I can't tell you all the times I have had others complain that perfectly healthy vines just up and died for no good reason. You check the area near the base and the vine is girdled. You ask if they use a weed whacker and of course most of them do. All it takes is a bit of a slip , and oooops...........
Also the original poster asked what pre-emergent is safe for use in a vineyard. While all these other replies suggest alternatives, that's not the question that was asked.