Looking for new genes for resistance to wheat stem sawflies
“Current resistance based on solid stem doesn’t always hold up,” said Syngenta Northern Plains Wheat Breeder Joe Smith. “Syngenta feels additional sources of resistance would be useful. This kind of research is good for Montana growers, but also could be useful for growers in neighboring states that are experiencing sawfly problems.”
Lyle McKeever of Loma said MSU researchers have conducted wheat stem sawfly research on his farm for about 10 years. His son, Terry, will be involved in the upcoming study by letting the scientists grow test plots of wheat on his farm.
“This area has some of the worst sawfly pressure in the state,” said the younger McKeever.
Not sure why, Terry McKeever said climate, temperature and elevation could play a role. At any rate, wheat stem sawflies have invaded the family’s farms since the 1970s. What started out as a nuisance has turned into major losses of yield.
“Solid stem helps a lot but those varieties don’t have the yield potential that some of the hollow stem varieties have,” Terry McKeever said.
Lyle McKeever said he reduced his problem by planting two varieties of solid stem wheat and planting spring wheat instead of winter wheat, but solid stem wheat isn’t totally effective. In fact, he calls it semi-solid wheat because some wheat stem sawflies still make their way into the stems. Spraying isn’t the answer either.
“You can spray for wheat stem sawfly,” Lyle McKeever said. “But you have to spray about every other day each week because it keeps hatching.”
Weaver said Montana growers estimate that wheat stem sawflies cause approximately $75-100 million damage a year in Montana, making this insect the most destructive wheat pest in the state. Overall losses to this pest have been estimated at $350 million for the entire Northern Great Plains.
Talbert added that, “Montana is the epicenter for wheat stem sawflies in our part of the world, so it’s a bigger deal for us than most people.”
Unless their life cycle is interrupted, adult female sawflies lay their eggs in the spring inside the wheat stem. During the summer, the larvae eat the inside of the wheat plant, disrupting the movement of sugar and water, weakening the plant and reducing yields. At the end of the summer, the larvae cut the wheat stems at the base so it can emerge the next year.
“That certainly appears to be the worst thing it does,” Talbert said.