Experiments were carried out to know if there were any differences among their properties of phytoalexins (PA) produced by different host and parasite combinations.
1) Seed-rooms of opened pea pods were mounted with conidia suspension of each of Ascochyta pisi, Glomerella cingulata and Gibberella zeae, and incubated at 20°C for 24 hours. These three kinds of suspensions were then collected and centrifuged to obtain the supernatants (PA-solution). Five ml of each PA-solution was extracted three times with equal volume of petroleum ether, and then the solvent was evaporated at 80°C. Ethanol was added to each of the residues and ultraviolet absorption of the ethanol solution was measured by spectrophotometer (Shimazu QB-50). Three curves thus obtained showed the same tendency, and was concluded that these three PA substances were chemically the same.
2) Seed-rooms of opened pods of rape (Brassica napus L.) and of the pods of common vetch (Vicia sativa L.), and leaves of broad bean (Vicia faba L.) from which the epidermis had been peeled off were mounted respectively with conidia suspension of G. cingulata. Thus three PA-solutions of different origins were obtained with the same method as described above. Ten ml of each PA-solution was extracted with equal volume of petroleum ether. Petroleum ether was evaporated under nitrogen gas at 20°C and 1ml of 3per cent ethanol was added to the residue. 0.2ml of each of three kinds of the liquids was mounted on a hole-slide-glass and its biological activity was assayed on conidia of G. cingulata. Parallel to the above experiment, 0.8ml of each of the liquids was diluted with 5ml of ethanol and ultraviolet absorption was measured. Three curves thus obtained and that of the PA liquids from pea were compared and found that these four PAs were distinctly different from each other.
It was concluded from these results that chemical nature of PA was specific to the host plant species and was not specific to the fungi that was introduced to the hosts.

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The fungicidal activity of phenylmercuric acetate (PMA) was assayed on the conidia of Cochliobolus miyabeanus by the use of slide-germination test method. The ED 50 of PMA was 0.04ppm, when PMA alone was dissolved in water. But the addition of 1ml of rice leaf juice per 2.5ml of the test solution raised the ED 50 of PMA up to about 20ppm. The juice was thus prepared by grinding 10g of leaves with water at 5°C, filling up to 150ml and filtrating.
The rate of the detoxication of PMA by the juice increased parallel to the amount of the added juice. The effect of the juice decreased by the oxidation during extraction and storage at 5°C. The dialysis of the juice revealed that the effective substance was present mainly in the protein fraction and partly in the low molecular fraction. PMA was detoxified by the addition of thiol compounds, such as cysteine, glutathione (reduced), egg-albumin, yeast-extract and sodium thiosulfate, as well as the rice leaf juice. Amino acids, vitamins, carbohydrates and inorganic salts, all of which did not contain the thiol-group, did not detoxify PMA.
From these results, the author concluded that the detoxication of PMA by the rice leaf juice was due to the formation of the mercaptide of phenylmercuric group with the thiol-group mainly of protein and partly of low molecular substances such as glutathione (reduced) present in the juice.

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1. Physiological characteristics of Xanthomonas oryzae, the causal organism of the bacterial blight of rice plant, have been studied by several authors, but there are some discrepancies in their results with regard to certain characteristics such as reaction in milk and reduction of methylene-blue. The present research was carried out to make these points clear and to elucidate the relationship between the physiological properties and pathogenicities of the bacterium. For this purpose, 20 isolates of different pathogenicities were selected from 118 isolates which had been collected from various districts of Japan.
2. All the isolates used in this experiment reduced methylene-blue, but not nitrate; produced ammonia and hydrogen sulfide, but not indole; gas production and diastase activity were negative; liquefied gelatin gradually; did not coagulate or digest milk; and discolored Litmus milk into blue. Thus the result differs from Ishiyama's original description as to the reduction of methylene-blue, the liquefaction of gelatin, and the production of hydrogen sulfide.
3. Isolates more active in liquefying gelatin were, with some exception, more pathogenic than those with less liquefying power, suggesting that there might be an intimate relationship between the liquefying power and the pathogenicity. There were some immunogenetical differences among the isolates in terms of the rate and strength of agglutination reaction, although the reaction was positive in all the isolates. The differences in the reaction, however, were correlated with the differences in the pathogenicity of the isolates.
4. The bacteria in culture were capable of decomposing xylose, arabinose, glucose, levulose, galactose, mannose, and sucrose, producing acids; and incapable of utilizing rhamnose, dextrin, starch, inulin, glycerol, mannitol, sorbitol, and salicin. Some of the isolates could not utilize arabinose.

