Stripe Rust Update in Washington 3/19/10

March 19, 2010

Xianming Chen
No stripe rust found in eastern Washington

On March 16, I was checking wheat fields in Walla Walla, Horse Heaven Hills, and Kahlotus areas in eastern Washington and did not found any rust, as expected. Wheat plants in early planted fields reached early jointing stage (Feekes 5) and those in late planted fields was in two to five-leaf stage (Feekes 1-3). In general, wheat crop in Walla Walla were more advanced than other areas. In the Horse Heaven Hills area, more fields were planted late than in the previous years. In the last year, stripe rust was first found in mid April in the area. We expect to see stripe rust around that time this year. I stopped by the Hermiston Station in Oregon and did not found rust also.

Severe stripe rust in western Washington

As expected, stripe rust has become very active in the Mt. Vernon area. As today, rust severity reached 50% on susceptible checks in our experimental fields. The relatively more severe stripe rust compared to the most previous years is due to the dryer and warmer weather conditions since the winter time, which is more favorable to wheat growth and stripe rust development than more rains and lower temperatures for that area. Wheat plants reached late jointing stage (Feekes 8 and 9). This area generally does not provide direct inoculum for the eastern side. However, growers in the Skagit Valley should consider using fungicides if susceptible wheat cultivars were planted.

Stripe rust in other states

Wheat stripe rust is widespread in Texas and Louisiana. With the recent storms, the disease is expected to further spread northwards and eastwards. In California, stripe rust was found by Dr. Kelley Richardson on rye and grasses back to February 8, but no stripe rust on wheat has been reported so far.