The Relation of Bloom-Applied Gibberellic Acid to the Yield and Quality of Thompson Seedless Raisins

Abstract

Gibberellic acid at 5 or 10 ppm was applied during bloom in four trials in commercial Thompson Seedless raisin vineyards in the San Joaquin Valley. These concentrations did not affect fruit maturity, raisin yields, or raisin grades; nor was the incidence of bunch rot influenced. Significantly increased, however, were fresh berry weights, which, in turn, were reflected in significantly heavier raisin berries. Although not measured directly no berry-thinning effect was noted.