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TEMPERATURE: This past week (June 20-26, 2022) the average daily temperature on the prairies was 1 °C warmer than the previous week and 1 °C warmer than normal (Fig. 1). Similar to last week, the warmest temperatures were observed across Manitoba and southeastern Saskatchewan. The prairie-wide average 30-day temperature (May 28 – June 26, 2022) was 0.5 °C cooler than the long-term average temperature. Average temperatures have been warmest across the southern prairies (Fig. 2).
Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of June 20-26, 2022.Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 28-June 26, 2022.
The growing season (April 1 to June 26, 2022) temperature for the prairies has been 1 °C cooler than climate normal values. A review of specific prairie locations illustrates that Grande Prairie was 1.8 °C cooler than average (Table 1). The growing season has been warmest across western Saskatchewan and southern and central regions of Alberta (Fig. 3).
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to June 26, 2022.
Table 1. Growing season (April 1 – June 26, 2022) temperature and rainfall summary for specific locations across the Canadian prairies.
PRECIPITATION: Weekly (June 20-26) rainfall varied across the prairies. Significant rainfall was reported across southeastern Saskatchewan (Weyburn – 82mm) and from Edmonton (66 mm) to Meadow Lake, Saskatchewan (52 mm). The Peace River region and southwestern Saskatchewan reported rainfall amounts that were generally less than 10 mm (Fig. 4). 30-day rainfall accumulation totals have been well above average across Manitoba and Alberta while rainfall accumulation has been well below normal across Saskatchewan (Fig. 5).
Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 20-26, 2022.Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (May 28-June 26, 2022).
Growing season rainfall for April 1 – June 26, 2022 continues to be greatest across Manitoba and eastern Saskatchewan; growing season rainfall remains below normal across central Saskatchewan and near normal for Alberta (Fig. 6; Table 1).
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to June 26, 2022.
The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Model outputs provided below as geospatial maps are a tool to help time in-field scouting on a regional scale but local development can vary and is only accurately assessed through in-field scouting.
SCOUT NOW – Some areas of the Canadian prairies are presently experiencing high densities of nymphs and economically important species are present. Review lifecycle and damage information for this pest to support in-field scouting.
Warm, dry conditions across central and southern regions of Saskatchewan have resulted in rapid grasshopper development. Model simulations were used to estimate grasshopper development as of June 26, 2022. The grasshopper hatch is nearly complete for the southern prairies (Fig. 1). Hatch is still progressing across the Parkland and Peace River regions. Based on estimates of average nymphal development, first to fifth instar nymphs should be occurring across southern and central regions of all three prairie provinces (Fig. 2).
Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 26, 2022.Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 26, 2022.
Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface.
The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds.
As of June 26, 2022, model simulations predict that larvae (surface) and pupae are present with limited occurrence of adults. In terms of occurrence of pupae, wheat midge development is most advanced across central Saskatchewan, Manitoba and the Peace River region (British Columbia) (Fig. 1). The first appearance of adults is predicted near Regina and across southern Manitoba (Fig. 2). Model projections for July 3, 2022, indicate that the first appearance of adults should begin across the central prairies and Peace River region over the weekend.
Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada,as of June 26, 2022.Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the adult stage, across western Canada, as of June 26, 2022.
In-Field Monitoring:When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 3). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
Figure 3. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.
REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.
Figure 4. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.
Economic Thresholds for Wheat Midge: a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and larval damage.
Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!
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.
Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.
Model simulations to June 26, 2022, indicate that the first generation of non-migrant adults (based on mid May arrival dates) are currently occurring across the Canadian prairies and that the start of the second generation is emerging in southern Manitoba (Fig. 1).
Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of June 26, 2022.
Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.
In-Field Monitoring:Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Figure 2. Diamondback larva measuring ~8mm long. Note brown head capsule and forked appearance of prolegs on posterior.
The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 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).
Figure 3. Diamondback moth pupa within silken cocoon.
1. REVERSE TRAJECTORIES (RT) Since May 1, 2022, the majority of reverse trajectories that have crossed the prairies have originated from the Pacific Northwest (Idaho, Oregon and Washington). This past week (June 21-27, 2022) the number of incoming trajectories was lower than the week of June 14-20, 2022 (Fig. 1).
Figure 1. Average number (based on a 5-day running average) of reverse trajectories (RT) crossing the prairies for the period of June 1-27, 2022.
a. Pacific Northwest (Idaho, Oregon, Washington) – The majority of Pacific Northwest reverse trajectories continue to pass over southern and central Alberta and western Saskatchewan (Fig. 2). This past week (June 21-27, 2022) the ECCC model predicted that 77 reverse trajectories would cross the prairies. This is significantly less than the number of reverse trajectories predicted for the period of June 14-20 (n=124).
Figure 2. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and June 27, 2022.
b. Mexico and southwest USA (Texas, California) – This week (June 21-27, 2022), a total of 13 reverse trajectories were predicted to cross the prairies (n=44 for June 14-20). Most reverse trajectories from this region of southern North America have crossed Manitoba during the 2022 growing season.
Figure 3. The total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and June 27, 2022.
c. Oklahoma and Texas – This week reverse trajectories have passed over Manitoba and Watrous, Saskatchewan (Fig. 4). This week there were significantly fewer (n=5) reverse trajectories than for the period of June 14-20, 2022 (n=33).
Figure 4. The total number of dates with reverse trajectories originating over Texas and Oklahoma that have crossed the prairies between May 1 and June 27, 2022.
d. Nebraska and Kansas – This past week (June 21-27, 2022), reverse trajectories originating from Kansas and Nebraska have crossed Manitoba and Yorkton, Saskatchewan (Fig. 5). The ECCC model predicted that 5 reverse trajectories passed over the prairies. This is a significant decrease from the previous week (n=51).
Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between April 1 and June 27, 2022.
2. FORWARD TRAJECTORIES (FT) The following map presents the total number of dates (since April 1, 2022) with forward trajectories (originating from Mexico and USA) that were predicted to cross the Canadian prairies (Fig. 6). This week (June 21-27, 2022) there was a decrease in the number of (n=19) forward trajectories predicted to cross the prairies (last week n=50). Results indicate that the greatest number of forward trajectories entering the prairies have originated from the Pacific Northwest (Idaho, Oregon, Washington), Montana and Wyoming.
Figure 6. Total number of dates with forward trajectories, originating from various regions of the United States and Mexico, crossing the prairies between April 1 and June 27, 2022.
View historical PPMN wind trajectory reports by following this link which sorts the reports from most recent to oldest.
The Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download a free copy to arm your in-field scouting efforts!
Review the Sweep-net Video Series including: • How to sweep a field. Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • What’s in my sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • Why use a sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020.
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
MANITOBA’SCrop Pest Updates for 2022 are up and running! Access a PDF copy of the June 29, 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! • Seedcorn maggot and wheat stem maggot in MB were new additions to the June 29 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. • Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of June 22, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.
ALBERTA’SInsect 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 so refer to the Live Map. • Cabbage seedpod weevil monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Cutworm live monitoring map for AB – Reports continue to come in so refer to the Live Map to review areas where cutworms are being found. Use this online form to report cutworms in Alberta.
