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Stripe Rust Update June 25 2015

By Xianming Chen
Stripe rust in Washington

Based on field observations in this week, winter wheat ranged from milk to ready to harvest and spring wheat from heading to soft dough stage depending upon locations. We have pretty much finished stripe rust note-taking in winter wheat nurseries across the state. In western Washington, stripe rust developed to 100% severity on susceptible varieties in our spring wheat experimental field near Mount Vernon (Skagit County). In eastern Washington, stripe rust varied in levels. At Lind (Adams County), susceptible entries of spring wheat had up to 5% severity, similar to the level of last report on June 11. At Walla Walla, spring wheat susceptible varieties had up to 80% severity near Walla Walla (Walla Walla County). Around Pullman (Whitman County), susceptible varieties of winter wheat had 80-100% severity and susceptible spring wheat varieties had up to 50% in our experimental nurseries. In the Syngenta breeding nurseries about five miles southwest of Colfax (Whitman County), up to 100% incidence and 80% severity occurred in some susceptible winter plots, and in the spring wheat field susceptible varieties had up to 100% incidence and 60% severity.

No significant stripe rust was observed in commercial fields of winter wheat and spring wheat due to resistance, early application of fungicides, and the drought since the second week of June in the spring wheat production regions.

Based on the weather forecast, the hot (upper 90s and three-digit temperatures of day time high) and dry weather conditions over this weekend and the next two weeks should stop stripe rust development.

Stripe rust in the country

Severe stripe rust continues damaging crops in Colorado, Nebraska, South Dakota, North Dakota, and Wisconsin, making 2015 another big epidemic year.

Washington State University