Good Fruit Grower

March 15

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Page 32 of 47 GOOD FRUIT GROWER MARCH 15, 2014 33 • The prebloom and bloom leaf removal in Riesling in 2013 accumulated sugar faster than the other treatments and may have led to the severe bunch rot in the prebloom and bloom treatments. • In Sauvignon Blanc, all leaf removal treatments in both years of the study resulted in higher skin tannins and phenolics than the control. • Early leaf removal may prove to be a practical addition to current vineyard management practices in eastern Washington. Unique discovery Moyer was most surprised that removing leaves early in the season near bloom did not result in looser clusters and smaller yields, something researchers have observed in Spain, Italy, and elsewhere. "We didn't see that," said Moyer. "We didn't see a change in yield or a change in cluster appearance, even going into the third year of study. That's a unique discovery relative to the European studies, but similar to other studies conducted in the Pacific Northwest." She said a possible explanation could be that vines in eastern Washington are able to recover quickly from leaf removal because of abundant sunlight and long days. "Young growing tissue is photosynthetically active, and we have so much more productive sunlight hours than in Europe and other places." Red varieties Moyer is now applying some of the leaf removal concepts to red wine grape cultivars. Similar studies with Pinot Noir have been conducted by Oregon State University's Dr. Patty Skinkis. OSU researchers are finding positive results from early leaf removal in reds, including reduced disease incidence and improved color and tannins. In 2014, Moyer will begin testing different timings of fruit zone leaf removal in com- mercial vineyards of red varieties. Both hand and mechanical leaf removal will be compared to no leaf removal. Mechanical leaf removal will be implemented at later timings (not prebloom or during bloom) to avoid damaging flowers and developing clusters. Fruit from the trial will be harvested and made into wine by WSU extension enologist Dr. James Harbertson. "We'll be looking to see if early leaf removal influences berry color or tannin struc- ture in finished red wines," she said. "Will it impact wine quality? And does late-season, mechanical leaf removal affect wine quality? These are some of the questions we want to answer." • Leaves on this vine were removed prebloom. early leaf removal PHOTO COURTESY OF WASHINGTON STATE UNIVERSITY

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