Eastern Wash. looks for wireworms

Extension educator says insect pressure often misdiagnosed

By MATTHEW WEAVER
Capital Press

Aaron Esser has gone through a lot of pantyhose in his search for wireworms.

Esser, the Adams County director and Washington State University Lincoln/Adams County Extension educator, uses the material in solar-bait traps to catch the pests, which have caused significant damage in wheat fields in Adams and Lincoln counties in the past few years.

"I went through 1,300 pairs of pantyhose this year," Esser said.

The traps use a wheat-corn mixture, held in the pantyhose. The traps are soaked in water for 24 hours before seeding, then placed in a hole up to 6 inches deep, marked with a flag and covered with a piece of plastic to help keep them in place.

The traps are pulled out of the ground after seven to 10 days and inspected for wireworms.

If a farmer doesn't have any wireworms in the trap, he probably shouldn't worry, Esser said. One to four wireworms should be treated with traditional rates of insecticide, and more than four should be treated with higher rates.

Esser said he has found as many as 39 in one pair of pantyhose.

"I don't think any farmer's immune from wireworms," he said.

Many farmers have had wireworm damage misdiagnosed as a weed infestation, soil-borne disease or simply disappointing yields, Esser said.

Esser is asking farmers to look in their fields for wireworms in order to determine the pressure.

The pest causes patchiness and increases weed infestations, Esser said.

Wireworm pressures are lower this year than last, but they are still causing damage, from Lincoln and Adams counties down into Whitman County, he said.

He said he believes the reduced pressure is due to the weather, cooler temperatures during trapping and the cycling of the insects

He is looking at various seed treatments -- including implementing a fallow period, different crop rotations and higher rates of insecticides Gaucho and Cruzer -- to control the wireworm and minimize pressure in the fields.

Esser said he believes a lot of the damage has occurred because of the removal of Lindane from the market, which farmers historically used to control wireworms.

On one testing site, yield was 17 bushels per acre when controls were used, compared with 12 bushels per acre without control.

Even with increased treatments, Esser said, there is still more damage than there should be in some of the fields.

"We should have had over a 30-bushel-per-acre yield potential there," he said of the testing site.

But even with the damage on that field, using controls netted $30,000 more in profit than no control, Esser said.

He is working with various chemistries and working to get one-time approval from the Washington State Department of Agriculture to use the pesticide Regent, although he said it's uncertain whether that will happen.

"I'm not planning my whole scheme of wireworm management based upon it being available," he said.

Matthew Weaver is based in Spokane. E-mail: mweaver@capitalpress.com.