番茄早疫病病原鉴定、生物学特性及防治药剂减药配比筛选

Identification and biological characterization of the pathogen causing tomato early blight and screening of dosage reduction proportions of the fungicide

摘要:

【背景】 旱地番茄是山西省长治市壶关县的特色产业之一。近年来由于降雨量增加导致番茄早疫病频发。【目的】 明确试验田番茄早疫病致病菌，并对其生物学特性进行分析。引入助剂激健，结合室内抑菌试验和田间试验筛选既减少苯甲·嘧菌酯用量又保证药效的最适减药配比。【方法】 采用形态学观察及分子生物学方法对分离纯化的病原菌W1进行鉴定，对其最适碳源、温度、光照及pH值等生物学指标进行研究。引入有机助剂激健，采用平板对峙方法进行室内减药抑菌活性试验，同时结合田间小区试验评价其防治效果。【结果】 菌株W1经形态学特征及分子生物学方法鉴定为极细链格孢(Alternaria tenuissima)，该菌株营养生长的最适碳源为果糖，最适生长温度为28 ℃，最适pH值为7.0，在全黑暗条件下菌丝生长速度最快。室内抑菌活性研究表明，苯甲·嘧菌酯配施激健的减药处理均对番茄早疫病菌有抑制作用，减药10%+激健的处理优于常规用药处理，抑制率为93.90%。田间第1次药后7 d减药10%+激健的处理和减药20%+激健的处理防治效果分别为77.54%和72.94%，田间第2次药后7 d减药10%+激健的处理和减药20%+激健的处理防治效果分别为83.40%和80.32%，均显著优于常规施药的防治效果。【结论】 极细链格孢为本试验田番茄早疫病致病菌。添加助剂激健可实现减少苯甲·嘧菌酯使用量且防治番茄早疫病的目的，其中苯甲·嘧菌酯使用量减少20%+激健的处理为最适用药配比。

Abstract:

[Background] Dryland tomato is one of the characteristic industries in Huguan County, Changzhi City, Shanxi Province. In recent years, increased rainfall has led to frequent outbreaks of tomato early blight. [Objective] To identify the pathogenic fungi causing tomato early blight in the experimental field and analyze their biological characteristics, we introduced the adjuvant Jijian and screened the optimal dosage reduction proportion that minimize the usage of difenoconazole+azoxystrobin SC while maintaining the efficacy through indoor antifungal tests and field trials. [Methods] Morphological observation and molecular biological methods were employed to identify the isolated pathogen strain W1. The biological indicators including optimal carbon source, temperature, light conditions, and pH value of this strain were studied. The organic adjuvant Jijian was introduced, and indoor antifungal tests were conducted via the plate confrontation method to optimize the dosage reduction proportion of the fungicide. Furthermore, field trials were carried out to evaluate the control efficacy. [Results] Strain W1 was identified as Alternaria tenuissima. The optimal carbon source, temperature, and pH for the vegetative growth of this strain was fructose, 28 ℃, and 7.0, respectively, and the mycelial growth was fastest under complete darkness conditions. Indoor antifungal tests showed that all dosage reduction treatments of difenoconazole+azoxystrobin SC combined with Jijian had inhibitory effects on the fungus causing tomato early blight. The 10% reduction+Jijian treatment was superior to conventional dosage treatment, with an inhibition rate of 93.90%. In field trials, the control efficacy of the 10% reduction+Jijian and 20% reduction+Jijian treatments was 77.54% and 72.94%, respectively, 7 days after the first application and 83.40% and 80.32%, respectively, 7 days after the second application, surpassing that of the conventional application. [Conclusion] A. tenuissima is the pathogenic fungus causing tomato early blight in this experimental field. Adding the adjuvant Jijian can reduce the usage of difenoconazole+ azoxystrobin SC while maintaining the control efficacy against tomato early blight, with 20% reduction in difenoconazole+azoxystrobin SC+Jijian being the most suitable treatment.