TY - JOUR T1 - Effects of Fruit-Zone Leaf Removal, Training Systems, and Irrigation on the Development of Grapevine Powdery Mildew JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2010.10084 SP - ajev.2010.10084 AU - Craig N. Austin AU - Wayne F. Wilcox Y1 - 2011/02/23 UR - http://www.ajevonline.org/content/early/2011/02/23/ajev.2010.10084.abstract N2 - Removing basal leaves 2 weeks postbloom significantly reduced powdery mildew (PM) severity on clusters in each year of a study in a New York Chardonnay vineyard. In contrast, removing leaves 5 weeks postbloom had no effect. The effect was not significantly different whether one leaf or two above and below each cluster was removed. Shoot density of VSP-trained vines was lower than for Umbrella-Kniffen training and was associated with a significant reduction in disease development in one year of the study, and when combined with early leaf removal in the absence of fungicide sprays, reduced mean disease severity by 32% relative to untreated clusters on Umbrella-Kniffen-trained vines. However, there was no effect of training system in the second year of the study. In South Australia, doubling the volume of irrigation water supplied to vines that received a standard reduced deficit irrigation program resulted in two- and seven-fold increases in foliar PM severity in two consecutive seasons. Our findings highlight that viticultural practices targeted primarily at controlling vine growth and crop quantity/quality can also significantly affect the development of powdery mildew. ER -