You haven't given enough information for a diagnosis.

Really good quality pictures could possibly help, but even that might not eliminate all possibilities. Probably your two best options are 1) look at some of the websites that list grape diseases and symptoms and try to narrow the possibilities down from there and/or 2) contact your local ag extension office and get their help.

Here are some websites that might help, although others could be found with a quick google search.
Growing Grapes in Kentucky by the University of Kentucky College of Agriculture
University of California IPM Online (see Diseases section)
Grape Disease Info by Penn State Extension Service

To contact your local ag extension office, find your county's office at this webpage:
Click-able County Extension Offices Map for Kentucky
The people at this office are there to help you. Your tax dollars go to pay their salary, so their help (most of it anyway) will be free! Expertise may vary from office to office, but they should be at least fairly knowledgeable of possible diseases (and especially those likely to be encountered in your area). When commercial farmers want advise, extension professionals are often their primary resource.