Table grape troubles

I have three Thompson seedless vines that, although produce well, I lose most of the crop to black rot. I've used sulfur, but that doesn't seem to be very effective. I don't want to use other fungicides. I'm considering pulling the vines. Two questions: Are there good producing table grape varieties that are very resistant or immune to black rot? What would my chances of success be if I grafted a resistant variety onto the existing Thompson rootstock. The current vines are 4 years old.

You may find this site helpful in your search for a table grape that is resistant to black rot.
http://winegrapes.tamu.edu/grow/tablegrapes.html
These other sites may be of help also. If you can't find the answer you seek, contact your local AgriLife Coop agent. A & M is improving its support of the grape industry and that also helps the home grower. As long as you are looking for grapevines resistant to black rot, get those that are also resistant to Pierce's Disease. Pierce's Disease is a greater problem in Texas because the glassy-winged sharpshooter is found all over Texas.
http://www.plantanswers.com/grapes_in_texas.htm
http://aggie-horticulture.tamu.edu/extension/fruit/piercegrapes/pdr.html
http://aggie-horticulture.tamu.edu/southerngarden/Texaswine.html
You might consider growing Muscadine grapes as they seem less susceptible to black rot.
http://www.texasgardener.com/pastissues/marapr05/Grapes.html

Try "Mars" or "Red Canadice" seedless. Both are pretty resistant to disease.

Thanks for your comments bettydee and riceke. I'll check those sites and varieties out. I haven't grafted anything in years, but I think it's worth trying as long as the varieties are compatible. I could try a couple different varieties and watch for black rot susceptibility and select the best performer. That should give me a several year jumpstart on production. I haven't seen any symptoms of Pierce's disease. I'm hoping that the isolation of my location will help prevent that from occurring, but I will definitely look for combining resistance to that disease also. Thanks again for your input.