Friday, 3 July 2020

Weekly Update (July 2, 2020; Wk 10) Otani, Weiss, Rounce, Trudel, Svendsen, Tansey, Turkington, Olfert, Vankosky

Happy Birthday Canada!

Warmer temperatures last week continue to move our growing season forward and there are more insects to prioritize on scouting lists again this week. Bertha armyworm pheromone monitoring numbers are coming in as cooperators work with their provincial networks to help assess risk levels in the form of cumulative moth counts.  We are also poised for wheat midge emergence across the prairies and we dedicate this Weekly Update and remember Dr. John Doane, an entomologist whose research on this pest and many other species contributed significantly to insect pest management on the Canadian prairies.

Access information to support your in-field insect monitoring efforts in the complete Weekly Update either as a series of Posts for Week 10 OR a downloadable PDF.

Stay Safe!


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

John Frederick Doane (14 April 1930 – 21 May 2020)

In memory 

John Frederick Doane quietly passed away on May 21, 2020, in his home in Saskatoon, at the age of 90 years.  Having grown up on a farm north of Toronto, John developed an interest in entomology at a young age, and began collecting insect specimens common to southern Ontario.  John received his B.S.A. in 1954 from the Ontario Agricultural College, now the University of Guelph; specializing in entomology.  Pursuing these interests, John immediately enrolled in graduate studies at the University of Wisconsin, completing both his M.Sc. (1956) and his Ph.D. (1958).  Shortly after graduating, he began a research career in agricultural entomology, receiving an Research Scientist position at the Agriculture Canada Research Station in Saskatoon that same year.  Interestingly, this cadre of  Research Scientists at the Centre still had a significant number of first generation entomologists appointed to the Dominion Entomological Laboratory at Saskatoon.

John Frederick Doane (14 April 1930 - 21 May 2020)
Photo taken July 2019

John adapted very quickly to the agricultural industry on the prairies, and his research over the years has significantly contributed to insect population monitoring.  His first research assignment was to assess and describe the ecology and behaviour of wireworms, a major pest of field crops at the time.  John began by investigating the ovipositional behaviour and fecundity of adults, as well as the effects of soil moisture and temperature on wireworm egg survival.  His studies, related to the response of wireworm larvae to carbon dioxide levels, contributed to the development of trapping and monitoring tools for larval populations.  In the early 1980s, Saskatchewan experienced an unexpected outbreak of wheat midge (Sitodiplosis mosellana).  John was asked to assemble a multidisciplinary research team with the objectives to determine the biology and ecology of this new threat to wheat production in the prairies.  His research promptly yielded important contributions: (i) the discovery of a significant biological control insect (Macroglenes penetrans), and (ii) the development of a sound wheat midge population monitoring protocol.  Through the successful implementation of conservation techniques, M. penetrans now controls an average of >30% of the wheat midge across Saskatchewan annually.  A study in the 1990s, showed that the dollar value of the parasitoid to the agriculture industry over the 10 years, was in excess of $248.3 million (equivalent of $422.5 million today).  The second highlight, a soil extraction protocol for wheat midge larval cocoons, provided a unique population density and distribution monitoring tool for both the pest wheat midge and it’s biological control agent.  This tool is still utilized today to forecast the risk to wheat production; the survey results being provided as mapped forecasts for producers on an annual basis.  Given the success of biological control agent (M. penetrans), John collaborated with international colleagues at CABI in Switzerland, to assess the viability of importing a second biocontrol agent for control of wheat midge.  This resulted in the successful introduction and establishment of Platygaster tuberosula.  In the late 1980s, wheat production south of the USA border was seriously threatened by Russian wheat aphid (Diuraphis noxia).  In response to this new threat, John manufactured and installed a series of suction traps as an early-warning system, from southern to northern Saskatchewan.  The 30ft high traps were designed to collect migratory aphid adults being transported north on wind currents from infestations in the USA.  The results indicated that southwest SK was occasionally at low risk, but the threat was significantly less than south of the border.

