Abstract: A fungal associate that proliferated on the soil surface during the 5-year continuous cultivation of Morchella sextelata was selected as the research subject. Identification was performed based on morphological characteristics and three molecular marker genes (ITS, LSU, RPB2). The mycelial growth rate method was used to evaluate the inhibitory effects and toxicity of five conventional pesticides against both the associated fungus and Morchella sextelata. The results indicated that the identified associated fungus was Botryotrichum sp. At the recommended field application concentrations, the inhibition rates of five pesticides,namely Kasugamycin + copper oxychloride, hymexazol, chlorothalonil, triadimefon, and mancozeb, on Morchella sextelata were 0.25%, 5.24%, 23.94%, 56.61%, and 70.32%, respectively. The corresponding inhibition rates on Botryotrichum sp. were 27.78%, 18.13%, 21.64%, 21.64%, and 49.71%, respectively. The EC₅₀ for Morchella sextelata were 12.079 8, 6.214 6, 25.460 9, 5.885 0 g/L and 14.336 6 g/L, respectively, while those for Botryotrichum sp. were 11.076 8, 9.487 4, 50.925 7, 18.835 3 g/L and 16.940 3 g/L, respectively. Based on a comprehensive analysis of inhibition rates and EC₅₀, it was concluded that Kasugamycin+copper oxychloride exhibited strong inhibitory effects against Botryotrichum sp., while demonstrating relatively low toxicity to Morchella sextelata. Therefore, Kasugamycin+copper oxychloride could be recommended as a fungicide for field control of Botryotrichum sp.

Key words: Morchella sextelata, associated fungus, identification, greenhouse continuous cropping, Botryotrichum sp., screening of prevention and control agents