Health or trees

This summer I have seen a lot of stress on plum and trident deciduous, losing leaves or insect holes and edge/tip discoloration and darkening/curling of leaves.

I’ve tried to use Neem oil when suspecting insects, or diluted Lime Sulphur for fungus—but learned it was not recommended. Water or heat stress tends to react at the leaf tips.

I have had Shishi Japanese Maple trees lose most leaves—and not sure if just sensitive to too much sun.