What's wrong with my grapevine?

[JayLondon]

Hi,
I'm growing a grape vine over my pergola. The plant is maybe 10 years old now and I never had any major issues.
It gets full sun all day (if we get any here...)
Many of the leaves have browned this year and it looks like something is wrong. About half the plant is affected. It looks like it starts with tiny brown spots.
I'm just north of London.

Does anyone know what this is and what I can do?

 

[MrFrench]

I can’t help you I’m afraid, but for context for anyone looking to this thread from outside the UK - we’ve had an incredible amount of rain this year and it’s been a cool start to the summer

 

[cmullin]

That looks like downey mildew. If you were in the US I would recommend you talk with your local agricultural extension agent. I don't know if the UK has the same structure. This is a blurb from the University of Michigan, but there are many publications about this. Also I could also be totally wrong.
https://www.canr.msu.edu/resources/michigan-grape-facts-managing-grapevine-downy-mildew

 

[Dennis Griffith]

Hi,
I'm growing a grape vine over my pergola. The plant is maybe 10 years old now and I never had any major issues.
It gets full sun all day (if we get any here...)
Many of the leaves have browned this year and it looks like something is wrong. About half the plant is affected. It looks like it starts with tiny brown spots.
I'm just north of London.

Does anyone know what this is and what I can do?
View attachment 113276View attachment 113277View attachment 113278View attachment 113279View attachment 113280View attachment 113281View attachment 113282View attachment 113283

Not sure whats available in the UK, but you might try mancozeb, captan, or copper. I've had the best luck with captan in treating downy mildew.

 

[NorCal]

Looks like mildew damage to me.

That looks like downey mildew. If you were in the US I would recommend you talk with your local agricultural extension agent. I don't know if the UK has the same structure. This is a blurb from the University of Michigan, but there are many publications about this. Also I could also be totally wrong.
https://www.canr.msu.edu/resources/michigan-grape-facts-managing-grapevine-downy-mildew

I was going to say the same, but my experience has mostly been with powdery mildew. What is your spray program?

 

[Dennis Griffith]

Unfortunately I live in the Ohio River Valley region, or as I call it 'Fungus Hollow". Hence, I have experience with both, and more.