Rust Update 4/17/10

April 17, 2010

Xianming Chen
Rusts in western Washington

We completed the first rust note-taking for the winter nurseries at Mt. Vernon on April 14. Wheat and barley were in mid jointing stage (Feekes 6-7). Both stripe rusts of wheat and barley reached 80% severity on susceptible entries, which was slightly higher than the rust at this location last year. Leaf rust of barley reached 60%, while leaf rust of wheat was not found. Powdery mildew was found on lower leaves of some wheat and barley entries. Scald was severe on some barley entries. In commercial wheat fields, stripe rust infection was common and most fields had been sprayed with fungicides.

No stripe rust in eastern Washington

On April 15, we were scouting wheat fields in the Horse Heaven Hills and Walla Walla regions and did not found rust. Last year, stripe rust was first found in these regions on April 17. Plants in most fields ranged from late tillering (Feekes 3) to mid jointing (Feekes 6), and had been sprayed with herbicides that might be mixed with fungicides for stripe rust control.

Stripe rust found in northern Oregon

We found two leaves with small sporulating pustules in wheat nurseries at the Hermiston Experiment Station. Stripe rust just started appearing.

Stripe rust in other states

Based on the reports from collaborators, stripe rust of wheat is widespread and causing damage in Texas and Louisiana and has been reported in Arkansas, Oklahoma, and Mississippi. In California, stripe rust of wheat was widespread and severity reached 90% on susceptible entries in experimental fields. Stripe rust was also found on rye and barley in California.