I hope someone can explain a few things about dormant oil for me. I just
can't find the answer in my google searches.
I have a couple of grape vines and an apple tree.
I understand dormant oil and lime sulpher is sprayed to kill overwintering
insects and that the oil smothers them. I can see why it has to be applied
before the buds open so the bugs don't start the damage. Instructions vary
regarding rain but presumably rain might wash it away.
What I don't understand is why it has to be applied when the temp is going
to be above freezing for 24 hours and not applied if a freezing trend is
forceast following the application.
Does anyone know the answer?
Thanks
Wayne in Ottawa
