Stripe rust update 03/19: Disease found across Eastern Washington

By Dr. Xianming Chen

On March 18, we were checking wheat fields in Franklin, Benton, Walla Walla, Columbia, Garfield, and Whitman counties. Wheat plants ranged from Feekes 3 to 6. Stripe rust was found in all counties. In Franklin County, stripe rust has developed quickly since the field check on March 3, forming rust foci (hot spots) of several feet in diameter. In Horse Heaven Hills (Benton County), rust incidence was much higher, reaching 40% incidence. Most of infections were still on low leaves but producing large quantity of rust spores.

In Walla Walla, Columbia, and Garfield counties, stripe rust incidence and severity levels were much lower in commercial fields compared to Benton and Franklin counties, and almost all observed infections were on middle and top leaves, indicating recent infections. However, the disease was severe on susceptible varieties in our experimental field in Central Ferry (Garfield County), where wheat plants reached Feekes 6 and rust was over 90% incidence, 80% severity on low to middle leaves, and reached 40% incidence and severity on top.

In Whitman County, stripe rust was first reported on cultivar Nova AX in the Penawawa area in the southwest corner of the county on March 6 by Morgan Menaker, Washington State University regional Extension agronomist. Yesterday (March 18), we found stripe rust in our experimental fields on the Palouse Conservation Field Station near Pullman. The rust incidence was low, and infections were on the first leaves, indicating that infections occurred before the winter. The observation of stripe rust at this location was about 5 weeks earlier than normal and 3 weeks later than the detection in 2011.

According to Dr. Ray Qin, stripe rust has been found in our stripe rust monitoring nursery at the Oregon State University Hermiston Agriculture Research and Extension Center (Umatilla County, Ore.).

Recommendations for control of stripe rust are the same as the previous. Please refer to “Stripe Rust Forecast and Update, March 4, 2026” for details. Generally, please start checking your fields and use fungicides at the time of herbicide application, if you see rust.

Stripe rust in the country
Since March 4, 2026, there have been no new states with reported stripe rust. So far, stripe rust
has been reported in Washington, Oregon, California, and Texas.