Evaluation of Mechanized Vineyard Production Systems for Barbera (Vitis vinifera L.) Grapevines Grown in the San Joaquin Valley

Abstract

The availability and cost of labor are important concerns for many California wine grape growers. Greater state and federal labor regulations, increased grower liability, increased efforts to control illegal immigration, and mandated increases in the minimum wage are causing growers to investigate production systems that may reduce labor requirements and costs. The purpose of this experiment was to determine the influence of training system and mechanization on vegetative growth, yield, fruit composition, labor requirements, and production costs for wine grapes grown in the San Joaquin Valley of California. Barbera vines grafted on Freedom rootstock were used in the experiment. Treatment variables examined were training system (bilateral cordon, non-positioned vs. bilateral cordon, vertical shoot positioned) and pruning method (hand vs. machine pre-pruning with hand follow-up). The experimental design used was a randomized complete block with data analyzed as a factorial. There were five blocks and all treatment combinations were evaluated. Data were collected during the 1994 and 1995 seasons for vegetative growth, yield, fruit composition, pruning labor requirements, and machinery performance. Few treatment effects were observed on vegetative growth, yield, and fruit composition during the course of this study. When significant differences were noted for these parameters, training system had a greater impact than pruning method. In contrast, labor requirements and production costs displayed a significant response to pruning method. Machine pre-pruning reduced pruning labor requirements from 41 man-hours per acre to 24–28 man-hours per acre per year. Pruning labor requirements were reduced by ≈40% and the costs associated with pruning were reduced by ≈30%.