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Oregon State University scientists, in the search for more selective alternatives to traditional broad-spectrum pesticides, are testing a variety of new reduced-risk materials to assess their fit in tree fruit production. The list of new materials registered for cherries continues to expand.

Dr. Helmut Riedl and research associate Allison Walston, OSU entomologists at the Mid-Columbia Agricultural Research and Extension Center in Hood River, discussed results of field trials evaluating new insecticides and miticides for cherries during the Sweet Cherry Growers Symposium held at The Dalles, Oregon.

Field trials in cherries were conducted in 2003 and 2005 to compare the effectiveness of four new materials on obliquebanded leafroller—Avaunt (indoxacarb), which is registered on apples and pears but not yet on cherries, Intrepid, Success, and a new anthranilamide compound DPX E2Y45 scheduled for registration in two to three years. Different rates of the four materials were also compared in the study.

Riedl noted that all four products provided similar control in 2003, eliminating live leafroller larvae after seven days of application. In trials in 2005, Intreprid produced similar results as Avaunt initially, but provided longer control of larvae and pupae.

Two-spotted spider mites are becoming more of a problem in Oregon cherry orchards, he said. “We are seeing more, and we’ve seen some huge populations where webbing is all over the trees.”

Miticide trials to control two-spotted spider mites have been conducted in pear blocks, but the data is transferable to two-spotted spider mites in cherries, Riedl said. Field trial data collected in 2005 showed that Envidor, a newly registered miticide for stone fruit, is effective in controlling the target pest.

“We saw the eggs after application, but they don’t hatch,” he explained.

In a pear thrips trial on cherries, the OSU scientists compared Success, Entrust, and thiodan to an untreated check. While the standard treatment of thiodan provided the best and longest control, both Success and Entrust were effective.

Riedl also evaluated the soon-to-be registered Centaur against Lorsban (chlorpyrifos) for control of San Jose scale on apples. Results should be similar in cherry orchards with San Jose scale. Again, the new chemical, applied at the crawler stage, was not as effective as the broad-spectrum Lorsban applied at delayed-dormant stage, but it did reduce the number of crawlers.

“There are available alternatives for organophosphates on cherries,” he said, adding that new registrations are coming, though more may be needed.