I have a Concord grapevine for many years now and for the past several years they consistently get a fungus or I am almost certain it’s black rot. It eventually (as the grapes mature) develops black specks all over leaves etc and the grapes prematurely dry up and fall off the vine. Since the plant is just blooming and small grapes are just developing, is there anything I can do to prevent this disease now? I prefer to use more natural , organic treatment since we do eat these grapes. I’m sorry I don’t have any pics yet to show this year . Any suggestions would be appreciated ! Thank you so much!
Hi- black rot is the most significant grape disease for backyard gardeners. There is no curative treatment for black rot once you see the symptoms. Grapevines are susceptible to this disease from the time the youngest shoots first emerge to 4-5 weeks after they bloom.
Management of black rot has to be done preventatively at the beginning of the growing season. Since your leaves may not be fully expended yet it may be possible to benefit from fungicide sprays if done very soon. Unfortunately, there are no good organic fungicides for black rot. Immunox and Mancozeb are the two most effective chemical fungicides.
In addition, clean up affected plant material and throw it in the trash (do not compost it). This will help to reduce the fungal inoculum (which could serve to reinfect the plants next year).
Please read more about this disease and learn about the VA Tech spray schedule for preventing and managing pest problems in the home orchard:
Home Fruit Preventative Spray Schedule and Management of Common Problems