番石榴枝枯病菌生物学特性及防治药剂筛选

    Biological characteristics and control agent screening of the guava twig blight pathogen

    • 摘要:
      目的 明确番石榴枝枯病菌Neopestalotiopsis egyptiaca的生物学特性,并筛选出有效的防治药剂,为番石榴枯枝病的防治提供理论依据。
      方法 通过单因素试验测定了不同培养条件对其生长及分生孢子萌发的影响,并采用菌丝生长速率法测定6种常用化学药剂对病原菌的抑制效果。
      结果 25 ℃、pH 5.0、24 h光照的环境有利于菌丝的生长;在20 ℃、pH 10.0、12 h光照的条件下,该菌的产孢能力显著增强;25 ℃、pH 7.0的条件有利于孢子的萌发;此外,菌丝和分生孢子均具有一定的耐盐性。供试的6种杀菌剂中,甲基硫菌灵和吡唑醚菌酯的抑菌效果较好,EC50分别为0.698 6和1.405 4 μg/mL。其次为春雷霉素和代森锰锌,其半最大效应浓度(Half maximal effective concentration, EC50)分别为244.477 1和365.990 5 μg/mL。
      结论 番石榴枝枯病菌N. egyptiaca适应性强,在较宽的温度和pH范围内均能生长;室内毒力测定结果表明,甲基硫菌灵和吡唑醚菌酯抑菌效果最佳,可作为田间防控的优选药剂。

       

      Abstract:
      Objective This study aimed to clarify the biological characteristics of Neopestalotiopsis egyptiaca, the causal agent of guava twig blight, and screen effective fungicides to provide a theoretical basis for disease control.
      Method The effects of different culture conditions on fungal growth and conidial germination were determined through single-factor experiments. The inhibitory effects of six common chemical fungicides were evaluated using the mycelial growth rate method.
      Result Optimal mycelial growth was observed at 25 ℃, pH 5.0, and under 24 h light exposure. In contrast, sporulation was significantly enhanced at 20 ℃, pH 10.0, and under 12 h light conditions. The optimal conidial germination occurred at 25 ℃ and pH 7.0. Furthermore, both mycelia and conidia exhibited certain salt tolerance. Among the six tested fungicides, thiophanate-methyl and pyraclostrobin showed the strongest inhibitory effects, with EC50 values of 0.6986 and 1.4054 μg/mL, respectively. Kasugamycin and mancozeb also demonstrated inhibitory activity, with Half maximal effective concentration (EC50) of 244.4771 and 365.9905 μg/mL, respectively.
      Conclusion N. egyptiaca exhibits strong adaptability, thriving across a wide range of temperatures and pH levels. In vitro toxicity tests indicate that thiophanate-methyl and pyraclostrobin are the most effective fungicides and should be prioritized for field control.

       

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