Xianming Chen
Stripe Rust of Wheat
In 2016, stripe rust was widespread in North America including Mexico, Canada, and the United States. In the United States, stripe rust was reported in 31 states (Texas, Oregon, Louisiana, Arkansas, Oklahoma, Washington, Colorado, Kansas, Mississippi, Georgia, California, Virginia, Montana, Indiana, Idaho, North Carolina, Tennessee, South Dakota, Kentucky, Illinois, Nebraska, Minnesota, Delaware, Florida, Michigan, Ohio, Wisconsin, Utah, North Dakota, Wyoming, and New York), the most wide distribution since 2010. The widespread and severe epidemic was mainly caused by weather conditions (mild winter, wet spring and early summer, and cool late spring and early summer) favorable to the pathogen survival during the winter time and to the disease development in the spring and early summer in most wheat growing regions.
In the Pacific Northwest of the United States (Idaho, Oregon, and Washington), stripe rust started much earlier than normal in most wheat growing areas due to the mild winter. Higher than normal precipitation from March to May and close to normal precipitation in June allowed stripe rust developed fast. The stripe rust season in the most wheat growing regions east of the Cascade Mountain range was very long, from early March to middle July, with active stripe rust pustules still on green plants of spring wheat in eastern Washington and northern Idaho in late July. Yield loss on highly susceptible varieties in experimental fields around Pullman, WA is estimated over 60% without fungicide applications. In commercial fields, stripe rust was generally under control by growing resistant varieties and widely using fungicides. The majority of wheat fields received fungicide application at the time of herbicide application, and many fields were sprayed two times or even three times. Although stripe rust is severe, Pacific Northwest has a bumper harvest in 2016
Stripe Rust of Barley
In contrast to wheat stripe rust, stripe rust was generally at low levels on barley. Barley stripe rust occurred in California, Oregon, Idaho, Washington, and Montana. A sample of stripe rust on barley was received from Minnesota in late July.
Other Rusts in the Pacific Northwest
Leaf rust of wheat was relatively low compared to the past in northwestern Washington, and basically absent in eastern Washington, with one sample collected in the Palouse region in late July.
Stem rust of wheat was also low in the Palouse region, and only one sample from one experimental line was collected in an experimental field in the region.
Barley leaf rust was severe in experimental fields at Mount Vernon in northwestern Washington, similar to the years in the region.