Orange areas on grape leaves
As I was picking off some Japanese beetles, I noticed some orange areas on some grape leaves. I am assuming it is a rust of some sort. I am not sure how to treat it.
Arapahoe County Colorado
Without a photo, we think it is black rot. See the information below for how to control it.
The Purdue information no longer seems to be available, but if you click on the Ohio State link, it provides a photo, information, and how to control it.
Hope that helps.