Diagnose my apple problem, please
I planted two baby apple trees in the spring. Early in the season, they both developed a problem with brown spots and aphids. I got rid of the aphids and, on one of the trees, the brown spot problem mostly went away and the tree grew quite a bit. The other tree didn't grow much and a lot of the leaves are covered with brown stuff.
The variety that grew well was Ashmead's Kernel. The spotty one is Frostbite.
This is my first time growing apples - can anyone tell me what this might be?