| The biological studies results show that the pathogen of the mullberry leaf blight(Hormodendrum mori Yendo) can grow and spore well on the PDA and the mullberry leaf juicemedium. The temperature range for the pathogen growth and sporogenesis is 10-38℃, with theoptimum at 25-30℃, the pH values range is 3-11, with the optimum at pH6-7 for the pathogenmycelial growth. The lethal temperature of the pathogen spore is 50-55℃. High humidity benefitthe growth and development of the pathogen. Continuous fluorescent light treatment favouredconidia production of the pathogen. Among 11 carbon sources and 11 nitrogen sources, fructose,mannitol and L-leucine are better than the others. The pathogen can not use cysteinc for it'sgrowth and development. Many fungicides treatment inhibited the growth and spore germinationof the pathogen. The benomyl has the best effect.The experiments and systematical observations, made during 2001-2005, showed that thereis a close relationship between the occurrence of the disease and temperature, humidity andrainfall in late April and early May. The spots were first found on the leaves when averagetemperature at 15℃or above. Severe epidemic occurred under the climate condition of 22-25℃,90％RH or above, especially in alternative fine and raining days. On the other hand, hightemperature and drought were unfavorable for the disease development. Overwintering spots onleaves are major primary infection sources. Poor draining and shading tended to facilitate thedisease development. Primary inocula largely affect early development of the disease.The disease resistance identification results show that there is great difference among thevarieties. Yu 71-1, Xiang 456 and Nongsang 14 are high resistance to the disease. But Yuesang11 and Xiangzasang 1 are very susceptible to the disease.Control methods were recommended that included field sanitation in winter, field drainage,using the resistance varieties and spraying benomyl at early stage of the disease during spring.
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