Stripe Rust Found in Horse Heaven Hills and Walla Walla 4/17/09

April 17, 2009

Xianming Chen

Yesterday, I was checking wheat fields in the Connell and Horse Heaven Hills areas (south-central Washington). Winter wheat crop ranged from early tillering (FS 2) to middle jointing (FS 6). Plants in many fields were not uniform, resulted from the moisture problem after planting.

Stripe rust was found in three fields in Horse Heaven Hills. Two fields are grown with Finley and Finley Clearfield and cultivar in the third field was unknown. Rust incidents were below 0.1%. Such level of rust occurred later than last year. In 2008, stripe rust was found in the first week of April and the distribution and incident were higher than those found yesterday. Growers in this area should check their fields in the next two weeks, especially the lower leaves. Fungicides may be applied if rust developed to 5 to 10% incidence (percent of plants or leaves infected) and/or severity (percent of leaf areas infected). Cultivar Bauermeister has HTAP resistance while Buchanan and Finley are susceptible to stripe rust.

Dr. Anmin Wan also found stripe rust, also in a very low incidence level, on the susceptible check wheat in our field nursery near Walla Walla (southeastern Washington). Growers in the Walla Walla area also should check their winter wheat fields especially if a susceptible variety is grown.

As late March, stripe rust developed to 30% severity on susceptible entries in our nurseries at Mt. Vernon in northwestern Washington. Some commercial fields had up to 10% severity of rust on lower leaves. The rust level was little bit lower, but close to normal.

Nationally, stripe rust has been reported in Texas, Louisiana, Georgia, Arkansas, California, and Arizona. In general, stripe rust has been low so far this year.