvae must feed on primary hosts to successfully develop. However, early in the spring and again in the fall, pea leaf weevils feed on virtually any species of legume, including the primary host plants of the other four Sitona species.

3. Foliar feeding damage is similar – According to Weich and Clements (1992), “careful scrutiny” is required to differentiate the feeding damage caused by different Sitona species feeding on the same host plant. Therefore, it is important to collect adult weevils for identification to confirm which species is responsible for foliar damage.

Figure 2. Characteristics of four of the five Sitona species found in Canada, useful when scouting for pea leaf weevils. See  also the pea leaf weevil monitoring protocol. Images © AAFC-Beaverlodge

Species pages for all five species available by searching the species names in the E.H. Strickland Entomology Museum: http://www.entomology.museums.ualberta.ca/searching.php

Figure 3. Clover root curculio (Sitona hispicula Fabricious).
Photo: © Donald Hobern  
Figure 5.  Alfalfa curculio (Sitona lineellus Bonsdorff). 
Photo: © by nc Chris Moody.
Figure 4.  Sweet clover weevil (Sitona cylindricollis Fahreaus). Photo: © Janet Graham.
Figure 6.  Clover root curculio (Sitona obsoletus).
Photo: by K. Walker

More information about pea leaf weevil (Sitona lineatus), and sweetclover weevil (Sitona cylindricollis) can be accessed on the Insect of the Week page. Information related to crop pests and their natural enemies can be found in the newly updated Field Guide and Cutworm Guide. Both are available for free download on our Insect Field Guide and Cutworm Field Guide pages.

Meghan Vankosky (@DrVanbugsky)

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:

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.

This week, 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, May 28 – June 3, 2019:

1. Pacific Northwest – Currently there is limited stripe rust development in the PNW, a low-moderate number of recent wind trajectories from the PNW, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie crop development, especially in spring cereals.  Thus, as of June 3, 2019, the risk of stripe rust appearance from the PNW is limited and scouting for this disease is not urgent.  

2. Texas-Oklahoma corridor – In general, crops are advancing towards maturity and thus will become less of a source of rust inoculum.  There have been no recent wind trajectories from this area, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie spring crop development.  Thus, as of June 3, 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 – Although leaf and stripe rust development continues in Kansas with a recent report of stripe rust in Nebraska, it is at low-moderate levels, although there have been reports of elevated levels in regions of Kansas.  There have been no recent wind trajectories from this area, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie crop development.  Thus, as of June 3, 2019, the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is low and scouting for these diseases is not urgent, but further development of rust in these regions 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 that have resumed growth this spring.  Scouting is especially critical where the variety being grown is susceptible to stripe rust.  Currently, there are no early spring reports of stripe rust on commercial fields of winter wheat in the prairie region.

5.  Access the full downloadable report.

Insect of the Week – Pea aphid (Hemiptera: Aphididae)

This week’s insect of the week is the pea aphid (Acyrthosiphon pisum). This long-legged, pear-shaped aphid is 3-4 mm long, light to dark green and each antennal segment is tipped by a black band. It feeds on field peas, alfalfa, broad beans, chickpeas, clover and lentils. Feeding damage can reduce yields due to lower seed formation and seed size. Leaves may turn yellow and overall plant growth can be delayed.

Pea aphids overwinter as eggs on the leaves and stems of perennial legumes (eg. clover or alfalfa crowns). They produce 2-3 generations asexually before winged females migrate to summer host crops where several more generations are produced. Winged sexual forms develop in late summer that mate and females return to winter host crops to lay eggs.

For more information about pea aphids, see our Insect of the Week page!

Pea aphid adult (L) and nymph (R)
©Mike Dolinski, MikeDolinski@hotmail.com

Weekly Update

Greetings!

Field crop entomologists across the prairies are on the move with surveying so the Weekly Update is restricted to the basics for Week 9.

