They could be sunburned. But that said, you don't say where they are brown.

Can you post pictures?

Probably bunch rot. A single spray of immunox the first week of June would probably lead to a huge crop of grapes- otherwise everything rots.

my grapes would rot every year until someone told me to use immunox which i did for the first time this year. its working a treat. no infection at all, though ive been spraying every 2 weeks pretty mucn since the leaves came out. my grapes r now about 2/3 developed and i sprayed them on sunday and probably will not spray them anymore this year. i will cut back on the spraying next year as hopefully, ive wiped out most of the overwintering spores.

Maybe so. But we still don't know where they're brown.

Can you post a picture?

The reason we're so confident about the bunch rot diagnosis(although with so little info mistakes are always possible) is that it is extremely common in the humid east. It starts with black spots on the tiney grapes and leads to completely rotten bunches before grapes can ripen. Seedless grapes are almost impossible to grow here without its control and Concords often succumb- especially during wet years. Once the innoculum is there, intervention will probably be necessary, at least for the following season.

Lychee, the only way to find out how little spray you can get away with is to take a chance. I gurantee you that if you stop spraying now your grapes will be fine. The rot has to get a foothold while the grapes are very small for some reason. A single spray may be risky, although I've had good luck with it but 2 or 3 sprays the last week of May into June has never failed me. I consider Concord to be less susceptible than most varieties I manage.

Sounds like black rot to me. The berries turn brown and start to shrivel-the black refers to the tiny fungal bodies and not the color of the grapes. Bunch rot (Botrytis) affects ripening berries (which will turn fuzzy), while black rot infection strikes early. Once the berries get near veraison (change color) and the sugars get above ~5-6 brix, they become resistant to black rot infection.

I agree with kiwinut, the most likely thing is black rot. I expect that is what harvestman may mean by bunch rot. Concord is highly susceptible to black rot.

Scott

Bunch-rot- black rot- you're probably right. I may have confused the name but what's is important is I know the treatment. It works so well, I haven't looked it up for about 10 years. I took the chance to find out how little I could spray to control it and now I can save you guys a lot of trouble. Of course, further south you'll have to tinker a bit. Kiwinuts research based info does not jive with my experience. My hunch is that myclobutanyl (Immunox) just knocks the innoculum out of town when you apply it early because I don't keep plants sprayed nearly as long as that info would suggest would be necessary.

Ok I checked my concord grapes just 5 days ago and they were doing wonderful, big and green and bunches of grapes but to day I look at them after all these days of rain and now they are reddish brown color on the grapes and the stems have some along with the leaves, just dusted them to for japenese beetles because we have bees we cannot use alot of insecticides. Any help?

If you have any uninfected bunches, you may try bagging them.

will they be safe to eat? even though they havent turned but the others have?

Bagging grapes seems to protect them from both disease and bugs/birds but the process is somewhat tedious. When I was researching this method it appears to have been in use since at least the late 1800's. I use a standard brown paper bag and staple it shut around the grape bunch. You may need to cut a slit or too on the bag to allow it to tightly shut. Most of the time the grapes come out of the bag in perfect shape...it's rather amazing that this works. ...and they should be safe to eat.