The sooty mould fungi of the subfamily Eucapnodieae occurring on the various plants associated with scale insects, aphides or the larvae of white flies in Formosa were collected by the present author. Since various spore forms often appeared on each colony of these fungi by contamination of other fungi, whether these spore forms in the perfect and imperfect stages of each species of these fungi belonged to the same species or not were determinated by the results of studies made on the cultures originated from single spore isolations. The diagnoses in both stages of these fungi, i.e. Copnodium Walteri Sacc., Scorias cylindrica Yam., Chaetoscorias vulgare Yam. and Capnophaeum fuliginodes (Rehm) Yam. are described in the present paper. Among them, three species being new to science the diagnoses of them are described in Latin as follows.
Scorias communis sp. nov. Figs. 11-16.
Pycnidiis gregariis, microxyphio-formibus longissime stipitatis, totaliter longitudine 308-1148μ longis; stipitibus synnematioideis, rectis vel leniter curvatis, raro superiore dichotomice ramosis, atris, opacis, 224-896μ longis, ad basim 23-46μ crassis, apice inflatis et pycnidiis ornatis; pycnidiis propiis ellipsoideis vel elongato-ellipsoideis, longiore rostratis, apicem versus attenuatis, atro-brunneis vel atris, opacis sed superiore pallide brunneis apice ostiolatis et hyalino-fimbriatis, partis pycnidiis 89-126μ longis et 30-69μ crassis, partis rostriformibus 70-168μ longis; pycnidiosporis ellipsoideis vel oblongis, continuis, hyalinis, 4-5.5×2-2.5μ; peritheciis sparsis vel subgregariis, piriformibus vel subglobosis, plus minusve stipitatis, apice plus minusve papillatis et indiskincte ostiolatis, glabris, coriaceis, mucilaginis, atris, 112-154μ altis, 93-133μ crassis, stipitibus 18-55μ altis et 48-53μ crassis; ascis clavatis, elongate-ellipsoideis vel clavato-cylindricis, apice late rotundatis et incrassatis, 4-8-sporis, aparaphysatis, 41-64×14-19μ; sporidiis elongato-obovoideis, apice rotundatis, ad basim obtusis, 2-5 (plerumque 3-4)-septatis, e hyalino dilute olivaceis, 17-28×4.5μ.
Hab. in foliis Coffeae libericae, etc., Formosa.
Scorias cylindrica sp. nov. Figs. 23-26.
Pycnidiis gregariis, cylindricis, rarissime dichotomice ramosis, rectis vel leniter curvatis, apicem versus non vel vix attenuatis, apice ostiolatis et non fimbriatis, atris, opacis sed ad apicem pallidioribus, 250-700μ longis, ad basim 16-32μ crassis; pvcnidiosporis ellipsoideis vel oblongis, continuis, hvalinis, 3.5-4.5×1-1.8μ; peritheciis sparsis, ellipsoideis vel ovoideis, plus minusve stipitatis, apice indistincte ostiolatis, glabris, coriaceis, muciiaginis, atris 84-126μ altis, 70-90μ crassis; stipitibus 28-112μ altis et 25-35μ crassis; ascis obovoideis vel clavatis, apice late rotundatis et incrassatis, 4-8-sporis, 23-39×9-11.5μ; sporidiis elongato-obovoideis, ad basim leniter attenuatis et obtusis, apice rotundatis vel obtusis, 2-3-septatis, e hyalino dilutissime olivaceis, 9-14×3-4.5μ.
Hab. in foliis Gardeniae angustae var ovalifoliae, etc., Formosa.
Chaetoscorias vulgare sp. nov. Figs. 17-22.
Pycnidiis gregariis, longissime stipitatis; stipitibus, synnematioideis, rectis vel plus minus curvatis, apicem versus attenuatis, raro superiors dichotomice ramosis, atro-brunneis vel atris, opacis, 140-1064μ longis, ad basim 25-69μ crassis, apice abrupte inflatis et pycnidiis ornatis; pycnidiis propiis ellipsoideis vel elongato-ellipsoiedeis, apice ostiolatis et hyalino-fimbriatis, 56-112×25-46μ; pycnidiosporis ellipsoideis vel oblongis, continuis, hyalinis, 3-6×1.5-3μ; peritheciis sub-gregariis vel sparsis subglobosis, apice plus minusve papillatis et indistincte ostiolatis, non vel plus minus tipitatis, superiors 1-8-setosis, coriaceis, mucilaginis, atris,

