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GRAPE GRO WING pre-fertilization June post-fertilization June Flower buds (one for each berry) normally bloom about six to eight weeks after bud break and allow for fertilization. July Varieties differ in cluster shape and weight. (Continued from page 54.) The practical limit of physiological fruit ripening is around 25º- 26º Brix. To exceed that, fruit must dehydrate, and as much as 25% weight loss occurs as fruit sugars increase to 28º Brix, ac- cording to "hang time" research done about six years ago. Wine- makers and growers are still in discussions about delaying harvest for "flavor development" to eliminate the flavor of green tannins and other compounds associated with under-ripe fruit. Certainly, the longer the fruit stays out ripening, the greater the risk of de- clining yields from dehydration, birds and other wildlife—and rot if untimely rains occur. Conclusions There still is no perfect way to predict harvest yields for winegrapes in most vineyards. Estimating yields by weighing clusters at the "lag phase" is certainly a well-accepted technique. Some new research methods include creating a trellis system that can actually weigh the fruit load and use electronic imagery to determine how much fruit is on the vine. Anything that can help growers and winemakers manage variable crops from year to year is helpful in the long run to managing a well-run winegrape and wine business. Glenn McGourty is the UC Cooperative Extension winegrowing and plant science advisor for Lake and Mendocino counties. He is the techni- cal editor for the "Organic Winegrowing Manual" published by the Uni- versity of California Agricultural and Natural Resources division. He also tends a 1-acre vineyard of the aromatic Italian winegrape variety Arneis on his property along the Russian River near Ukiah, Calif. 56 Wines & Vines JUne 2012 EVQ_ENARTISFERM PRIMITIVO TR.indd 1 13/04/12 13:23 CLINE CELLARS CLINE CELLARS