Good Fruit Grower

March 1

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In 2011, Miller gained up to 200 growing degree-days for vines enveloped in plastic for 40 days. Enveloping for 60 days could add 500 to 700 growing degree-days to a season, he said, depending on the length of time the plastic was up and the variety. Flowering dates for vines inside the plastic were from eight to 21 days earlier than for control vines; flowercapping dates were 13 to 27 days earlier than the control. Early harvest potential Miller sees great potential to advance harvest by two to four weeks in a cool year when using the plastic, and in a warm year, still advance harvest and produce higher quality grapes. Harvesting earlier could also help reduce yellow-jacket damage and avoid feeding from migratory bird flocks. ���In a bad year, you���d get something of value instead of 12 months of work for zero benefit,��� he said. In the past, Miller has sold his grapes to western Washington wineries. But he said that this year, he plans to keep his grapes to make wine for private enjoyment. ��� PHOTOS COURTESY OF TOM MILLER Tom Miller devised a spool mounted on a tractor for easy dispensing of the plastic shrink-wrap film. Tom Miller set up tenting trials in his Dungeness Bay Vineyard. TOPPING shoots R etired veterinarian and horticulturist Dr. Tom Miller says topping shoots when they reach the trellis midwire will help avoid early bunch stem necrosis in vines that have been enveloped in plastic. The Sequim, Washington, vineyardist recommends installing the shrink-wrap envelope in the vineyard around the first of May, removing it around the first of July. Wrapping the vines with the shrink-wrap material hastens maturity by adding growing degree-days to the cool climate of the Puget Sound. ���It���s best to schedule the shrink-wrap for no more than 50 to 60 days,��� he said, adding that tenting longer than 60 days may reduce yields. Vines are treated normally once the wrap is taken off. The material is not reusable and must be disposed of when removed. When shoots reach the trellis midwire, he opens the top of the wrap to reduce transpiration, condensation, and humidity. Thus far, powdery mildew hasn���t been a problem with plastic-wrapped vines. Miller found that topping the shoots helps avoid early bunch stem necrosis, a problem he encountered the first year of experimenting with the plastic envelope. Because he is forcing early flowering and shoot growth, the new shoots have a big demand for carbohydrates and tend to starve the fruit clusters for carbohydrates, he explained. ���The first year, I ended up with a lot of early bunch stem necrosis,��� he said. ���The stems were shriveling and falling off because of the excess nitrogen and ammonium that had built up. The shoots were just getting fried.��� By cutting back the shoots that have grown above the midwire at flowering, the vine sends carbohydrates back to the fruit instead of keeping it in the shoots, he said. Since he began topping, he has prevented early bunch stem necrosis and increased fruit set. ���M. Hansen ���Savings in hand thinning time and/or increases in fruit sizes resulted in a net positive impact of $123/ha to $1368/ha compared with hand thinning alone.��� - Baugher, Schupp, et al. Mechanical string thinner reduces crop load in various stages of bloom development in peach and nectarine trees. HORTSCIENCE 45(9): 1327-1331, 2010 Manufactured by; 4825 Union Rd. Beamsville, ON Canada 905.563.8261 A Bartlett Company P.O. BOX 550 Fowler, CA 93625 559.834.1588 Dealer in South Western US: 105 N Spokane Rd. Moxee, WA 98936 1.800.827.0972 Dealer in North Western US; Designed with Versatility in mind. Attach to your current hedging arm and thin the tops and sides of your peach trees. Same controls, but all mechanism is built right into the frame. GOOD FRUIT GROWER MARCH 1, 2013 35

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