Grape vine problem

[Primrose]

Can anybody suggest what's happened to my 10 year old grape vine which has never suffered problems before. Lots of the leaves are showing green "blisters" which are a slightly lighter green colour than the leaf and the underside of the leaves where this has occurred have turned into creamy white blotches. There's no powedering and I can't find any trace of any insects or mites. The grapes are still developing and looking fine. I'm wondering whether I can just trim off and destroy all the affected leaves without causing damage to the fruit.

[Pumpkin Patch]

Hello Primrose
We have a vine that is about 40 years old and so far (touch vine wood) we just trim of anything ta looks suspicious and burn i or compost it seperatly. So far tough love seems to work fine! We also have to give it a good hair cut to allow enough/more light throug to the tomatoes and the grapes seem quite happy with this treatment too. Earlier this year we got green bubble/bliter things on the leaves so we cut them affecter greenery out and have no seen any more. Sorry I dont know anything more specific but vines once established are quite ok to be tough with.

[FelixLeiter]

It might be Phylloxera. It is an insect pest that protects itself within galls — the blisters you've seen. It is not a problem in Britain but 150+ years ago nearly saw off the French vineyards when the pest was first inadvertently imported. It can be fatal if the insects infest the roots. Most vines are now grafted as a defence. They form galls on the roots, too. Some chemical controls have been found to be of only limited effectiveness. I wouldn't worry too much about it taking hold on your vines, though: winter cold will kill it off.

[Primrose]

Thanks to you both. I've been picking off most of the affected leaves and putting them in the dustbin. The fruit so far doesn't seem to have been affected and when the leaves finally fall in autumn I'll try and destroy them as well.