I have seen this on just about every bunch. Some of the grapes are raisin-ing up. What causes this? On the left of this picture is one of the worst ones.
Thanks.
I’d guess they have their skin pierced thus ripen sooner and desiccate faster.
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My grapes also do that. I don’t know the cause, but it is either a disease or the cluster deciding to shed a few grapes to not ripen fully for some reason.
Much of the raisening I see is due to bird strikes allowing dessication.
Do you spray with fungicide? Black rot when present will still effect some of the grapes from time to time that the fungicide didn’t reach. Any good fungicide such as captan gets rid of black rot. There will be brown spots on the leaves but not a lot of them. The grapes look great until harvest and with black rot the crop shrivels up. It leaves mummified grapes for the next year and lesions on the vines.
My grape bunches have quite a bit of this. What is that and what spray to use if it’s still worth saving at this point?
I think it’s some sort of fungus, just wonder if Immidan spray can fix it?
Tom
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That is probably black rot. You needed to have sprayed Immunox after grape bloom, something to do next year. For this year you can pick of the bad ones and spray and should still come through OK.
I do one spray of Immunox per year and get pretty clean grapes… they are one of the easier crops to grow (but, you do need to protect from the birds).
Thanks Scott.
I’ll spray Immunox asap then. This black rot thing did not show until last couple weeks but seems aggressively expanded. I hope it’s not too late…
Tom
Scott,
I forgot to ask, how many time do I need to spray the Immunox? With sticker? And until all grapes are gone? Or many more times after harvest?
And possibly during dormant to prevent future rots?
Tom
Tom, I just spray it once a year, or maybe twice if I have some left in the tank from another spray. I don’t think it helps as a dormant spray, use copper for disease control on grapes in dormant season. It should not need a sticker.
Thanks Scott.
There shouldn’t be any issue with the chemical burning leave at this stage, right?
Tom
Tom,
Do you have any lesions on the vines? Was this the first year this happened? This will help identify and treat the disease https://www.youtube.com/watch?v=R38gR9OaE4Q
I believed that this is the first time that I see black rot on my grapes. Last year, I only have 3 small bundles. This year, I counted that it produced more than 20 bundles…
Would that abundance caused the fungus thing? Or simply the steamy hot weather is conducive for black rot?
Last question that I forgot to ask. Do I spray the entire vine and the grapes or just spray the grapes only?
Tom
The weather is perfect for black rot. Do you have brown spots on the leaves in places? Spray everything including the vine,leaves, and the grapes. I used captan for black rot when my grapes got it.
Well, I must mark it on my calendar … 2016 - another year of black rot wiping out or seriously infecting 5 of 6 grape vines.
I used Mancozeb according to directions and it looked good up until a week ago then they all started showing the signs.
I’m thinking it must be the hot and humid periods here.
I’ve never had a good grape season.
Sorry to hear that Laura. I would get some Immunox for next year, use Mancozeb early and Immunox several weeks later. Mancozeb is only a protectant, whereas Immunox is a curative. So, first protect then cure what didn’t get protected. I have had good luck using myclobutanil (Immunox) plus sulphur.
Laura?
Would IMMUNOX do any good now?
The bunches are showing infected grapes.
It will help some since it it curative - maybe it will save grape #6…
I click on your “B” and it says your name is Laura, thats why I called you Laura.
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I don’t know how “Laura” got there. That’s not me.
Anyway, some of the 5 are better off than others. A couple of them are very bad shape. I ordered the IMMUNOX last night. Should be here by Tuesday. Sure would be nice to get some decent bunches this year.
Thanks for the suggestion.
For what it’s worth you are Laura no more. It is gone. I had notice it a few days ago and thought that Bubbabgone and Laura just didn’t seen to go together.