Hi- we don't see foliar leaf disease symptoms in the photos. The browning is most likely the result of some type of burn (phytotoxicity), possibly from pesticide applications. Captan, in particular, can burn young apple leaves that have not yet formed a waxy cuticle. (Note: never apply Captan with or immediately after an application of horticultural oil or dormant oil.)

Any browning or curling that happened before the first application could have been caused by aphids or one or more environmental factors like , low soil moisture, low temperature bud damage, and excess fertilizer salts. Also, sometimes when trees go into the fall dormant period weakened they don't have sufficient food reserves to sustain all of the new spring growth resulting in leaves turning brown and dying.

Follow all label instructions when applying pesticides.
Jon