Abstract: By using Malus×robusta（CarriŠre）Rehd as the test material，the pathogenic fungi were isolated using tissue isolation method，and their pathogenicity was determined according to Koch’s postulates.The morphological characteristics of the pathogenic fungi and rDNA⁃ITS sequence analysis were combined to identify the types of pathogenic fungi，their biological characteristics were investigated，and through indoor toxicity tests，the most virulent chemical fungicides were selected against the pathogenic fungi of Malus×robusta rot disease，in order to provide reference basis for the comprehensive prevention and control of Malus×robusta rot disease. The results showed that the two strains of pathogenic fungi HL⁃23 and HL⁃100 isolated from Malus×robusta suffering from canker were both Valsa mali.The biological characteristics of strains HL⁃23 and HL⁃100 were analyzed by measuring the colony diameter via the cross⁃method.The results showed that strains HL⁃23 and HL⁃100 were most suitable for cultivation on PDA medium.The optimal pH value for mycelial growth was 5.0，and the optimal temperature was 25—30 ℃.They were suitable for growth under 12 hours of light and dark alternation conditions，the optimal carbon source was sucrose，and the most suitable nitrogen source was ammonium dihydrogen phosphate.The toxicity of nine commonly used chemical fungicides，such as difenoconazole and azoxystrobin，against the pathogenic fungi HL⁃23 and HL⁃100 of Malus×robusta rot disease was determined through indoor plate experiments. It was found that the inhibition rates of nine fungicides on the same type of fungal strains HL⁃23 and HL⁃100 were significantly different.The best inhibition effect was difenoconazole，with EC₅₀ values of 0.010 9—0.0110 mg/L；The second was azoxystrobin，with EC₅₀ values of 0.015 8—0.018 1 mg/L.

Key words: Malus×robusta rot disease, Pathogen identification, Valsa mali, Biological characteristics, Toxicity test

摘要： 以感染腐烂病的八棱海棠为试材，采用组织分离法分离病原菌，并依据柯赫氏法则确定其致病性，结合病原菌形态学特征及rDNA-ITS序列分析鉴定病原菌的种类，研究其生物学特性，并通过室内毒力测定从9种常用化学杀菌剂中筛选出对八棱海棠腐烂病病原菌毒力最强的药剂，以期为八棱海棠腐烂病的综合防控提供参考依据。结果表明，从感染腐烂病的八棱海棠中分离获得的2株病原菌HL-23和HL-100均为黑腐皮壳属真菌Valsa mali。采用十字交叉法测量菌落直径分析菌株HL-23和HL-100的生物学特性，结果表明，菌株HL-23 和HL-100最适宜在PDA培养基上培养，菌丝生长的最适pH值为5.0，最适温度为25~30 ℃，适宜在12 h光暗交替条件下生长，最适碳源为蔗糖，最适氮源为磷酸二氢铵。通过室内平板试验测定了苯醚甲环唑、嘧菌酯等9 种常用化学杀菌剂对八棱海棠腐烂病菌HL-23和HL-100的毒力，发现各杀菌剂对HL-23和HL-100这2株同类型病菌菌株的抑制率具有明显差异，抑制效果最好的为苯醚甲环唑，EC₅₀ 为0.010 9~0.011 0 mg/L；其次为嘧菌酯，EC₅₀为0.015 8~0.018 1 mg/L。

关键词: 八棱海棠腐烂病, 病原鉴定, Valsa mali, 生物学特性, 毒力测定