Identification for anthracnose pathogen of Paphiopedilum and selection of its indoor chemical control chemicals

ObjectiveAnthracnose pathogen of Paphiopedilum was identified and indoor control chemicals were se-lected to provide theoretical basis for prevention and control of Paphiopedilum anthracnose.MethodThe samples of Paphiopedilum with typical anthracnose symptoms were collected.The pathogen was isolated and cultured through tissue isolation.Anthracnose pathogen of Paphiopedilum was identified by morphological observation and rDNA-ITS sequence analysis.The biological characteristics such as pathogen mycelial growth,spore production and spore germination were determined by experiment including indoor temperature,illumination and culture media with different pH values,carbon and nitrogen sources.Sensitivity to 12 fungicides of anthracnose pathogen of Paphiopedilum was tested and then fungi-cides with fine effects were selected to conduct indoor toxicity test.ResultThrough morphological observation and rD-NA-ITS sequence analysis,the anamorph of isolated anthracnose pathogen of Paphiopedilum was Colletotrichum gloeo-sporioides,belonging to Colletotrichum,Melanconiales,fungi imperfecti.The temperature for mycelial growth and co-nidial germination was 9℃to 36℃,and the optimal temperature was 27℃.Sporulation temperature was 12-36℃,and the optimum temperature was 30℃.Lethal temperature for C.gloeosporioides mycelia was 55℃maintaining for 20 min, and lethal temperature of conidia was 50℃maintaining for 30 min or 55℃maintaining for 20 min.pH range for both my-celial growth and sporulation was 2-13 and the optimum pH for the both was 8.pH range for conidial germination was 2-12 and the optimum one was 7.Continuous illumination was good for mycelial growth,sporulation and conidial germina-tion.The carbon and nitrogen sources in media had significant difference on mycelial growth,sporulation and conidial germination(P<0.05).Under the concentration 500 mg/L,hymexazol,sulfur·Jialiulin,Fufuxin and prochloraz-manga-nese chloride complex could effectively control mycelial growth and sporulation of anthracnose pathogen,the success rates were both 100.00%.Among the four fungicides,prochloraz had the strongest toxicity and reaction sensitivity,and its concentration for 50% of maximum effect(EC50)was 0.09 mg/L.ConclusionThe anthracnose pathogen of Paphiope-dilum is Colletotrichum gloeosporioides. Hymexazol,sulfur·Jialiulin,Fufuxin and prochloraz can effectively control Paphiopedilum anthracnose,and prochloraz-manganese chloride complex with concentration of 500 mg/L has the best control effects.