우리 나라의 未記錄 病인 Rhizoctonia solani Kuhn에 의한 배추 밑동썩음病(Bottom rot)에 대한 南部地方秋播露地栽培 時의 發病消長과 防除方法을 檢討하였다. 本 病의 發病은 定植 20餘日 經過後, 배추의 生育中期부터 發病되기 始作하여 結球期에 增加하는 傾向이었고, 收穫期의 發病株率은 平均 52% 程度였다. 그 被害는 秋播露地栽培보다 비닐하우스를 利用한 半促成栽培에서 甚하였고, 初期에 心葉까지 感染된 羅病株는 萎縮되어 生育이 極히 不良하여 結球가 되지 않았다. 羅病株에서 分離한 R. solani의 RDA培地上에서 菌絲 生育適?은 20~25℃였고, 菌絲融合群은 第Ⅱ群 第1型으로 分類되었다. 배추, 무우, 참깨 및 유채의 幼苗에 接種했을 때 立枯率이 매우 높았고 상치, 토마토, 오이에서는 立枯率은 낮았으나 發芽가 2~3日 遲延되었다. 防除藥劑는 發病初期부터 pencycron Wp.를 10日間隔 3回 處理한 것이 防除價가 80%로 優秀하였다.
Bottom rot of Chinese cabbage (Brassica pekinensis Rupr) hitherto undescribed in Korea is caused by Rhizoctonia solani Kuhn. Development of bottom rot in fall crops was observed and the efficiencies of fungicidial control in naturally infested field in Southern region were studied. Bottom rot symptom started to develop in 20 days after transplanting 20 day old seedlings, which corresponded to the middle growing stage. At the heading stage, the infection rate increased substantially, which progressed upto an average of 52% at harvesting time. The overall infection rate was about 30% in Chinese cabbage field under plastic film house cultivation. However, disease intensity of fall crops was less severe than that of crops in plastic film house, where plants infested earlier, stunted and their growth was extremely poor. Optimum temperature for mycelial growth of bottom rot isolates of R. solani was 20-25C on potato-sucrose agar. This fungus was highly pathogenic on seedlings of Chinese cabbage, radish, sesame and rape resulting in high percentage of damping-off. For other crops, such as lettuce, tomato the cucumber, the germination was delayed for 2-3 days and the percentage damping-off was lower. Anastomosis group of this fungus was idenlfied as AG Ⅱ-1. Soil drenching of fungicide pencycron WP., three applications at 10 day interval, was effective ; indicating the most promising one with control value of 80%.