Pest alerts on rise following mild winter

Codling moths are among the pests reported this spring. A mild winter allowed many pests to survive.

YAKIMA, Wash. — A presentation on the use of nematodes to attack codling moths and other tree fruit pests drew audible comments of amazement from growers Dec. 5 at the Washington State Tree Fruit Association annual meeting. 

Close-up video showing the microscopic organism burrowing into codling moth larvae gained first buzz among more than 200 growers. More chatter flowed later when presenter, Diana K. Londono, a scientist with BASF Corp., in response to questions, said the company has commercial nematodes available specific to spotted wing drosophila larvae and are working on one for mealy bugs, a vector for little cherry disease. Both are problematic in cherries.

Entomopathogenic nematodes, meaning nematodes specific to only infecting insects, can be applied through sprays or drip irrigation to tree canopies, trunks or soil to attack pests, Londono said. 

The nematode, steinernema carpocapsae, is specific to the codling moth and Oriental fruit moth, she said. Usage for apple aphids is being studied."

The microscopic round worms occur naturally in soil, but BASF is the world’s largest producer of them in large-scale bioreactors, she said. A bacteria inside the nematodes kills the insects, she said. 

“It’s not a silver bullet. You have to apply it with other things with chemicals or biological controls. It’s suitable for organic farming and it leaves no residue on crops,” Londono said. 

Londono’s talk was one of several in a session on disease and pest management.

Elizabeth Beers, entomologist at the Washington State University Tree Fruit Research and Extension Center, Wenatchee, reviewed the status of several pests and told about her field trials dispersing sterile codling moths from British Columbia by drone to disrupt codling moth mating in Okanogan orchards. She said she’s “cautiously optimistic” about it as a supplement to other treatments.

Beers said brown marmorated stink bug is spreading throughout the state and that she is enhancing the spread of a natural predator, samurai wasp of Asia, that is following it. 

Spotted wing drosophila are spreading slower than some pests. Apple clearwing moth, in the early stages of infiltration from Canada, and apple leafcurling midge are relatively new pests she’s monitoring. 

Spotted lanternfly, from Asia, was first detected in Pennsylvania in 2014 and hasn’t made it to Washington yet but loves grapes, Beers said.

Vince Jones, another center entomologist, talked about the redesign of the WSU Decision Aid System for growers and its new models forecasting the best timing for battling the apple grain aphid, rosy apple aphid and woolly apple aphid. New models also are coming for pear psylla and western tentiform leafminer, as are new fruit growth models for Honeycrisp, Fuji and Golden Delicious. 

Pesticide effect models will be released in January, and a new recommendation is to apply the first codling moth spray at 400 degree days instead of 375. 

Tobin Northfield, the center’s newest entomologist, said he’s excited to research how protective netting, wood mulch and weed management may keep pests down.

Louis Nottingham, a post-doctoral research associate at the center, reported on pear psylla trials and said a mixture of kaolin clay and oil called Surround still works best, followed by multiple applications of newer soft pesticides in summer. 

Peter Shearer, entomologist at Cal Poly State University, said oriental fruit moth, active in organic cherries in southcentral Washington, was found in East Wenatchee and Chelan for the first time this year and is likely to worsen. He said it is readily managed with mating disruption. 

Central Washington field reporter

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