John was appointed Head of the Integrated Pest Management Section of the Saskatoon Research Station in 1982, and the Head of the amalgamated Cereals Protection Section in 1989.  John served as E.S.S. President in 1967 and 1978, and served a term as a member of the E.S.C.  Governing Board.  He will also be remembered as a founding  member of the national AAFC Biological Control Working Group, a group that is still very active in 2020.  He retired in 1993, taking an extended self-guided tour of south east Asia, including India and Malaysia.  Upon his return, John remained active in retirement, co-authoring several scientific articles, most recently a bio-climate modelling paper on wheat midge in 2020.

- Submitted by O. Olfert

Weather synopsis

Weather synopsis – This week (June 22-28, 2020), prairie temperatures were warmest in Manitoba and eastern Saskatchewan (Table 1).  Seven-day cumulative temperatures varied across the prairies (Fig. 1).  Average 7-day temperatures continue to be warmest across Manitoba and eastern Saskatchewan and coolest across most of Alberta (Table 1). The weekly average temperature at Winnipeg (20.8 °C) was 6 °C warmer than Grande Prairie (Table 1; Fig. 1).  

Table 1. Seven-day temperature and rainfall summary (June 22-28, 2020).


Figure 1. Observed average temperatures across the Canadian prairies for the past seven days (June 22-28, 2020).

Average 30-day (May 30 - June 28, 2020) temperatures continue to be cooler in Alberta and areas north of Saskatoon than in southern Saskatchewan and Manitoba (Table 2, Fig. 2).  The average 30-day temperature at Winnipeg and Brandon continues to be greater than locations in Alberta and Saskatchewan (Table 2).  Based on growing season temperatures (April 1 – June 28, 2020), conditions were warmest for southern locations (Table 3). 

Table 2. 30-day temperature and rainfall summary (May 30 -June 28, 2020).

Figure 2. Observed average temperatures across the Canadian prairies for the past 30 days (May 30-June 28, 2020).

Table 3. Temperature and rainfall summary for the growing season (April 1 - June 28, 2020).

Cumulative rainfall for the past 7 days was variable (Table 1; Fig. 3). Lethbridge reported 23.3 mm and 7.7 mm was recorded at Swift Current (Table 1). Cumulative 30-day rainfall was greatest across central regions of Alberta (Table 2; Fig. 4).  Rainfall amounts were lower across the southern prairies (Fig. 4). Total 30-day rainfall at Winnipeg, Brandon, Regina and Swift Current has been less than 65 mm (Table 2; Fig. 4).  Rainfall amounts have been greater across central regions of Alberta and Saskatchewan (Fig. 4).  Saskatoon has reported 131.9 mm (279% of normal) in the past 30 days (Fig. 5).  Growing season rainfall (percent of average) is below normal southern Saskatchewan and most of Manitoba (Fig. 5; Table 3).  Rainfall amounts are above average across central regions of Saskatchewan and across Alberta (Fig. 5; Table 3).


Figure 3. Observed cumulative precipitation across the Canadian prairies for the past seven days (June 22-28, 2020).

Figure 4. Observed cumulative precipitation across the Canadian prairies for the past 30 days (May 30-June 28, 2020).

Figure 5. Percent of average precipitation for the growing season (April 1-June 28, 2020). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (28Jun2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-June 30, 2020) is below (Fig. 6):
Figure 6. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-June 30, 2020). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (02Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 10 ºC, April 1-June 30, 2020) is below (Fig. 7):
Figure 7. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-June 28, 2020). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (02Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The highest temperatures (°C) observed the past seven days ranged from <17 to >32 °C in the map below (Fig. 8).
Figure 8. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-June 28, 2020). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (02Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Finally, the map below reflects how many days >25 °C have occurred so far across the prairies as of June 30, 2020 (Fig. 9). 
Figure 9. Number of days with temperatures above 25 °C)observed across the Canadian prairies this growing season  (April 1-June 30, 2020). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (02Jul2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

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

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 June 28, 2020, the grasshopper model estimates that hatch is nearly complete (Table 1).  The prairie average, is 77% (71% last week).  The majority of the nymphal population is predicted to be in the first to third instars (Table 1; Fig. 1).  This week, 5th instar nymphs are predicted to occur in some locations (Fig. 1).  Across the prairies, populations are predicted to be 21, 22, 21, 23, 11 and 2% in egg, first, second, third, fourth and 5th instar stages,  respectively (Table 1).  

