Abstract

Preventing young blueberry (Vaccinium corymbosum L.) plants from fruiting can increase their vegetative growth. In previous studies, gibberellin (GA) applications reduced flowering in highbush blueberry, but the response was variable and cultivar dependent and was studied mostly using potted nursery plants. The purpose of this work was to determine whether floral induction can be inhibited by GA in plants established in the field, particularly on newer cultivars now being widely planted. Foliar sprays were applied in several experiments with different application intervals and concentrations; the efficacy was determined by counting the number of initiated floral meristems. GA applications in July and August were more inhibitive than those in September and October, while cultivars did not vary in their response. GA significantly reduced flower bud numbers in three separate studies, but the greatest reduction (49%) required repeated applications from July to October. The results indicate that GA may have limited commercial utility for preventing fruiting in highbush blueberries under field conditions. However, further studies are needed to determine how vegetative growth is affected by the partial inhibition of flowering.