PORTLAND — Peter Shearer doesn’t like to be the bearer of bad news, but two of the region’s worst invasive pests are poised to attack fruit and berries again this year and researchers haven’t yet found a surefire way to stop them.
Speaking Tuesday at the Northwest Agricultural Show in Portland, Shearer said growers must closely monitor their orchards and fields to avoid damage from the spotted wing drosophila fruit fly and the brown marmorated stinkbug.
Shearer, an entomologist with Oregon State University’s Mid-Columbia Agricultural Research and Extension Center in Hood River, said traps and tight intervals of the proper pesticides are the best weapons for now. Researchers are looking for biological controls — a tiny wasp that feeds on stinkbug eggs shows some promise — but it’s too early to know if predator bugs will make a difference or cause more problems by attacking on beneficial insects.
Spotted wing drosophila caused significant damage to cherries in 2012, Shearer said, causing growers to be more attentive in 2013. They’ll have to remain vigilant this year, as the flies have shown they can survive Oregon’s chilly winters.
“They are ready to go when the weather warms up,” he said.
The stinkbugs were first found in the Pacific Northwest near the Portland International Airport in 2004, and have since spread south to the Willamette Valley, east up the Columbia River Gorge and into eastern Washington, Shearer said.
The first regional commercial damage occurred in Vancouver, Wash., in 2013, when the bugs harmed a grower’s peppers, apples and Asian pears, Shearer said. A localized infestation was discovered last year in Sacramento, potentially threatening severe damage to specialty crops. The stinkbugs love Oregon hazelnuts, Shearer said, and may develop a taste for California almonds.
Farmers in mid-Atlantic states deal with brown marmorated stinkbugs by “spraying and spraying and spraying,” Shearer said, but that practice kills off beneficial insects as well. “There goes our IPM (integrated pest management) programs,” he said.
Another speaker Tuesday, orchardist Tim Dahle, reviewed some of the novel methods he uses to grow cherries and pears in The Dalles and Hood River.
Dahle said he pays particular attention to restoring and maintaining organic material in the soil. In the orchard rows, he currently uses a system of irrigation tube topped by layers of wood chips, compost and fabric.
Straw, wood chips and cover crops such as creeping red fescue all help add nutrients, retain moisture and prevent erosion, he said. White fabric reflects light up into the center of trees, improving photosynthesis, Dahle said.
Dahle said he obtains wood chips by chipping old orchard trees and by hitting up landscaping crews, utility companies and road departments for extra material they may have. A box of cherries goes to those willing to drop off chips, he said.
“The battle of organic matter is one we have to win,” Dahle said. “It has to become our style of farming.”
To control mice and gophers in the orchard, Dahle has placed 150 nest boxes for barn owls and other predatory owls.
Even a 5 percent occupancy rate is worth the trouble, he said.
“Barn owls are worth thousands of dollars” in prevented damage, he said. “The number of pocket gophers they eat is phenomenal.”