Abstract: In order to provide the scientific basis for developing fungicide from Acorus tatarinowii, the antifungal stability of A. tatarinowii ethanol extracts were tested by mycelial growth rate method,the inhibition rate of conidial germination were determined by microscope concave slides method,and the preventive effects of A.tatarinowii ethanol extracts on Botrytis cinerea were determined by pot-culture method. The results showed that the antifungal activity of A.tatarinowii ethanol extracts was not influenced by pH or UV-irradiation, the antifungal activity decreased when the temperature was higher than 78 ^oC,and increased when the concentration of saccharose in culture was higher than 0.08 g/mL,it was stable when stored at 22~28 ℃ or 4 ℃.Its EC₅₀ and EC₉₀ on grey mould spore germination were 0.0109 g/mL and 0.0318 g/mL,respectively. Its EC₅₀ and EC₉₀ on preventive effects in green house were 0.0221 g/mL and 0.1533 g/mL, respectively. In conclusion, the spore germination and growth of mycelial can be effectively inhibited by ethanol extracts from A.tatarinowii. A.tatarinowii can be used for the further development of a Chinese herbal fungicide.

Key words: Acorus tatarinowii, ethanol extracts, Botrytis cinerea, stability, spore germination, control effect