Polyporus orientalis is a stipitate yellow fungus described first by LLOYD in 1912. But so far as the writers know, the present fungus seems to be a species endemic to Japan. Although UMEMURA and YASUDA have already published brief notes on this fungus in Japanese, only the morphological description has been known up to the present time. According to the writers' investigations, the fungus is widely distributed in the southern part of Honshu as well as in Kiushu and parasitic commonly on the roots of pine trees, causing very slowly white pockets in the woody tissue. In the vicinity of Kyoto the fungus was often found on the dead and living roots of Pinus dens flora S. et Z. in many places, where trees of more than thirty years growth are found. In the present paper the results of the writers' investigations on the morphological characters, as well as the reactions of the yellow pigment of the sporophores to various chemicals, are first described. Pure cultures of the fungus were readily obtained by placing a piece of the fungus tissue and also of the rotting wood on an agar plate in PETRI dishes. The growth habits of the mycelium on sixteen different media were compared. For the most favorable agar and the most favorable liquid media the apricot decoction proved to be best. The relation of temperature to the growth of the fungus was studied by growing the mycelium on poured plates of apricot decoction agar, of potato decoction agar and of soy agar, after SAITO, incubated at different temperatures. It was found that the optimum temperature for the growth of the mycelium of this fungus lies between approximately 28° and 32°C. But Commonly its vigorous growth was shown at from 32° to 24°C. Its maximum and minimum temperatures seem to be about 38°C. and a little below 12°C. Fmally the writers classified the fungus as belonging to the group of lignin dissolving fungi.
1. The present paper deals with the yellow blight of wheat leaves caused by a species of Helminthosporium, which seems to have no previous records. 2. The name Helminthosporium Tritici-vulagaris n. sp. is suggested to designate the fungus, the diagnosis being given in the preceding paragraph. 3. Investigations on the present fungus were carried out chiefly on the morphological characters of the conidiophores and the conidia, produced on the host plant in field and also on culture media. 4. The parasitic nature of the fungus under considerartion has been ascertained by successful inoculations on wheat leaves.
1. The present paper is intended to report the experiments on the mode of overwintering and the primary infection of Piricularia Oryzae, the causal fungus of the blast disease of rice plants. 2. The conidia on any parts of the diseased rice plants or the mycelium within the tissue of the diseased spots must be considered as the principal overwintering organs of this fungus. 3. In the present experiments, conidia on the diseased straw and seeds kept in dry condition at room temperature retain their vitality during more-than one year, but those kept on the soil, as well as in the barnyard manure, lost their vitality in the next spring. 4. The mycelia in the diseased tissue which kept in dry condition alive far longer than the conidia under the same condition, and in the case of diseased node, the mycelia retain their vitality more than 1058 days, while those under the moist condition lost their vitality at the middle of April in the next year. 5. The overwintered mycelia abundantly produce conidia on the surface of the substratum under the moist condition. The luxurious formation of conidia occurs in temperature from 18°C. to 30°C. 6. The conidia which overwintered on the diseased straw, as well as those formed on the surface of the diseased tissue under the moist condition, are capable to infect the healthy rice plants. The conidia on the surface of apparently healthy seeds which taken from the diseased rice plants and the mycelia penetrated into the tissue of partially blasted-seeds give rise the wilting of rice seedlings when the seeds are planted in the next year. Thus they may serve as the most important source of the primary infection of this fungus. 7. To control of the blast disease of rice plants, some treatment on the diseased straw and seeds must be needed. For the severely attacked straw, its burning or mixing to barn-yard manure and fodder is the best method. Moreover, hot water treatment is recommendable for the affected seeds.
The disease known under the name of “Bakanae-Byo” is one of the destructive diseases of the rice-plant in Japan. Commonly the disease occurs in seed-beds, but does not kill the attacked seedlings immediately. The diseased seedlings grow somewhat abnormally, showing a taller and more slender appearance in leaves and culms than those of normal growth. Their colour becomes, therefore, yellowish-green to pale in the advanced stage. Such an abnormal growth of the aerial parts is supposed to be caused by the presence of the mycelium of a species of Fusarium in the tissue of the foot of the plants attacked. The present paper deals with the occurrence of the disease by inoculation of the causal organism and also of seemingly the same appearance of seedlings without this organism. The latter case is called “Bakanae” phenomenon in the present paper. The pathological meaning of the distinction between the “Bakanae” disease and the “Bakanae” phenomenon is discussed in detail. The summarized conclusions are briefly stated as follows. 1. The “Bakanae” disease was proved to be caused by a species of Fusarium isolated from the tissues of the infested plants. According to the writer's experiments it is clear that the fungus has the power of attacking rice-seedlings germinated in perfect health, causing the characteristic overgrowth. 2. The fungus in question has never shown any pathogenicity to check the growth of the seedlings, as shown by Piricularia Oryzae Br. et Cav., Helminthosporium Oryzae Brada de Haan, and Hypochnus Sasakii Shirai. On the contrary, it has rather tended to stimulate its abnormal growth. 3. The filtrate of the cultured solution of the causal fungus-Knop's solution containing glucose in various percentages-was able to produce the phenomenon characteristic of the “Bakanae” disease, as recently mentioned by Kurosawa. Owing to the absence of the mycelium of the causal fungus, the writer considers it correct to call it the “Bakanae” phenomenon, as compared with the natural condition in the occurrence of the disease. 4. Differing from the filtrate of the fungus in question, the filtrate of the cultured solution of Helminthosporium Oryzae Breda de Haan parasitic commonly to the leaves of the rice-plant failed to produce any overgrowth of the leaves and culms.
The writer, during recent years, has been engaged in the study of the disease of the insect-powder plant (Chrysanthemum cienrariifolium (Trev.) Bocc.) in Okayama prefecture, and found out that following six kinds of diseases exist on the host: the blight (Diplodia chrysanthemella), the small sclerotium disease (Sclerotinia minor), the large sclerotium disease (Sclerotinia Libertiana), the sclerotium wilt (Hypochnus centrifugus=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 description of this species is as follows. Pycnidia immersed or erumpent, flaskshaped or irregular, black, 60 to 141μ usually about 100μ in diameter. Pycnidia prodaced on pure cultures are somewhat larger, being on acid standeard agar 81 t0 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 or 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 appeared 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, irregular. Apothecium produced usually one, rarely two from single sclerotium; disc saucer shaped, 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. The measurements 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, Gnaphalium japonicum, Lactuca brevirostris, Asteromaea indica Erigeron linifolius, 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 caused by a welt known fungus Sclerotinia Libertiana Fuck. The symptom of the disease 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 average 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 (Lév.) Tul., a fungus which is very widely distributed and attacks many other cultivated plants in this country.