Once symptoms manifest, especially for diseases, it's usually too late to treat or prevent damage to the tree (or its crop) for that year. Preventative insect and disease pesticide sprays begin early for fruit trees (around the time buds are first swelling, if not before) and continue well into the growing season, given the variety of ailments apples and other common fruits are vulnerable to. We can't see the symptoms clearly enough in the photos to make a definitive diagnosis, but we think there may be indications of Plum Curculio egg-laying damage and possibly also some rust infection on the developing fruits.

You can compare symptoms you're seeing with the information in our Growing Apple and Pear Trees in a Home Garden web page, which links to additional pages about specific pests and diseases, as well as a booklet about pesticide spray recommendations. (It's a long document, but you can search it for "apple" to find the relevant entries.)

The base of the tree's trunk looks very close to lawn. This poses a risk of bark damage, if a mower or weed-whacker were to hit the trunk or cut into bark; such wounds can cause serious damage that cannot be remedied. We recommend mulching a wider zone around the tree, using a mulch layer only about 2-3 inches thick and keeping it off the trunk entirely. Keeping turf and weeds away from the trunk also reduces root competition with the tree and reduces how many pests or diseases can be harbored nearby by those other plants.

Miri