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Aphids suspected in wheat withering

Published on December 17, 2010 3:01AM

Last changed on January 14, 2011 6:39AM

Invasive insect a threat to cereal crops

Invasive insect a threat to cereal crops

OSU agents seek to confirm cause of baffling phenomenon


Capital Press

Aphids are emerging as a likely cause for withering thousands of acres of wheat in Oregon's Umatilla and Morrow counties.

In Umatilla County, the Oregon Department of Agriculture is investigating complaints of wheat dying on 16 fields totaling 4,000 acres in early November. In Morrow County, Oregon State University Extension agents are also investigating similar circumstances on 35,000 to 40,000 acres.

OSU Extension personnel have indicated aphids were present in Umatilla County, said Dale Mitchell, assistant administrator of the Oregon Department of Agriculture pesticides division in Salem.

But Mitchell said there hasn't been confirmation. His investigation is looking at many potential causes, including pesticides and plant pathogens. He said he will work with OSU staff to evaluate any relationship between aphid populations and the reported symptoms in Umatilla County. He is awaiting the results of plant residue and plant pathology sample tests.

Larry Lutcher, Oregon State University Extension agronomist in Heppner, Ore., expected test results on the Morrow County fields by the end of this week, but noted aphids are a likely cause.

There were many aphids in the area during the fall, including some Russian wheat aphids and a lot of bird cherry-oat aphids, Lutcher said.

"It's possible there are people out there that have experienced this before," he said. "We just haven't found them yet."

Echo, Ore., farmer Shannon Rust, the 2010 Morrow County president of the Oregon Wheat Growers League, said a similar situation occurred in 1998 or 1999. In that instance, the cause was aphids, she said.

This time, Rust said, she has heard about farmers spraying for insects and possible problems with the fungus pythium and root rot.

Lutcher will hold a meeting Jan. 11 in Ione, Ore., to discuss the situation in Morrow County and possibly Umatilla County "in greater detail."

Keith Pike, professor and entomologist at the Washington State University Irrigated Agriculture Research and Extension Center in Prosser, Wash., stressed he had not seen the fields first hand.

"I've never seen symptoms this time in the year -- late in the fall -- that would match up to what I'm hearing over the phone," he said.

Aphids possibly stressed the plants, which could have contributed to the situation, Pike said.

"I don't think it would necessarily be the only factor, based on what I've experienced over lots of years," he said.

In their 2010 aphid alert, OSU Extension agents Silvia Rondon and Mary Corp recommended growers check fields monthly in the winter and weekly in the spring. The alert cited an abundance of aphids in the fall of 2010.

Chris Rauch, who farms near Lexington, Ore., said he had experienced some yellowing on his wheat, but not withering of the entire plant. He attributed the cause to insects and weather.

"You see it from time to time, but maybe this year's a little more," he said. "In my case, I think it's more bugs. With the wet weather and wet ground, it could be bugs and some sort of disease."

The farmers who could tell they had a problem sprayed their fields earlier, Rust said.

One of her neighbors had seen some yellowing on his wheat, but sprayed for insects and saw an improvement as snow melted off the week of Dec. 6.

"He's very happy, just looking, but in the spring is when we'll really be able to tell," Rust said. "We'll just wait and see what happens, and then plan our attack mode after that."


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