Access the Weekly Update as a series of Posts for Week 09 (July 05, 2018). A similarly abridged downloadable PDF will be available Friday.   Review the “Insect of the Week” for Week 9!

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 week staff have been busy surveying so we direct you to the AAFC Drought Watch maps in addition to the following updates.

The average temperature (14.6 °C) this past week (June 25 – July 2, 2018) was almost 2 °C warmer than long term average values (Fig. 1). 

Figure 1.  Average temperature the past seven days (June 25-July 2, 2018).

Once again, the warmest weekly temperatures occurred across MB. The 30-day (June 2-July 2) average temperature (14.3 °C) was approximately 0.5 °C warmer than long term average (Fig. 2). Average June temperatures were above normal across the entire prairie region (Fig. 3). 

Figure 2.  Average temperature the past 30 days (June 2-July 2, 2018).
Figure 3.  Monthly mean temperature differences from Normal for the month of June 2018. 
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (03Jul2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1529635048320).

Weekly and 30-day total precipitation was slightly above average (Figs. 4 and 5). The wettest (30-day) region was across eastern areas in SK and southern MB, while western SK and most of AB continue to be dry.

Figure 4.  Cumulative precipitation the past seven days (June 25-July 2, 2018).
Figure 5.  Cumulative precipitation the past 30 days (June 2-July 2, 2018).

The growing degree day map (GDD) (Base 10ºC, March 1 – July 2, 2018) is below:

The growing degree day map (GDD) (Base 5ºC, March 1 – July 2, 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.

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – As of July 2, 2018, the warm, moist conditions in Manitoba are predicted to be favourable for emergence of wheat midge adults, while dry conditions in Alberta and Saskatchewan should result in delayed emergence (Fig. 1).  Some populations may have greater than 50% emergence. Oviposition is predicted to have begun and larvae may be appearing in wheat heads. 

Figure 1. Percent wheat midge adult emergence based on model simulations for April 1-July 2, 2018.

Model runs for Saskatoon SK (Fig. 2) indicate the midge emergence is slower than  predicted emergence at Brandon MB (Fig. 3).  The delay in midge emergence is related to dryer dryer conditions in June 2018 in Saskatchewan. 

Figure 2.  Predicted wheat midge phenology for April 1-July 2, 2018, at Saskatoon SK. 
Figure 3.  Predicted wheat midge phenology for April 1-July 2, 2018, at Brandon MB.

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.

Predicted bertha armyworm development

Bertha armyworm (Lepidoptera: Mamestra configurata) – BAW populations are predicted to be in the larval stages and may have begun feeding within the plant canopy on leaves. Figure 1 illustrates that BAW oviposition is complete and  that the population is in the larval stage for populations near Brandon (Fig. 1). 

Figure 1.  Predicted BAW phenoloyg at Brandon MB. 
Values are based on model simulations for April 1-July 2, 2018 (projected to July 10, 2018)

Many thanks to those who are checking a bertha armyworm pheromone trap on a weekly basis.  Please use the reference photo below kindly shared by Saskatchewan Agriculture to aid your identification and reporting of trap interceptions.  Note the kidney-bean white-patterned shape on each forewing but also know other cutworm species can resemble bertha armyworm moths.  Check carefully and thanks for your help!

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.

Keep track of the Provincial Entomologist Updates for the latest in-season pheromone trap monitoring results for 2018.  

Saskatchewanians can view the latest pheromone trap interceptions below kindly provided by Saskatchewan Agriculture.

Albertans can access the online reporting map (screenshot retrieved 04Jul018 provided below for reference:

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.

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).  

As of July 2, 2018, the predictive model output indicated that the average instar = 3.7, with 1st instar (5%), 2nd (12%), 3rd (24%), 4th (34%), 5th (23%), and 2.4% in the adult stage. The most rapid development occurred across southern MB and southeast SK (Fig. 1). 

Figure 1.  Grasshopper development (average instar stage) based on model simulations for April 1-July 2, 2018.

