Why are my apple trees experiencing problems?
Question:
There are potentially a couple of things going on here. The circular spots on the leaves in your first image look very much like cedar apple rust, a common fungal condition for apple trees. As you’ll read in that link, this is rarely fatal for the tree and most specimens tolerate varying levels, as long as the infection doesn’t get extremely widespread. Typical antifungal management strategies like proper pruning, removal of dead and diseased tissue, prompt cleanup of any fallen foliage or fruit debris (many fungal pathogens overwinter on infected plant tissue that has fallen to the ground), and cleaning/sterilizing tools after use can help mitigate infections. Sometimes, though, we get a warm, moist season like this summer and fungi thrive. Fungicides aren’t usually recommended for cedar apple rust.
I’m more concerned about the wilting and dieback on the branches, as that can by symptomatic of both fire blight and black rot in the apple tree. I can’t identify any cankers on the stem tissue, but the persistent dead leaves still clinging to the stem are worrisome. The treatment for black rot (a fungus) would be similar to above, but fire blight is bacterial and would have different recommendations.
Because these are relatively young trees, if you’re willing to wait and see how things go with the antifungal management strategies discussed above, I would recommend pruning out the dead branches and seeing if the condition recurs. If these are trees you don’t want to risk losing, I would submit your photos and possibly a physical sample to the UMaine Plant Disease Diagnostic Lab for testing–there is small fee for their service, but they are more reliable than my visual diagnosis and you’d have confirmation of any pathogens present.
Good luck and happy gardening.