Lagerstroemia indica has powdery mildew because the tree is too big. Is there any way to treat it from below?

The high-pressure sprayer can spray water more than 6 meters high. The most direct and effective method is to spray chemicals directly on the tree crown. There are many drugs for powdery mildew, which are sold in your local drugstore. If you don't understand, you can ask them, and they will prescribe medicine for treating powdery mildew of trees. Just buy a high-pressure sprayer. I often encounter this problem. The tree is too high, so I'll buy one at home.