Model output for Saskatoon illustrates that populations are primarily in the 4th and 5th instars with appearance of a few adults (Fig. 2).   By comparison, model output based on long-term climate data indicates that grasshopper populations should on average only be in the 3rd and 4th instars (Fig. 3).

Figure 2.  Predicted grasshopper phenology at Saskatoon SK.
Values are based on model simulations for April 1-July 2, 2018.
Figure 3.  Predicted grasshopper phenology at Saskatoon SK.
Values are based on model simulations for Long Term Climate Normals.

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.

Lygus in canola

Lygus bugs (Lygus spp.) – As of July 2, 2018, the model indicates the Lygus populations range from the 1st instar stage to adults with most of the population being at the 4th and 5th instar stages (Fig. 1).  Warmer temperatures have resulted in rapid development in southern Manitoba and southeast Saskatchewan. 

Figure 1.  Predicted Lygus development (average instar stage) based on model simulations for April 1-July 2, 2018.

This week, model runs were conducted for Saskatoon, Lethbridge and Grande Prairie to compare site specific development. The Lygus model output suggests that Saskatoon populations should be primarily be in the 3-5th instar stages (Fig. 2) with development predicted to be marginally slower in Lethbridge (Fig. 3). Populations near Grande Prairie are predicted to be in the 3rd instar stage (Fig. 4). 

Figure 2. Predicted Lygus phenology for April 1-July 2, 2018, for Saskatoon SK.
Figure 3. Predicted Lygus phenology for April 1-July 2, 2018, for Grande Prairie AB.
Figure 4.  Predicted Lygus phenology for April 1-July 2, 2018, for Lethbridge AB.

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.

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.

Download the Field Guide

If you haven’t downloaded the FREE field guide yet, please do so now!

Field Crop and Forage Pests and their Natural Enemies in Western Canada: IDENTIFICATION AND MANAGEMENT FIELD GUIDE

The 152-page, full-colour field guide, now available online, is designed to help you make informed decisions in managing over 90 harmful pests of field and forage crops in Western Canada. Better decision making helps save time and effort and eliminates unnecessary pesticide applications to improve your bottom line. The guide also helps the reader identify many natural enemies that prey on or parasitize pest insects. Recognizing and fostering populations of natural enemies will enhance their role in keeping or reducing pest populations below economic levels.

Find links to download the FREE Insect Field Guide.

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. At posting time, specific updates (June 20, and 27) would not open on the Manitoba website – please keep trying though!

Saskatchewan‘s Crop Production News for 2018 is posted with Report #3 now available. Insect monitoring information is included in the article, “Canola plants disappearing? Scout the field to look for cutworm damage”. Saskatchewan growers can review articles 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 4, 2018, by Mark Cutts) highlights the importance of field scouting now. You can review the Weekly Insect Update (posted by Scott Meers on June 21, 2018) noting that bertha armyworm moths were detected this first week of pheromone monitoring (check online map), onset of flowering in canola signalling the need for in-field monitoring for cabbage seedpod weevil, continued grasshopper calls from the south and advice to scout now while nymphs are easier to manage, Nutall’s blister beetle transiently showing up in some fields (blister beetle post), and the presence of the beneficial stiletto fly larvae which is a predator within the soil profile and targets wireworm larvae.

Previous Posts

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

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

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
West nile virus – Week 8
Wind trajectories – Week 6
Wireworm distribution maps – Week 6
White grubs in fields – Week 8

Weekly Update – Wheat midge

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

Simulation modelling is used to predict wheat midge emergence across the Canadian prairies.  The model has not changed significantly from last week. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.  


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

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


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




Economic Thresholds for Wheat Midge:

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

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

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



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

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


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

Weekly Update – White grubs in field crops

Scarabaeidae – Reminder – Each June brings scattered reports across the Prairies of white grubs associated with crop damage.  In fact, several species of Aphodius, Phyllophaga, Polyphylla or even small Aetenius produce larvae described as “white grubs”.  


