Look like wooly aphid (the silkies of the aphid world!) Given time, they WILL take out your tree from the roots. Some apples are more susceptible than others, so check if you have a susceptible rootstock that risks the tree life more.
Many controls will work: ladybug, lacewing, wasps, birds, soapspray... tweezers!
Location: Zone 4b
posted 3 years ago
I couldn't say for sure, but here is a site that's proven to be quite valuable to me... Hope it helps you out.