The respiration rates of leaves systemically infected with CMV (ordinary strain) were compared with those of locally infected leaves.
Nicotiana tabacum (Bright Yellow) was used as the systemic infection plant and Vigna sinensis Endl. (variety Kurodane-Sanjaku) as the local infection plant. The upper surface of the leaf of a given position was inoculated by rubbing with the sap expressed from tobacco leaves infected systemically by CMV. After inoculation, respiration of detached infected leaves were measured periodically with a Warburg respirometer.
1. The increase in respiration of leaves infected by CMV was observed immediately after the inoculation in the systemically infected plants as well as locally infected plants. The rate of increase in the systemically diseased tobacco leaves was greater than that of locally infected cowpea leaves.
2. In the systemically diseased leaves, the respiration increased until 24hrs. after the inoculation, then decreased to the rate of respiration in healthy leaves within the subsequent 48hrs. This remarkable increase in respiration apparent simultates with the those of multiplication of the virus, suggesting its relation to the formation of the virus.
3. In the locally infected cowpea leaves, the rate of respiration showed two peaks, namely at the 9th hour after the inoculation and during a period from the 13th to the 17th hour, the latter being in accord with the development of local lesions.
4. The first peak on the curve of respiration in cowpea leaves, seems to correspond to the peak on that of systemically infected tobacco leaves. Judging from the experiments on enzyme inhibitors and observation on the development of local lesions, the second peak is considered to be related to the multiplication of the virus, but to the activity of the polyphenol oxidase. Thus, the process of the increase in respiration in the local infection during a period of a few days after inoculation.

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When the fruit of kaki (Diospyros kaki Linn. f.) is invaded by Gloeosporium kaki Hori, the causal fungus of kaki anthracnose, softening occurs within the whole fruit. The experiments in this paper were chiefly performed to elucidate the connection between the macerating enzymes of the pathogen and the soft rotting of the host. The following results obtained indicate an impossibility of the fungal enzymes to cause the softening of kaki tissue in vivo.
The crude preparation from soy liquid culture was found to contain considerable amounts of endo-PG, endo-PMG, exo-PG, and cellulase Cx. Endo-PG and endo-PMG seemed to macerate the disks of potato tuber and kaki fruit, but no other macerating enzyme than these could be demonstrated. The experiment with the crude enzyme preparation from soy liquid culture showed that it required 2, 000 PMG-unit per ml to macerate kaki fruit. The strength of this activity corresponds to about 30∼50 times of that required to macerate potato tuber. Such an active secretion has neither been detected on the kaki solid culture, nor on the soft rotted fruit invaded by the causal fungus.

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The stems and leaves of seedlings of Triticum vulgare (Norin No. 16) were irradiated at second leaf stage by X-rays at 5kγ. The seedlings were inoculated 10 days after irradiation by spraying with an aqueous uredospore suspension of Puccinia triticina. The first leaves of the seedlings were removed 10 days after inoculation and the size of uredosori was measured. The size of uredosori on plants whose whole bodies or stems were irradiated were about 1.7 times larger than that on the control and the plants whose leaves only were irradiated.
Seedlings of T. vulgare (Norin No. 50) at second leaf stage were irradiated by gamma-rays at 0.1, 0.25, 0.5, 1, 2.5, 5 and 10kγ. The seedlings were inoculated 6 days after irradiation by spraying with the uredospore suspension. Seedling length was measured 7 days after irradiation, and then the size of the sori was measured 12 days after inoculation. Inhibition of seedling growth increased with the increase of the dosage, but there was no further decrease in the seedling lengths at dosages above 1kγ. Also, the size of the sori increased with the increase of the dosage, but it did not further increase at dosages above 5kγ.

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By partitioning intervarietal variation in the blast-disease susceptibility of wild rice strains into components of inherent and environment-respondent susceptibility and interaction between them, the magnitude of roles played by them could become comparable with each other. The three parameters given by the ratio of each variance component to total variance are investigated with respect to four possible cases. The so-called true and field resistance of host plants can also be defined by these variance ratios. The meaning of the parameters in relation to plant breeding is discussed.

