A Gardeners Forum Forums General Discussion Plant pests and problems Greenhouse Grapes split, white fuzz

For 8 years my greenhouse grapes were luscious. Could not find anyone to help me with info re: pruning, feeding or watering, so I just winged it. Lightly fertilized with horse manure-compost. Kept clear of weeds, watered once a week. For the last 2 years grapes have started to split around now - some survive, but they're smaller and there are fewer bunches. This year is the worst. Here are two photos. Can you help??
http://www.soroptimistfortbraggca.org/thisnthat/Grapes.html

Also, can anyone identify the type of grape?

thanks.

Lynne

Welcome, Lynne.
I couldn't find any direct diseases that match your description or picture. But I did find this link about pruning for you. And some basic grape care.

OK, I researched further and found this:
"Your grapes may have downy mildew, which is a problem that can return every year. Unless the treatment you are using is for that specific problem, it may not do anything. Downy mildew is common in regions such as the southeastern United States, where it is warm and wet during the vegetative growth of the vine. Downy mildew is caused by the fungus Plasmopara viticola. The fungus overwinters in infected leaves on the ground and possibly in diseased shoots. The overwintering spore (oospore) germinates in the spring and produces a different type of spore (sporangium). These sporangia are spread by wind and splashing rain.

Any practice that speeds the drying time of leaves and fruit will reduce the potential for infection. Sanitation is important. Remove dead leaves and berries from vines and the ground after leaf drop. A good fungicide spray program is extremely important. Downy mildew can be effectively controlled by properly timed and effective fungicides. Some that you can use are Dithane M-45, Mancozeb or Maneb.

Take samples to your local Extension office and they should be able to identify your problem. Once you diagnose the problem, you can get the specific control agent."