Wheat virus is bigger problem in Pacific Northwest than previously thought

Wheat soil-borne mosaic disease is a bigger problem in the Pacific Northwest than previously thought, according to a recent study.

An Oregon State University research team found that the virus that causes the disease is more widely distributed in the Walla Walla Valley – and causes more yield loss – than previously estimated. Significant reductions of grain yield, biomass and heads per area have been documented in association with the virus that causes the disease. The disease as first detected in the valley along the Oregon and Washington border in 2008.

For their study, the researchers conducted yield loss estimates due to the disease in 15 commercial winter wheat fields across the Walla Walla Valley in the spring seasons in 2017 and 2018, in the highly susceptible winter wheat variety, UI Magic. Yield loss estimates associated with the disease were made from severely infected patches within fields.

The researchers’ findings have been accepted by the journal Crop Protection and are in the process of final publication. The Oregon Wheat Commission provided funding for the study.

Christina Hagerty, an OSU assistant professor and wheat pathologist, was the lead author on the study. Hagerty conducts research and performs OSU Extension outreach at the Columbia Basin Agricultural Research Center outside of Pendleton.

“Since 2008, Extension efforts have increased awareness of wheat soil-borne mosaic symptoms among growers in the Walla Walla Valley,” Hagerty said. “So, it’s possible the virus distribution hasn’t expanded since 2008, but it is only now being recognized and accurately diagnosed.”

Soil-borne wheat mosaic virus can cause severe stunting and yellow-pale green mosaic pattern in susceptible wheat, barley and rye cultivars that are planted in the fall.

The first visual evidence of infection in a growing season usually occurs in the spring, after the crop begins to green up. However, in some years the symptoms are expressed in the late fall or early winter, especially in warmer climates.

Growing resistant or tolerant varieties is the most effective method of control.

Hagerty is the co-author of an OSU Extension field guide for diagnosing wheat soil-borne mosaic disease and other common wheat maladies of the Pacific Northwest.

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