View full abstract

Chinese milk vetch (Astragalus sinicus L.) was seeded at various rates and on different dates, to study the relation between the microclimate in the tuft and the development of the Sclerotinia rot.
In the sunny daytime, the air temperature within the tuft of milk vetch, especially in the plots of thick stands, was lower than in the temperature screen. While, in the daytime with heavy cloud or at night, the temperature within the vetch tuft was higher than in the temperature screen, in proportion to the density of the stand.
The temperature of the soil at 1cm depth showed the same tendency of fluctuation with the temperature in the tuft. Accordingly the extreme differences of air and soil temperatures by day and night was least in the tuft of the thickest stand.
The air humidity in the tuft was higher than in the temperature screen and was highest in the plot of thick stand. The quantity of dew formed at night on the plants per unit area was greater in the plot of thick stand than in the thin stand, but vice versa when calculated on the basis of individual plant.
The incidence of Sclerotinia rot was high in the plot of thick stand of milk vetch. It may be explained by the microclimatical difference above described.

View full abstract

1. The present paper deals with the results of the experiments on the effect of congored and chrysoidin upon the metabolism of Cochliobolus miyabeanus in culture.
2. In the nutrient solution containing a minute amount of azo-pigments, the mycelial growth of the fungus is accelerated more than in the control solution, increasing the consumption of glucose and nitrate in the solution. The retardation, however, took place, when a large amount of pigment was added, showing the decrease of the consumption in glucose and nitrate. The economic coefficient of glucose, in other words, the mycelium synthesized per one gram of glucose consumed, becomes high in the culture solution containing minute amount of pigment.
3. The pathogenicity (aggressive power) of the conidia of the fungus to rice plants decreased, when cultured on the media containing azopigments.

View full abstract

1. In the present paper the writer deals with the results of the experiments on the resisting power of urediospores of Puccinia triticina to low temperatures. The urediospores to betested were collected in May from wheat leaves in the field.
2. The germination percentage of urediospores which were kept under -10°C in dry condition, reduced rapidly after one day and almost lost their germinabiliay after 60 days, when they were brought into the refrigerator directly from room temperature (ca. 20°C). In this case the spores were not in perfectly dry condition, because of high moisture content in the interior of the refrigerator.
3. The urediospores in water suspension kept in the refrigerator seemed to die more rapidly than those in dry condition. This is probably due to freezing of water. The result of the experiments on the present fungus, however, was not so clear as that on Puccinia simplex in the previous experiments.
4. The resisting power of the urediospores to the low temperature of -10°C increased remarkably, as was noted when the affected leaves were incubated under a temperature of -4°C, and them the water suspension, of the spores brought into the refrigerator of -10°C.

View full abstract

The symptoms of cucumber mosaic, which was noted in Tokyo in 1950, consisted mainly of mosaic and chlorotic spots on the leaves. Characteristic symptoms of yellow mottle or green warts on the fruits, as described by Doolittle and other investigators in U.S.A., were not observed. Greenhouse experiments showed that the virus was readily transferred by mechanical inoculation using earborundum, or by aphids, viz. Myzus persicae and Aphis gossypii or through dodder, Cuscuta japonica, but not transmitted by cucumber beetle, Aulacophora femoralis. Tests for seed transmission yielded negative results. The virus was capable of infecting hosts including 26 species of 11 families in 34 species of 13 families tested. On cucumber, muskmelon, zinnia, tobacco, tomato, spinach, corn, Commelina nudiflora, etc., systemic infection was obtained inducing the symptoms of mosaic, veinclearing, veinbanding and less frequently malformation of the leaves. Loca lnecrotic spots were developed on the inoculated leaves of watermelon, Cucumis Melo var. Conomon, cowpea (black seeded), broadbean, pea, sesame, Tetragonia expansa, Chenopodium album, etc. The virus was infectious after heating at 60° for 10 minutes. Tolerance to dilution varied according to tests from 1:1000 to 1:5000. Inactivation by aging in vitro was 2 to 4 days at room temperature. As a result of comparison of the symptoms, host range and physical properties, the virus under consideration is regarded to be identical with Cucumis virus 1 (Marmor cucumeris Holmes). The apparent mild symptoms of cucumber may be attributed to the tolerance of the Japanese varieties to the virus.