Table 1. Results of grasshopper simulation (Melanoplus sanguinipes) development as of June 28, 2020.




Figure 1. Predicted average instar stages of grasshopper (Melanoplus sanguinipes) populations across
the Canadian prairies (as of June 28, 2020). 

Warmer conditions across southern regions of the prairies should result in rapid development of 1st to 3rd nymphs (Table 1).  This week 5th instar nymphs are predicted to appear at Regina, Brandon and Winnipeg (Table 1).  The two graphs compare development for Saskatoon (Fig. 2) and Winnipeg (Fig. 3).  Grasshopper populations near Saskatoon are predominantly in the 2nd and 3rd instars (Fig. 2) while populations near Winnipeg are expected to be primarily 3rd and 4th instars (Fig. 3).
Figure 2. Predicted grasshopper (Melanuplus sanguinipes) phenology at Saskatoon SK.
Values are based on model simulations (April 1-June 28, 2020).

Figure 3. Predicted grasshopper (Melanuplus sanguinipes) phenology at Winnipeg MB.
Values are based on model simulations (April 1-June 28, 2020).

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

Bertha armyworm monitoring

Bertha armyworm (Lepidoptera: Mamestra configurataModel simulations for June 28, 2020, indicate that 26% of the population is in the pupal stage (compared to 69% last week), 52% in the adult stage (26% last week), and 20% are predicted to be eggs (5% last week).  Larvae are predicted to begin to occur (2%) this week. Across the Parkland and Peace River regions BAW populations are predicted to be transitioning from the pupal to adult stage (Fig. 1).  BAW adults should be showing up in traps.  Populations across southern regions are primarily in the egg stage (green region in Fig. 1).  Over the next 7-10 days larvae should begin to appear in this region.  

Development near Brandon (Fig. 2) is predicted to be ahead of fields near Saskatoon (Fig. 3).  First instar larvae are predicted to be occurring in southern Manitoba (Fig. 3). 


Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population at adult stage as of June 28, 2020

Figure 2. Predicted bertha armyworm (Mamestra configurata) phenology at Saskatoon SK as of June 28, 2020.
Figure 3. Predicted bertha armyworm (Mamestra configurata) phenology at Brandon MB as of June 28, 2020.

Figure 4. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

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

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images above (Fig. 4) to help identify egg masses and the economically important larvae in canola.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta 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.

Predicted wheat midge development

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

As of June 28, 2020midge model runs indicate that, where midge are present, pupation is occurring across Alberta, northwest Saskatchewan and southern Manitoba (Fig. 1).  Simulations suggest that the first adults might be emerging now (Fig. 2).  


Figure 1. Predicted  percent of population of wheat midge (Sitodiplosis mosellana) at pupal stage across
the Canadian prairies (as of June 28, 2020).
Figure 2. Predicted  percent of population of wheat midge (Sitodiplosis mosellana) at adult stage across
the Canadian prairies (as of June 28, 2020).


Females lay eggs on developing wheat heads.  This typically occurs in evenings when winds are calm. The wheat midge monitoring protocol suggests that wheat fields should be inspected for adults in late June and early July as wheat heads are emergingThe next three weeks are very important for monitoring wheat midge populations for the purpose of making management decisions.  

Simulations were run to July 21 to assess population development over the next three weeks.  The first two graphs illustrate that adult wheat midge populations near Saskatoon (Fig. 3) and Lacombe (Fig. 4) are expected to emerge on June 30 and July 1, respectively.  


Figure 3. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK projected to July 21, 2020.


Figure 4. Predicted wheat midge (Sitodiplosis mosellana) phenology at Lacombe AB projected to July 21, 2020.

Oviposition will occur soon after adult emergence.  Adult numbers are predicted to peak in mid July (Fig. 3 and 4).  A comparison of the synchrony between wheat midge and wheat is represented in Figure 5 and indicates that adult emergence and oviposition may occur when the crop is most susceptible near SaskatoonThis information can be used as a guide to determine when fields should be monitored.
Figure 5. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Saskatoon SK projected to July 21, 2020.

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.

Diamondback moth

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

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

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

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


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


Figure 2. Diamondback moth pupa within silken cocoon.

Economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1  (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  (approximately 1-2 larvae per plant).

Figure 3. Diamondback moth.

