Yellow Spots on Apple Tree Leaves

Question

I have a 5-year-old semi dwarf Mcintosh apple tree and it has tons of yellow spots all over the leaves. On the underside of the leaves under the spots, it’s kind of furry/fiberous (not sure how to explain it). It turns some of the leaves completely yellow.

Answer 1

It sounds like you may have wooly aphids. This article will help you with that:
http://www.nysipm.cornell.edu/factsheets/treefruit/pests/waa/waa.asp