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Pest Management Don't forget cherry fruit fly Spotted wing drosophila has grabbed people's attention, but cherry fruit fly is still the key pest. by Geraldine Warner G rowers should not allow concern about the new pest spotted wing drosophila to divert their attention away from their key pest, cherry fruit fly, says Tim Smith, Washington State University extension educator. Spotted wing drosophila made headlines in 2008 when it was first reported in berries in California. Unlike other common vinegar flies, this species can infest fruit before harvest. The following year, California cherry growers were losing crops to the new pest. In 2010, it was reported as far north as British Columbia, Canada, and in parts of Washington and Oregon and was trapped in large enough numbers to cause industry alarm. But Smith said spotted wing drosophila was much more of a threat in California than the Pacific Northwest for several reasons. First, commercial cherry growers in California don't have cherry fruit fly and don't typically apply insecticides as the fruit ripens. In addition, because of the mild climate and abundance of other hosts, the pest can be active there year round. Even so, California growers have been able to control the fly the last couple of seasons by spraying with effective materials two to three weeks before harvest, Smith said. "Their situation is a lot worse than ours in terms of pest pressure, but they only had to alter their spray program a little bit to keep this pest under control." Disruption In the Pacific Northwest, the winters are cold, and fewer susceptible crops are grown. Cherries and stone fruits are vulner- able as they ripen on the tree, but trapping throughout Washington has shown that the pest is most active in the fall. Growers in early maturing districts might not even need to worry about the fly, Smith said. "It may not show up until you're done with harvest," he said. "We think in the fall it's getting on dropped fruit and it explodes because it has a lot of host material to live on." In terms of market disruption, cherry fruit fly has a much greater potential impact for Northwest producers, Smith said. Though countries that don't already have spotted wing drosophila don't want it, there are not many places where it is a quarantine pest. It is native to Asia, and so is not a trade issue in that region. The pest spreads very rapidly, and before long will probably be found worldwide, Smith said. Northwest growers should keep in mind that cherry fruit fly is their key pest, because of the serious quarantine ramifications. He believes that the number of cherry fruit fly larvae found in fruit at warehouses increased last year as people became more concerned about the new pest. Previously, many growers had been successfully controlling cherry fruit fly with the GF-120 (spin- osad) bait, an attract-and-kill product that can be quickly and cheaply applied to trees from an all-terrain vehicle. "Last year, we advised you not to use GF-120 because it's not really effective against spotted wing drosophila," Smith said. "We take that halfway back now. I think you can use GF-120, especially early in the season." Not vulnerable Cherries need to be protected from cherry fruit fly for about four weeks before harvest. During the first half of that period, the fruit is probably not very vulnerable to spotted wing drosophila, and few drosophila are around, so growers can use GF-120 for the first couple of weeks and then use products that will control both pests for the last two weeks, Smith said. "So, you can get out your GF-120 sprayers and four- wheelers and concentrate on effective cherry fruit fly early on and shift over when we start telling you spotted wing drosophila has shown up in your area, or, if you trap for them, you find them," Smith said. He noted that the spotted wing drosophila is not a difficult insect to kill. WSU entomologist Dr. Elizabeth Beers said spinosad products, such as Entrust, Success, and Delegate, are now labeled for control of spotted wing drosophila. The residues seem to dissipate quickly on the fruit so that they're not likely to exceed maximum residue levels in overseas markets. • ISOMATE -CM FLEXTE - CM FL -CM F L E X ® LEX ating Disruption Technolog echno Sustainable Mating Disruption Technology for Your Growing Needs of 200-400 dispensers per acre off 200-40 00 dispensers per acr pensers per acr www.goodfruit.com GOOD FRUIT GROWER MARCH 1, 2012 21 pe MICHAEL BUSH