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

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

Pea leaf weevil

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

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


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

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


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


Figure 2. Weevil larva in soil (Photo: L. Dosdall).


Figure 3. Pea nodules damaged by larval feeding (Photo: L. Dosdall).

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

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

Cereal Aphid Manager

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

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist's (AAFC-Saskatoon) Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
  • the number of aphids observed and how quickly they reproduce
  • the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
  • the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
Frequent in-field scouting, supported by the app's dynamic threshold, allows growers to weigh the above factors and the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
To learn more and to download, go to AAFC's CAM webpage

CAM Homepage

CAM monitoring report and recommendation

Field Heroes

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

Real Agriculture went live with a weekly Pest and Predators podcast series!
• Access Episode 1 - Do you know your field heroes?
• Access Episode 2 - An inside look at the Prairie Pest Monitoring Network.
• Access Episode 3 - How much can one wasp save you?
• NEW- Access Episode 4 - Eat and be eaten — grasshoppers as pests and food

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


Provincial Insect Pest Reports

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

Manitoba's Crop Pest Updates for 2020 are available. Access the July 1, 2020 report. The
summary indicates t
here are, "High levels of grasshopper nymphs have been found in many areas. Armyworms are being found in cereals and forage grasses in the Eastern, Interlake and Central regions. Some thistle caterpillars are being noted on soybeans and sunflowers."

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

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

Crop reports

Click the provincial ministry name below to link to online crop reports produced by:
• Manitoba Agriculture - Other viewing options include subscribing to receive or access a PDF of June 30, 2020 report.
• Saskatchewan Agriculture  or access a PDF of June 16-22, 2020 report.
• Alberta Agriculture and Forestry or access a PDF of June 23, 2020 report.

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the June 29, 2020 edition).

Monarch migration

We again track the migration of the Monarch butterflies as they move north by checking the 2020 Monarch Migration Map!  A screen shot of the map showing reported first sightings of adults is below as reference (retrieved 02Jul2020) but follow the hyperlinks to check the interactive map! 

Check your milkweed!  Those incredible spring monarchs have made the long journey north to the Canadian prairies and they need a safe place to lay eggs where their larvae can feed and grow! 



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 fascinating insect. 

Prairie Crop Disease Monitoring Network

The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of  prairie pathologists working together to support in-field disease management in field crops.  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.  Read the OVERVIEW describing the collaborative nature of this effort and the methods employed.  

Wind trajectory and cereal rust risk assessment and need for in-crop scouting in the Prairie region, June 23-29, 2020


1. Pacific Northwest

i. There were a moderate number of reverse wind trajectories that passed over the PNW region and into the prairies.  Locations with the highest number of days with events (4-5) with reverse trajectories from the PNW included: Lethbridge (5), AB; and Gainsborough (5), Kindersley (4), and Regina (5) SK.  The remaining locations in Alberta, Saskatchewan and Manitoba had 1-2 days with events, except for Fort Vermilion, Grande Prairie, Manning, Sedgewick and Wanham, AB, which had no events from June 23-29, 2020 (Table 1).  

ii. Currently there appears to be relatively low levels of stripe rust development on commercial winter wheat crop in the PNW.  The spring wheat crop is somewhat smaller in acreage and appears to have limited stripe rust development, while fungicide applications may limit further stripe rust development in PNW spring wheat crops.  

iii. Prairie temperatures were warmest in MB and eastern SK and seven day cumulative varied across the prairies (Figure 7).  Average 7 day temperatures continue to be warmest across MB and eastern SK and coolest across most of AB (Figure 7) . The weekly average temperature at Winnipeg (20.8 °C) was 6 °C warmer than Grande Prairie.  Cumulative rainfall for the past 7 days was variable (Figure 9). Cumulative 30 day rainfall was greatest across central regions of AB. Rainfall amounts were lower across the southern prairies (Figure 10).  

iv. Winter wheat crops are progressing into flowering or are finishing flowering, while Prairie spring wheat development ranges from tillering to booting/head emergence.  

