Poorly grape vine advice.

[Leezy2]

My grape vines have suddenly taken off this year, much to my relief. All was going well and one vine even had a couple of bunches of grapes (at least a year earlier than I was expecting). Then, it’s got poorly! Some grapes started turning a deep red colour, thought they were ripening, and now all will drop off with the slightest touch. Leaves have started turning as if it’s Autumn already, but I’m wondering if it’s a disease now. I’m in france so we’re still averaging 20° plus at the moment. Any help gladly received, as always!

[Leezy2]

Sorry, other photos were too big, had to reduce them!

[Deltawhiskey]

Hi Leezy2,
Firstly, this looks like a white grape which obviously should not change colour. How long have the vines been planted? I ask this because it is normal to only crop in the third year.
It is difficult so see in the picture but it may be Black Rot. Does the change in colour begin in a small dark purple spot then grow to cover the rest of the grape? I get a bit of this on one of my vines and I remove the affected grapes and throw them in the bin. It is a fungal infection that can be controlled by making sure all infected grapes are removed and not allowed to stay on the ground. Spraying with antifungals from early bud burst can also control the problem.
Hope this helps. If I am wrong please post a bigger picture and we may be able to come up with another idea.

[Deltawhiskey]

Hi again,
Just seen the other pictures. The red leaves may indicate a lack of micronutrients such as magnesium. I spray from bud burst with Epsom Salts together with a seaweed fertiliser in my antifungal spray which enables micronutrients to be absorbed through the leaves.
David

[Leezy2]

Thanks Delta,
It’s an Autumn Royal, red seedless dessert grape, at least that’s what it was bought as!
Spent the first year in a pot and is now in its second Summer in the garden, so third year overall. Was still quite small at the beginning of the season though, it’s made up for that!
Here’s a couple of close ups. You can just see the start of it on the grape on the left of the second photo. It’s the fact that the leaves are turning as well that made me think disease, or is this normal?

[nickdub]

No expert on grapes, but I wonder if it might be lack of water ? Takes a while for plants to form an extensive root system so that they can cope with dry periods ...

[Deltawhiskey]

Hi Leezy,
It certainly looks like black rot but black rot tends to turn each grape into a hard ‘mummy’. Yours look quite soft. It does look like some sort of fungal infection. I have seen odium look like this. If the leaves turning red are the result of a lack of micronutrients it is probably a different issue to the grape problem.
Sadly, this years grapes are probably lost and should be removed and disposed of. You could try to remove the damaged ones in the hope that the others will be ok. Speak to one of the winegrowers in your area and they may be able to help with the diagnosis and may even give you information on what to spray with.
I feel your pain.
David

[Deltawhiskey]

Hi Leezy,
I have just had some problems with my grapes, due probably to the warm humid weather. If the discoloured grapes are soft, it is probably Botrytis. Remove the bad grapes and increase the air flow by removing the lower leaves. If you can get hold of an antifungal spray give them a spray every couple of weeks stopping a month before harvest.
Next year spray when the first leaves come out and continue every two weeks until flowering. Continue after flowering and you should be clear.
Make sure when you remove this years bad grapes that you put them in the bin to prevent the spores contaminating the vines next year.
David