I've used Roundup and Surflan. Roundup is probably what you are thinking about. But don't get it on the grape foliage. Surflan or Treflan will provide residual control. Treflan is best incorporated but I think you can water it in like Surflan.

thanks i will try round up

Round up does work, I use it around my vines. Just be careful not to get any on the leaves and try not to get it on the trunk either. I shield the trunks when I spray. Also make absolutely sure that whatever you use does not contain 2,4-D because grapes are VERY sensitive to 2,4-D. My neighbor used weed and feed (2,4-D) on his yard, which is a pretty good distance from my vines and the ones closest to his yard had quite a lot of damage.