Previous PCDMN blog posts have highlighted potential emerging stripe rust issues in the USA; unfortunately this may mean stripe rust issues for Prairie wheat growers. Stripe rust risk forecasts from Dr. Chen, USDA-ARS and Washington State University (WSU), indicated the risk of stripe rust for 2024 for the eastern PNW is severe and susceptible winter wheat varieties will potentially incur yield losses (https://www.wawg.org/stripe-rust-report-warmer-november-december-dont-bode-well-for-susceptible-varieties/; https://smallgrains.wsu.edu/first-stripe-rust-forecast-of-the-2024-season/; https://www.wawg.org/march-1-stripe-rust-forecast-calling-for-epidemic-levels-for-eastern-washington/). In addition, Dr. Chen reported stripe rust symptoms, indicating overwintering of stripe rust on winter wheat in the Pacific Northwest (PNW). On March 19, 2024, Dr. T. Murrary, WSU, referred to Dr. Chen's forecasts and emphasized a potential stripe rust issue for the PNW in 2024, while indicating that not since February 2011 have symptoms of stripe rust been observed this early (https://smallgrains.wsu.edu/stripe-rust-324/). Overall, rust risk forecasts for the PNW and the early occurrence of symptoms suggest the PNW may be an important source of stripe rust inoculum for Prairie wheat growers in 2024.
In addition to the occurrence of symptoms in the PNW, there have also been multiple early reports of stripe rust on winter wheat in Texas and Oklahoma in late February and continuing into late March ( (S. Baker, Stripe rust at Chillicothe, TX, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, February 26, 2024; https://twitter.com/J_SBaker/status/1752818506674929882). Most recently Dr. M. Aoun, Oklahoma State University (OSU) wheat pathology program, reported that stripe rust is developing in Jackson and Tillman Counties in SW Oklahoma (https://spotlight.okstate.edu/wheat-pathology/2024/04/02/wheat-disease-update-2-april-2024/; https://twitter.com/OSUwheatdisease/status/1775200213545959453; https://twitter.com/osuwit/status/1774638870660804917; https://twitter.com/OSUwheatdisease/status/1772315284025593930; https://twitter.com/OSUwheatdisease/status/1770869304529199247). Interestingly, Dr. B. Carver, OSU wheat breeder, indicated that not since the "early 2000s" have there been such early observations of increased levels of stripe rust. Dr. M. Aoun also observed stripe rust symptoms in research plots in Payne County, and suggested that forecast cooler wetter conditions could promote further stripe rust development in Oklahoma.
Although no stripe rust in Kansas has been reported, Drs. K. A. Onofre and E. De Wolf, Kansas State University, recently indicated that observations from Texas starting in late January 2024 and favourable weather conditions suggest stripe rust may be an issue in 2024 (https://eupdate.agronomy.ksu.edu/article_new/outlook-for-stripe-rust-in-2024-kansas-wheat-crop-584-3). They emphasized the value of monitoring winter wheat for stripe rust symptoms as further crop development occurs. Further development of stripe rust in the Texas to Nebraska corridor over the next 1-2 months could pose a risk for Prairie wheat growers, especially in central to eastern regions.
Stay tuned for our regular weekly PCDMN rust risk forecasts starting in mid-May (https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html), while further updates on the US rust situation will be posted on the PCDMN blog.