Hi Ya,
I've killed young rootstocks by spraying them with Carbaryl. If the
tree is already stressed, you may end up worse off.
I've no experience with partial sprays and their effect.
Karl
In that case, maybe it's just as well that it rained, unexpectedly,
right after I sprayed it. I think I'll give it up now, since it's
getting late in the season anyway. I'll see what drops and thin by hand
later in the season.