Good Fruit Grower

February 15

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ho would have guessed that a city boy from Michigan's auto town would end up in southern Oregon spending decades to help pear growers and packers better manage postharvest rots and decay? Even Dr. David Sugar, once a Detroit city boy, is surprised at his career path. Sugar, a plant pathologist at the Southern Oregon University Research and Extension Center in Medford for more than 35 years, retires in May. His research on postharvest fungal decay and diseases of pears has taken him to packing houses, cold storage rooms, and pear orchards in the Pacific Northwest, and to foreign countries like Argentina and Spain to deliver his postharvest gospel. His current research projects include evaluating thermofogging as a postharvest fungicide treatment on Bosc pears, integrating pre- and postharvest strategies to control decay, evaluating the effect of fireblight materials on pear finish, and pear ripening. Thermofogging Thermofogging, a method of applying fungicides to cold storage rooms for decay control, is relatively new in the United States, although it's been in use in Europe for around 20 years. Globally, more than 1.3 million bins of fruit were treated in 2013, according to Pace International, LLC. In the Pacific Northwest, 700,000 bins in 440 rooms were treated last year. Pace developed the electro-thermofogging system called ecoFOG as a way to protect fruit in storage without drenching. The technique vaporizes the fungicide into a warm, fine fog to surround the fruit, and their exfiltration technology prevents release of fogging substances into the atmosphere. Thermofogging eliminates the need to dispose of large volumes of fungicides in drench solutions. Since the first fungicide ecoFOG ETO (ethoxyquin) was registered by Pace for thermofogging in 2005, three others have been approved in the United States: ecoFOG 170 DPA (diphenylamine); ecoFOG 160 PYR (pyrimethanil), also known as Penbotec; and ecoFOG 80 FDL (fludioxonil), also known as Scholar. "It's a technique that's really catchng on within our industry," said Sugar. "We want to find out if it's worthwhile for Bosc in our district and if it fits with our pattern of handling pears." Sugar has studied thermofogging in a commercial pear packing house in Medford for the last two seasons. In the 2012 season, Sugar worked with Naumes, Inc., to evaluate Penbotec (pyrimethanil) as the thermofogged fungicide. Last year, he studied the application of Scholar. In 2013, fludi- oxonil was newly registered for thermofogging. In the first year of the study, Sugar found a 25 percent decrease in infection from gray and blue mold, and a smaller reduction in side rot. Gray and blue mold cause most of the decay problems in the Northwest, although in Medford, side rot is the bigger problem, he said. Results from the second year are still being analyzed. Sugar noted that having two fungicides registered for thermofogging gives packers more options for managing fungicide resistance. Research has shown that using the same fungicide in the packing house for five years in a row creates a risk of resistance. "Bosc are so rot prone that the variety really calls for doing everything you can throw at it," Sugar said. In the Medford district, thousands of field-run Bosc bins are stored in controlled atmosphere rooms for later packing. Drenching is not done on the truck, and the packing houses do not use a drench during the packing process, he said, leaving fruit vulnerable to decay during storage. "Research has shown that decay gets very hard to control if it goes unchecked beyond three weeks from infection. By thermofogging the room within a week from harvest— which is a critical moment—we can hopefully provide more protection." Sugar is also concluding several years of research to develop decay control strate- gies for winter pears that integrate pre- and postharvest treatments, using preharvest fungicides and resistance stimulants, such as calcium sprays that work to enhance the fruit's resistance to decay. Sequential treatment programs, consisting of calcium and ziram in summer, a preharvest fungicide application, a postharvest fungicide or biocontrol, and storage in modified-atmosphere packaging, were the most effective in controlling decay. Inducing ripening capacity Another recent project of Sugar's focuses on conditioning regimes for d'Anjou and Comice pears and looking for ways to accelerate the ripening process with Pear research NEVER ENDING Oregon State University researcher is retiring in May after studying pear diseases for more than 35 years. by Melissa Hansen Diseases & Disorders 20 FEBRUARY 1, 2014 GOOD FRUIT GROWER

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