Good Fruit Grower

February 15

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10 FEBRUARY 15, 2016 Good Fruit Grower D r. Parama Sikdar and her assistant Emmi Klarer inspected thousands of Red Delicious apples one by one, huddling over a table in a Stemilt Growers warehouse stairwell in Wenatchee, Washington. "It's warmer in here," Sikdar said, still bundled in a beanie and thick hoodie to ward off the chill from the cold storage just on the other side of the door. Besides, the window light helped them spot evidence of rot, which they documented with a black Sharpie right on the fruits' skin. Sikdar, a plant pathologist with the Washington State University Tree Fruit Research and Extension Center, is part of a team of Wenatchee researchers trying to help growers stave off three types of fungal diseases that prompted China to temporarily cease imports of U.S. apples in 2012. Meanwhile, other team members search for rot-resistant alternatives to the ubiquitous Manchurian crab apple pollinizers that also maybe won't pop so darn many tractor tires. The group is in the second year of a five-year $1.9 mil- lion U.S. Department of Agricultural Foreign Agricultural Service grant from the Technical Assistance for Specialty Crops program. After one year of work, Sikdar and her colleagues have determined that a combination of aggressive Manchurian pruning and post-harvest fungicide treat- ments "significantly" reduce the incidence of two of those three fungal infections, speck rot (Phacidiopycnis washingtonensis) and sphaeropsis rot (Sphaeropsis pyri- putrescens), in apples as they sit in cold storage. Now, Sikdar is measuring how much each technique — prun- ing and fungicide treatment — works individually. In the meantime, she recommends growers prune Manchurians after twig dieback in a vertical shape to reduce overhanging limbs, avoid using overhead sprin- klers as much as possible, remove the trimmings from the orchard to limit the spread of the disease and remove fruit mummies after harvest. Manchurian connection Manchurian crab apples and Snowdrift crab apples are the most common pollinizers in Washington's apple industry. Manchurians bloom early in the season, which is why growers began using them in the 1980s, along with Snowdrifts that bloom later. In the past, growers have been hit-and-miss with pruning the spindly, unruly Manchurians, choosing to spend their money on the fruit trees instead. Afterall, more growth on pollinators just means more flowers for the bees. Meanwhile, Manchurian branches are so hard and thorny they've been known to pop tractor tires. "They're just like having nails out in your orchard," said Denny Hayden, a Pasco area grower. Hayden had always pruned his Manchurians, just to keep them from taking up too much space in his high-density blocks. He first tried using solid foam tires, but those made tractors hard to drive. He now instructs crews to haul away the prunings and burn them, an extra Getting to the ROT OF THE PROBLEM Researchers studying how best to prevent spread of disease from Manchurian crab apple pollinizers. by Ross Courtney Diseases Good Fruit Grower Ad Display Advertising Third Page Block 6.75 X 6.5 Premium Quality Oregon Rootstock For over 70 years TRECO ® has been a leader in the propagation of premium rootstock. The foundation of your orchard starts here…TRECO ® TRECO ® -Oregon Rootstock & Tree Co. Inc. • 10906 Monitor McKee Road NE • Woodburn, OR 97071 Call Toll Free: 1.800.871.5141 Fax: 503.634.2344 • Email: VISIT OUR NEW WEBSITE WWW.TRECO.NU

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