Removal of all infected leaves is mandatory....those can't be 'cured' and will be a source of reinfection as long as they remain. The plucked leaves should be physically removed entirely from the garden, as well any leaves that may have fallen to the ground. Housekeeping chores play a very important role in the prevention of this particular disease. Unless the infection is very bad on numerous plants, chemical control is not called for. Just groom the plants periodically, washing your own hands and clippers so not to spread the disease.

Well it looks like it's Apple Maggot. This site had some good controls. https://www.planetnatural.com/pest-problem-solver/tree-pests/apple-maggot-control/ Based on the life cycle keeping it clean ( I hope the bear comes by soon to eat all the apples) and then applying the nematodes. Are there better nematodes than others? Or is a nematode is a nematode is a nematode? Then some of the Orchard spray and kaolin spray when it flowers next year.

Brachychiton

C² Solutions - Do you mind my asking where you acquired the wood piece? It does certainly look like it was used as a mantle. Have recently purchased a similar piece of wood for our outdoor fireplace (on screened in porch.)