Cool, wet weather has caused a major outbreak of stripe rust this spring in much of Washington’s and Oregon’s wheat fields.

The window to make applications has disappeared for much of the wheat fields, according to crop development status reports. Once wheat is headed out there’s little to no economic benefit to applying fungicides, according to agronomists familiar with stripe rust.

Aerial application of fungicides in a timely manner is the main artillery being used to counter the fungus problem as quickly as possible. Aerial applicators have been flying sunup to sundown when the weather permits (other than days of wind and rain).

Xianming Chen, USDA Agricultural Research Service plant pathologist, reported around 2 million of Washington’s 2.3 million acres of wheat had stripe rust.

Capital Press provided an opinion shared by many in Washington. Most farmers had to spray twice, according to Tom Mick, CEO of the Washington Grain Alliance in Spokane. Some farmers were evaluating a third fungicide application as the window of application closed.

"This is devastating. We haven't had an outbreak like this in decades," Mick was quoted as telling Capital Press. "The economic impact right now is hard to determine. It will vary, region to region, but yields could be down 15 percent."

The rust is widespread in wheat on both sides of Oregon, too, and could result in an average crop loss of 10 percent, according to Mike Flowers, extension cereals specialist at Oregon State University. There are 950,000 acres of wheat in Oregon per the most recent USDA estimates.