Stripe Rust Update, April 17, 2022

Stripe Rust in the Pacific Northwest

By Dr. Xianming Chen

On April 13 and 14, we were planting spring cereal nurseries and taking the first notes of the winter nurseries at Mount Vernon, Washington. The winter plants were at jointing stage ranging from Feekes 4 to 6. Wheat stripe rust was up to 60% severity on susceptible varieties (Figure 1). Barley stripe rust up to 40% severity was observed on susceptible varieties. Although barley stripe rust was relatively uniform and severe compared to this time of the last year, the severity of wheat stripe rust is normal for this location.

On April 15, we were checking winter wheat fields in the Horse Heaven Hill area in Benton County, Walla Walla County, Columbia County, and Garfield County of WA and Umatilla County of Oregon. Winter wheat ranged from Feekes 3 to 6. No rust was found on wheat plants, but stripe rust was found on wild grass (Figure 2) in our winter wheat stripe rust monitoring nursery at the Hermiston Station, OR. No stripe rust was found in the monitoring nursery at Walla Walla, WA, different from the observation of stripe rust at this location this time of the last year.
FigureStripe rust on winter wheat.Figure 1. Wheat stripe rust in winter wheat nurseries at Mount Vernon, WA on April 14, 2022Stripe rust on wild grass. Figure 2. Stripe rust on wild grass (Hordeum spp.) in a winter wheat nursery at Hermiston, OR on April 15, 2022Similarly, stripe rust was observed on wild grasses, but not on wheat plants in our winter wheat nursery and breeding nurseries at Central Ferry, Garfield County, WA on March 30, when we were planting spring cereal nurseries.As stripe rust pressure is currently low in the eastern PNW, fungicide application is not recommended in the early growth season for winter wheat, unless stripe rust is observed in fields.

Stripe Rust in the Country

In addition to Washington and Oregon, wheat stripe rust has been reported so far in Louisiana and Texas.