Rust

These leaf spots may be rust, a fungal disease. Plus the tree is probably going dormant. Rust diseases is more prevalent in humid climates. It doesn’t usually kill the plant, but the problem should be addressed asap to prevent further spread. When all the leaves drop dispose of them; do not compost! Rake up all old leaves from the base of the plant. Rust spores grow in standing water on leaves and the spores spread when rain or irrigation water splashes them onto neighboring leaves. Spores can overwinter on plant material. Suggest you spray with fungicide (often a sulphur spray-nurseries will have other options) as a dormant spray and maybe when new growth comes on in the spring – and keep it handy just in case you see rust developing early next summer.