California: Lodi Mechanized Pruning Trials in Progress

(Wines&Vines) - Paul Verdegaal, the University of California Cooperative Extension viticulture advisor for San Joaquin County, updated growers on two mechanized pruning field trials in progress to evaluate and compare different trellis systems for managing vine balance at Lodi Grape Day, held Feb. 4 at Hutchins Street Square.

 Providing background on the experiments, Verdegaal noted that traditional vineyard management philosophies commonly tend toward one of two extremes: A California Coastal/French winemaking philosophy is that only low yields can produce high-quality grapes and wine. On the other extreme, a traditional Central Valley grower philosophy is that high yields are necessary to compensate for low grape prices and the need for mechanized operations.

 As Verdegaal explained: “While overcropped vines can occur and often result in sound but average or below-average quality fruit, there is more evidence from research and field experience to indicate that high yields on properly designed and machine-adapted vineyard systems can produce quality wines. In summary, a ‘balanced vine’ can produce economic yields and high-quality fruit.”

Mechanized pruning equipment and practices have been used to some degree for more than 30 years in vineyards worldwide. Mechanical “pre-pruning” has been more commonly used to remove the bulk of pruning vegetation prior to hand pruning follow-up. Mechanically pruned, or “box hedged,” vineyards that require little or no hand follow-up have been successful in Australia and some California vineyards. Some growers have tried to adapt and retrofit existing vineyards and trellis systems to mechanical pruning, and it has sometimes been used to improve yields and economics in low-performing vineyards. However, designing and planting a vineyard specifically for mechanized operations from the ground up is the best way to optimize vine management for yield and quality.

Labor availability and costs in California are factors that increasingly favor mechanization. As new vineyards are planted and redeveloped, more growers are designing vineyards to optimize mechanized pruning, harvesting and other operations.