大麻白星病の研究

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1. The morphological, physiological and pathological studies were made on the leaf-spot of the hemp (Cannabis sativa L.) caused by Septoria Cannabis (LASCH) SACC. 2. The disease in question seems to appear first in the early summer on the leaves of the plants, especially on the lower ones. The spots are ellipsoidal or polygonal and yellowish to grayish brown. The disease spreads gradually as the season becomes warmer during June to July, often resulting in the premature fall of the leaves. 3. The pycnidia of the fungus are generally formed under the epidermis of the upper surface of the leaf, being immersed in the palisade tissue, and the epidermis are perforated by minute ostioles. The pycnidia are spherical or flat in shape and measure about 27.5 to 115.5 μ in diameter and are light brown in colour. The pycnospores are filiform, straight or slightly curved, smooth and hyaline. Their measurements are 12-46×2-3μ and the septa are 0 to 5, commonly 3. In culture media the pycnidia are 85 to 465μ in diameter and their colour is brown or black, while the characters of pycnospores are the same as those observed on affected leaves. 4. The cultural characters of the fungus were studied on ten different media. It was found that the most suitable medium for the mycelial growth was potato decoction agar and that for the formation of pycnidia and pycnospores was hemp decoction agar and soy agar after SAITO's formula. 5. The relation of temperature to the growth of the fungus was studied on soy agar, potato decoction agar and on nutrient agar with pepton. It was found that the optimum temperature for the mycelial growth was 25℃, the minimum below 9℃, and the maximum about 35℃. 6. The relation of hydrogen-ion concentration to the mycelial growth was studied on RICHARD'S agars of different hydrogen-ion concentrations which were prepared using caustic soda and sulphuric acid. The growth occurred in media the pH of which were from pH 1.8-2.2 to 9.8 <, and at 5.2 the most favourable growth was observed. 7. The relation of hydrogen-ion concentration to the growth of germ-tubes from pycnospores was studied by sowing them on RICHARD's solution of different pH. The highest percentage of germination was shown at pH 4.2-8.2 and it was low at pH 2.2. At pH 9.8 < the germination took place moderately. 8. The inoculation experiments using the pycnospores produced on hemp decoction agar were carried out with success on leaves of the host plant. The incubation period of the disease was about 6-7 days in September.
日本植物病理学会の論文
1936-06-20

大麻白星病の研究

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