How to control Lagerstroemia indica pests and diseases?

In sooty blotch, there were scattered gray-black to black radial lesions in the early stage of the disease, which formed black mold of coal pollution and affected photosynthesis. When planting flowers in protected areas, pay attention to ventilation and light transmission, reduce humidity, keep a certain spacing between potted flowers and prune them reasonably. When the illness is mild, it can be wiped and rinsed with water; Eliminate aphids and scale insects; Spraying 500-800 times solution of 50% carbendazim wettable powder and 500 times solution of 70% thiophanate methyl.