I wish I had asked that question before I planted 100 crabapple trees that produce a lot of small apples that hang on the tree and don't get eaten. I do have a few Southern crab apple trees that have apples big enough to fall off the tree and always get eaten.
I have the same two varieties (Calloway and Dolgo) but they are still too young to produce fruit. I assume they are desirable to deer though because The Wildlife Group sells them for that specific purpose.
