The Pacific Northwest wheat crop is at the point when adult plant stripe rust resistance is kicking in and hot, dry weather has slowed the disease’s development, a top researcher says.
Stripe rust in winter wheat fields is under control, but low levels of rust pustules are still active in spring wheat, said Xianming Chen, research plant pathologist at the USDA Agricultural Research Service in Pullman, Wash.
Fungicide application is no longer needed except in late-planted fields, at higher elevations or where there is a lot of soil moisture, Chen said.
Stripe rust was still severe this year, especially in winter wheat, Chen said. Late plantings and early fungicide applications reduced the amount of stripe rust in spring wheat, he said.
The disease can reduce yields in a highly susceptible wheat variety by up to 60 percent. No highly susceptible winter wheat varieties are grown in the region, but popular varieties such as Xerpha, Clearfield 102 and Eltan can have a yield loss of as much as 30 percent, Chen said.
As farmers consider fall planting, Chen recommends that farmers consider a variety that has high resistance to stripe rust.
Syngenta Ovation has more resistance but still needed a fungicide application this year.
Spring wheat varieties JD, Diva, Louise, Whit, UI Platinum, Dayn and Glee are resistant. Babe, WestBred’s WB 1035CL+ and Syngenta’s SY 605 CL are particularly susceptible, he said.
Chen hopes to see more acres of the Washington State University soft white spring wheat Seahawk and the WestBred hard red spring wheat Expresso, which don’t require any fungicide applications.
In addition to the Western states, stripe rust has also been reported in Texas, Louisiana, Arkansas, Mississippi. Noth Carolina, Oklahoma, Kansas, Wisconsin, Virginia, Delaware, Tennessee, Michigan, Kentucky, Nebraska, Indiana, Georgia, Arizona, Montana, Colorado, South Dakota, North Dakota, Minnesota and New York.
Chen said the disease’s distribution was similar to last year. The biggest losses were last year in the Great Plains, while damage was less this year, due to relatively dry conditions in Texas, Oklahoma and Kansas, he said.