Effects of Soil Solarization for Control of Cucumber Wilt -Suppression of Fusarium oxysporum f. sp. cucumerium and Promotin of Cucumber Growth-

태양열 소독에 의한 오이덩굴쪼김병 방제 -병원균 생장억제 및 오이생육촉진에 미치는 비닐 피복효과-

The effects of solarization on the suppression of soilborne plant pathogen and the growth promotion of cucumber plants were examined in artificially infested soil by vinyl mulching and not mulching from July 25 to August 25, 1983. During the solarization period, the highest temperatures were $58^{\circ}C,\;45^{\circ}C,\;and\;42^{\circ}C$, at 5cm, 15cm, and 25cm of soil depth respectively. The inoculum of cucumber wilt pathogen, Fusarium oxysporum f. sp. cucumerinum, was mixed with soil 30cm deep and saturated with water. The pathogen was completely killed after 30dys of solarization in 5cm soil depth and 98 percent of inoculum was eliminated in 15cm soil depth. But the survival rate of the fungi in 25cm soil depth of solarized plot did not show significant differences compared with those in nontreated plot in 5cm and 15cm depth. Although some of the pathogenic fungi might survive from solarized soil in 15cm and 25cm depth, the ability of microconidia production was reduced significantly The number of microconidia grown on Komada's medium in isolates the primary colonies from solarized soil was less than that in isolates from nontreated soil approximately by one fourth. The first subcultured solates from the solarized soil grown on potato dextrose agar also produced a small amount of microc. onidia compare with that of subcultured isolates from nontreated soil. Cucumber seedlings planted in the soil collected from solarized plot grew much better than that in the soil from nontreated plot at any of soil loved, especially in 5cm of soil depth. And the fruits harvested from cucumber plants grown in the solarized plot were more in number and leavier in weight than that from nontreated plot. Besides the typical symptom development, significant growth suppression wvas recognized with increase of inoculum density of F. oxysporum f. sp. cucumerinum at early stage of cucumber seedlings in steam sterilized soil.

오이를 재배했던 비닐하우스 토양에 병원균을 전면 접종하고 1983년 7월 25일부터 8월 25일까지 포리에칠렌 필림을 멀칭하여 태양열소독 효과를 실험하였다. 멀칭처리 기간중 토양의 일중 최고온도는 깊이 5cm에서 $58^{\circ}C$, 15cm는 $45^{\circ}C$, 25cm는 $42^{\circ}C$에 달했다. 태양열처리 한지 32일 경과후 지표로부터 5cm이내의 토양에 있던 병균은 완전히 사멸되었으며 15cm 까지는 $98\%$ 이상 소멸되었으나 25cm 토양은 무처리와 차이가 없었다. 그러나 태양열처리한 토양에서 분리한 균주는 무처리 토양의 균주보다 소형포자 생산량이 현저하게 감소되었다. 멀칭처리에 재배한 오이는 생육이 월등히 좋았는데 특히 5cm 이내의 토양에서 두드러지게 나타났으며 노지재배의 경우도 생장과 수량이 무처리에 비하여 현저히 좋았다. 병원균 F. oxysporum f. sp. cucumerinum은 오이 유균에 외관상 나타나는 병징 이외에도 전염원의 농도가 증가됨에 따라 오이 생육이 비례하여 억제됨을 나타내었다.