Mainly harmful to leaves. At the early stage of the disease, yellow and white spots appeared on both sides of the leaves, and then the central part of the disease spots protruded into dark brown vesicles, which burst and emitted rusty brown powder, which was the summer spores of the pathogen. In the later period, dark brown spots appeared in the ward, and after rupture, dark brown powder was emitted, which was the pathogen winter spore, and finally the leaves fell off orange. Winter spores overwinter on the sick and disabled, and continue to do harm in the next year, which seriously affects the yield.

Prevention and control methods:

After harvest, clear up the fields, concentrate the sick and disabled, burn them deeply, and eliminate the source of overwintering diseases.

Increase the application of phosphorus and potassium fertilizer to improve the disease resistance of plants.

At the initial stage of the disease, 25% triadimefon 1000 ~ 1500 times or 97% sodium chloride 300 times was sprayed every 7 ~ 10 days for 2 ~ 3 times, and sprayed on both sides of the leaves.