Stripe rust in the eastern Pacific Northwest
Yesterday, we were checking winter wheat fields in Whitman, Garfield, Columbia, Walla Walla, Franklin, and Adams counties in Washington. Winter wheat ranging from early jointing (Feekes 5) to early flowering (Feekes 10.51). Stripe rust was not found in any of the checked commercial fields and not found in our stripe rust experimental plots in Central Ferry (Garfield County) and Walla Walla. Also, no rust was found in the breeding fields in Central Ferry, which was inoculated in the third week of April. In the Palouse region near Pullman, stripe rust developed to the level of relatively easy to find (Figure 1) in our winter wheat experimental fields, which were inoculated on Aril 10, and started producing spores in the experimental fields of winter and spring barley plots (Figure 2), which were inoculated on May 4. In our stripe rust monitoring nurseries in Walla Walla, stripe rust was usually first observed in early March and last year was on May 12. No rust at that location and other regions so far this year indicates a very low stripe rust pressure, which can be attributed to the very cold period of late December, 2022.
Figure 1. On May 16, 2023, stripe rust was observed in a winter wheat nursery near Pullman (Whitman Co.), WA, which was inoculated with wheat stripe rust on April 10.
Figure 2. On May 16, 2023, stripe rust was observed in a barley nursery near Pullman, WA, which was inoculated with barley stripe rust on May 4.
Because the current stripe rust pressure is very low, fungicide application is generally not recommended in the eastern Pacific Northwest. However, fields planted with susceptible varieties (stripe rust ratings 7 to 9), such as winter wheat varieties WB4303 and UI Magic and spring wheat WB6341 and WB-1035CL+, should be checked on a weekly basis, and a fungicide can be applied if rust is found.
Stripe rust in the country
So far, stripe rust has been reported on wheat in Texas, Washington, Oklahoma, Louisiana, Kansas, Virginia, and Oregon. In general, wheat stripe rust has been at low levels. In addition to Washington, barley stripe rust has been reported in Arizona.
Shipping address for stripe rust samples
As Johnson Hall has been demolished, and my office has been moved, please use our new shipping address for sending stripe rust samples:
Xianming Chen/Meinan Wang
410 SE Dairy Rd, 114B – 101
Pullman, WA 99164