Good Fruit Grower

December 2011

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Peter Hall explains how the Exosex mating disruption system works. Pheromone lures and pheromone-impregnated powder are placed in dispensers on a 20-meter (66-foot) grid in the orchard. Male moths that are lured into the dispensers, which resemble wing traps, and become coated with the powder. Their pheromone receptors become overloaded so they cannot detect females. When they exit the dispensers, the males act as mobile pheromone dispensers, causing confusion among other male moths and reducing their chances of mating. He applies it whenever the weather allows at a rate of 5 kilos in 500 liters of water per hectare (equivalent to around 5 pounds of potassium bicarbonate in 50 gallons per acre). Although he makes 20 or more sulfur applications a year, as well as numerous mildew sprays, research in Wales has shown that the carbon footprint of making so many passes through the orchard is still less than if he applied conventional fungicides, he said. "You're never going to find the perfect system unless you're going to have GMO [genetically modified organism] technology and your trees are going to generate their own nitrogen and harvest water from the atmosphere as well as being scab, mildew, and pest resistant," he commented. Pests The two major pests he has to deal with are the blue bug aphid (rosy apple aphid) and apple sucker (Psylla mali). Both appear in the orchard early in the season. As soon as the buds burst, he applies simple soap, preferably on a rainy day. "It's amaz- ingly difficult to find a mizzly day when you want one," he remarked. "It's easy when you don't." He finds soap as effective as conventional pesticides, and it allows predators to play a role as the season progresses. Also, it's unlikely that the pests will acquire resistance to drowning, he quipped. For codling moth, he uses mating disruption and the codling moth granulosis virus. Years ago, he tested a mating disruption system developed by BASF to control codling moth and tortrix (leafrollers). It worked like a dream, he said, but the company could not justify the great expense of registering the product for the relative small amount of crop it would be used on. Since 2007, he's been using Exosex. Fruit damage from codling moth at Hall's orchard has ranged from 0.5 to 1.5 percent. • We'll take your project from concept to completion. WA# CONCOC 132313 Call 509.848.3363 Fax:509.848.2038 www.concordconstructioninc.com www.goodfruit.com GOOD FRUIT GROWER DECEMBER 2011 49 geraldine warner

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