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A comprehensive description of the symptoms caused by cucumber mosaic virus (CMV) on various hosts is given, as observed on naturally affected plants as well as mechanically inoculated plants with several strains of CMV.
Infection with CMV gives generally a stunting effect on the host plant. In tomato, Linaria bipartita, etc., rosette symptom has been occasionally noted. As foliage symptoms, mosaic is the most common. Before mottle, there usually appears vein-clearing, vein-banding or chlorotic spot. Bright yellow spots have been observed frequently in infected plants of pansy and celery. Sometimes on red pepper and gladiolus, white mottling occurred. Mosaic symptoms are usually associated with distortion of the leaves. In extreme case, CMV causes fern-leaf in tomato, Linaria, etc. Distinct ruffling is seen on the leaves of Datura, Japanese radish and others. Inoculations with the isolates from pansy showing yellow ring spot, and from Galega officinalis, produced ring spot on tobacco. A noticeable, virulent strain has been isolated from a markedly yellowed plant of pansy; the virus produces systemic necrosis on tobacco, petunia, etc. and eventually kills the top (Fig. 7).
Enations have been observed on leaves of naturally affected plants of petunia, scabiosa and cucumber. In case of cucumber, the symptom was reproduced by inoculation. The cucumber variety, Shin aonaga-jibai, seems to be liable to develop enations. An isolate of CMV from chrysanthemum produced on leaves of tobacco peculiar outgrowths (Fig. 10), similar to those observed by Smith (1951).
The most usual symptoms on the flower were break of petals, and mottle of calyx. In primula, color of petals, as a whole, turned pale. In tobacco and petunia, affected with isolates from chrysanthemum and from Japanese radish, prominent malformation of flower was observed in addition to break (Fig. 11 and 12).
Symptoms on fruits of cucumber are usually not conspicuous. This may be explained by the tolerance to CMV in the commercial varieties of cucumber in Japan. Chlorotic spots appear often at the stem-end of fruit. The most pronounced symptoms have been found on a squash variety, Tokyo (Cucurbita maxima); the fruits are distinctly mottled and warted. In red pepper and tomato, yellow mosaic may occur on the fruits. Fruits of eggplant sometimes are suppressed in colouring and turn whitish.
On inoculating mechanically, local lesions developed on the inoculated leaves of plants in 20 species covering 9 families. Local lesions may be in the form of necrotic solid spot, necrotic ring, grayish spot with brown border, concentric ring, or chlorotic ring, as illustrated in Figs. 14 to 18. The type and development of lesions depend on the strains of the virus, kind of host plant and season of the year. In Chenopodium anthelminticum and C. album, no further development than local lesion was observed, whereas in legumes and tobacco, local lesions caused by certain strains of CMV were followed by streak along the vein, extending to stem, or by systemic mottling.
There has been found no symptomless carrier. X-bodies were not observed in trichomes and epidermis of tobacco, tomato, cucumber and corn leaves infected with CMV.

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1. When mulberry trees affected with dwarf disease sprout in April, typically crinkled leaves are not seen but normal or smaller subnormal leaves are produced in the beginning. Subsequently, typical crinkled leaves appear gradually.
2. At Taimei village in Kumamoto Prefecture, the symptom of this disease showing crinkled leaves appears before the cutting back of mulberry trees in June. At Kikuchi city, on the other hand, the symptom does not appear before the cutting back but on the newly grown shoots after cutting back in June.
3. At Taimei village, the symptom always makes its appearance in May irrespective of the time of cutting back. At Kikuchi city, on the other hand, when diseased trees are cut back in winter the symptom begins to appear in May, but when mulberry trees are cut back in June and July, the symptom appears in these months.

