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Mildew on grapes

wildlife, gardening, environment, Rural living, Pets and Vets
granretire
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Mildew on grapes

#157724

Postby granretire » August 7th, 2018, 3:37 pm

This is my first year of growing grapes in a greenhouse and I find that many of the bunches are infected with mildew. The door has been open night and day for weeks as has the the roof window. Should I remove all bunches that are infected? I have been removing infected leaves, but I notice that even the stems of the plant have it in places. Guidance please.

ReformedCharacter
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Re: Mildew on grapes

#157726

Postby ReformedCharacter » August 7th, 2018, 3:47 pm

granretire wrote:This is my first year of growing grapes in a greenhouse and I find that many of the bunches are infected with mildew. The door has been open night and day for weeks as has the the roof window. Should I remove all bunches that are infected? I have been removing infected leaves, but I notice that even the stems of the plant have it in places. Guidance please.


This may help - if you haven't already read it...

https://www.rhs.org.uk/advice/profile?pid=569

RC

granretire
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Re: Mildew on grapes

#157918

Postby granretire » August 8th, 2018, 1:36 pm

Yes, I had read it, but it doesn't answer my question about removing the mildewy grape bunches

88V8
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Re: Mildew on grapes

#166171

Postby 88V8 » September 13th, 2018, 8:54 pm

Belatedly.... yes, remove them but once the mildew has set in the process is pretty inexorable.

The other problem is that the fungal spores will overwinter on the vines, and next year it will all start up again. Commercial vineyards run heavy fungicide spray programmes to control mildew. Timing of the spray is important, as is the ambient temperature.

You could try a thorough tar oil winter wash to reduce the spore carry-over, and to an extent one can minimise the problem by keeping a very open canopy, but realistically once you have an infection, that's it.

A shame to give up after just one year, but I would grow something different in your greenhouse.
Figs?
Kiwi?

Ivor

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Re: Mildew on grapes

#166307

Postby Cornytiv34 » September 14th, 2018, 1:00 pm

Some mould is good. See Noble Rot details here

https://en.wikipedia.org/wiki/Noble_rot
https://winefolly.com/tutorial/they-call-it-noble-rot-botrytis/

I have no knowledge of the types of disease/rot or treatments but it might be worth checking with someone who has more knowledge. Mrs Cornytiv is an RHS member and sends plant samples to them. I do not know if this is available to non members but a telephone call might help.

Mike


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