Do regular apple trees cross pollinate crab apple trees and vice versa? The reason I ask is last year I realized I had a crab apple tree that I never new existed until it randomly produced apples. I don't know what caused it to produce. I potted some fruit trees near the crab apple tree last year. Did that help pollinate the crab apple? The only apple tree I potted was a staymen apple tree but I did pot a few pear trees and plum trees.
Any info is appreciated.