We recently purchased a property that has quite an old grape arbor (Concord grapes supposedly). The plants have been very lush with beautiful berries forming. Suddenly, the other day spots and rotting appeared on the berries (photos attached). We have had an unusual amount of high humidity lately and hot weather -- some afternoon thunderstorms too. I've also included a photo of the entire arbor to show how dense it is with plant material. I'm just not sure how to tell if it (the "ick") is due to a fungus or lack of air circulation? I very new to the whole "grape" growing thing . . . and we would like to eventually move the plants and grow them on more of a trellis system. But, sad to say, I don't think we will have any grapes for harvest this season. Any help would be HUGELY appreciated. Also, is it true that Concord grapes ALWAYS have to be sprayed on a regular basis during the growing season to prevent fungus?
The disease looks like bunch rot of grapes (Botrytis cinerea), a fungus. Your grapes look like they need to be drastically thinned out. Poor air circulation promotes fungal diseases like Botrytis. Regarding Concord grapes, here in the Pacific Northwest they seem more disease resistant than hybrid varieties. Mine never get Botrytis, for instance, while it regularly occurs on adjacent Himrod and Interlaken, among other hybrids.
Vitog -- Thanks for your input. After doing some more research I figured it was either that or black rot (same thing?/similar -- still fungus). I have also sent an email and photos to our local county extension agent that works through Virginia Tech. I figured there may be some specifics as they apply to grapes grown in our region vs. some others . . . as well as treatment/prevention techniques. Yes, these vines have been severely neglected for years!! I'm hoping that we can successfully move them when the time is right and treat them nicer in hopes of bountiful, disease-free crops in the future. :-) Again, thanks for taking the time to reply to my post. SQ
