Stripe Rust Update 5/30/03

May 30, 2003

Xianming Chen
Keynotes in this report
  1. Stripe rust is developing quickly on susceptible hard red winter wheat in the Palouse region.
  2. The club wheat ‘Edwin’ has stripe rust not seen before.
  3. Barley stripe rust is showing up in the eastern Washington.

Stripe rust is increasing on winter wheat in the Palouse region. On May 28, highly susceptible winter wheat lines had up to 20% stripe rust in our experimental nurseries around Pullman, WA. In a commercial field planted with ‘Columbia 1’, a susceptible hard red winter wheat, about four miles north to Pullman, stripe rust reached 5% severity and 10% incidence with highly susceptible infection types. The rust level in this field warrants fungicide application. In fields planted with soft white winter wheat, stripe rust infection was common, but mostly with resistant to moderately resistant reactions, as expected. A low level severity of stripe rust, but with susceptible infection types, was found in a winter wheat field near Genesee, Idaho. Stripe rust has not been found on spring wheat in the Palouse region yet, but is expected to show up on susceptible wheat fields soon.

On May 29, Gary Shelton and I was checking stripe rust in variety trials and commercial fields in Othello, Moses Lake, and Lind in Washington State. Various levels of stripe rust severities (from 1 to 10%) and reactions (resistant to highly susceptible) were found on both winter and spring wheat crops. In general, commonly grown cultivars had reactions to stripe rust as expected. However, ‘Edwin’, the second mostly grown club wheat last year, had intermediate to susceptible reactions at the Lind variety trial, which were not seen in the past. Fields of ‘Edwin’ should be watched for stripe rust development.

A week ago, it was reported that fields of the soft white winter wheat ‘WPB 470’ in the hill foot area of the Walla Walla County, WA had considerable stripe rust with hot spots. The field was recommended to spray.

As usual, stripe rust reaches its infection peak on winter wheat and barley, and is developing quickly on spring wheat and barley in northwestern Washington. Susceptible spring wheat entries had up to 30% of severity in the experimental nurseries at Mt. Vernon, WA by May 29. In this location, barley stripe rust is also developing in the spring barley nurseries.

This is the first report of barley stripe rust in the eastern Washington (regions east of the Cascade Mountains). On May 29, a winter barley field of ‘Hoody’ at the WSU Othello Experiment Station had 5% stripe rust with highly susceptible infection types. At the station, spring barley ‘Bob’ and ‘Calypso’ (98NZ223) had trace stripe rust on the lower leaves. In one of our spring barley nurseries near Pullman, WA, one pustule of stripe rust was found on May 28.

With showers today in many regions of the eastern Washington, northern Idaho, and northeastern Oregon and continuing rust-favorable temperatures forecasted for the next 10 days, stripe rust will continue developing in the Pacific Northwest.