Two to 3 millimeters sounds about right but.... but.... pre-flower
stage? Do you mean to say that it's not really grapes falling off but
flower buds?
I just went back to your original post to try to make sense of this. Are
you talking about the tiny buds that would turn into the entire cluster
of grapes and not just a single grape?
I bet that's it and I don't know what is going on. I can't think of
anything that would eat them but not the new leaves. Maybe a
neighborhood birds has developed a taste for those buds?

Steve


Ed wrote:
I guess what you're saying is possible. I'm still not sure
if they're at the stage you mention. They are still really
small, maybe 2 to 3 millimeters across, definitely pre-flower
stage since they've just started forming. Thanks.

Steve wrote:

It's normal for the small grapes that came from flowers that didn't
get pollinated to fall off. On mine, some of the tiny grapes fall off
the cluster leaving most of them to continue on. Could this fit what
you are seeing?

Steve