Good Fruit Grower

March 15

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Pollination Can pollinizer pruning reduce fruit rot? Manchurian crab apples are thought to be sources of disease inoculum. by Geraldine Warner runing of crab apple pollinizers is being explored found that Manchurian crab apple trees, as a way to reduce the incidence of two postharwhich are widely planted in orchards as vest fruit diseases that have closed the Chinese pollinizers, are particularly susceptible to Crab apples infected by Sphaeropsis pyriputrescens are market to U.S. apples. the disease and serve as a mummified. The two fungal diseases are major source of inoculum. Sphaeropsis pyriputrescens (known as However, Snowdrift sphaeropsis rot) and Phacidiopycnis pollinizers don't appear to be susceptible twigs and cankers could reduce the inoculum in an washingtonensis (speck rot). Both were to the disease. orchard and the incidence of disease in commercial fruit. —Mike Willett discovered in Washington State within the Dr. Yong-Ki "Richard" Kim, a former Previous research has shown that the spores of both past decade and have since been reported in British postharvest pathologist with Washington State University sphaeropsis rot and speck rot are dispersed by water, Kim Columbia, Canada, and New York. who is now manager of plant pathology with Pace Interreported to the Washington Tree Fruit Research CommisThe fungal spores that infect fruit originate from national, LLC, is heading a research project to find out sion, which is helping to fund his project. Rain is rare in cankers on dead, dying, or weak wood. Scientists have how pruning Manchurian crab apples to remove diseased Washington orchards in summer, but water from overtree irrigation, evaporative cooling, or even undertree sprinklers that are aimed high, can also move the spores around. When the spores land on fruit, the fungus penetrates the fruit tissue through openings such as stomata, Engineered for cracks, or lenticels. Symptoms of decay aren't usually seen until after the fruit has been harvested and stored for two performance, durability, to three months. "That's the goal." reliability, and longevity! Discover the Chinook fan blade advantage. # Increased Radius Coverage by 80-150 Feet with Same HP Draw # Air Flow Starts 14'' from Hub # Donier Swept Tip—Reduces Tip Drag # The Only Fan Blade with the "Trailing Edge Wedge" Need better performance & coverage? Trial the Chin ook bl at our expens ade e! Judge for your self! Satisfaction Guaranteed! (widens sector angle and increases air velocity) # Advanced Flow Design # Increased Horsepower # LESS FUEL CONSUMPTION # Quality Built, Affordable, Fast Payback Returns H.F HAUFF . COMPANY INC. 1801 Presson Place Yakima, WA 98903 509-248-0318 fax 509-248-0914 hfhauff@gmail.com www.hfhauff.com 24 March 15, 2013 GOOD FRUIT GROWER FORD TR ITON V-1 0 IVECO N EF 6.7 DI or ESEL Fungicides Both diseases can be controlled with postharvest drenches of the fungicides thiabendazole (TBZ), Scholar (fludioxonil), and Scala (pyrimethanil). In trials, preharvest sprays with Pristine (pyraclostrobin with boscalid), Topsin M (thiopananate-methyl), and Ziram (zinc dimethyldithiocaramate) reduced the rots but were less effective than postharvest treatments. Ten years ago, Kim and Dr. Chang-Lin Xiao, then plant pathologist at WSU, began to study when, during the growing season, the fruit becomes infected. They inoculated fruit each month and found that the fruit was susceptible to sphaeropsis rot any time during the growing season, but that it was most susceptible close to harvest. Other scientists discovered the same trend with speck rot. Because the crab apples mature earlier than commercial apple varieties, highly infected crab apples increase the risk of commercial fruit becoming infected before harvest. So, if preharvest fungicides are used, they need to be applied close to harvest, otherwise they will lose their efficacy, Kim said. Although most apples stored long term are treated with a postharvest fungicide, there have been cases where the rots still developed in controlled-atmosphere (CA) storage, Kim reported. For example, in one lot of Red Delicious apples stored in CA for nine months, 24 percent of the fruit developed sphaeropsis rot, and 194 bins of apples had to be thrown out. The disease also affects other apple varieties, including Fuji, Golden Delicious, Granny Smith, and Gala. China Over the past few years, both rots have been detected in Red Delicious apples exported to China. As a result, China listed them as quarantine pathogens and closed the market to U.S. apples in August 2012. www.goodfruit.com

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