North Georgia Vineyards

UGA Extension Blog

Wine Grape Sour Rot Management During Pre-Harvest and Harvest

We are observing some sour rot again this year.  I talked to Megan Hall from Cornell, and she indicates that a combination of an insecticide for Drosophila species (fruit fly) management and a material such as Oxidate for bacteria and yeast management will help to substantially reduce sour rot development.  This is not published information, but she has three years of data to support the premise.  Megan states, “If a grower knows that they regularly see sour rot in a particular variety, I recommend beginning to spray at approximately 15 Brix using OxiDate and MustangMaxx weekly until harvest.”  You will actually need to rotate other chemical insecticides with MustangMaxx for resistance management.  I am not really worried about resistance development with Oxidate, but do follow all labels.  The insecticide is very critical to the management, and this is strictly a preventative program.