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).