Problem plum-Tips for growing plums

No plums this year. It snowed on the blossoms so naturally no bees or other pollinators were out. This plum also has a problem. It had a major infestation of white flies and aphids. I have treated the underside of the leaves with a mild insecticidal soap. It is better to get a commercially blended organic insecticidal soap rather than try to make your own as too many soaps have salts in them. The salts will cause "burning" of the leaves-equally as detrimental to the plants as the parasites. I am also encouraging spiders to help keep any that might have survived. I will also routinely spray the leaves with a strong stream of water to eliminate any that may return. The problem is that the damaged leaves cannot be made better. It will weaken the tree and so I will have to maintain a diligent vigilence next spring to make sure the tree revives. I am told by an OSU master garden, who is well educated about fruit trees, that this is a common problem in the Northwest and that white flies and aphids actually kill a lot of young plum trees.