WENATCHEE -- Softer pesticides are working against the cherry fruit fly, and another cherry pest can be controlled usually by removing piles of prunings and old wood from orchards, tree fruit experts say.

GF-120, a bait for the cherry fruit fly that's squirted -- not sprayed -- on trees, kills flies that feed on it and probably will be more heavily used this year, Tim Smith, Washington State University Extension tree fruit specialist, told orchardists at the North Central Washington Stone Fruit Day last Tuesday.

About 300 growers attended the one-day conference at Wenatchee Center which was sponsored by the WSU Extension and the Washington State Fruit Commission.

Spinosad, the active ingredient in GF-120, is biologically derived from a fermented bacteria discovered in an abandoned rum distillery on a Caribbean island in 1982 by a vacationing scientist.

Spinosad, which is used in the softer pesticides Success, Spintor and Entrust, is "beyond belief safe," is almost non-toxic to mammals and is not an organophosphate or carbamate pesticide, Smith said. Organic growers have accepted spinosad as an organic product, he said.

Organophosphates and carbamates, generally regarded as harsher pesticides, include guthion and malathion and have effectively controlled the cherry fruit fly for many years.

Some softer pesticides not only kill adult flies but may kill young larvae after they enter cherries which would be a first in pre-harvest treatment, Smith said.

The cherry fruit fly, native to North America, is the primary sweet cherry pest in the Northwest. It is well controlled, rarely found in commercial orchards and, as a quarantined pest, isn't tolerated in packed fruit.

The cherry fruit fly lives in unsprayed backyard cherry trees and natural seedling trees, Smith said.

There are 650 backyards with cherry trees in the Wenatchee and East Wenatchee areas, alone, according to the Chelan-Douglas County Pest Board, Smith said. Not all have cherry fruit flies, he said.

Smith often is called to spray backyard trees that are infested. He said he will be looking for more this year to test softer pesticides.

Shothole borer, a bark beetle that leaves cherry tree bark replete with tiny holes, is a minimal pest industry wide but is a big problem for some growers, Smith said.

Little was known about it, and growers said they wanted to know more, he said.

At the Tuesday conference, Mike Doerr, research associate at the WSU Tree Fruit Research and Extension Center in Wenatchee, told growers what he's learned about the bug in two years of research. He said the best way of controlling it isn't with pesticides but simply removing prunings and wood piles from orchards. Shothole borers live in debris piles.

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