無菌的かつ簡単に多量の遊走子のうを形成させるための新しい方法を試案した。供試菌はPhytophthora capsici No. 65である。培地としては, 菌糸の生育良好で, 良質の遊走子のうを形成するものとしてV8ジュースを選出した。100mlのフラスコに入れた30mlの液体培地中で, 28℃, 3週間, 前培養した菌そうを, ブフナー滬斗を用いて, 殺菌水にてよく洗浄し, あらかじめ, 湿った滬紙2枚を敷いておいたペトリ皿に移し, 障子紙を張った木枠のふたをかぶせ, 螢光灯照明付28℃定温器中に並べておくと, 36∿48時間後, 表面に多量の遊走子のうの形式がみられた。この遊走子のうは気中性で, 小型の薬さじで容易にかき取ることができる。本法はP. palmivolaおよびP. melonisにも適用して多量の遊走子のうを得たが, P. parasitica, P. citrophthoraおよびP. heveaeでは満足すべき結果が得られなかった。A new method for obtaining abundant zoosporangia of Phytophthora spp. is described in this paper. The V-8 juice medium was favorable for both mycelial growth and zoosporangium formation of Phytophthora capsici Leon. No. 65. Thirty ml of the medium in each of 100ml Erlenmeyer flask was sterillized by autoclaving at 121℃ for 15 minutes. This medium was inoculated with a 5mm diam. disk of mycelium grown on potato dextrose agar plate at 28℃ for a week. After 3 week incubation period at 28℃, mycelial mat was removed from the flask, and rinsed with sterilized deionized water through a Buchner funnel with a sheet of filter paper (Fig. 1). The clean mycelial mat then put on 2 sheets of moistened filter paper in a Petri dish. The Petri dish was covered with a special paper lid (Fig. 2), and placed in a 30℃ incubator illuminated with fluoresent lamp. One of the important points of this method is to use the paper lid instead of the ordinary glass lid of Petri dish. The paper lid keeps the surface of mycelial mat in moderately dry condition. The another point is to illuminate with fluorescent lamp. Both dry condition and illumination seems to be very effective for sporangium production by this fungus. Numerous zoosporangia were formed on the surface of mycelial mat after 36-48 hours. They were easilly collected by a small spatula. This method has so far been found to be applicable to P. palmivola and P. melonis, but not to P. parasitica, P. citrophthora and P. heveae. In general, this method seems to be practicable for the fungi which produce aboundant spores on the surface of the host plant in field