Recently, crop damage reports have been associated with a grub identified as the larvae of the beetle Aphodius distinctus (see below). This common beetle is not known to be a pest, but there is an ongoing effort to gather information to develop a ‘pest’ profile.  Additional information is online at Top Crop Manager. Please send reports of this insect and associated information to Dr. Kevin Floate (Agriculture and Agri-Food Canada, Lethbridge, AB).

Weekly Update – Painted Lady Butterfly

Painted Lady Butterflies (Lepidoptera: Vanessa cardui) – Back on Week 6, we posted information and links related to the adult.  


UPDATE – This week, Alberta Agriculture & Forestry reminded their network of cooperators to watch for V. cardui larvae because the species has a broad host range and can feed on soybean (Action threshold=>25% defoliation), sunflowers, borage and dry beans in addition to several species of thistles (including Canada thistle) and mallow. 

In addition to the Week 6 information linking to the Butterflies of Canada entry for Vanessa cardui, the Butterflies and Moths of North America website tracks confirmed sightings of V. cardui (screenshot provided below).

The Butterflies and Moths of North America website also includes some verified photos of larvae to compare to when scouting.  Here’s screenshot below of the photo provided by T. Stout to hasten the need to link to this valuable resource!






Weekly Update – Monarch migration

We again track the migration of the Monarch butterflies as they move north by checking the 2017 Monarch Migration Map!  A screen shot of the map has been placed below as an example (retrieved 22Jun2017) but follow the hyperlink to check the interactive map!  They’ve migrated into southern Manitoba (various), southeast Saskatchewan (near Rhein), and now Alberta (near Sylvan Lake)! 

Weekly Update – Previous Posts

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


Alfalfa weevil (Week 7)

Brood X Cicadas


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

Diamondback moth

Flax scouting chart
Flea beetles


Grasshopper development (Week 8)

Iceberg reports

Lily leaf beetle


Pea leaf weevil
PMRA Pesticide Label Mobile App
Provincial Insect Pest Reports (Week 8)


Nysius niger (Week 8)

Ticks and Lyme disease

Weather radar

Wind trajectories


Insect of the Week – Cereal aphids

This week’s Insect of the Week is the group of aphids known
as cereal aphids. These aphids include the corn leaf aphid, the English grain
aphid, the oat-birdcherry aphid and the Russian wheat aphid. They feed on
cereal crops and are vectors of viruses, causing lower crop quality and yield. There are several natural enemies of cereal aphids, including various species of wasps and beetles. 

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

English grain aphid – adult, nymph (Tyler Wist, AAFC)



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

Weekly Update – Greetings!

Greetings!

This week AAFC Staff are out surveying so the Weekly Update will be released in segments.  Please access the series of Posts for Week 9 (Jun 29, 2017) to reach the most up-to-date information.   


Remember, if we’re in the field, you should be too!


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 easy steps!

Weather Synopsis

Weather synopsis – Our AAFC Staff are busy surveying this week so be sure to check back for updates!


Precipitation for the growing season is presented below (April 1-June 27, 2017) followed by the precipitation expressed as Percent of Normal for the same period.



Over the past seven days, the greatest precipitation fell in northern growing areas along areas typically grouped as Boreal Plains (June 21-27, 2017).  Southern Alberta, southeast Saskatchewan and southwest Manitoba received the lowest amounts of precipitation over the same period.



The lowest temperatures across the prairies over the past seven days (June 21-27, 2017) are mapped below.  Although there was little chance of frost, much of the prairies recorded lows ranging from 0-4°C.



In contrast, the highest temperatures recorded over the past seven days (June 21-27, 2017) are presented below.  The field crops in some of these areas endured daily fluctuations of 20-25°C.

The updated growing degree day map (GDD) (Base 5ºC, March 1 – June 25, 2017) is below:



While the growing degree day map (GDD) (Base 10ºC, March 1 – June 25, 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.

