Wind trajectory and cereal rust risk assessment and need for in-crop scouting in the Prairie region, May 25- June 1, 2020
1. Pacific Northwest – There were a relatively high number of reverse wind trajectories that passed over the PNW region and into the prairies. Locations with the highest number of days with reverse trajectories from the PNW for May 26 to June 1, 2020 included: Beiseker (4), Lethbridge (7), Olds, and Provost, AB (4); and Kindersley, SK (4). However, currently there appears to be limited stripe rust development in the PNW, cool dry conditions over most of the Prairie region, except central Alberta, and early stages of Prairie spring wheat development. Thus, as of June 1, 2020 the risk of stripe rust appearance from the PNW is limited and scouting for this disease is not urgent. However, locations with 3-7 reverse trajectory events from the PNW may be at a slightly increased stripe rust risk, especially for winter wheat crops. As of June 3, 2020 there have been reports of stripe rust in western Idaho. Thus, given the proximity to the Prairie region these reports serve as a warning that farmers and crop scouts in the western Prairie region of Canada should be on the look out for stripe rust, especially in winter wheat fields in southern Alberta.
2. Texas-Oklahoma corridor – Currently, there is limited leaf and stripe rust development in this corridor. Moreover, there were a relatively low number of recent wind trajectories from this area for most prairie locations, cool dry conditions over most of the Prairie region, except central Alberta, and early stages of Prairie spring wheat development. Thus, as of June 1, 2020 the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is limited and scouting for these diseases is not urgent. Finally, crops in Texas and Oklahoma are at or approaching maturity with harvesting occurring in many areas in Texas and thus this region is of limited concern as a source or rust inoculum.
3. Kansas to Nebraska corridor – Currently, there is primarily some stripe rust development in Kansas, while we have had the first reports of stripe rust at low levels in Nebraska. Moreover, there were a relatively low number of recent wind trajectories from this area for most prairie locations, cool dry conditions over most of the Prairie region, except central Alberta, and early stages of Prairie spring wheat development. Thus, as of June 1, 2020 the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is limited and scouting for these diseases is not urgent. However, Brandon and Carman, MB had 3 and 2 days, respectively with reverse trajectory events from the Kansas/Nebraska region for May 26 to June 1, 2020, and thus rust risk may be slightly increased for these areas, especially for winter wheat crops. There are also initial 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. 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 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 winter wheat.