Brown spot disease was treated with triazole drug spray with internal absorption and conduction, and sprayed again every 5-7 days.
Leaf steaming caused by physiological disorder of root system. First, steam burns. It is currently in the high temperature season. After heavy rain or flood irrigation, soil moisture evaporates rapidly, and leaves near the ground are burned by high temperature steam. If nitrogen fertilizer is applied before rain or watering, some ammonia will be contained in the steam, and the "steam damage" of leaves will be more serious. The second is physiological dehydration caused by rapid transpiration of leaves. After heavy rain or flood irrigation, the soil permeability becomes worse, the root system is in a state of hypoxia, the absorption capacity is weakened, and a large number of capillary roots die, which can not supply water and nutrients to the leaves in time. However, under the current climate conditions, the transpiration of leaves is very strong. The bigger and thicker the leaves, the greater the transpiration intensity, and the root system can not be supplied in time, which leads to rapid transpiration and physiological dehydration of the leaves, as if they were scalded by boiling water. After the weather is clear, spraying potassium dihydrogen phosphate+amino acid on the leaves for nutrition, regulating the tree potential and enhancing the stress resistance of the tree. Loosening underground soil, flushing humic acid and trace element fertilizer to stimulate root growth.