Expert: Ag pest not likely a threat here

Winter's a killer for the spotted wing drosophila, a WSU professor said Thursday.


WALLA WALLA -- A insect that harms fruits in California, Western Washington and Oregon is not likely to be a threat here, a local pest control board was told Thursday.

The pest in question is the spotted wing drosophila, a midge-sized fly that attacks berry and grape crops, as well as other fruits. But the Walla Walla Valley's climate will likely prove a major barrier to the insect.

"Winter is really a bottleneck for these flies," said Douglas Walsh, a Washington State University professor and coordinator of the integrated pest management program at the WSU research station in Prosser.

Walsh spoke to the Walla Walla Horticultural Pest and Disease Control Board about the potential threat at its meeting Thursday.

In his talk, Walsh recapped how the pest has spread from Asia to the United States and elsewhere. But the insect "is a fair-weather fly," he noted.

Due to its climate, Walla Walla County is projected as being an unsuitable area for the fly to settle in, as is most of the greater Columbia Basin, Walsh said.

"I really think the growers here in the Walla Walla Valley are going to dodge the bullet here," he said.

Trapping programs have also indicated that where the fly is found in this region, the population starts very small and doesn't peak until late in the fall. By then, harvest seasons for host plants are finished or mostly finished.

"The fly isn't around when you're harvesting commercial fruits," Walsh said.

After a discussion, board members voted 3-1 to put the pest on its target list of pests to monitor and, if necessary, control.

"I think we all agree, potentially it's not a problem, but it's enough of a threat to monitor for," said board member Tom Waliser.

Andy Porter can be reached at or 526-8318.


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