NEW GROWTH REGULATOR USES FOR NEW YORK VITICULTURE

The use of gibberellic acid and ethephon to thin the crop of grapevines and the use of ethephon to reduce juice acidity and increase fruit color of grapes was investigated. Bloom GA sprays reduced crop, but led to undesirable second year effects. Second year effects were minimized by earlier application and reduced GA concentration. Ethephon applied at bloom reduced crop, but because of its growth retardant activity did not increase vine capacity. Ethephon applied post-veraison decreased acidity and increased color of cultivars which do not form well developed abscission layers but resulted in increased acidity and lower sugar in cultivars which do.