View full abstract

Leaf-press-juices of 53 higher plants were compared on their inactivating power against Tobacco mosaic virus.
No connection was found between the taxonomic group such as family or genus of the plants and the inhibitory power of their juices.
Among the plants known to contain much tannins, followings were found to have powerful inhibitory effects upon TMV infections: Acer insulare, Aesculus turbinata, Aralia elata, Camellia japonica, Distylium racemosum, Geranium nepalense, Lagerstroemia indica, Punica granatum, Robinia pseudoacacia, Sambucus sieboldiana, Thea sinensis.

View full abstract

During the seven year period (1943∼49), take-all disease of wheat and barley was quite severe, presumably predisposed by insufficient manuring during and after the war. The outbreak in 1948 was most severe and widespread. This study was undertaken to find out a method available for estimating the loss in yield, 20 to 30 days before harvest, of wheat infected by take-all. A naturally infected wheat field of 0.7 acre in area was divided into 20 plots, a row of 180cm length was chosen at random in each plot, and wheat plants on the row were sampled. The average culm lengths, the total numbers of culms, the total grain yields, and the weight of thousand grains of these 20 samples were recorded (Table 1). As shown in Fig. 2, it was found that there was a linear relation between the average culm length and the grain yield of each sample. The degrees of disease severity, as expressed by the decrease in culm length and grain yield, could be classified into three distinct groups, viz., none or light, moderate, and heavy. The indices of average grain yields of these groups were 100, 70, and 45, and those of the corresponding average culm lengths were 100, 90, and 60 respectively. This may be due to the fact that optimum infection usually occurs twice in a growth period of wheat, viz., in autumn and in early spring; the earlier the infection occurs, the heavier is the damage. No clear difference in grain yield was found betwee“none” and“light”groups. The possibility of estimating the loss in yield for the whole area of affected field by applying the regression line of grain yield. on culm length was discussed.

View full abstract

The present paper describes the experimental results on the amount of free auxin in normally growing plants compared with that of abnorml ones such as the virus-infected body and the various fungous galls caused by blister blight, rust, white rust or smut.
The avena test was done by regular Went's method and its modified one: The tip of the coleoptile of oats was cut off at the place 2cm below from, the tip after 3 hours from the 1st cutting, and then the small agar piece was put on the cut head. The observation was done after 14 hours.
The agar pieces containing free auxin was prepared as follows: The agar pieces are immersed into the pressed-out juice from the tissue, or else a tissue piece of definite volume is put on the agar plate. The results are briefly stated as follows:
1. The amount of free auxin (examined, by the modified method and the pressed-out juice) tested with eleven fungous galls are given in Table 1. Usually in these galls the free auxin is contained in greater quantity than in the healthy tissues, and the upper part of leaf-blade contained free auxin in greater quantity than the lower part.
2. According to the results obtained by the modified method, the free auxin in the tissues of nine galls formed on the stem and the leaf-blade are contained in greater quantity than that of the healthy ones (see Table 2), and the amount of free auxin in these experiments showed smaller figures than in the case with the pressed-out juices.
3. The lateral migration of free auxin through the tissue in the fungous gall is possible, though the migrating quantity is smaller than in the case of vertical migration. Any growth-inhibiting substance is not found in the galls (see Table 3).
4. In the experiments with the modified method, the amount of free auxin in the stem of virus-infected potato and radish shows smaller quantity than that of the healthy ones (see Table 4).
5. The amount of free auxin (examined by the Went's method and the diffusion from the tissue) in the young stems of sweet potato infected with mosaic-virus shows smaller in quantity than that of healthy ones, and the culture test of the healthy stems also shows better growth (see Table 5-7).
6. From the experimental results above mentioned, the writer considers that the relation between the abnormal growth (hypertrophy or dwarfing) caused by the fungi or the virus correlates proportionally with the amount of contained free auxin n the tissues.

View full abstract

At definite intervals after spraying α-Naphthalene acetic acid (1:20, 000), the half-leaves of Nicotiana glutinosa were inoculated with pressed juice from tobacco mosaic diseased leaves of Nicotiana tabacum by carborundum method and the number of lesions developed was measured.
The results revealed the presence of inhibitory effect to tobacco mosaic virus in the treated plants up to 96 hours after spraying α-N. A. A.
The treated leaves showed higher activity of catalase than untreated ones.
It is suggested that the high activity of catalase in the treated leaves may decrease the susceptibility of host plant to the tobacco mosaic virus and may be one of factors causing the inhibitory effect.