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1. In the present paper, an investigation has been made on the susceptibility to Helminthosporium leaf spot of rice plants grown in various nutritional conditions with different amounts of elements. The growth of plants, the content of inorganic elements and carbohydrates, the intensity of respiration and the intensity of photosynthesis in leaves were also measured considering the relation to the disease susceptibility.
2. The susceptibility was expressed as the total number of spots per unit length of leaf and the index of spot enlargement (per cent of large spots to the total number). The index of spot enlargement correlated positively with the respiratory intensity of leaves, but negatively with the growth of the plants or with the P-R ratio (the ratio of photosynthetic-to respiratory intensity). However, the total number of spots was not related to any of the above three factors. Judging from the above results, the index of spot enlargement is more significant to the susceptibility than the total number of spots. On the other hand, the susceptibility showed no clear relation to the content of inorganic elements and carbohydrates in leaves.
3. The susceptibility was decreased in plants grown in nutritional solutions with an excess nitrogen (+N) or potassium (+K). The presence of manganese (+Mn), iodine (+I) and zinc (+Zn) also decreased the susceptibility. On the contrary, excess in phosphorus (+P), deficiency of nitrogen (-N), potassium (-K) and magnesium (-Mg), or the presence of cadmium (+Cd) and cobalt (+Co) increased the susceptibility.

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Fifty five isolates of Xanthomonas oryzae were collected from various localities of Japan. The isolates were obtained in mass condition from diseased leaf specimens put on the slants of potato semi-synthetic media.
Each isolate was inoculated to slants of potato semi-synthetic media containing 1, 000ppm and 100ppm of dihydrostreptomycin sulfate, and were incubated at 25°C for 10 days.
Twenty three of the isolates developed well on the media containing 10ppm of dihydrostreptomycin sulfate. 16 of them developed well even on the media containing 1, 000ppm of dihydrostreptomycin sulfate. It may be noticed that most of the places where the resistant isolates were collected had never been sprayed with dihydrostreptomycin sulfate for the protection of the bacterial leaf blight disease of rice.
Proportions of dihydrostreptomycin resistant cells in each isolate were assayed. For this purpose, EDTA-Fe media added with dihydrostreptomycin sulfate at concentrations of 1, 000, 100 and 10ppm, were used. EDTA-Fe medium is suitable for development of colonies starting from single cells. The prepared plates were kept at 25°C for 8 days, and then produced. colonies were counted.
The proportions of the resistant cells contained in the isolates were much different from one isolate to another. Usually, the higher the concentration of dihydrostreptomycin sulfate, the fewer were the colonies produced. Some isolates, however, contained almost 100 per cent of resistant cells against even 1, 000ppm of dihydrostreptomycin sulfate.
It was considered that the wide distribution of the dihydrostreptomycin resistant isolates of X. oryzae, from practical view, would be important, because it might limit the use of the antibiotic against the bacterial leaf blight disease of rice.
A little difference, not so significant as against dihydrostreptomycin sulfate, was found among the isolates in their resistance against l-chloramphenicol and cellocidin.
l-chloramphenicol is considered to be the most effective antibiotic for the protection of bacterial leaf blight disease of rice, but the action of this antibiotic on most of the isolates in vitro tests was not completely cidal after 15 days incubation at the concentration of 100ppm.

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1. Die Reispflanzen verlieren ihre Widerstandsfähigkeit gegen Piricularia oryzae Cav., wenn sie während der: Inkubationszeit kurz welken. Das Verhältnis wird aber mit wachsendem Abstand von der Infektion verschoben, und die graphische Darstellung des Verhältnisses macht eine Kurve, die der aus der Fleckengrößeverteilung gewonnenen zeitlichen Verlaufskurve der Widerstandsfähigkeit des Wirtsgewebes ähnlich ist.
2. Dasselbe tritt auf, wenn Blätter der Reispflanzen in warmes (um 46°C) Wasser augenblicklich gebeizt werden.
3. Es wird theoretisch durch die Funktion e^{-∫t₀f(τ)dτ} nachgewiesen, daß das an stark abwehrendem Zeitpunkt schlecht behandelte Wirtsgewebe anfälliger ist, als an schwach abwehrendem Zeitpunkt.
4. Auf diesen Gründen liefert die Schlechtbehandlung des Wirtsgewebes eine andere Methode, wodurch man den zeitlichen Verlauf der Widerstandsfähigkeit von nicht behandeltem ursprünglichem Wirt beschreiben kann.

