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Expert tells farmers to get early handle of Russian thistle

Published on April 25, 2013 3:01AM

Last changed on May 23, 2013 8:50AM


Capital Press

A Washington researcher for the USDA advises farmers to get early control on the weed Russian thistle.

Frank Young, weed scientist and cropping systems specialist for the USDA Agricultural Research Service in Pullman, Wash., said the weed is prevalent throughout the season.

"It's a problem in the crop, it's a problem post-harvest and it's a problem in fallow," Young said.

Russian thistle can reduce yield by 50 percent if not controlled, Young said, since it competes for water, light and nutrients.

Young and Washington State University Extension specialist and professor Bill Pan have studied the weed and found that its roots grow extremely rapidly compared to its shoots, which gives it a competitive advantage in the growing crop.

After harvest, late-blooming thistle can use a lot of water during the fall growth period, requiring farmers to replenish during the winter.

A healthy winter wheat crop competes against the Russian thistle, which typically begins to emerge about this time of year or a little later.

Farmers can use chemical control or an undercutter, Young said. The weed is resistant to some herbicides, such as sulfonylureas like Finesse, Glean and Amber. Young recommends rotating herbicides and controlling the plant when it's small in the crop.

It's a little early for the weed to be emerging in fallow ground. If it does, Young said, it's extremely small and could be eliminated by recent frosts.

Young doesn't expect to see a higher amount of Russian thistle than normal, but hopes to give farmers enough information to work with it.

The weed springs up in rangeland, crop land and non-cropland, he said.

"It's a very prolific seed producers, from the Dakotas west in every state," he said. "It really loves the hot, dry weather."

Also known as tumble weed, it's an annual weed spread by seed.

"It's migratory because it tumbles - you can control it, your neighbor may not and then it might blow into your field from his," Young said. "Russian thistle and some of the mustards are what you see in the fall blowing across or racing you on the highway."

Larger tumbleweeds can produce several hundred thousand seeds, Young said.

"It's a constant issue, where it costs money to try to manage it," said Tereasa Waterman, education manager for the Idaho Wheat Commission, of Russian thistle.

The commission had scheduled a webinar devoted to the weed for April 30, but it has been canceled and will be rescheduled for a later date, Waterman said.

"It's kind of always there," Young echoed.




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