葡萄の一新病害輪斑病の研究

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1. The present paper deals with the studies carried out by the writers on some morphological, physiological and pathological characters of the new fungus which causes a leaf-blight of grape-vines. 2. On culture media such as stancard agar, potato sucrose agar and grape-leaf decoction agar, the fungus grows well, constantly producing conidia though perithecia have never been found. 3. By articial inocultations with conidia or ascospores infection is obtained on American barieties (Vitis lavuruscana, but not on European varieties (Vitis vinifera). 4. Incubation period of the fungus is about 15 to 20 days when inoculated with ascospores and about 15 to 16 days in the case of conidia. 5. Ingection only results when the spores are inoculated under surface of the leaves. 6. It is proved by cytological investigation that the penetration of the fungus is through stomata by means of germ-tubes. 7. The primary infection may be established by ascoepores only, because the longibility of conidia is at most to May. 8. The formation of perithecia begins in November, taking a form first like a sclerotial body and ascospores are formed in Jnne to July. 9. The optimum grouwth of the fungus is at 20-25℃. 10. The disease and its causal fungus are briefly described as follows : In August 1925, a new leaf-bright of grape-vines was observed by one of the writers in vicinity of Okayama. From the end of July to November the disease is noticeable by causing concentric large brown spots on the leaves and shedding the leaves prementurely. As the symptom of the disease very much resembles that of well known leaf-blight caused by Isariopsis clarispora (B. et (:) Sacc., so the disease has often been confounded by viticulturists. But the disease in zuestion is easily distinguishable from the latter by the concentric spots, giving the lesions a 'target-board' effect. The causal fungus of the disease is hitherto undescribed, therefore the name 'Acrospermum viticola' is proposed for the fungus. Acrospermum viticola Ikata n. sp. Perithesia stage : Perithethia usually develop under the surface of the fallen leaves, at first as small black dots, later very conspicuous thorn-like appearance. They are scattered, free, superficial ; lavceolate or clavate, some-what compressed ; black in color ; leathery thick-walled ; measuring 900-2100μ in length, 195-445μ in diameter. Asci are hyaline long, cylindrical, thin-walled with round apex ; 225-413μ long, 2.5-3.5μ wide ; 8 spored without paraphyees. Ascospores are hyaline, very slender, long filamentous, non-septate ; measuring 152-280μ long, 1-2μ wide, 189.5×1.5μ in average. conidial stage : Conidiophores singly arise from creeping mycelia grown under the surgace of the diseased leaves and not from mycelia in the host tissue directly. After the primary conidiophores grow up in some length, their apex swells like a head where conidia set on abundantly ; the secondary conidiophores then arising from the basal part of the head also form heads and conidia. Thus the formation of conidia is repeated in two to several times. Conidiophores are multiseptose, usually simple, rarely branched, light brownish yellow in color, 1-3 septate, very variable in length from 30 to 300μ and 3 to 4μ in width including scccondary conidiophores. The primary and the secondary conidiophores are 1-3 septate, 25-90μ long and 3-4μ wide with many conidia on the head. Conidia are verticillate, cylindrical or ellipsoid. The attached parts of sterigmate are tapering and their apposite ends are round, somewhat curved to one side. They are hyaline, non-septate when young, light yellow grey, 3-4, usually 1-2 septate when matured, 7.5-16.3μ long and 2.0-6.0μ wide, averaging 10.8×2.7μ in size. This conidial stage belongs to the genus Spondylo ladium or Acroth cium. Habitat : The fungus is collected in Okayama in September, 1925 and Fukuoka in November 1929 by S. ikata and in Chiba in 1914 by S. Hori.
日本植物病理学会の論文
1931-03-30

葡萄の一新病害輪斑病の研究

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