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January 2018 WINES&VINES 129 PRACTICAL WINERY & VINEYARD GRAPEGROWING LEARN MORE McFadden-Smith, W., and W.D. Gubler. 2015. "Sour Rot." Compendium of Grape Diseases, Disorders and Pests, Second Edition W.F. Wilcox, W.D. Gubler and J.K. Uyemoto, eds. Measurements of canopy density showed HW vines to have significantly greater den- sity than VSP vines between the vineyard floor and fruiting zone, due to the umbrella- like structure provided by their drooping shoots. This likely provided less ventilation and a more favorable microclimate for dis- ease than the VSP system, where vines were denser above the trellis wires due to upright growth of the shoots and their retention by catch wires. Integrated control is necessary The sour rot complex is a dynamic system involving yeast, AAB and Drosophila fruit flies. The species of yeast can vary, as it can for the AAB and fruit flies, yet all three components must be present in order for symptoms to develop. An integrated control program for sour rot should utilize both canopy management and spray applications that target yeasts, AAB and Drosophila spp., although the best protocol for timing of s u c h s p r a y a p p l i c a t i o n s h a s y e t t o b e determined. Additional trials under commercial or large-plot conditions should help identify the most efficient timings to balance the compet- ing desires to minimize spray applications while maximizing control, although existing data suggest that control is likely to be maxi- mized by initiating sprays before an epidemic is in progress. It is important to note that these studies have been conducted with a susceptible cultivar in a climate favorable to develop- ment of severe disease symptoms. While we did not specifically study cultivars and cli- matic variables, management recommenda- tions may vary for vineyards with cultivars that have thicker skins and looser clusters and/or in a less conducive environment for the disease. Nevertheless, this perspective on under- standing the sour rot complex is not only ap- plicable to New York grapegrowers but may be pertinent to growers worldwide who experi- ence sour rot as a challenge in their vineyards. The sour rot complex is somewhat unique because we are targeting multiple unrelated causal organisms in control programs, but now there is a more comprehensive understanding of how the disease develops and, in turn, how to manage it. Megan Hall was a graduate research assistant at Cornell University's New York State Agricultural Experiment Station and is now an assistant professor of viticulture at the University of Missouri. Gregory Loeb is a profes- sor in the Department of Entomology at Cornell Univer- s i t y. Wa y n e W i l c o x i s a p l a n t p a t h o l o g y a n d plant-microbe biology professor at Cornell University. The authors extend special thanks to Finger Lakes grape- growers for allowing the use of their vineyards for disease sampling and monitoring. This project was funded by the New York Wine and Grape Foundation, the Dyson Fund and a USDA Specialty Crop Block Grant administered through the New York Department of Agriculture & Markets. Vineyards with cultivars that have thicker skins and looser clusters are less susceptible to the disease.