Water Conservation in Wine Grape Production

An infrared thermometer (IRT) was used to schedule irrigation and impose selected levels of stress in two vineyards during the 1992 season. Cabernet Sauvignon vines in Paso Robles, CA and French Colombard vines in Ripperdan, CA were used in this project. Water was applied to drip irrigated vines only when IRT measurements indicated a certain level of water stress. If vines were below that stress level, water was withheld until stress increased to the selected level. Treatments were imposed from berry set to harvest. Water use was reduced during the berry set to harvest period by up to 50.3% and 39.0%, respectively for Cabernet Sauvignon and French Colombard vines. Treatments which exposed vines to moderate levels of stress for the entire berry set to harvest period produced the greatest reductions in water use. Irrigation scheduling treatments had no significant effect on yield or dormant pruning weight of Cabernet Sauvignon vines. However, growth and yield of French Colombard vines were significantly reduced by all programmed water stress treatments. Fruit maturity was generally advanced by increasing water stress but differences were often not statistically significant. These results are preliminary and several more years of data collection are required before equilibrium results are obtained. The Wade Manufacturing Pulsator microsprayer was subjected to further developmental testing in the Center for Irrigation Technology sprinkler testing laboratory to refine its application pattern. A commercial plot was established in a Chardonnay vineyard near Los Alamos, CA and field testing of the Pulsator occurred this spring. Analysis of data is not complete but it appears that the Pulsator microsprayer was as effective as overhead sprinklers for frost protection.