Galls of some type. My plum tree is covered with them this year. They are from particular wasps laying eggs in the young leaves. Your squiggly ones don't look familiar to me though.

I've got something going on with one or two of my chokecherry trees. I was pruning today - OMG they are just loaded with fruit this year - and found a lot of little white bumps all over the leaves. They seem too big to be aphids. No damage to the tree as of yet. Have no idea what they are but I'm hoping a bird or two comes along and takes care of the problem - if it is a problem - for me. But it's only 1 or 2 trees out of about 30 so unless it starts to spread, I'm not going to worry about it.

Thanks Gil and Pudge, I guess I'll sit back and watch them hatch ;)

Sharon

I had something similar happen to my Linden tree. It spread to my chockcherries too. Which were right beside it.
It kept getting worse as the years went by.
I was told that it was some kind of mite.
Both of these trees are gone now. I haven't had any trouble with it spreading to my other trees.

You might have to spray it early in the spring as it is leafing out if it continues.

Shelley

Most often galls like this are are caused by a type of mite. But it's not a terrible one, and really, they only cause cosmetic damage. Maples, members of the Prunus genus(including plum), hackberries and oaks are the most common trees affected.

Thanks Shelley and Rick for your comments, yes they really look ugly, hopefully the birds and the hard rains will get rid of them ;)

Sharon

Thanks Rick, didn't know about the mites. I thought they were from wasps.

what's this?

I have three pictures (2/3)

I have similar things on chokecherry,.. apparently not damaging, only cosmetic.
Now I remember on the neighbors elm tree every year,...it's gone now, [cut down] because it was getting too big and messy with all those seeds.

Here is a link that might be useful: Leave disease

Thanks! The cosmetic is not pretty but we can live with that. LOL!