Grapevine - Is this mildew?

[jpdw]

As the title!!

We've found these bobbles on some leaves of one of our vines.

The underneath of the bobbles is grey. The description seems to match some description of mildew, but I'm not sure.


If it is, what's the best course of action?

Thanks!

[WendyC]

A photo of the underneath would be handy bug I'm pretty sure that's not mildew. I suspect something (aphid or leaf sucker) damaged the bud before the leaves unfurled. Pick it off if it bothers you.

[jpdw]

Underside of leaf - you can see a few grey patches.

[muddled]

bugs...not mildew.

is it on all the leaves or just one or two?
if only a couple, pick them off and dispose of them (not in your compost)

If its all the leaves then more drastic action may be needed...

[Kirk]

Not sure but try looking up "vine louse". It leaves gauls on leaves and is/was present in Europe. So would expect that there are occurances of it in the UK.

Nothing I find looks a great match to your picture, so every chance equally that it is not.

Seems that it/they infest the roots, and so the grapes are usually on rootstocks that are resistant. I am guessing they infest the roots, get into and up the plant, form a Gall, hatch and head off to infest another.

Likely going to need a few more images to get a better idea.

I guess it is either just something that lays eggs on leaves and has found your vine suitable - in which case pluck them off or spray or whatever, or it is more serious as in the above.

Is the vine on a rootstock ?? Just in case someone has grown/rooted it from a nice green vine shoot, in which case there will be no resistance.

[jpdw]

Thanks both for the replies.

It's only on a few leaves ( probably less than 1 in 20 ) so definitely not rampant over the vine. The vine is grafted and was originally purchased from a UK retailer, probably 10 years ago now.

Googling 'vine weavel' links to Phylloxera which i'd definately heard of -- having read the wikipedia page, I dont think what we're seeing on the leaves is what's shown in the wikipedia images. The legions on our vine are less pronounced - more like indentations.

Unless the proportion of infected leaves gets a lot higher, I think we'll go with picking off affected leaves and see what happens.

[Scarlet]

I think it maybe a mite as Wendy and Muddled has said - Grape gall. Remove the leaves and burn.
Pests and Deseases: show

[jpdw]

I have an incinerator ( = "bin with hole in the lid" type) on my plot, so burning the bad leaves will be no trouble!

[Scarlet]

I'd try to make sure you have every one...ive got a leaf miner problem on my conker tree, I try every year to burn as many as possible but I have to wait for them to fall