View full abstract

(1) This paper deals with the results of experiments on the effect of autoclaving upon changes of pH value of culture solutions adjusted with acid and alkali and their relation to the mycelial growth of Stagonospora carpathica. The adjusted pH value of a modified Czapek-Dox medium changes also by leaving as it is without the fungus growth.
(2) The potato decoction with 2% glucose and a modified Czapek-Dox medium change their pH values by autoclaving. In the writer's experiment, all of the media showing alkaline reactions lower than pH 11 changed their pH values to about pH 5.8. The mycelial growth of Stagonospora carpathica, the causal fungus of the brown spot of broad bean, was tested in these media by inclubating for 10 days at ca. 26°C. The results show clearly that the higher the initial pH value before autoclaving is, the weaker the mycelium grows in dependentof the pH value after autoclaving. This fact is probably due to the decomposition of glucose in media.
(3) The pH values of the modified Czapek-Dox solutions in the alkali-side fall remarkably within 2 days, when they are left in the laboratory without planting of the fungus. Such falling in the pH value is probably due to the fact that the alkali in media absorbs carbon dioxide from the air.
(4) From the results of the above experiments, it may be concluded that, for the purpose to minimize or avoid such obstacles, the sugar- and the mineral salts solutions must be mixed aseptically, after they have been autoclaved, and the fungus is desirable to be transplanted on such medium as soon as possible.

View full abstract

The present paper deals with the results of surveys on the incidence of cereal stripe rust, caused by Pucc. glumarum E. et H., in Fukushima Prefecture, and consideration on the regional difference of its distribution.
The disease appears almost all over the prefecture, but it is usually not severe, except for Shirakawa district, where it attains sometimes to an epidemic extent in individual fields.
The following factors are considered to be the cause of occurrence of this epidemic; (1) delayed growth of the cereal crops as the result of cold winter; (2) delayed appearing of leaf rust which may compete with stripe rust; (3) low temperatures during late May-early June; (4) proximity to localities where the disease appears earlier, i. e. Kantodistrict and other south-western localities of Japan; (5) prevalence of south and south-west wind s in the season and (6) cultivation of susceptible varieties.

View full abstract

The present work was undertaken in order to investigate the effects of X-ray radiation upon the pathogenicity and antigenicity of tobacco mosaic virus (TMV).
The virus preparation used in this work was the aqueous suspension of TMV purified by Bawden's procedure. The antiserum was prepared by injecting rabbits with the purified TMV. The infectivity of the irradiated virus was tested by the half-leaf method using Nicotiana glutinosa as assay plants. In serological tests of TMV, the precipitin reaction was used. The virus preparation 2 or 3mm thick in a Petri dish of 5cm in diameter was irradiated at 5cm distance from an anticathode of an X-ray tube run at 60KVP and or 10mA. The mean wave-length of X-ray used in this work was 0.4Å, and dosages measured were 2400r/min. in the case of 15mA and 1600r/min. in that of 10mA. The pH of the virus preparations were 6.0∼6.2 and their temperatures were 14°∼20°C during the irradiations, and as the X-ray tube employed was water-cooled no rising of temperature of the preparations due to the irradiations was recognized.
The results of experiments are summarized as follows:
(1) The non-infective preparations of TMV which had been inactivated by X-ray radiation always showed to be serologically active, and it was moreover found that the serological activities of irradiated preparations increased within the limits of dosage used in the experiments, on the contrary of decreasing of the infectivity (Tables 1 and 2).
(2) The logarithm of the surviving fraction has been plotted against the dosage of irradiation according to the results of the virus activity assay (half-leaf mnethod), and the survival curve was shown by a straight line (Fig. 1 and 2). Consequently, these results seem to agree with the view that the inactivation of virus by ionizing radiation is caused by a single ionization or a single cluster of ionization, as the inactivation follows a simple exponential curve.
(3) The inactivation doses (the 37% doses) were estimated from the above-mentioned curves, to be approximately 28×10⁴r in the case of preparations of 0.2% and 2×10⁴r in the occasion of 0.02%.

View full abstract

For estimating the degree of damage of the rice plants affected with sheath blight (Hyp. Sasakii Shirai), following formula has been proposed.
Degree of severity(%)=3n₁+2n₂+1n₃+0n₄/3N×100
where, N=n₁+n₂+n₃+n₄: n₁…number of stems having affected upper leafsheaths up to the top leaf: n₂…number of stems having blighted upper leafsheaths except the top leafsheath: n₃…number of stems having blighted leafsheaths except uppermost 2 leafsheath: n₄…number of stems having the 4 uppermost leafsheaths healthy.

View full abstract