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Concord Grape vine with brown grapes #758906
Asked June 28, 2021, 5:59 PM EDT
I have a Concord grape vine which is about thirty feet long growing on a fence in full sun. It is about five years old and was pruned in February according to instructions I found on the web. Last year I noticed that the still-green grapes were turning brown randomly and over the course of several weeks, they all turned brown and fell to the ground. It took about two days for them to turn brown, shrivel up and then fall. Unfortunately, I am beginning to see the same problem this season. I would appreciate any information you could provide. Thank you.
Baltimore County Maryland
Expert Response
It would be easier to diagnose with photos of the symptoms, but this sounds like black rot of grapes, a common disease for that crop. Here is more information: https://extension.umd.edu/resource/grape-diseases
The link on that page to a spray schedule leads you to a Virginia Tech publication detailing what products to use, and when, for control or suppression of disease. It's a long document because it encompasses many topics, but you can search it for "black rot" and "grape" to more quickly find what you need. Fungicides are preventative measures only and cannot cure existing infection, so treatments need to begin early in the season in order to minimize chances of disease. Outbreak severity is also dependent on the weather, so some years infections may be more extensive than others based on temperatures and rainfall.
Miri
Thank you for the photos. Yes, unfortunately this does look like classic black rot symptoms.
Miri
