Good Fruit Grower

February 15, 2017

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16 FEBRUARY 15, 2017 GOOD FRUIT GROWER I t took just two years for the powdery mildew that New York grape growers were trying to kill to develop resistance to their sprays. In 1997, growers began spraying azoxystrobin. They noticed resistance in 1999. Fortunately for Washington growers, they don't need to spray as often in their drier climate, and they can learn from New York, said Michelle Moyer, viticulture extension specialist for Washington State University. All the same, fungicide resistance is a real threat to Washington's grape industries, but growers can do things to manage it, Moyer told them in November at the Washington State Grape Society annual meeting in Grandview. Here are some of her tips: View FRAC as a friend: The organization, the Fungicide Resistance Action Committee, is a coalition of chemical manufacturers and university scientists that advise how to use products in a way that minimizes resistance pressure. Companies want their products to work for you. If they don't, you won't buy them. FRAC organizes fungicides into groups based on their modes of action to help growers rotate those products. Read up. Moyer recommends two websites that discuss fungicides and resistance: Pacific Northwest Pest Management Handbooks ( plantdisease/pesticide-articles) and FRAC ( resistance-overview). Keep the canopy open. Use irrigation management, pruning and other techniques to ensure your canopy remains open. Sunlight in particular is a natural killer of powdery mildew. Spray at the right time: Spray early in the season, before veraison. Avoid using synthetic materials if pow- dery mildew is already visible in the field. This includes late-season botryticides that also have activity against powdery mildew, as that timing might select for mildew resistance. Spray in the right place. Hit the canopy, not above or below it. That wastes chemicals and leads to resistance due to insufficient product hitting the plant. Putting the fight back in fungicide Grapes WSU extension specialist shares tips to overcome spray resistance. by Ross Courtney CALL TODAY for the dealer nearest YOU! We've got you covered Get results with The Wedge TOLL FREE: 855-855-0318 • (800) 876-2767 ® Prevents Fire Blight in Apples & Pears • Effective alternative to antibiotics • Ideal for IPM programs • Efficacy is comparable to conventional products • No development of pathogen resistance • No pre-harvest interval or chemical residues • Safe for bees and beneficial insects Blossom Protect ™

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