Crossbow is a vegetation management product which means it is not very selective, it will kill almost anything. Although it should not harm a tree when used at recommended levels if it gets on the base of the tree, it will harm a tree if you spray it on the foliage.
Asiatic/Oriental Bittersweet is an invasive species and difficult to eradicate and control. We recommend that you speak to the manufacturer Dow AgroSciences for information on treating with Crossbow as it is not listed on the label. They can be reached at 800.992.5594. We also suggest speaking to a Master Gardener in your area by clicking the link below for more treatment advice.
As long as Crossbow is not applied directly to the grapes or the drift did not contact the grapes that would not be the cause of the yellow and wilting leaves. It would be best to further examine the grape vines to confirm if a disease or other issue could be the cause.
It is recommended that you wait at least 2-3 days after mowing to apply Crossbow Herbicide.
To get the best result with Crossbow Herbicide
Do not apply Crossbow Herbicide to, or otherwise permit it to come into direct contact with cotton, grapes, tobacco, vegetable crops, citrus, flowers, fruit or ornamental trees, or other desirable broadleaf plants and do not permit spray mists containing it to drift onto them.
Crossbow Herbicide should not harm established trees if it is not applied directly to them.