Stripe rust update 05/17: Current pressure very low

By Dr. Xianming Chen

On May 16, 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 in our winter wheat experimental fields, which were inoculated on April 10, and started producing spores in the experimental fields of winter and spring barley plots, which were inoculated on May 4. In our stripe rust monitoring nurseries in Walla Walla, stripe rust is 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.

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 WB1035CL+, should be checked on a weekly basis, and 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