Obtaining The Fungicides For Controlling Melanose And Studies On Synergistic Mechanism Of Fungicide Mixtures

Alternaria brown spot is a major fungal disease of citrus caused by Alternaria alternata.At present,there are no registered fungicides to control this disease in China.In this paper,the mycelium growth rate method and spore germination method were used to screen the effective single agent and mixed combinations of fungicides for Alternaria brown spot fungus,and then to explore the synergistic mechanism of the mixed combinations,in order to obtain the synergistic combination of fungicides to using in actual production.（1）The fungicide 45%Prochloraz microemulsion has a good inhibitory effect on mycelium growth of Alternaria brown spot fungus and the spore germination of Alternaria brown spot fungus,EC₅₀ is 0.8798mg/L and 0.3035mg/L,respectively.（2）The synergistic effect of inhibiting mycelium growth by single agent was significantly increased by mixing 3%zhongshengmycin wettable powder with other four kinds of internal absorbent agents.The synergistic effect of inhibiting spore germination by single agent was significantly increased by mixing 70%Propineb wettable powder with other four kinds of internal absorbent agents.（3）The synergistic mechanism of the synergistic combination of fungicides was related to the leakage of essential substances such as intracellular reducing sugar and protein,which may be related to the destruction of cell membrane by the fungicides.