半夏疫病病原鉴定和防治研究

Identification and control of Phytophthora blight of Pinellia ternata

为了明确甘肃清水半夏疫病的病原及其防治药剂,对该病病原菌进行了分离鉴定,并筛选防治该病的药剂。结果表明:半夏疫病的病原为寄生疫霉(Phytophthora parasitica Dast.),寄生疫霉菌丝生长最适pH、温度分别为6.8与27.3℃;室内药效比较表明,58%甲霜灵.锰锌可湿性粉剂和70%甲基硫菌灵可湿性粉剂药效最好,1 200倍抑菌率均为100%;田间药效试验表明,58%甲霜灵.锰锌可湿性粉剂500倍液药效最好,施药2次防效为97.4%,70%甲基硫菌灵可湿性粉剂500倍液施药2次后防效仅达71.5%。

Phytophthora blight of Pinellia ternata was found as an important disease late in the growing season in Tianshui Production Base. In order to study the pathogen and its proper fungicides to instruct agricultural production, the pathogen was isolated and identified following Koch＇s postulates. Six fungicides were screened in laboratory experiments and field tests. The results showed that the pathogen was identified as P. parasitica Dast. According to the morphological features, culture characteristics and the test of pathogenicity of the pathogen, the optimal temperature and pH for mycelial growth of P. parasitica Dast. were 27.3 ℃and 6.8, respectively. Fungicide tests indicated that 58% metalaxyl-mancozeb WP and 70% thiophanate-methyl WP were the most effective in laboratory experiments. The control effect of 58% metalaxyl-mancozeb WP （500 fold dilution） to the growth of P. parasitica Dast., based on field tests, was higher than that of 70% thiophanate-methyl WP （500 fold dilution）, and the efficacy were 97.4% and 71.5%, respectively.