除蟲菊の病害に就て

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The writer, during recent years, has been engaged in the study of the disease of the insect-powder plant (Chrysanthemum chenrariifolium (Trev.) Bocc.) in Okayama prefecture, and found out that follwing six kinds of diseases exist on the host : the blight (Diplodia chrysanthemella), the small sclerotium disease (Sclerotima minor), the large sclerotium disease (Sclerotinia Livertiana), the sclerotium wilt (Hypochnus contrifugus=Sclerotium Rolfsii) the fusarium wilt (Fusarium sp.) and the septoriose (Septoria chrysanthemella)., All fungi causing these diseases except the last one, were isolated and cultured purely, and their pathogenisities were proved respectively by the inoculation experiments. Among the diseases, however, more extremely prevalent are the blight, the small sclerotium disease, and the large sclerotium disease. The fusarium wilt may be serious but not so prevalent, other diseases being minor importance. (1) The blight. This disease caused by a species of Diplodia, which is hitherto undescribed and named here the writer as Diplodia chrysanthemella nov. sp.. The deseription of this species is as follows. Pycnidia immersed or erumpent, flaskshaped or irregular, black, 60 to 141μ usually about 100μ in diameter. Pycnidia produced on pure cultures are comewhat larger, being on acid standeard agar 81 to 360μ on boild potato 200 to 340μ, and on mannit agar 115 to 300μ. Pycnospores ellipsoid unicellular and hyaline when young, but usually two or rarely three celled and brown of light olive when matured; 6-13μ×3-6μ, generally 6-9μ×3μ in average 11μ×3.6μ. The measurements of pycnospores produced on the culture media do not differ from natural ones. Conidiophores are very short and slender. The fungus flourishes well in various media and produces pycnidia. It attacks the leaves, leaf-stalks, flowers and stems and causes leaf, stem or ray blight of the host. (2) The small sclerotium disease This disease caused by the attack of Sclerotinia minor Jagger, a species which is known to be found the lettuce, celery and other crops causing their decay disease in America. It is very interesting to know its occurrence in Japan. No report ever apeared on this fungus from this country. Sclerotia are very small, having onion seed appearance ; 0.2 to 4mm. mostly 0.5 to 2mm. in diameter : stalks slender 2 to 5mm. long, 0.3 to 0.5mm. in diameter. Micro-conidia formed on the culture media but not in nature. Themeasurements and the morphological characters of the asci and ascospores agree with Jagger's original description. The inoculation experiments proved that this fungus attacks the insect-powder plants, and also Artemisia vulgaris, lettuce and celery. It attacks the host in the parts of the stem and the leaf tauched to the soil at first, so that the plant soon began to wilt and to decay or dry out, and finally forms numerous sclerotia on the decayed area. (3) The large scleroatium disease. This disease eaused by a welknown fungus Sclerotinia Lilertiana Fuck. The symptom of the discase is very alike to that caused by Sclerotinia minor, but the shape and size their sclerotia, produced on the host plants or the culture media are very different. The measurements of the size of naturally produced sclerotia of this species are 2×2mm to 12×7mm., in averge 6×3.6mm. So both species can easily be distinguished even on the host plant. (4) The sclerotium wilt. It caused by Sclerotium Rolfsii Sacc.=Hypochnus centrifugus (Lev.) Tul., a fungus which is very widely distributed and attacks many other cultivated plants in this country. Its damage is not condidered as so serious. (5) The fusarium wilt. The disease caused by an undetermind species of Fusarium. The plants attacked in their leaves and stems wilt suddenly and dry up, the basal part of stems becamming greyish black in colour. (6) The septoriose. This disease caused by Septoria chrysanthemella Sacc., which is known to cause the black spot disease of the cultivated chrysanthemum i
日本植物病理学会の論文
1928-10-26

著者

鑄方末彦
農事試驗場中國支場

除蟲菊の病害に就て

スポンサーリンク

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