甘肃省辣椒疫病病原菌鉴定及生物学特性研究

 甘肃省辣椒疫病发生严重,天水地区及兰州市发病面积高达70%～80%。1988年对该病进行了病原菌的分离鉴定,从分离的菌株中选取7株作进一步研究,比较了菌落形态、菌丝直线生长速度、最高生长温度。无性孢子囊变异性大,平均25.1～36.8μm,长宽比1.4～1.6:1,乳突明显(2.7～3.1μm),偶见双乳突。藏卵器球形,大小28.3～33.9μm×26.3～32.7μm。雄器大小13.5～14.9μm×9.0～11.5μm。卵孢子大小23.6～27.4μm。有性繁殖和Phytophthora capsici A₁及A₂标准菌株相配能产生有性孢子,但自交不孕。供试菌株对孔雀石绿不敏感,同时能利用淀粉作为碳源,50ppm恶霉灵对供试菌株仅有轻微抑制作用。根据上述,甘肃省辣椒疫病菌初步定为P. capsici.经室内药效测定以瑞毒铜1000倍,大富丹1000倍及杀毒矾M81000倍最佳。

Identification and Biological Studies of Phytophthora Causing Blight of Peppers in Gansu

In recent years, a serious disease of Phytophthora blight of peppers has happened in Gansu. The isolation, inoculation and identification of the causal organism were made with the materials from Tianshui, Lanzhou and Zhangye prefectures. Comparative experiments were tested for colony morphology, linear mycelial growth, and maximum temperature of growth. The sporangia vary in size, Length/breadth being 1.4～1.6: 1, conspicuously papillate, usually with single papilla. The oogonia are spherical, (28.3～33.9)×(26.3～32.7)/μm in diameter, antheridia are (13.5～14.9)×(9.0～11.5)μm in diameter, oospores are 23.6～28.0μm in diameter. Oospores were produced when isolates paired with A₁ and A₂ mating type of P.capsici, but they are selfsterile. The isolates are not sensitive with malachite green. All testing isolates showed the capability of starch utilization. The growth of mycelium was only slightly inhibited by 50ppm hymexazol. By comparing with the characteristics of many Phytophthora species, this isolate was identified to be P.capsici. Besides, the fungus is very sensitive to Ridomil-Copper sulphate, Dafudan, and Sandofan M8 in laboratory experiments.