Stripe Rust Update 4/4/13

April 4, 2013

Xianming Chen
Wheat stripe rust in Washington

We were check wheat fields in Whitman, Adams, Lincoln, Franklin, and Benton counties in eastern Washington, along Highways 23 and 21, the border of Adams and Lincoln counties, and Horse Heaven Hills yesterday (April 3). Winter wheat crops ranged from Feeks 3 to 6, mostly 3-5. No rust was found in Whitman Co. In the Ritzville and Odessa areas (Adams and Lincoln counties), stripe rust was relatively easy to found, mostly on the low leaves and actively producing rust spores. Sporulation (producing spores) was on leaves infected before the winter. Most fields in these areas were sprayed with herbicides and presumably with fungicides. In fields east of Connell (Franklin Co.), stripe rust was also found, although at relatively low incidences compared with the fields in Adams and Lincoln counties. In the Horse Heaven Hills area (Benton Co.), we did not find stripe rust. Herbicide (maybe with fungicide) application was done in most early planted fields.

By the last week, stripe rust had developed up to 20% incidence and 50% severity in susceptible spreader rows in our winter wheat nurseries near Walla Walla.

By early this week, stripe rust had developed up to 70% severity and almost 100% incidence in susceptible spread rows in our winter wheat nurseries at Mount Vernon (Skagit Co.) in northwestern Washington.

The stripe rust management recommendations made early last month are still valid. The early application of fungicides should be done together with herbicides in the fields grown with susceptible or moderately susceptible varieties or stripe rust can be found in the fields.

Wheat stripe rust in other states

In addition to Washington, wheat stripe rust has developed to significant levels in Arkansas, Texas, Louisiana, Mississippi, and California. Fungicides have been used to control stripe rust in these states.