Effects of Early Bloom Sprays of Ethephon on Irrigated and Nonirrigated Vines of Zinfandel Grapes

Abstract

Exogenous applications of ethephon at the early bloom stage were applied to mature Zinfandel grapevines at 1000, 300 and 1000 ppm to the apical portion of the vine, cluster area only, or topped vines, respectively. The vine topping treatment (1000 ppm ethephon) reduced the weight and volume per berry relative to the 300 ppm ethephon treatment (cluster area only) and 1000 ppm ethephon treatment (apical portion of the vine). The topping treatment (1000 ppm ethephon) reduced the pruning weights relative to the 300 ppm ethephon treatment (cluster area). The ethephon treatment to the cluster area resulted in a significant increase in soluble solids, but did not significantly increase the total yield. Ethephon at 1000 ppm (apical portion of vine) decreased the yield of second crop and the 300 ppm treatment (cluster area) resulted in an increase in the weight per cluster.