Gymnosporangium Haraeanum SYD. is one of the oriental species of pear rust fungi and passes its life-cycle developing O and I on the Japan pear and III on the Juniper-tree (Juniperus chinensis and J. chinensis var. procumbens). In the later stage of the pear rust disease we, not infrequently, observe the occurrence of natural infections wholly devoid of aecia. Following study was made to find out how such things happen and to clarify the sexual behaviour in the fungus. Numerous monosporidial infections were obtained by sowing the sporidia sparsely on the pear leaves. Every monosporidial infection formed spermogonia, which excreated spermatia-containing nectar. At the end of about eleven weeks after inoculation, a large majority of such infections remained sterile, i. e. failed to produce aeciospores when they were kept in isolated condition; while the better part of those infections to which nectar containing spermatia had been transferred from several of the other infections began to develop aecia within about sixteen days after the treatment and then they behaved themselves normally in the course of the production of aeciospores. When a few monosporidial infections occurred close together, mixing of nectar resulted from coalescence of them and in such cases also aecia were produced in high percentage. Filtered spermogonial nectar which was free from spermatia had no such function as to induce the formation of aecia. Thus, the spermatia of the fungus have a role of supplying to the mycelia of monosporidial infections the opposite sex element. The fungus is heterothallic in a broad sense.
The writer reported already the results of his investigation on the histological changes of hypertrophied buds of the Camellia (Camellia japonica L.) caused by Exobasidium Camelliae SHIRAI. In the vicinity of Kyoto, the same plants are attacked very often by a different fungus belonging to the same genus, which is treated by HARA under the name of E. Camelliae SHIRAI var. nudo SHIRAI. The disease under consideration attacks the young leaves causing the circular spots as in the case of the blister blight of tea plant caused by E. vexans. The disease spreads sometimes to the petioles and also attacks the young green stems. The present paper deals with the results of the writer's investigation on the histological changes of deformed leaves, petioles and stems caused by this disease. Differing from the results of previous investigation on the hypertrophied buds, the deformation in the present disease seems to be occurred by hypertrophy of the cells only. Hyperplasia do not take place in all the affected parts and consequently the number of the layers of cells is not changed. The arrangement of the hypertrophied cells is regarded clearly as to be osmomorphosis. The hymenium of the causal fungus, having apparently exogenous appearance, develops at first under the epidermal cells or in the intercellular spaces of one to three subepidermal layers of cells. These overlying layers of cells rupture later, exposing the hymenium.
The mycelial development of Piricularia Oryzae CAV. is generally poor in òrdinary synthetic nutrient solutions. The authors carried out cultural experiments of this fungus with several synthetic nutrient solutions in an attempt to set up a formula of somewhat more suitable one for the culture of the present fungus. Based upon the results obtained in the cultural experiments the authors contrived the following formula of a synthetic nutrient solution: Potassium nitrate (KNO3) 2.0g Monopotassium phosphate (KH2PO4) 0.5g Dipotassium phosphate (K2HPO4) 0.5g Magnesium sulphate (MgSO4·7H2O) 0.5g Calcium chloride (CaCl2) 0.1g Ferric chloride (FeCl3) trace§ Sucrose 30.0g Redistilled water 1000.0cc § One drop of 5% FeCl3 solution for 30cc of the nutrient solution. Hydrogen ion concentration of the present solution was about pH 6.3, and a slight precipitation unavoidably took place. The fungus grew tolerably well in this nutrient solution, and a grayish olive colored mycelial colony developed in 30 cc of this solution by a culture in a thermostat at 28°C for 30 days was measured to be more than 4 mg in dry weight. The present formula would be recommended as a suitable synthetic nutrient solution for the mycelial development of Piricularia Oryzae CAV.
In field observations it has been noted that the rice blast disease outbreaks severely after the stormy weather. To study this connection experimentally, the present work was carried out. Rice plants were exposed to an artificial strong wind for several hours, and then the blast fungus, Piricularia oryzae CAV., was inoculated to them. As the results of the experiments, a marked increase of the infection was observed on the treated plants. This may be attributed mainly to the facilitated infection occurred through the wounds produced on the foliage leaves due to the mutual rubbing or fluttering in the strong wind. Furthermore some physiological disorders of the host plant brought. about by remarkable dryness or mechanical injury of the leaves induced by the wind, were noted also as the possible factors lowering the resistance against the attacks of the present fungus.
