Is this black rot, or something else?

[Ryan Osborne]

We put in a first time vineyard this year in May and have seen good growth so far. Over the last week, a fair number of vines have developed leaf spots. The first thing that comes to mind is black rot.

Since green growth started, they have been sprayed twice. They were sprayed with captan a week ago, and with neem 2 or 3 weeks prior.

Is this looking like black rot, or should we be considering something else?

 

[VinesnBines]

Neither captan or neem protect from black rot. Use mancozeb since they are none bearing. What varieties?

 

[Ryan Osborne]

Neither captan or neem protect from black rot. Use mancozeb since they are none bearing. What varieties?

It’s across 7 varieties: gewurztraminer, gruner, Riesling, cab franc, Lemberger, Pinot noir, and cab Sauv. It’s about 50% of the vines evenly spread across 1 acre.

Obtaining mancozeb is in the works. My other guess would be possible chemical burn from too strong of a mix of captan (.4lb of 80wdg captan/3 gal water) for the new shoots. It all showed up since the captan spray last weekend. Should we just assume black rot and spray with mancozeb asap?

 

[VinesnBines]

I had chemical burn but I blamed malathion. The leaves were burned and looked different than yours. Still I suggest mancozeb because it is easier on the vines and controls black rot but not powdery mildew.