Isolation and identification of pathogen of Trichoderma disease in Pleurotus citrinipileatus and screening of plant bacteriostatic agents

【Objective】To clarify the pathogen species of Trichoderma disease in Pleurotus citrinipileatus and screen effective plant bacteriostatic agents,which could provide theoretical basis for scientific diagnosis and field control of Trichoderma disease in Pleurotus citrinipileatus. 【Method】The contaminated packets of Pleurotus citrinopileatus were collected from the edible fungus cultivation base of Zhifusenhua Agricultural Cooperative in Dengtai Village,Longju Town,Wanzhou District,Chongqing City. The pathogenic bacteria in the contaminated bags of Pleurotus citrinopileatus were isolated by tissue separation method,and the pathogens were identified by morphological characteristics and molecular biology methods. A total of 32 kinds of common medicinal plants were extracted by alcohol solution to form extract. The effects of different medicinal plant extracts on the mycelium growth of pathogens were determined by mycelium growth rate method. The optimal concentration of fungicides was determined by minimum inhibitory concentration（MIC） and minimal bactericidal concentration（MBC）. The inhibitory effects of fungicides on pathogens were evaluated by spore germination experiment. 【Result】Two Trichoderma strains were isolated from the contaminated packets of Pleurotus citrinopileatus and identified as Trichoderma longibrachiatum and Trichoderma atroviride. The results of bacteriostatic experiment showed that the extracts of Coptis chinensis Franch. and Glycyrrhiza uralensis Fisch. had the better inhibitory effects on Trichoderma longibrachiatum,the average mycelium growth inhibition rates were 94.54% and 81.90%,both MIC and MBC were 15.60 and 31.25 mg/mL respectively,and the highest spore germination inhibition rates were 97.73% and 96.95% respectively. The median inhibitory concentration(EC₅₀) were 1.0670 and 2.2260 mg/mL respectively. The comprehensive effects of Coptis chinensis Franch. extract on Trichoderma atroviride was the best,with an average mycelium growth inhibition rate of 65.82%,MIC of 250.00 mg/mL,spore germination inhibition rate of 89.21% and EC₅₀ of 34.1080 mg/mL. 【Conclusion】T. longibrachiatum and Trichoderma atroviride are the main pathogens that contaminate P. citrinopileatus. The extracts of Coptis chinensis Franch. and Glycyrrhiza uralensis Fisch. can effectively inhibit these 2 pathogens and can be used as plant bacteriostatic agents in the cultivation of edible fungi.