Help! Grapevines aren't looking good - Need advice please

**Kirk** · 29-05-2017, 05:21 PM

Sort of the first one that looks like it is Red Blotch Disease, although most references are to the US vines, but I suppose it will get here sometime.
https://pnwhandbooks.org/node/2776/print

If you google for "grape vine disease identification" you gat about 3 or 4 references down a set of images of possibilities and look about 5 rows down for RBD, or find one that looks a better match.

Not sure what if anything can be done and not sure it does a lot other then reduce the crop. Simply have not read anything that says it will kill the plant, but have not really looked in depth either.

If it is on all 3 then I doubt you will clear it from them all, so it will remain. Cannot see anything as a treatment. It says it is systemic to the whole plant, so appears not to be a case of remove infected leaves and possibly prune out bits.

Not sure if the virus will remain in the ground either.

**Kirk** · 29-05-2017, 05:40 PM

More I read the more doubt I have, the one I mention seems to have no references in the UK and there is very strict control on the import of such from the US.

Also just about everything seems to redult in dried edges and red markings.

Does leave a simple option that last month was excessively dry, and the vine may simply be dropping leaves to conserve water, and as in autumn it removes the useful stuff and leaves the tanins behind so the leaves dry up and go red.

As said everything seems to give much the same markings so picking the exact cause is not simple. Reading bits it seems that identification is by virus analysis and determination and less by simple observation.

**ladybirdbug** · 30-05-2017, 04:36 PM

Originally posted by Kirk View Post

More I read the more doubt I have, the one I mention seems to have no references in the UK and there is very strict control on the import of such from the US.

Also just about everything seems to redult in dried edges and red markings.

Does leave a simple option that last month was excessively dry, and the vine may simply be dropping leaves to conserve water, and as in autumn it removes the useful stuff and leaves the tanins behind so the leaves dry up and go red.

As said everything seems to give much the same markings so picking the exact cause is not simple. Reading bits it seems that identification is by virus analysis and determination and less by simple observation.

Hi Kirk, thank you so much for doing research & helping me out

I don't think it will be that it was too dry last month as it gets watered often (too much!) by my family.

I really appreciate you taking the time to do some research for me, I will keep you updated on how it looks

**Deltawhiskey** · 31-05-2017, 12:24 PM

Hi ladybirdbug,
I have looked at a load of pictures of diseased grapevines most of which are out of the UK. One of the most promising for the UK is magnesium deficiency. On a very acid soil the vine has difficulty in drawing magnesium from the soil resulting in red markings on the leaves.

The RHS recommends a foliar spray with Epsom salts 20g/litre with a few drops of washing up liquid to help the spray stick. In the long term mulch with well rotted organic matter. I have 60 vines in their first year and have a slightly acid soil, so will be looking out for the same thing.

I hope this helps.

David

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Help! Grapevines aren't looking good - Need advice please

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