Out of three young apple trees, one in particular has been suffering with pest problems, mainly aphids. I check it almost daily, and probably once a week on average I find aphids swarming a terminal bud. It's usually many or none, and when I see them I just smoosh them off gently with my fingers. Today I checked the trees and see these patches of fuzzy white growth on that troubled tree:
I did a little research online and see woolly aphids as a potential culprit. I did have aphids as I mentioned, but I haven't seen any there in a few days - this is a lot of material appearing fast! Last I checked this tree was just two days ago.
@Stormy has mentioned that mulching potted trees with wood chips is a bad idea. The other young apple trees don't have wood chips and they are having fewer pest problems, so that seems like good advice. Tomorrow I'll have gardening time and plan to brush off these fuzzy growths and repot this particular apple tree in some fresh soil with no wood chips on top. Any other advice to go along with identification of these growths is appreciated!