What is this?

[HillPeople]

Hello grape growers. So far his year we have only been dealing with an invasion of Rose Chafers. We have many wild blackberries in the neighborhood, and it appears they like grape leaves even more than blackberries. But today we noticed a few leaves on our LaCrescents have developed a brown blight?
Would like to identify it. We have been really wet here for the last two weeks if that has any bearing on this. Thanks in advance.

 

[jamesngalveston]

have you had a lot of wind.

 

[HillPeople]

have you had a lot of wind.

Yes James, we have had a lot of severe winds.

 

[grapeman]

LaCrescent seems to get this fairly easily, especially when it is wet. It is I suspect a disease and not nutrition, but I could never pin down exactly what it is. It just does not look like any of the common diseases. Hopefully somebody can ID it for you and I.

 

[HillPeople]

Looks like it might be black rot The conditions lately certainly favor it.
http://msue.anr.msu.edu/news/regional_reports_on_michigan_fruit_may_29_2012

 

[lawrstin]

That looks like black rot to me. Any spots or mummies on your clusters? How often are you spraying fungicide?

 

[grapeman]

Usually black rot lesions on the leaves are more scattered than this leaf. Maybe you could show us another leaf so we can be sure.