I have seen many years of problems with plants and many diseases that come from air and fungal problems, much of which is from to much rain. Had a call about worms on trees. I sprayed evergreens with garlic and it does kill them. It will control worms as even a pesticide will not. The worms have an oily film on their bodies and if sprayed with a surfactant they will drown as the surfactant will dissolve the oil in the bodies and water will drown them.
All controls depend on persistance of the chemical or organic material used, nothing works quickly.
Garlic has more going for it than does a chemical pesticide. Write your plant wish questions and I will try to answer. Save old bricks and old planter edging to use at a later date for new landscapes.