(1) 本報文はPhytophthora macrosporaに基因せる小麥黄化萎縮病に就き報告し,主として分生胞子竝に其の他の胞子型の測定的觀察及分生胞子の發芽に就き記述したものである。 (2) Phytophthora macrosporaは秋播小麥を侵害して特異の萎縮性病状を現し,被害株の越年と共に病状を持續し,出穗期に至つて葉面に分生胞子を形成した。分生胞子は葉の裏面よりも表面に多く,葉片基脚部より中央部に亙つて多く存し,先端部には少ない。葉縁より中助間の縦溝に沿ひ氣孔細胞上に點々と生ずる。 (3) 分生胞子は野外に形成せられたものは57.5-97.5×30.0-65.0μ,平均74.6×46.8μであるが,水中に於て形成せしめたものは65.0-112.5×32.5-55.0μ,平均87.37×43.75μであつた。游走子は12.5-16.25×10.0-12.5μ,平均14.17×10.8μ球嚢は徑10.0-16.25μ,平均12.8μ;藏卵器は55.0-100.0×50.0-95.0μ,普通は62.5-75.0×56.5-72.5μ,平均69.12×65.13μ;藏精器は側着, 22.5-41.25×12.5-22.5μ,平均27.75×15.15μ;卵胞子は42.5-72.5×42.5-70.0μ,平均60.25×56.67μであつた。 (4) 分生胞子竝に游走子形成の適温は11°-24℃であつて, 1分生胞子を完成するに要する時間は3時間乃至4時間,游走子逸出迄には少くとも8時間以上を要し,更に游走子が静止し球嚢となつて,これが再び發芽する迄には19時間内外を要するものと認められた。尚,分生胞子は稀に發芽管より直に菌絲を生ずることもある。 (5) 水稻及小麥に生じた分生胞子及水稻,小麥,裸麥,燕麥,玉蜀黍,キンエノコロ,メヒシバ等に生じた卵胞子の比較を行つた結果は,寄主を異にしても前記胞子の大さには殆ど大差なく,從來の多くの觀察の如く同時に各種の禾本科植物を侵すことも考慮して病原菌は皆同一種であると認めた。 (6) 本病原菌は,其の分生胞子の形態學的性質に據りPhytophthora屬に隷屬すべきものと認め, Phytophthora macrospora (SACC.) S. ITO et I. TANAKA n. comb.とし, Sclerospora macrospora SACC., S. Kriegeriana P. MAGN., S. Oryzae BRIZIを其の異名とする。
(1) The present paper deals with the study carried out by the writers on a new fungus which causes an anthracnose disease of jute. (2) The jute anthracnose affects the stems, leaves and pods of this crop and its presence in Kumamoto and Shizuoka Prefecture was first observed in 1938. In the next year it has been found in Aichi Prefecture. (3) The causal organism has been isolated and its pathogenicity has been proved by inoculation experiments. The incubation period is about three days. (4) As the fungus seems to be new to science, the name Colletotrichum Corchorum is proposed and a brief technical description is given, as follows: Colletotrichum Corchorum IKATA et TANAKA nov. sp. Lesions on stems, leaves and pods, brown to black, not sunken, definite in outline. Acervuli black, superficial, scattered; stroma patelliform, 100-350μ in diameter by 25-50μ high; setae several to abundant, originating from margin of stroma, yellowish brown to black and becoming lighter toward the apex, 2 to 5 septate, 36-117 μ long by 3.6-5.0 μ wide. Conidiophores simple, hyaline, arising from stroma, 15-35 μ long by 3-4 μ wide; conidia abundant, non-septate, hyaline, curved, bluntly tapered, oblong-fusoid to falcate-fusoid, 12-25×3.6-6.0μ, with 16-22×4μ as the most common size. HAB: Parasitic on stems, pods and leaves of Corchorus capsularis L. (5) The optimum temperature for growth of the fungus is 30°C. (6) The disease is seed-borne, the fungus mycelium exists in the seed and spores are adhering on the external part of seeds.