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A disease of oats hitherto unrecorded in Japan was found in Okayama Prefecture at 1952. The same disease was found later in Chiba Prefecture. The disease is characterized by diffuse halo-like discoloration around elliptic or streaky leaf lesions.
A bacterium was isolated, and on the base of its morphology, cultural characteristics, and inoculation tests, it was identified as Pseudomonas coronafaciens (Elliot) Stevens, which is known to cause the halo-blight of oat in U.S.A.
Characteristics of this bacterium was found to be as follows:
Rod-shapes, 0.4∼0.6×1.5∼2.5 microns; capsulate; motile with one to three polar flagella; no spore. Gram negative. Aerobic. Beef peptone agar colonies, round to irregular, white, circular, flat, smooth or with slightly raised margins, smooth to slightly contoured. Beef bouillon moderately clouded with flocculent white pellicle. Gelatin liquefied slowly. Milk not coagulated and not peptonized. Litmus milk no reduction. Nitrate slight reduction. Ammonia produced, but no hydrogen sulphide nor indol. Uschinsky's, Fermi's and Fraenkel's solutions, good growth; not with Cohn's solution. Acid but no gas from sucrose, glucose, xylose, galactose, fructose, arabinose, mannitol, glycerol; no acid nor gas from maltose, rhamnose, lactose, dextrin, ethyl alcohol, inulin, inosite, soluble starch. Starch hydrolysis moderate. Optimum temperature 22.5°C, maximum 33°C, minimum 4°C.
Host: (spray inoculation) Avena sativa L.
(Multiple needle inoculation) Avena sativa L., Hordeum distichum L. emend Lamark, H. vulgare L., H. vulgare var. nudum Hook., Secale cereale L., Triticum sativum Lam., Agropyron tsukusiense var. trasiens (Hach.) Ohwi, Alopecurus aequalis Sobol., Andropogon scoparius Michx., Beckmannia syzigachne (Steud.) Fernald, Bromus catarticus Vahl., B. inermis Leyss., Dactylis glomerata L., Lolium italicum Braum, Lycopersicum esculentum Mill., Oryza sativa L., O. sativa var. terrestris Makino, Panicum miliaceum L., Phleum pratense L., Poa annua L., Polypogon fugax Steud.

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In the summer of 1961, potato plants (var. Benimaru) naturally infected with a yellows-type virus disease were found from three different regions of Hokkaido. The affected potato plants were stunted, produced chlorotic axillary shoots which had an upright habit, and the younger leaflets were dwarf showing marginal chlorosis and downward cupping.
Tomato plants grafted with the affected potato scions produced chlorotic and slender apical shoots having yellowish leaflets about two weeks after inoculation. In the advanced stage of infection the axillary growth was promoted and the petioles grew long forming arches. The symptoms of potato and tomato plants, produced by this new disease are different from those produced by potato witches' broom and other yellows-type diseases of potato found in Japan. Therefore, the authors name this new disease“Potato yellows typeIII”to distinguish it from types I and II which have been classified by Oshima in 1960. Type I is a strain of aster yellows virus.
Top grafting of the affected tomato scions were made using 14 species in 5 genera of Solanaceous plants as stock plants. Eleven species of them showed obvious symptoms and most of the symptoms were readily distinguishable from the symptoms which were produced by the other yellows-type diseases, but some of them resembled each other in the certain stages of infection. The most characteristic symptoms were observed in Nicotiana glutinosa and N. tabacum var. Samsun, in which this new disease produced narrow dwarf apical leaves curving downward and could be clearly distinguished from potato witches' broom and aster yellows (Type I), N. glauca showed no symptoms, but was proved to be a symptomless carrier by the results of return inoculation. Both potato witches' broom and aster yellows viruses were carried in this species without producing symptoms. The disease could not be transmitted from tomato to petunia by graft inoculation, although the scions continued to grow on the stock plants for a long time. Transmissian to petunia was successful if infected Datura plants were used as scions. Physalis floridana and Capsicum annuum produced no symptoms, but no subinoculations were tried using these plants as inocula.

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1) In an early period of growth, no correlation was found between peroxidase activities and the degree of late blight resistance of potato varieties. This correlation became apparent as the potato plants mature.
2) Potato varieties which differ in lateness of maturing have their own pattern of peroxidase activity as the plant mature, and the highest value of peroxidase activity obtained from leaves growing midway up the plants were correlated with the lateness in maturing of the variety.
3) It is concluded that peroxidase activity relates directly to the lateness in maturing of varieties, which results in an indirect correlation between its activity and the degrees of late blight resistance.
4) A slight correlation was found between phenol oxidase activity and the degree of the resistance estimated by artificial inoculation procedure.

