April 18, 2009. This elm that I repotted about 40 days ago has some kind of insect damage. At least, I think it's insect damage. I saw some very tiny black things on this tree and my seju elm about 8 days ago. I blew them off with a stream of water. Now I'm wondering if these are some type of eggs.
Of course, it could also be disease. I really don't usually have health issues with my trees. I suppose I've been lucky until now. But the point is that I'm not sure what it is, nor do I know how to treat it!
APRIL 25 UPDATE:
I learned after visiting the county extension office that this is a gall caused by a mite. It may be in the eriophye category, but I don't remember exactly what type she said it was. She did mention several times that it resembles the nipple gall which often affects hackberries.
My plan now is to innoculate those plants that may be susceptible by spraying them with an insecticidal soap. Around late June I will leaf prune the elm and spray it with the soap. I hope that this works.