Montana researchers scan wheat lines to fight sawfly

A five-year $500,000 USDA grant will help Montana State University researchers screen wheat germplasm for resistance to the rising pest wheat stem sawfly. It's moving southward, but there's potential for the insect to turn up in the Pacific Northwest, based on a history of sporadic outbreaks, says MSU entomologist David Weaver. Weaver says efforts could help fight the sawfly throughout wheat-growing regions in the northern hemisphere.
Matthew Weaver

Capital Press

Published on November 15, 2013 8:12AM

The federal government is supporting Montana researchers working to eliminate the growing insect pest wheat stem sawfly.

The USDA National Institute of Food and Agriculture has provided a five-year $500,000 grant to Montana State University researchers, including wheat breeder and project leader Luther Talbert.

MSU entomologist David Weaver said the grant aids efforts to evaluate ancestral wheat lines for host-plant resistance for the insect. Certain traits in wheat might influence how likely a female insect is to lay eggs or kill most of the pests, he said.

The researchers will screen 4,000 to 5,000 wheat lines for resistance traits, according to an MSU press release. New resistance genes will be incorporated into new varieties of wheat.

Sawflies are historically located in wheat-growing areas in Montana, South Dakota and Wyoming. They are spreading southward to Nebraska, Kansas and Colorado, which is unusual, given the logistics suggested by global warming trends, Weaver said.

"The grass is ripening earlier and it's synchronizing closer to when the wheat is harvested," he said. "It's making it so the insect is shifting to use wheat more than it would have historically."

The sawflies have been found in the Swan Valley of Idaho and have turned up in Washington in small outbreaks in the last decade, in the Palouse and Snake River basin.

"The fact that it happened once suggests that you can definitely have the potential to have a wheat stem sawfly problem in your area," he said.

Sawflies are a global issue in wheat-producing regions in the northern hemisphere, Weaver said, and finding varieties that sawflies tend to die in could help efforts worldwide.

Other options include trap cropping, or planting varieties that females like to lay eggs in on the outside of fields and varieties they don't like on the interior, and use natural enemies like parasitic wasps.

Solid-stem wheat varieties are typically the most effective protection against the sawfly, but come with a diminished yield, said Cassidy Marn, marketing director for the Montana Wheat and Barley Committee.

Because the sawfly primarily damages the stem and not the kernel's quality, many producers wind up swathing their crop later, which increases fuel costs, Marn said.

Sawflies overwinter in the soil, making insecticide application difficult.

Marn said rotation crops have helped, but the sawfly is moving into barley and winter wheat from spring wheats.

MSU is in the process of completing an economic study on the impacts of the sawfly. The committee believes the sawfly will damage 15 to 20 percent of the state's total wheat production each year, Marn said. According to the university, Montana growers estimate roughly $75-100 million damage each year in Montana and estimated $350 million in overall losses for the entire Northern Great Plains.

Weaver hopes to be narrowing down on the targeted resistance genes and working to breed the traits into existing germplasm at the mid-point of the five-year grant.

David Weaver and Matthew Weaver are not related.



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