Cabbage seedpod weevil

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

CSPW emerge from overwintering in the spring as soil temperatures warm to ~15°C.  CSPW utilize several flowering hosts including wild mustard, flixweed, hoary cress, stinkweed and volunteer canola.  CSPW move to canola during the bud to early flower stages and will feed on pollen and buds, causing flowers to die.

The map below reflects CSPW densities observed in 2015.  Growers situated within or adjacent to areas of the map highlighted yellow, orange and red will need to be scouting with a sweep-net as their canola fields initiate flowering.




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

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


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


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


Also watch provincial reports for updates on surveying underway now.  Alberta Agriculture & Forestry has released a new live CSPW map and online reporting tool for growers.  A screenshot (retrieved 29 Jun 2016) is included below.


Provincial Insect Pest Reports

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

– Manitoba’s Insect and Disease Update which includes alfalfa weevil and descriptions to aid scouting for cereal leaf beetle (June 22, 2016, prepared by John Gavloski and Pratisara Bajracharya).
– Saskatchewan’s Insect Report which mentions redbacked cutworms but emphasizes scouting for cabbage seedpod weevil, wheat midge and grasshoppers (Issue 4, prepared by Scott Hartley).
– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on June 23, 2016) including cabbage seedpod weevil on early canola in southern Alberta, cereal leaf beetle reports on wheat and barley but also the benefits of its parasitoid, Tetrastichus julis.

Weekly Update – Crop reports

Crop reports are produced by:

– Manitoba Agriculture, Rural Development (June 27, 2016)
– Saskatchewan Agriculture Crop Report (June 20, 2016)

– Alberta Agriculture and Forestry (for June 21, 2016)

Weekly Update – Previous Posts

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

Canola scouting chart
Wind trajectories
Cutworms
Flea beetles in canola
Predicted cereal leaf beetle development
Predicted lygus bug development
Predicted wheat midge development
Pea leaf weevil monitoring
Crop protection guides
Using Environment Canada’s radar maps to follow precipitation events
Iceburg reports

Monarch migration

Weekly Update

Greetings!

A downloadable PDF version of the complete Weekly Update for Week 9 (June 29, 2016) can be accessed here.  

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

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



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

Weekly Update – Weather Synopsis

Staff are busy surveying so some maps are not available this week.

Warmer temperatures were observed throughout the prairies and the west was drier compared to the east.


The Accumulated Precipitation the past 7 days (June 22-28, 2016) is below:



The map below reflects the Accumulated Precipitation for the Growing Season so far for the prairie provinces (i.e., May 1-June 26, 2016):





Compared to last week, overnight temperatures were warmer during the past 7 days.  The map below shows the Lowest Temperatures the Past 7 Days (June 22-28, 2016) across the prairies:



The map below shows the Highest Temperatures the Past 7 Days (June 22-28, 2016):





The updated growing degree day map (GDD) (Base 5ºC, March 1 – June 26, 2016) is below:





While the growing degree day map (GDD) (Base 10ºC, March 1 – June 26, 2015) 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 – Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata) – This week, moths are expected to complete their yearly flight.  Reporting sites across the prairies have generally reported lower cumulative interceptions with some exceptions in Saskatchewan.  

Provincial staff coordinate BAW pheromone trapping across the prairies and summarize cumulative counts in report or map formats:
● Saskatchewanians.… Male moths have been intercepted at multiple sites in Saskatchewan with some sites reporting higher risk values (Insect Report-Issue #4, prepared by S. Hartley).  
● Manitobans.…. Low numbers of male moths have been intercepted throughout the province but review the values in the most recent Insect and Disease Report prepared by J. Gavloski and posted June 22, 2016.  

● Albertans.…..  Refer to the live 2016 map reporting Bertha armyworm pheromone trap interceptions.  A copy of the map (retrieved June 29, 2016) is below for reference.

Weekly Update – Grasshoppers

Grasshoppers (Acrididae) – Previous model predictions related to hatch and nymphal instar development can be reviewed here.  


