You may find this YouTube video to be of interest. With the amount of Pierce’s disease (PD) we are observing lately, we need to consider alternatives to Vitis vinifera and susceptible hybrid cultivars, especially at lower elevations and latitudes throughout Georgia. In light of our need for production of quality grapes in the presence of Xylella fastidiosa, the bacterium that causes PD, the PD-resistant cultivars from Dr. Andy Walker’s breeding program in California might be of value to Georgia wine grape production, and we are testing these vines in multiple locations. The video shows the end-of-season downy mildew and rots on a red wine grape cultivar Camminare Noir [94% Vinifera PD-tolerant UC Davis selection 07355-75] and a white wine grape cultivar [07370-84] [94% Vinifera PD-tolerant cultivar], both selections from the Andy Walker breeding program at UC Davis.  Both cultivars eventually developed significant downy mildew on leaves and bitter/Macrophoma rots on fruit.  The red cultivar was relatively clear of downy mildew and rots until two weeks prior to this video, whereas the white variety developed significant disease levels much earlier. Full fungicidal spray programs, similar to those developed for standard Vinifera grapes, will be required for these grape cultivars if grown in Georgia or anywhere in the Southeast.  However, as long as we develop and utilize effective fungicide programs, the PD resistance in these vines will allow excellent fruit production — without vine loss to this devastating disease. This research is part of a Ph.D. project developed by Shane Breeden, a graduate student in the Plant Pathology Department at the University of Georgia.  It is financially supported in part by a grant from the Southern Region Small Fruit Consortium.   

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