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As has previously been reported, when potted diseased trees with severe symptom are kept at 37°C, the symptom disappears in two weeks. Results in line with this finding have been obtained by means of heat treatments of scion-woods.
Diseased scion-woods were obtained in summer. These were placed in a thermostat at 40±1°C for 12 hours, 15 hours, 18 hours, 21 hours, 1 day, 1.5 days, 2 days, 3 days, or 4 days; at 45±1°C for 6 hours, 12 hours, 18 hours, 1 day, 2 days, 2.5 days, or 3 days; at 50±1°C for 3 hours, 6 hours, 12 hours, 18 hours, 1 day, or 1.5 days. Then they were cut and grown in pots in a greenhouse. All the plants treated at 40°C for 12 hours, 15 hours, or 18 hours, at 45°C for 6 hours, or at 50°C for 3 hours developed shoots showing severe symptom. None of the plants treated at 45°C for 2.5 days, or 3 days, or at 50°C for 1 day, or 1.5 days developed shoots showing any symptom.
Diseased scion-woods obtained in summer were immersed in a bath at 45±1°C for 4 hours, 6 hours, or 8 hours; at 50±1°C for 20 minutes, 30 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 3 hours, or 4 hours; at 55±1°C for 1 minute, 3 minutes, 5 minutes, 10 minutes, 20 minutes, or 40 minutes. Then they were cut and grown in pots in a greenhouse. All the plants treated at 50°C for 20 minutes, or at 55°C for 1 minute developed shoots showing severe symptom. None of the plants treated at 50°C for 4 hours, or at 55°C for 40 minutes developed shoots showing any symptom.
It is suggested that the virus becomes inactivated in the affected shoots by treatment for 2.5 days at 45°C, or 1 day at 50°C, in dry heat; for 4 hours at 50°C, or 40 minutes at 55°C, in hot water.

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The present investigation was undertaken to ascertain the difference of fungicidal activity of methyl bromide to the fungal spores settled on the hulled rice and to the mycelia grown on or in the hulled rice. The hulled rice to be inoculated was sterilized at 12lbs. for 20 minutes by autoclaving.
Several grades of hyphal growth in the rice grains were obtained by changing the time of incubation. Microscopical observations were made on hand sections or frozen sections of the rice grains.
With regard to the resistance of spores and mycelia to methyl bromide, the latter has less resistance than the former. The mycelia were completely sterilized by fumigation at 45mg/l, 25°C for 18 hours, but the spores required 50mg/l for their complete sterilization.
The methyl bromide resistance of the hyphae within the grain varied according to the extent of mycelial invasion, the resistance of mycelia invaded in the aleuron layer being apparently less than that in the starch layer. The hyphae in the central part of the grain could be sterilized by about the same dosage as in the case of the spores on the grain surface.

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(1) Multiplication of tobacco mosaic virus (TMV) on the duck-weed (Spirodela polyrhiza) was ascertained by the following experimental results.
i) Duck-weeds were inoculated with TMV by a rubbing method. A small quantity of TMV was recovered 3 and 5 days after inoculation, but a larger quantity of the virus was estimated 10 days after from the inoculated fronds of duck-weed (Table 1 and 2).
ii) Duck-weeds were infected with 1:1, 000 dilution of leaf juice from infected tobacco with TMV, but only rarely with 1:100, 000 dilution (Table 3).
iii) The dilution end point of duck-weed juice, 20 days after being inoculated with TMV, was found to be 1:10, 000 (Table 4).
iv) Juice from duck-weeds, 20 days after inoculation, was almost completely neutralized with TMV-antiserum (Table 5).
v) One frond of duck-weed having 3 or more fronds was inoculated with TMV, and the inoculated frond was separated from the non-inoculated fronds. TMV was not recovered from these non-inoculated fronds, when separation from the inoculated frond was made 1, 3 or 5 days after the inoculation, but was recovered when was made 10 days after the inoculation. Besides, TMV was detected 30 days after the inoculation from young fronds which were newly formed from the inoculated fronds.
(2) Besides the rubbing method, duck-weeds could readily be infected by shaking powerfully by a hand or by a shaker for 0.5 to 5 minutes in small bottles containing diluted TMV juice, carborundum powder and the plants (Table 6).

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