Researchers explore biological control options, carefully timed applications

By MITCH LIES
Capital Press

Northwest apple growers -- faced with a phase-out of organophosphate insecticides -- are adapting to new pest-control regimes, according to a Washington State University scientist.

Jay Brunner, an entomologist at the Wenatchee Tree Fruit Research and Extension Center, said growers appear to have successfully controlled codling moth and leafrollers in apples this year despite the initiation of a four-year phase-out of organophosphates.

Two insecticides registered last year, Delegate from Dow AgroSciences and Altacor from DuPont, apparently are helping.

"They appear to be working well," Brunner said.

Growers this year can apply a maximum of three treatments of organophosphates, or OPs. The EPA phase-out limits growers to a maximum of two applications next year and to one in 2011 and one in 2012.

Use of organophosphates in apples will be banned beginning in 2013.

Growers for years have relied on organophosphates as their primary control tool for codling moths and leafrollers, applying the product as much as five times in some years.

Brunner and other scientists are helping growers adopt new pest-control regimes that rely less on the broad-spectrum organophosphates and more on the new softer, target-specific insecticides.

As part of their new pest-control strategy, growers are relying more on beneficial insects to help control the damaging insects, Brunner said.

But while the new insecticides aren't as harmful to the biocontrol agents as organophosphates, they still apparently affect beneficial insects. Scientists now are studying if altering the timing of sprays minimizes the impact of the newer insecticides on beneficial insects.

Scientists in Washington, Oregon and California recently received a $2.25 million grant, part of which will be used to study when biological control agents are most susceptible to sprays.

One key to minimizing the activity on biocontrol agents is better understanding when beneficials are present, Brunner said.

"We have models for pests, but no models for their natural enemies," he said.

One secondary impact growers are experiencing from the loss of organophosphates is increased pressure from woolly apple aphids, Brunner said.

"While woolly apple aphid wasn't the target (of the organophosphate sprays), we know that using organophosphates for codling moth control suppressed woolly apple aphid," Brunner said.

Scientists are encouraging use of biological controls for the aphid in absence of organophosphates.

Staff writer Mitch Lies is based in Salem. E-mail: mlies@capitalpress.com.