Wheat streak mosaic virus destroys about 20 million bushels each year

By MATTHEW WEAVER

Capital Press

Researchers are teaming up to fight wheat streak mosaic virus.

USDA's National Institute of Food and Agriculture recently awarded a $3.4 million grant to researchers. Montana State University Extension plant pathology specialist Mary Burrows is leading the Montana team, alongside researchers from universities in Colorado, Kansas, Nebraska, Oklahoma, Texas and the USDA Agricultural Research Service.

The states grow more than 1 billion bushels of wheat per year, and wheat streak mosaic virus destroys about 20 million bushels each year, according to MSU.

Pests such as the wheat curl mite carry the virus. The impact can range from negligible to 100 percent loss, Burrows said. Spring wheat is more susceptible than winter wheat.

The wheat curl mite and virus are both fairly common in the Pacific Northwest, said Washington State University plant pathologist Tim Murray. Because of lower temperatures during the growing season the concern isn't as great for Northwest farmers, he said.

By delaying fall seeding to late September or October, Northwest farmers avoid problems, Murray said. Spring wheat is seeded before conditions warm up enough for the insect and virus to become active.

There have been a few sporadic epidemics of the virus in the past 30 years in the northern belt of Washington around the Wilbur area, Murray said, particularly when a hail or thunderstorm occurs just before harvest in mid July or August. If the grain germinates, the virus could build up and infect the new crop when it's planted.

Efforts to develop a perennial wheat variety in Eastern Washington likely won't be successful unless there's good resistance to the virus, Murray said.

"Once the plant is infected, it remains infected for the life of the plant," he said. "It has the potential to become a reservoir for the (virus) and the insect vector."

The researchers are looking for chemical controls for mites. They will develop a map and model to predict risks for farmers.

High nitrogen levels encourage the disease, Burrows said.

"Often when a grower has a problem, he wants to add nitrogen to try to increase his yields, but what he actually does is make the disease a lot worse," she said.

There are some resistant varieties, but none in the northern Great Plains, Burrows said. New strains of the virus have been found in resistant lines, Burrows said.

Part of the project includes developing classroom lessons for students, Burrows said.