What is this on Regent vine leaves

[tdah1986]

Hi all

I had this come up on last year's growth too. Seems to affect some leaves, and canes in places. Doesn't seem to kill the leaf though - any ideas what it is?

Vine is Regent, growing in London, UK.

Thanks for any pointers,

Tom

 

[tdah1986]

I think it might be leaf roll disease (virus), which would be sad as apparently only cure is destruction of vines

 

[tdah1986]

Just had a look my vines (I only have 3) and it seems they all have this to an extent - just removed these leaves, but it's probably not worth removing them if the virus is in the whole plant. Prob won't destroy them as there aren't any other vines in the area, and they seem pretty strong otherwise.

 

[terrymck]

Does your local ag college have the equivalent of what we call the agricultural extension office? a place where the public can have an expert look at your problem.

 

[grapeman]

Another good possibility is a phosphorous deficiency which has a much better prognosis. Try a bit of a foliar application of a phosphorous containing fertilizer and see if it improves. If not it may indeed be a virus.

 

[v8rx7guy]

My Regent leaves did the exact same thing this summer... I didn't pull mine off like you did and the leaves which were affected ended up dying and falling off . Were you able to figure out what was causing this?

 

[tdah1986]

Hi guys. The vines are still with me but I seem to have the same problem this year. The vines were fine last year though and produced lots of fruit and growth. It's only a hobby for me and there's little chance of it spreading given I'm based in quite a built up area in London, so I'll carry on searching and seeing if it truly is a virus.

Cheers, Tom

 

[tdah1986]

Here's this year's picture

 

[Masbustelo]

Is it the older leaves that look bad? And new looks fine? If so I think mineral deficiency. Can you show us the entire vine. Standing back a little?

 

[balatonwine]

Looks like either potassium deficiency:

http://www.omafra.gov.on.ca/IPM/english/grapes/plant-nutrition/potassium.html

or leaf roll virus:

http://www.omafra.gov.on.ca/IPM/english/grapes/diseases-and-disorders/leafroll.html

Comparison image between the two :

http://www.omafra.gov.on.ca/IPM/images/grapes/ocw/glv-ocw-k.jpg

Obvious rolling of the leaves would lead to the conclusion it is leaf roll virus. Only mid-shoot and basal leaves being affected would more direct toward potassium. Else, tissue analysis would tell you which one it is for sure, which should be done anyway without expert on site examination before applying any specific treatment. But baring such on site expert or analysis, experimenting by spraying foliar potassium on some leaves to see if that helps is to consider.

However, the most recent photos, especially the central leaf which is heavily red with some yellow has the very characteristic pattern with the green margins only around the veins for leaf roll virus (and it looks like it is starting to "roll" as well on the right side). Not saying it is leaf roll virus, but those are suspicious symptoms.

 

[v8rx7guy]

I too, have it again on one of my 4 vines this year. Very, very similar and I am on a different continent! Where did you buy from?

My crop was also just fine last year, so not a huge concern for me in 2017

 

[tdah1986]

Thanks all, for the informed responses and links. I too suspect it might be leafroll from this, that seems to be the closest match.

Regent vines are meant to have superior resistance to mildews and the like (which is why I selected them for the UK, given the temperate climate). As everyone probably knows, this variety was developed from a cross in Germany. I've been searching through German language forums and found one other possibility called "Rotter Brenner" which seems to be an internal fungus that Regent is highly susceptible to. It's early days and I'm trying to translate everything using google, but if this looks more likely than leafroll I'll report back.

I bought the vines 2 years ago from a UK distributor. They were grafted so there's also the chance that the rootstock was infected.

 

[balatonwine]

My Turan grapes are sustainable to Rotter Brenner (literally "red burner/torch" but the disease in English is commonly know instead as Red Fire). This disease, in its classic form, will look more like someone took a flame to part of the leaf and burnt it. I went out to look today, and was "lucky" (or do I mean unlucky) enough to find one infected leaf as an example, and how it deserves it's name:

 

[tdah1986]

Ah thanks, so it doesn't look like that after all on that basis!

 

[Daniliniho]

Hello guys! I'm wondering what grapes I have at my grandmother? I live in Lithuania (Eastern Europe). Hardiness Zone is 5.

 

[tdah1986]

Hi guys.

Thought I would update on this. I left the property a few years ago and took some cuttings from the vines which were growing strongly and were high yielding despite the leaves.

The cuttings have grown ungrafted in my south London soil. Each year I observe a similar effect on the leaves. It doesn't seem to affect their strength but what I have noticed is that:

• It starts with the oldest leaves first. Those which have been affected by gall mite (common) are most affected and I wonder if this is the vine killing off those deformed firsr mover vines.
• The leaf first shows red tinges before drying out and falling off
• The fresh canes also have a red tinge.

I've used sulphate of potash to feed during growing season and can't say I have detected a change.

Perhaps by providing this update someone somewhere will find it useful one day.

 

[Xnke]

It's leafroll virus and the plants should be destroyed and replaced.