In 1957, vines of Zinfandel, Red Malaga, Tokay, and Ribier grapes were sprayed, at four developmental stages, with gibberellin in a range of 0 to 25 ppm. In the spring of 1958, certain seeded varieties showed severe injury as a result of the higher concentrations of gibberellin. In 1958 and 1959, therefore, those experiments were followed up with the work reported in the present study, designed to determine the degree of recovery in vines injured by gibberellin.
