Defoliation responses of different grapevine cultivars to postharvest ethephon treatments

Abstract

The defoliation responses of several grapevine cultivars to postharvest ethephon sprays at 0, 500, 2000, 5000 ppm were observed. Sprays were applied at the beginning of October to vines of Barbera, Carignane, Emerald Seedless, Ribier, Ruby Seedless, Thompson Seedless and Flame Tokay cultivars. The most effective concentration was 5000 ppm. The defoliation response varied greatly among the varieties. Barbera and Carignane were almost completely defoliated 20-30 d after treatment, whereas Flame Tokay showed no response. However, high concentrations of ethephon resulted in a considerable delay in shoot development the following spring. Defoliation induite en differents cepages par un traitement avec de l'ethephon apres la vendange La defoliation causee par des traitements d'ethephon (0, 500, 2000, 5000 ppm) a ete etudiee sur differents cepages (V. vinifera). Les applications ont ete faites le 10 octobre sur les cepages a raisin de table et de cuve ci-apres: Barbera, Carignane; Emerald Seedless, Ribier, Ruby Seedless, Thompson Seedless et Flame Tokay. La concentration de 5000 ppm se revela la plus efficace. La defoliation des plantes traitees a ete tres differente selon les cepages: Barbera et Carignane par exemple ont ete presque completement prives des feuilles apres 20-30 d du traitement, tandis que le Flame Tokay ne donna qu'une tres faible reponse. Il faut signaler en tout cas que les concentrations les plus fortes d'ethephon ont cause un retard considerable dans le debourrement du printemps suivant.