相思樹銹病菌夏胞子に對し,抵抗性を異にする假葉各部分間の細胞學的研究を遂行した結果 (1) 幼嫩な感受性部分に於ては a. 附着器より氣孔を通り侵入した菌絲は,氣孔下嚢を形成し,容易に隣接細胞中に吸器を形成する。夫の後,組織中に侵入した菌絲は,一般に,周圍の柵状組織中には殆んど吸器を挿入せず,直に内方の海綿状組織細胞中に侵入し,吸器を形成しながら冬胞子堆形成迄該部に於て發達する。夫の間,寄生關係には何等不親和性を認められない。 b. 菌が寄主組織中に蔓延するも,未だ實際に吸器の侵入を蒙らない細胞は,夫の葉緑粒及光力的合成能力を漸次退化減少するも,吸器の侵入により,再び之等は復活し,益々夫等の機能は旺盛になり,寄主葉肉組織中に多量の貯藏澱粉粒を形成する。 c. 夏胞子の侵入に依り,寄主細胞は多少肥大する場合はあるも,全く増生しない。 d. 之の時代の吸器は何れも基部に頸を有して居り,掌状を呈する隣接細胞中の吸器を例外とし,一般に單一型である。而して,之の吸器は老成すると寄主細胞から誘導されたと推察される厚膜に包まれて枯死して居る。 (2) 極く幼嫩な免疫性乃至強抵抗性部に於ては,氣孔の分化不充分な爲め,菌は一般に侵入し得ず,僅かに發達せる氣孔を通じて辛じて侵入し,氣孔下嚢を形成した場合に於ても,直に枯死するか,又は吸器を形成した場合に於ても, 2-3日中に枯死する。之の際,寄主細胞も菌の侵入に對し,非常に敏感であり,直に壞死し,何れが先に枯死せるか,不明な場合も認められるも,一般に菌の枯死が早い樣である。猶,該部に於ては,附着器下の孔邊細胞及夫に連絡する表皮細胞の壞死する場合も屡々見られる。 (3) 成熟せる免疫性部分に於ては,若し附着器が形成され,寄主體中に侵入した場合には,容易に氣孔下嚢を形成するも,直に枯死するか,又は極く初期の吸器を形成するも直に枯死する。然るに,之の際,寄主細胞は菌に對して抵抗力強大にして,一般に,氣孔下嚢の周圍の細胞膜の肥厚の外,殆んど變化を認めない。 (4) 以上の如き觀察の結果は,既に報告せる寄主組織中の有毒物質の存在を尚立證し,且つ,本菌の抵抗性は全く原形質的性質のものである事を暗示して居る。 擱筆するに當り,終始御懇篤なる御教示を賜りたる松本教授に滿腔の謝意を表す。
Trichoderma viride (Trichoderma lignorum) is found to be a beneficial fungus parasitizing the sclerotia and mycelia of sclerotial fungi and often doing to death. The fungus is, on the other hand, a weak parasite to sweet potatoes and also a harmful one to depress the growth of various crops, but the detrimental effect is rather greater on pathogenic fungi than on crops. It seems to be quite hopeful to use Trichoderma as an agent for controlling biologically sclerotial diseases and other fungous ones.
1. A white mosaic of tobacco was found in tobacco growing district near Hukuoka, which is different from JOHNSON's “white mosaic”. 2. This virus is infectious to most species of solanaceous plants, but no infection occurs on cucurbitaceous plants. 3. In general, the virulence of the virus is not so destructive, but petunia is retarded its growth severely. 4. Mottlings are produced when Nicotiana sylvestris is inoculated with the virus. 5. The present virus may be a strain of tobacco common mosaic virus (Nicotiana virus 1) which causes white mottlings on tobacco.
1. In 1936 a new leaf disease of Camellia japonica var. spontanea was found in the Tokyo Imperial University Forest, Kiyosumi, Awa; and its symptom, etiology, pathology and distribution were studied. 2. On the upper surface of the leaf, there first appear minute discolored specks, which gradually enlarge to circular spots, 2-4 mm in diameter. The spots, having indistinct margins, are at first pale green and become later greenish white. Turning black in the centers, the spots assume “snakeeye” form. 3. The disease is caused by a parasitic fungus. It invades through the stoma on the under surface of the leaf into the mesophyll, and forms its stroma in the respiratory cavity. The invaded tissues perish and turn brown, while the cells surrounding them undergo division. The stroma, breaking the overlying epidermis, is exposed as a conical protuberance, measuring 1 mm in diameter and 0.5 mm high. On the stroma, many synnemata are developed, measuring 70×850μ, producing conidia in Penicillium type. The conidia are hyaline, ovoid or ellipsoid, and catenate, measuring 6.0-10.6×3.5-4.5μ. 4. The “leaf spot” is proposed as the name of the disease and the causal fungus is described under the name of Graphiothecium Kusanoi sp. nov.