vine disease?

[grapeman]

From the picture it looks like black rot. Do the spots have a dark brown border?

 

[berrycrush]

From the picture it looks like black rot. Do the spots have a dark brown border?

Yes there is a dark brown border. Should I spray it with Mancozeb?

 

[grapeman]

Mancozeb protect the leaves from new infection. Once you see it, it is too late to prevent it. If it is just a small amount, spraying will help keep it from spreading. Keep in mind you should not spray with it within 66 days to harvest.

 

[berrycrush]

Mancozeb protect the leaves from new infection. Once you see it, it is too late to prevent it. If it is just a small amount, spraying will help keep it from spreading. Keep in mind you should not spray with it within 66 days to harvest.

I see. I don't have clusters this year, and the leaves are less than 10% affected. Should I leave it alone for now?

 

[grapeman]

I would spray them for about another month. After that it affects the vines a lot less. If you spray now, you will lessen the infection of the whole vineyard.