The following image showing various stages of Camnulla pellucida is provided below – note that adults have wings extending the length of the abdomen whereas nymphs lack wings but develop wing buds that will eventually mature to wings.  


Generally, the economic threshold for grasshoppers in cereals is 8-12 per square metre but will vary by crop and growing conditions.

Figure 1. Life stages of Camnulla pellucida which including eggs, first-fifth instar nymphs and adult (L-R).
Biological and monitoring information related to grasshoppers in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta, British Columbia 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” – both English-enhanced or French-enhanced versions are available.

Weekly Update – Swede midge

Swede midge (Contarinia nasturtii)  – Reminder – Pheromone traps captured the first swede midge of 2016 between May 25 and 31 in northeastern Saskatchewan.  This is substantially earlier (6-7 weeks) compared to 2014 and 2015. 

The earlier emergence pattern is likely due to the mild winter and warm spring weather combined with adequate moisture levels. Emergence traps indicate a moderate number of swede midge have emerged near Carrot River, Saskatchewan, and producers should monitor their canola fields for damage symptoms. 

Figure 1. Swede midge infested canola buds which are enlarged with sepals fused together. 


Figure 2.  Swede midge large (~1mm long; yellowish-white) feeding within canola flower.


Swede midge scouting tips for in-field monitoring:
• 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.
• Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.

Note the distribution map of confirmed symptoms and populations of swede midge (red dots) on the Canadian prairies  (Soroka and Andreassen 2015).


Weekly Update – Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) – Reminder – Back in May, the cereal leaf beetle (CLB) bioclimatic model was utilized to help predict when eggs and larvae might appear in fields along with its parasitoid, Tetrastichus julis. 

Recall the following (posted May 25, 2016) – Predicted dates of peak emergence of CLB eggs and larvae:




Cereal leaf beetle larvae hatch from eggs in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 1).  When the larva completes its growth, it drops to the ground and pupates in the soil.  The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Figure 1.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.

Monitoring:
Give priority to following factors when selecting monitoring sites:
   □ Choose fields and sections of the fields with past or present damage symptoms.
   □ Choose fields that are well irrigated (leaves are dark green in color), including young, lush crops. Areas of a field that are under stress and not as lush (yellow) are less likely to support CLB. 
   □ Monitor fields located along riparian corridors, roads and railroads. 
   □ Survey field areas that are close to brush cover or weeds, easy to access, or are nearby sheltered areas such as hedge rows, forest edges, fence lines, etc.

Focus your site selection on the following host plant priorities:
   □ First – winter wheat. If no winter wheat is present then;
   □ Second – other cereal crops (barley, wheat, oats, and rye). If no cereal crops are present then;
   □ Third – hay crops. If no hay crops or cereal crops are present then;
   □ Fourth – ditches and water corridors


Sweep-net Sampling for Adults and Larvae:
 ● A sweep is defined as a one pass (from left to right, executing a full 180 degrees) through the upper foliage of the crop using a 37.5 cm diameter sweep-net. 
 ● A sample is defined as 100 sweeps taken at a moderate walking pace collected 4-5 meters inside the border of a field.  
 ● At each site, four samples should be collected, totaling 400 sweeps per site.  The contents of each sample should be visually inspected for life stages of CLB and all suspect specimens should be retained for identification.  
 ● Because the CLB larvae are covered in a sticky secretion, they are often covered in debris and are very difficult to see within a sweep-net sample. 
 ● To help determine the presence of CLB, place the contents of the sweep net into a large plastic bag for observation.



Visual Inspection:
Both the adults and larvae severely damage plants by chewing out long strips of tissue between the veins of leaves (Fig. 1), leaving only a thin membrane. When damage is extensive, leaves turn whitish. 

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.

Weekly Update – Alfalfa weevil

Alfalfa Weevil (Hypera postica) – 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).



Updated – Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models.  The aim or the modelling is to predict the development of Alfalfa weevil (Hypera postica) across the prairies and to help growers time their in-field scouting as second-instar larvae are predicted to occur.  Compare the following predicted development stages and degree-day values copied below (Soroka 2015) to the map below.




