What's wrong with our grapes?

prairiemoon2 z6 MAAugust 3, 2014

I posted earlier in the season about our grape vine grown from seed, that had developed quite a few bunches of green grapes on it. I've been watching them turn dark and shrivel up and I'm frustrated trying to figure out what is going wrong with them. The foliage on the plant looks healthy and not yellowing or giving any indication of drying out. This is what one bunch I just pulled off the plant looks like. There are still some healthy green bunches at the top but quite a few more that look like thisâ¦..

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Have you had a heat wave? Ours go like that when it goes past 95 degrees for more than a day at a time. Not all the grapes ripen at the same time and the riper ones turn into raisins while the greener ones stay green. As long as the stem doesn't dry up mine will continue to ripen.

    Bookmark   August 3, 2014 at 7:43PM
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How long has this grape vine been growing in the present location? Maybe the roots and stems are not yet developed enough to support fruit.

    Bookmark   August 3, 2014 at 10:03PM
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prairiemoon2 z6 MA

Princesspea, I guess it was hot for awhile, but it's been much cooler than normal for the past week and doesn't look like that's going to change soon either.

Eric, it's been growing in this location for three years. It may be of note, that it's growing in a small opening in a small patio built of pavers. I wonder if that might have anything to do with it?

Is it possible I should be watering it more? I usually water it when I water the vegetable garden and we've had a fair amount of rain recently.

And I guess I'm just thinking, that if the foliage looks healthy that has to be the only way that I have of knowing that the plant is getting all it needs. Why would the foliage look healthy but the grapes be drying up on the vine?

    Bookmark   August 4, 2014 at 4:13AM
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prairiemoon2 z6 MA

And here's a link to previous post on this grape vine.

Here is a link that might be useful: I thought I had grapes...

    Bookmark   August 4, 2014 at 4:15AM
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Did you spray fungicide for black rot or any of the other fungal maladies that seem to plague grapes in humid climates?

    Bookmark   August 4, 2014 at 9:03AM
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prairiemoon2 z6 MA

No, I grow organically and never use any products like that. So you don't think it's just not getting enough water, but it might have a fungal infection? Wouldn't that show up on the foliage too? And if it has one, does that mean all the grape bunches will go the same route? Will that fungus be systemically part of the vine from now on, or is there a chance it wouldn't come back next year?

    Bookmark   August 4, 2014 at 10:01AM
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Any brown spots on your leaves or black wounds on the cordons/trunk? Looks like black rot is possible. Also for your zone after 3 years I would stop watering it all together unless there is a long dry spell or it looks stressed. The roots are probably deep enough to retrieve ample water. What varietal is it?

    Bookmark   August 4, 2014 at 11:52AM
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Search for 'black rot grapes' on Google and look at the images.

    Bookmark   August 4, 2014 at 12:09PM
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prairiemoon2 z6 MA

Yup, that's what it is, black rot. Thanks jtburton for the suggestion about google images. Very easy to figure out looking at that. *sigh*

So I expect all the grapes are lost, right? So what do I do with the vine at this point? Since I grow organically, there's very little I would be willing to spray them with. Should I just cut it back to the ground and hope for a better year next year?

    Bookmark   August 4, 2014 at 3:59PM
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I don't have enough experience with grapes to provide any recommendations for you on next steps. I grow my grapes as part of an overall berry patch and had not until now worried too much about grape production due to the vine immaturity. This year is my first year (3rd year) with anything worth protecting, grape production wise. For my berry patch location, I do not think I can grow them without using an anti-fungal spray routine.

It is my understanding that some lime sulfur formulations quality as "organic", so you might be able to use this as a dormant spray if your grape varieties are not sulfur sensitive. You might want to check with your local Ag extension office for more help... :-)

    Bookmark   August 4, 2014 at 4:12PM
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Scott F Smith(6B/7A MD)

The only organic option for black rot is copper. I have had good luck with it but its a lot of work and you don't want to use much copper long term.

If your grape was a store grape it is probably vinifera, the European type. Those are impossible to grow organically, well, its possible but you will be out there coating everything with copper every other week. I would dig it up and get a highly disease resistant grape. Steuben for example is one. Double A Vineyards has a good list of disease resistance information, get one strongly resistant to black rot and downy mildew.


    Bookmark   August 4, 2014 at 8:41PM
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prairiemoon2 z6 MA

Thanks Scott, that's probably just what I'll do, because I don't want a perennial problem and coating something with copper doesn't sound like a very good long term solution.

Thanks for the reference to where I can purchase one. I am in zone 6a, so I assume they will have one for my zone.

I had actually not intended to grow grapes per se, I was just given grape seeds in a seed trade as an extra and for fun, tried to germinate it. Now I wish I had done some research and been more intentional about it, because it takes so much time to start one and grow to fruiting size. Hate to have to start all over, but oh well.

    Bookmark   August 4, 2014 at 9:01PM
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Of the 6 varieties I'm trying to grow, 'Mars' has been the most disease resistant. With minimal spraying, I have been able to get close to a 50% crop to this point and I have about 2 weeks to go to harvest them. They have an intense grape flavor but they are a slip skin variety. It was purchased as a 2-year vine and it was planted in 2012. It has a least a dozen bunches on it although that may be too many (e.g. over cropping) but just not sure.

    Bookmark   August 4, 2014 at 9:13PM
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Hey Scott,

I have a grape vine question. One of my Candice grape vines I planted 2 years ago is under performing (e.g. a runt). I hate pulling it after waiting 2 years but if it is always going to under perform, I'm thinking that I might be better off replacing it with another grape vine that has the potential to grow better. I planted a Reliance last year in the same row and it is already longer and fuller than the 2-year old Candice.

I have (Almost) Seedless Concord, Himrod, Niagara, Candice, Reliance, and Mars varieties. If I replace it, do you have any suggestions for a fresh eating variety...preferably not slip skin.

    Bookmark   August 4, 2014 at 9:57PM
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prairiemoon2 z6 MA

JTBurton, I would need to have a grape that would produce a crop with no spraying whatsoever. If that's not possible, I may decide to grow something else.

    Bookmark   August 4, 2014 at 10:05PM
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My grape vines are right next to several varieties of blackberries (e.g. triple crown, black satin, prime ark 45, and Ouachita) and while the blackberries do get minor leaf spot fungus during the season, they have not required yet required spraying for fungus or insects. My grapes, on the other hand, don't make it out of May before they need sprays. Bird predation is probably the biggest issue I faced until I purchased some good netting this year.

The Triple crown blackberry can produce a lot of fruit by year 3, enough to freeze and perhaps make into wine if you want....and it it thornless.

    Bookmark   August 4, 2014 at 10:27PM
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jt...are they eating them when unripe also? Birds haven't ever bothered my grapes and I'm curious (though thankful) as to why?
A Montmorency cherry right next to one group of them gets absolutely hammered by birds the second they turn red.

    Bookmark   August 5, 2014 at 10:39PM
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My birds will start sampling them when the blackberries turn red but I think that's because I have red raspberries too. The birds even eat the yellow raspberries. I haven't noticed a lot of grape loss but I also have so many grapes that are spoiled by black rot that maybe the birds are taking a pass for now. I did cover my Mars grape vine with netting to protect them just in case since that's the only vine with a decent number of grapes. They are almost ripe and have that intense foxy flavor.

    Bookmark   August 5, 2014 at 10:53PM
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