We adopted a field investigation to learn occurrence situation and observed biological characteristics of pathogen by using laboratory experiments.

The results showed that the disease mainly affected the leaves, petiole, and inflorescences of weeping willows. The pathogen was identified as Melampsora coleosporioides. The suitable urediospore germination temperature of weeping willow rust ranges from 20 to 28. The optimum temperature is 22, and germination begins at 2 h. Urediospore germination requires a high humidity, and has a poor adaptability to high temperatures. This is consistent with the frequent occurrence of weeping willow leaf rust during spring and autumn, which are rainy and warm. Melampsora coleosporioides can overwinter on leaves infected with teleutosori, but the influence of teliospores is unclear, and no heteroecism has been found. In addition, the rust can also overwinter on leaves infected with uredinium, which is the main source of infection in the early spring of the following year. After several infections by urediospores, the disease reached peaks in May and September. During the process, heteroecism did not occur.

This study clarified the pathogen and occurrence law of weeping willow leaf rust in Huangshan Region, and laid the foundations for further research concerning the prevalence, prediction and pesticide control of the disease.