1. Hoping that the experimental results may aid the solution of the problem as to what the stimulating substance in the filtrate of the cultured solution of the “Bakanae’-fungus really is, the experiments were conducted from six different phases. 2. The optimum concentration of the filtrate resulting the “Bakanae” symptom seems to be between 10 and 1%. 3. The function producing the symptom is not common to the species of Fusarium, at least to Fusarium Lini. 4. The growth promoting substance is thermostable, neither enzymic nor volatile. 5. The substance is adsorbed completely by animal black. 6. The substance is diffusible through the semipermeable membrane. 7. By the difference of the cultural solution of the fungus, the filtrate does not cause the “Bakanae” symptom, for example the filtrates obtained from the cultures in the RICHARDS' solution omitted KH2PO4 or MgSO4 or both of them do not cause any overgrowth of the rice-seedlings but checked its normal growth.
An accessory food substance was proved to be essential to the growth of Bact. hyacinthi SMITH It was contained more in the bodies or staled solution of Bact. solanacearum and less in oryzanin; both readily being available to the organism. This substance was denatured by filtrating through filter paper and destroyed by heating at 100°C for 30 minutes in successive three days. It is soluble more in water than alcohol. From its nature the author is inclined to believe that it may be identical with vitamine D, a cleavage from vitamine B as shown by FUNK and DUBLIN. The amount of this substance, necessary to the growth of the organism, is fixed; it being 3 per cent in beef bouillon when oryzanin employed as the source of this substance. Its excessive amount had no noticeable influence on the growth of the organism, but its low amount limitted the growth of it as proportional to its content. In the case of the excessive supply of the substance, the final growth of the organism, in spite of its amount, was always the same, though slightly favourable growth was observed at the beginning. It may be attributable to the population density of the organism. The intermittent growth was observed in the course of their culture, which seems to be comparable to ‘Hexenrings’ in fungus plate.
The present paper deals with a bacterial rot of sugar beet which prevails over Heijô, nothern part of Korea, causing yellowish soft rot and producing odor peculiar to the disease. Inoculation experiments showed the pathogenicity on carrot root), radish (root), potato (tuber), and tomato (fruit). The causal organism was compared with Bact. beticola, Bac. Betae, Bact. Serbinowi, specially Apl. teutlium, the causes of sugar beet diseases. And also comparison was made with Bac. aroideae, Bac. carotovorus and Bac. atrosepticus, the Causes of Vegetable diseases. No organism were found to be identical with the organism in question. Therefore, Bac. betivorus is proposed for the organism. A description of the organism is given as follows: Bacillus betivorus n. sp. A short rod with rounded ends, single, in pairs, or sometimes in long filaments in beef bouillon containing salts; motile by means of 2 to 6 peritrichiate flagella; Gram's negative. It forms no spores or capsules. It produces round or amoeboid homogenous thin colonies with smooth and entire margin on beef agar; clouds bouillon promptly and forms pellicle; liquefies gelatine; coagulates milk. It reduces nitrates; produces indol or hydrogen sulphide; produces gas from sucrose and glucose; is facultative anaerobic or aerobic. Optimum temperature for growth is about 35°C, min. at 12°C, max. at 45°C and thermal death point 50°C for 10 minutes.
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 standard agar, potato sucrose agar and grape-leaf decoction agar, the fungus grows well, constantly producing conidia though perithecia have never been found. 3. By artificial inoculations with conidia or ascospores infection is obtained on American varieties (Vitis laburuscana) 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. Infection only results when the spores are inoculated under the 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 ascospores 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 growth of the fungus is at 20-25°C. 10. The disease and its causal fungus are briefly described as follows: In August 1925, a new leaf-blight 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 prematurely. As the symptom of the disease very much resembles that of well known leaf-blight caused by Isariopsis clavispora (B. et C.) Sacc., so the disease has often been confounded by viticulturists. But the disease in question 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, somewhat 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, nonseptate; measuring 152-280μ long, 1-2μ wide, 189.5×1.5μ in average. Conidial stage: Conidiophores singly arise from creeping mycelia grown under the surface 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, 1-5 septate, very variable in length from 30 to 300μ and 3 to 4μ in width including secondary 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.