leaf curl on fruit trees

Last year we had a problem with leaf curl on our plum trees. Should I spray for this now, or do I wait until these trees actually leaf out. It is still cold here, and so far nothing is leafing out, but trees are starting to form buds. What do you recommend for treatment of this? Any help would sure be appreciated. Thanks in advance!

If your problem was the fungal problem that's similar to peach leaf curl then you may have missed your window of opportunity--I think this is one where you need to spray before the buds break for best results
http://www.ipm.iastate.edu/ipm/hortnews/1997/6-13-1997/peachplum.html

But there are aphids that also cause leaf curl on plums, so if that's what caused your problem last year then there may be some things you can still do now to help prevent the problem
http://www.ipm.ucdavis.edu/PMG/r611301811.html

Gee, I really don't know what caused the problem, but from the links you provided, I am more inclined to think that it was aphids, although we didn't see them in the leaves. Thanks, the info you provided is very informative! I had a really hard time trying to figure out what the problem even was last year, and leaf curl was the only thing that I could come up with. Never had plum trees before, and they were here when we bought this house. Not even sure if they are wild plums or not. They are sure not very big, but they make really good jam & jelly! Do you know if there is anything else that would cause some of the leaves to curl? Is there anything else I should be watching for?

Sorry--don't have any more info for you. I know a little bit about peach leaf curl and suspected that plums might get a similar thing, but when I googled to find references on treatment, the aphid references popped up. The only other thing I know of that makes leaves curl is leafrollers, but those are easier to figure out--if you unroll the leaf you'll find the critter inside. I don't know if they typically bother fruit trees or not.

It may not be too late to treat Fungal Leaf Curl although I have not heard of it affecting plum trees here. Put on a good cover of Copper spray up to flowering will help usually Copper Oxychloride is used but check with your Dept of Ag. You can do a follow up spray if only a few flowers are open because the Copper will burn the flowers but on plums the loss of a few flowers won't matter. The Copper spray will also help control several other diseases of stone fruit so is always worth while to put on a cover spray in late Winter. If your problem is Aphis then you should be able to see them in the curled up leaves and spray with a systemic insecticide.
Brian

Thanks, Brian. I'll pick up some copper spray tomorrow. I am sure that I can find someplace open, even though it is Easter. So for we have no leaves or blossoms on anything as spring is really late appearing this year. So I will get the tree sprayed right away while everything is still just starting to form buds. Never saw any aphids last year when we opened the leaves, but I suppose that they could have left by then. Anyway, I'll try it just to be on the safe side! Thanks again everyone!

Since you have not had bud burst as yet it will pay to use a White oil with the Copper this helps the Copper to spread all over the plant but also smothers Aphis and Mite eggs so you can get both possible problems with one go. This spray is safe up to the buds just starting to burst known here and probable with you too as "The Pink Bud Stage"
Brian