1987 Volume 53 Issue 4 Pages 531-539
Fusarium wilt of bottle gourd (Lagenaria siceraria Standl.) caused by Fusarium oxysporum f. sp. lagenariae is a serious and wide-spread soil-borne disease in Japan. In some fields of Tochigi prefecture, welsh onion (Allium fistulosum L.) has been mix-cropped customarily as an associate crop with bottle gourd. Those fields showed little occurrence of the disease, in spite of continuous cropping of bottle gourd. This phenomenon suggested the relation between mix-cropping with welsh onion and control of the disease. From the subterranean parts of the welsh onion, Pseudomonas gladioli were isolated frequently, and some of these bacterial isolates showed antifungal activity to F. oxysporum f. sp. lagenariae on BPA plates. But as they were usually pathogenic to roots of welsh onion, we had to select, for practical use, isolate that antagonized strongly to F. oxysporum f. sp. lagenariae, had no pathogenicity to welsh onion or other plants, and multiplied well on subterranean parts of welsh onion. Such an isolate P. gladioli M-2196 (isolated from Miltonia sp.) was selected from 90 isolates of Pseudomonas spp. from 20 kinds of plants. For the purpose of biological control of Fusarium wilt of bottle gourd, we cultured P. gladioli M-2196 on BP broth up to 109 cells/ml, dipped the root systems of associate crop (welsh onion or chinese chive) in the cultural suspension for five min., and then bottle gourd was mix-cropped with associate crop in infected soil. With this treatment, occurence of Fusarium wilt was districtly suppressed. This mix-cropping using associate crop with P. gladioli M-2196 seemed to be a beneficial technique for biological control of soil-borne fungal diseases.