v. There have been reports of stripe rust in western Idaho and on June 16 and June 30, 2020 from southern Alberta, specifically the Counties of Lethbridge, Cardston, and Forty-Mile.  On June 19, 2020 there was a report in Alberta with the observation of stripe rust in winter wheat yield trials at AAFC Beaverlodge.  Stripe was also just observed in wheat plots at the University of Saskatchewan in Saskatoon (Randy Kutcher, personal communication).  Given the appearance of stripe rust in three counties in southern Alberta, at Beaverlodge in the Country of Grande Prairie, and the first observations in the Saskatoon area of Saskatchewan, farmers in these regions should be on the look out for stripe rust in wheat.  Special focus should be on wheat fields seeded to varieties rated as susceptible or moderately susceptible.  These recent observations indicate that Prairie regional sources of inoculum may become more important with further crop and disease development.  

vi. Thus, as of June 29, 2020 the risk of stripe rust appearance from the PNW or from regional sources is low to moderate (Figure 12).  However, some locations may be at an increased stripe rust risk, especially where there were 4-5 reverse trajectory events from the PNW or in Prairie regions where stripe rust has been reported.


2. Texas-Oklahoma corridor
i. Currently, farmers in Texas and Oklahoma have or will soon be finished harvesting their winter wheat crops, and thus no longer represents a significant source of cereal rust inoculum for movement into the Prairie region.


ii. Thus, as of June 29, 2020 the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is nil and scouting for these diseases is not urgent.  

3. Kansas to Nebraska corridor 
i. Currently there appears to be relatively low levels of stripe rust development in the Kansas to Nebraska.  Looking at specific locations in Prairie region and reverse trajectories, only 8 of 29 locations had only 1-2 days each with reverse trajectories originating over the states of Kansas and Nebraska from June 23-29, 2020, with the remaining locations having zero.  Locations with 1-2 days with events included: Gainsborough (2), and Yorkton (1), SK; and one event each for Brandon, Carman, Dauphin, Portage, Russell, and Selkirk, MB.  The remaining locations had no events from June 23-29, 2020 (data not shown).  

ii. Prairie temperatures were warmest in MB and eastern SK and seven day cumulative varied across the prairies (Figure 7).  Average 7 day temperatures continue to be warmest across MB and eastern SK and coolest across most of AB (Figure 7) . The weekly average temperature at Winnipeg (20.8C) was 6C warmer than Grande Prairie.  Cumulative rainfall for the past 7 days was variable (Figure 9). Cumulative 30 day rainfall was greatest across central regions of AB. Rainfall amounts were lower across the southern prairies (Figure 10).

iii. Winter wheat crops are progressing into flowering or are finishing flowering, while Prairie spring wheat development ranges from tillering to booting/head emergence.  

iv. In Kansas the winter wheat crop is rapidly maturing with harvesting occurring in some areas, and thus no longer represents a significant source of rust inoculum.  The Nebraska winter wheat crop has mostly headed and in some areas is starting to turn with harvest 1-2 weeks away.  With the Nebraska winter wheat crop progressing towards maturity and harvest, and given limited reports of disease, this state is becoming less of a potential source of rust inoculum.  

v. Thus, as of June 29, 2020 the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is limited and scouting for these diseases is not urgent (Figure 13).


vi. There continue to be reports of low levels of stripe rust in South Dakota and Wisconsin.  Thus, given the proximity to the Prairie region, these reports serve as a warning that farmers and crop scouts in the central to eastern Prairie region of Canada should be on the look out for stripe rust, especially in winter wheat fields.

4. Rust appearance in the Prairie region
i. Where farmers or consultants noticed stripe rust development on winter wheat in the fall of 2019, it is recommended to scout winter wheat fields that have resumed growth in spring 2020.  Scouting is especially critical where the variety being grown is susceptible to stripe rust.  

ii. Currently, there have been five reports of the initial appearance of stripe rust on Alberta winter wheat on June 5, 16, 19, and 30, 2020 in the Counties of Lethbridge, Cardston, and Forty-Mile in southern Alberta and in the County of Grande Prairie in the Peace Region of Alberta (Figure 2).  On July 2, 2020 there was also an initial report of stripe rust in the Saskatoon region (R. Kutcher, personal communication).  Given the appearance of stripe rust, farmers in these regions should be on the look out for stripe rust in wheat.  Special focus should be on wheat fields seeded to varieties rated as susceptible or moderately susceptible.