Black rot and grapes

Asked July 26, 2016, 3:59 PM EDT

We bought 3 grape plants all Minnesota winter hardy, seven years ago. We have had wonderful grapes until last two years. Having looked at your disease section for grapes, I believe that Black Rot is the problem. I sprayed last year and was able to save some of the crop. I sprayed this year as well, but probably too late and lost most of the crop. My question is, should I prune everything down to the ground, get rid of any infected leaves and dried up grapes that are infected? I look forward to hearing back from you. Thank you. Barb

Wright County Minnesota grapes black rot horticulture

1 Response

Thank you for the question. It does look like black rot in the photos. If you cut the plants down now, new growth will be stimulated using up precious energy resources the vine needs to get through the winter. Remove the affected grapes and leaves and discard. This will allow more air flow through the plant and minimize the growth of the black rot. The remaining leaves will continue to photosynthesize and add to the plant's energy reserves. Proper dormant pruning and excellent fall clean up will help reduce the chance of disease. Please read the following publication from Extension to learn more:

http://articles.extension.org/pages/31134/black-rot-of-grapes

Thank you for contacting Extension.