For the week of June 26, 2016, the following map predicts the developmental stages for alfalfa weevil and corresponding degree-days.  Areas highlighted orange are predicted to find fourth instar larvae so scout for major leaf feeding then compare larval densities to the action threshold for alfalfa weevil!



Economic thresholds for Alfalfa weevil (adapted from Soroka 2015) vary by crop type (hay or seed), area fed upon and larval densities.

In hay fields, forage losses can be economic if one or more of the following symptoms are noted:
● if 25-50 % of the leaves on the upper one-third of the stem show damage, or
● if 50-70% of the terminals are injured, or
● if 1 to 3 third or fourth instar larvae occur per stem (with shorter stems having lower economic thresholds and 3 or more larvae requiring treatment no matter what the alfalfa height), or 
● 20-30 larvae per sweep occur when 12% leaf loss is acceptable.
● Also consider these two points:
      1. Early cutting of the first growth of alfalfa or insecticide treatment will reduce alfalfa weevil populations.
      2. If the hay crop value is high and weevil injury is seen or 2 or more larvae per stem reappear in regrowth after cutting, insecticide may be necessary (if a second cut is anticipated). 

In alfalfa seed fields:
● Economic thresholds are 20-25 third to fourth instar larvae per sweep or 35-50% of the foliage tips showing damage. 
● Thresholds increase with the height of the alfalfa, and decrease in drought conditions. 
● Also know that several small wasps parasitize alfalfa weevil larvae and adults, and in the past these natural control agents kept the weevil in check in most years. One of these wasps, Bathyplectes curculionis (Thomson), parasitizes alfalfa weevil in Alberta and Saskatchewan, and is now found in Manitoba.

Weekly Update – Small scarab beetle

Small scarab beetle (Coleoptera: Aphodius distinctus) – Reminder – This is the time of summer that farmers will be seeing larvae of a small scarab beetle (Aphodius distinctus) in their fields.  There have been scattered reports each June of large numbers of beetle grubs in crops associated with crop damage (e.g., canola, corn, dry bean, onion, pea).


Please help researchers compile information related to this species so they might confirm its pest status!  Information is posted about the beetle and the survey.  Here’s how you can help:

1. Please send reports of high white grub densities and associated crop damage to Kevin.Floate@agr.gc.ca (403-317-2242). 

2. Live larvae accompanied by the following field information would be extremely helpful please – contact Dr. Kevin Floate if you have a sample!

3. Include answers to the following so the pest status for this species can be ascertained:  
     – Previous crop?
     – Legal land location or latitude+longitude?
     – Irrigated or not?
     – Was composted manure added this spring?
     – Surface residue in spring?


Weekly Update – Multitude of Mayflies!

Mayflies on your radar?!  Unusually large numbers – enough to repeatedly show up on eastern weather radar systems in North America, have been emerging and they’ve made the news!  


See and read more about mayflies on Bug Guide which is where this wonderful photo by Werner Eigelsreiter is posted.

Mayflies occur in rivers, streams, ponds and lakes and they are an important food source for several species of fish.  The aquatic nymph develops through several stages then moves to the surface to molt into a winged sub-adult that flies to nearby plants and molts again into an adult that usually live only for 48-72 hrs.  

Mayflies belong to the Order Ephemeroptera and you can see and read more about them on Bug Guide’s website.  

Insect of the Week – Rove beetle

Rove Beetle (predator and parasitoid)

Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] 

This week’s Insect of the Week is the rove beetle (Delia spp.), is a generalist predator. The adult feeds on aphids, mites and larvae of many species under plant debris, rocks, dead animals, dung and other materials. The rove beetle larvae have similar hosts as the adult; the larvae of Aleochara spp parasitize various fly species including cabbage root maggot.

For more information about rove beetle, the pests it controls and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).

Adult rove beetle. (c) AAFC-Tyler Wist