2021 Cereal Rust Risk Report (May 12-20, 2021)

The latest Prairie wind trajectory cereal rust risk report is available for download now at the following link: May 12-20, 2021 report.  

As of May 20, 2021 the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows:

Pacific Northwest – Even though there were a number of reverse wind trajectories that passed over the PNW region and into the prairies, given limited stripe rust development in the PNW, generally dry Prairie weather conditions during the week of May 10-16, 2021, and early stages of Prairie crop development, as of May 20, 2021 the risk of stripe rust appearance from the PNW is limited and scouting for this disease is generally not urgent.

Texas-Oklahoma corridor – Given limited leaf and stripe rust development in this corridor (especially Texas), a smaller number of recent wind trajectories from this area, generally dry Prairie weather conditions, and early stages of Prairie crop development, as of May 20, 2021 the risk of leaf and stripe rust appearance from the Texas-Nebraska corridor is low and scouting for these diseases is not urgent. 

Kansas-Nebraska corridor – Stripe rust is continuing to develop in Kansas, and is progressing in Nebraska, while there were limited to no recent wind trajectories from this area into the central to western Prairie region.  However, there have been a number of trajectories that have passed over the central to eastern Prairie region.  Overall Prairie weather conditions have been dry during the period of May 10-16, 2021, and generally dry in Saskatchewan and Manitoba from April 17-May 16, 2021.  Prairie spring wheat development is still early, while winter cereals continue to develop.  As of May 20, 2021 the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is low for the central to western Prairie region and moderate (mainly for stripe rust) for the central to eastern Prairie region.  Scouting for these diseases in winter wheat fields is recommended over the next 1-2 weeks, especially those planted to stripe rust susceptible varieties. 

Recent reports of stripe rust in Minnesota and Illinois suggest more northerly development of this disease and as a consequence growers in the central to eastern Prairie region should be on the look out for stripe rust over the next couple of weeks, especially in fields planted to susceptible winter wheat varieties. 

Mid-week mini cereal rust risk update - May 19, 2021

There has been a significant increase in the number of wind trajectories, originating over a number of states in the USA, that have crossed the prairies (Fig. 1). These air currents may introduce cereal rust spores into to the Prairie region. ECCC trajectory models indicate that air trajectories, originating over the Pacific Northwest (Idaho, Oregon, Washington), have crossed Alberta, Saskatchewan and western Manitoba (Fig. 2). Trajectories originating over Texas and Oklahoma have passed over eastern Saskatchewan and Manitoba (Fig. 3). A third group of trajectories, originating across Kansas and Nebraska have also crossed eastern Saskatchewan and Manitoba (Fig. 4). Though these US regions can be a source of cereal rust spores, the ECCC models predict air movement, not actual occurrence of cereal rust spores.  However, stripe and leaf rust continue to develop in the Oklahoma to Nebraska corridor, while development of stripe rust has generally been more limited in the Pacific Northwest.  Dry conditions in some Prairie regions and early crop development, especially in relation to spring cereals, may limit the risk.  However, scouting of winter wheat fields over the next 1-2 weeks, especially those planted to stripe and leaf rust susceptible varieties, should be considered in Prairie regions where these trajectories have occurred. 

The full PCDMN weekly cereal rust risk report will be available later this week and will include an overview of the cereal rust situation in key source regions in the USA.  

The PCDMN thanks Ross Weiss and Meghan Vankosky, AAFC Saskatoon, Jennifer Otani, AAFC Beaverlodge, and the PPMN for passing along this recent wind trajectory information. 

Figure 1. Summary of the average number (5 day running average) of reverse trajectories that have crossed the Canadian prairies (May 1-19, 2021).

Figure 2.  The green region indicates potential introduction of stripe rust uredospores from the Pacific Northwest (Idaho, Oregon, and Washington) to the Canadian prairies (May 18-19, 2021).

Figure 3.  The green region indicates potential introduction of stripe and leaf rust uredospores from Texas and Oklahoma to the Canadian prairies (May 18-19, 2021).

Figure 4.  The green region indicates potential introduction of stripe and leaf rust uredospores from Kansas and Nebraska to the Canadian prairies (May 18-19, 2021).

Stripe rust in 2020

As of July 2, 2020, 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 (except of Figure 2 taken from Cereal Rust Report Week 8).  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.

Figure 2. Reported observations of stripe rust in Alberta as of June 30, 2020 (indicated by yellow highlighted areas). Reports are courtesy of: 1) Lethbridge County, Dr. Reem Aboukhaddour, AAFC Lethbridge, June 5, 2020 (https://twitter.com/ReemWheat/status/1269109731337142274); 2) Lethbridge County, Agronomist Lyle Jensen from June 16, 2020 (https://twitter.com/LyleJensen6/status/1272925759183577088); 3) County of Grande Prairie, personal communications on June 19, 2020 from Jeremy Hodges and Henry Klein-Gebbinck, AAFC Beaverlodge, Beaverlodge, Alberta; 4) Cardston County, personal communication, June 30, 2020, Mike Harding, AAF Brooks; and 5) Foremost area of the County of Forty-Mile, personal communication from Joal McCordick, Syngenta, southern Alberta, via M. Harding, AAF Brooks, June 30, 2020.

Read the full Cereal Rust Report for Week 8 (June 22-29, 2020).
Follow @PCDMN for updates.