Good Fruit Grower

July 2016

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30 JULY 2016 Good Fruit Grower A trio of pest consultants has concluded that transporting urban organic waste would likely spread the dreaded apple maggot to orchards in rural Washington and rec- ommended heating yard and food scraps before hauling them to areas the pest hasn't already reached. The consultants published their results in early May in a pest risk assessment, gauging the likelihood that the apple maggot would hitch a ride on compost feed stocks hauled from areas quarantined for the pest — primarily the Puget Sound region — to eastern Washington compost facilities. Today, the 271-page, $200,000 technical document, paid for by fruit industry assessments, provides a guidebook for state officials, recycling companies, cities and counties searching for a way to meet a growing demand to compost while still protecting Washington's most valuable agricultural commodity from one of its most feared pests. The goal is to do both, to "co-exist," said Laurie Davies, manager of the Washington state Department of Ecology's Waste to Resources program, which regulates commercial scale composting. "We don't want solid waste to stop moving because of apple maggot," she said. "If it doesn't move, we have a health issue." About the assessment The assessment paints an alarming picture for the spread of apple maggot, or Rhagoletis pomonella, a pest common in feral orchards and backyard fruit trees in much of western Washington but quarantined since the 1980s to prevent it from reaching the eastern Washington counties that produce apples. The apple maggot directly attacks fruit, turning the flesh brown and mushy and causing apples to drop early. It has never been found in commercial fruit in Washington, yet many international trading partners consider it a pest of concern. The consultants from Colorado, Massachusetts and England concluded the risk of spreading the maggot through waste hauling is "likely to occur with low uncertainty" if compost companies do not treat it first. They traced four hypothetical routes for the maggot, called pathway analyses, each through a different eastern Washington composter, and gauged different levels of risk. Every composter handles their feed stocks, sometimes called municipal green waste or MGW, in different ways. Overall, the risk posed by R. pomonella moving on waste from the quarantine area is unacceptable, they determined. Tree fruit industry officials praised the report's strong language for validating their concerns. Their painstaking methodology left few stones unturned and little room for argument, said Mike Willett, manager of the Washington State Tree Fruit Research Commission. For example, consultants normally would run only one pathway analysis, he said. "There was dispute about how much pest risk there was," said Jon DeVaney, president of the Yakima- based Washington State Tree Fruit Association, which represents growers and packers. The third-party document concludes that the risk is "higher than a lot of people suspected." The state still has a long way to go before implementing any of the recommendations or allowing any more transfer of yard compost outside the quarantine. The state currently has imposed a moratorium on any such transfers. The consultants, all well known in the pest control industry, suggested mechanically heating the compost material to kill all life stages of the apple maggot before moving it across quarantine lines. Entomologists from the U.S. Department of Agriculture have shown that heating will work in small quantities but have not tested it on a broad commercial scale. (See "Dealing with apple maggot in yard waste" in the March 1, 2016 issue.) State officials will lean on the assessment to develop protocols for ensuring the yard waste is treated, said Kirk Robinson, deputy director of the Washington State Department of Agriculture, the agency charged with preventing the spread of farm pests. They have no deadline in mind for that to happen, he said. History of green waste Composting, though more common as urban areas have grown, is not new. Over the past 20 years, the state Department of Ecology has been regulating the disposal of food scraps and yard clippings from cities through composting to divert it from landfills, where it may leach into groundwater and cause greenhouse gasses as it breaks down. The Ecology Department writes the regulations while county health districts issue permits. For years, the city of Seattle had sent much of its waste to Cedar Grove, a company with facilities in Everett and Maple Valley, helping turn compost into a business enterprise. "It is a commodity and it's a big business," said Davies of the Ecology Department. However, composters in Puget Sound are running out of room, prompting local governments to seek help from eastern Washington facilities, usually located farther from metropolitan centers and closer to farmers who purchase the finished compost as fertilizer. Assessment analyzes risk for spread of apple maggot Pest, plant experts find transporting and composting urban organic food and yard waste poses threat. by Ross Courtney Courtesy ryan Leong The PacifiClean composting facility in Quincy, Washington, is shown operational in the spring of 2015. Concerns over the spread of the apple maggot have prompted state authorities to stop composting activity, at least temporarily. Determing the risk O n March 31, Washington Gov. Jay Inslee signed into law Senate Bill 6605, which requires local agencies and the state Department of Ecology to gauge — with the state's Department of Agriculture — the risk of spreading pests when making solid waste regulations. It took effect June 9. For more information, visit

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