Experts anticipate stripe rust epidemic

Researchers at Washington State University predict the Pacific Northwest, including the Palouse, will see a stripe rust epidemic this year.

Stripe rust, a fungus that infects wheat and can sharply reduce wheat yields, is also known as yellow rust for the yellow spores it leaves on wheat, rye, barley and other grasses.

Xianming Chen, research plant geneticist for the United States Department of Agriculture Agricultural Research Service at Washington State University, said depending on the susceptibility of the wheat variety, stripe rust can reduce wheat yields up to 90 percent.

Chen said the fungus absorbs water and nutrition from the wheat, and by doing so changes the color of the wheat and reduces photosynthesis, quality and yield.

He said stripe rust threatens wheat every year, but severe stripe rust years are caused by warm weather during the winter months, like what was experienced this past winter.

Chen said he has traveled around the Palouse in recent months and located stripe rust, which he added is currently quite common around Pullman.

He said he will continue to look for stripe rust this spring, but as wheat develops and changes color from green to yellow, the fungus becomes harder and harder to find.

While it’s expected to be a year where stripe rust experiences rapid growth, he doesn’t expect it will be as bad as 2011, one of the most severe stripe rust years.

“The earlier it’s detected, the more severe,” Chen said.

Usually stripe rust will start popping up on the Palouse during the second week of May, but he said it is being found about three weeks earlier this year, or one month later than it was detected in 2011.

Chen said 2011 also saw wet weather continue into the warmer months, which helped the fungus grow and spread.

He said this year is forecast to be warmer and drier than 2011.

Chen said in 2011 about 25 million bushels of wheat were lost to stripe rust. He said that was about an 18 percent to 20 percent loss in yield for winter wheat and about an 8 percent loss of spring wheat. He estimated this year will see about a 10 percent loss in winter wheat yields if fungicides are not used.

While the disease can be killed by fungicide, it can also be spread by the wind.

Chen said it is common to find the disease in the corners of farmers’ fields, which are often missed when it comes to being sprayed with fungicide.

“We have more stripe rust than any region in the U.S.,” he said. “This is the most damaging disease in our area on wheat.”