I'm interested to see what others say on this. I don't see any problem with it- I recently chopped up my grape vine prunings to about 8" long and spread them under a couple pear trees (on top of the wood chips).

Thinking about it now, I wonder if the black rot which strikes grapes could cause any problems for apples or pears. I didn't have much of that this year, as I bagged most of my grapes. So they were safe (from black rot at least), until animals ripped through the bags and ate them all.

My vines do have powdery mildew, but I don't think these came from my vines, I think they came from a vineyard which would have sprayed to avoid this. The fact that I already have powdery mildew in the yard I think is bad enough (I have to do something about it this spring), it affected my corn, squash and artichoke late in the growing season last year (the artichoke lost those leaves and looks great now). The material I have is very small, probably 1" long by 1/8" wide. It was put out in the front yard and used as mulch for some flowers before I moved in, and none of those were affected by any rot.