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The present paper deals with the results of experiments on the blast-controlling effect of several kinds of fungicides absorbed by roots of rice seedings, and the behavior of conidia of Piricularia oryzae in water drops on leaves of treated seedlings. The fungicides used in these experiments are follows: mercuric chloride, copper sulfate, phenylmercuric acetate (PMA), phenylmercuric dinaphthylmethane-disulfonate (PMF), n-trichloromethylthioterahydrophthalimide (Captan), 2, 3-dichloro-1, 4-naphthoquinone (Dichlone), tetramethylthiuramdisulfide (TMTD), and Blasticidin-S (Bl-S).
Before or after the inoculation of the causal fungus, the roots of rice seedlings, raised for 8 days, were dipped in the fungicide solutions, or spraying of fungicide was made on their leaves. All the fungicides used seemed to have an influence on the pathogenic fungus developed in tissues of the suscept, decreasing the incidence of the blast disease. There was no correlation between the grade of conidial germination in water drops on leaves and the grade of formation of lesions.
Okamoto and Yamamoto (1958) proposed that water drops on leaves of treated seedlings may act indirectly to inhibit the conidial germination. In the present investigation, however, conidia in water drops on leaves of treated seedlings seemed to contact directly with the fungicide exuded through epidermis. It is likely that the inhibition of conidial germination is attributable to direct action of fungicide, but not to indirect one.

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Tulip mosaic virus (=Tulip breaking virus), in diseased plant tissues or tissue extracts, was vacuum freeze-dried, and stored for 315 days at 0-5°C, without loss of infectivity, as determined by expression of flower breaking in tulips (William Pitt) inoculated at emergence stage. Infectivity was maintained in leaf, petal, flower stalk tissue, and leaf extract, but not in petal extract.
Infective virus was recovered from diseased leaf tissue which was finely scissored and dried on calcium chloride or on silica gel and stored for 311 days at 0-5°C. Similar successful preservation was obtained by freezing leaf or petal tissue and storing at -20°C.
These methods made it practicable to detect the virus within suspected or masked tulip or lily plants.

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Nutritional physiology of Xanthomonas oryzae, the causal bacterium of the bacterial leaf blight of rice plant, has been studied with special reference to mineral salts and vitamins, in order to find out suitable synthetic medium for multiplication of this bacterium.
The constitution of the basal medium used was as follows: l-glutamic acid 2g, KH₂PO₄ 2g, sucrose 20g, and one liter of distilled water. Inoculum which had been cultured on agar slant of the ring-rot-bacteria medium was washed three times with distilled water by centrifugation, 8, 000rpm for 15 minutes, and multiplication of the bacteria was assessed by the use of nephelometer.
By this treatment, slight amounts of nutritive contaminants in the inoculum could be eliminated. Absence of any contaminated metal ions in the basal medium was ascertained by colorimetric tests using appropriate organic reagents.
Optimal concentration of phosphate in the basal medium was found to be 0.2 per cent in the form of KH₂PO₄. Addition of FeSO₄⋅7H₂O (0.01∼0.001 per cent), MgCl₂⋅6H₂O (0.5∼0.01 per cent) or MnSO₄⋅4H₂O (0.1∼0.001 per cent) markedly increased the multiplication of the bacteria; furthermore, when these two or three elements were added together, the multiplication was accelerated.
On the other hand, 0.1∼0.01per cent of CuSO₄⋅5H₂O or 0.1∼0.001 per cent of ZnSO₄⋅7H₂O inhibited the multiplication of the bacteria, while lower concentration of these elements as well as CaCl₂⋅6H₂O, H₃BO₃, Na₂MoO₄, and KI, regardless of concentration, did not show any acceleration of multiplication.
This bacterium does not require vitamins as indispensable growth factors for its multiplication, but 0.5μg per ml of riboflavin, thiamin, or calcium pantothenate, and 1.0μg per ml of nicotinic acid or pyridoxin gave some stimulative effects on the multiplication of the bacteria. On the contrary, 0.5μg per ml of p-aminobenzoic acid and 1.0μg per ml of cholin or i-inositol showed inhibitory effects.

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