One would need more information to really help beyond a WHAG. For example, early season fungus damage, can look like nutrient deficiency during late season senescence.
So a few questions:
- What variety of grape is this?
- What was your pest spray schedule, if any (fungicide and/or insecticide), and what products did you use?
- What was the weather like this year? Dry? Very wet? Etc.
- Is this issue affecting all plants, or just some?
- Is this issue recent or did you notice this or any other issues with these vine's growth during the spring or summer? (Nutrient deficiency is often first noticed as a spring and summer event, during plant growth, not really so much a late summer/autumn event).
-This is Itasca. I also have Marquette and Petite Pearl that seem to be unaffected.
-I did not spray anything except Sevin for the beetles
-Wet all year
-This started a month ago and is getting worse. Before this, everything has bee fine. A few cordons have shriveled and died off.