The present investigation was undertaken to evaluate the controlling effect on rice blast in relation to the structural modifications of chlorophenylhydrazine and β-acylchlorophenylhydrazine derivatives.
Chlorophenylhydrazine-oxalate, -hydrochloride, -sulfate and -nitrate showed high protective effect upon rice blast in the pot tests in greenhouse.
A series of β-acylchlorophenylhydrazines was tested against rice blast. Results showed that highest controlling effect among 29 β-acylchlorophenylhydrazine derivativea was obtained at a chain length of 1-2 carbon atoms of acyl radical. β-formyl- and β-acetylchlorophenylhydrazines showed marked protective and therapeutic effects on rice blast in the pot tests in greenhouse. They also gave good controlling effect equally or more or less inferior to the organic mercury, phenylmercuric iodide, in protective spray and blasticidin-S in therapeutic spray in the seedling bed tests in field.

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Studies were carried out with the efficacy of 1-(3, 4-dichlorophenyl)-2-acetylhydrazine (I) and 1-(4-chlorophenyl)-2-acetylhydrazine (II), which showed the strongest and the most consistent effect on rice blast control among β-acylchlorophenylhydrazine derivatives, in suppressing developing mycelia and germination of spores of Pyricularia oryzae in vitro, on leaves and in tissues of rice plant.
Compounds I and II were found to possess complete sporostatic property at 125ppm on the slide glass, and both I and II at 175ppm and above prevented the mycelial growth in shaking culture. While mycocidal action of these compounds were stronger than sporocidal action.
On the leaves of rice plant, both I and II at 1000ppm did not prevent sufficiently spore germination and appressorium formation, but suppressed markedly the mycelial development in the host tissues as well as blasticidin S, a therapeutic agent.
These results suggested that the principal locus of inhibition of β-acylchlorophenylhydrazines against rice blast fungus in the protective and the therapeutic tests was at the stage of mycelial development in the tissues, and not at the stage of spore germination and appressorium formation upon leaves of rice plant.

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1. The conidia of Cochliobolus miyabeanus and the chlamydospores of Ustilaginoidea virens, and the conidia of Piricularia oryzae lost germinability by compression of 2, 500kg/cm² and 2, 000kg/cm², respectively, for 10 minutes. The germ-tubes of C. miyabeanus affected by hydrostatic pressure were slender and shorter than those of the normal. Conidia of C. miyabeanus compressed at 2, 000kg/cm² for 10 minutes, and those of P. oryzae pressured at 1, 000kg/cm² for 20-30 minutes, germinated bearing a 3-5-branched germ-tube.
2. The germination index of these fungi decreased with the length of time of compression at 1, 000, 1, 500 and 2, 000kg/cm², except of that of C. miyabeanus which compressed at 1, 000kg/cm². Tolerance of conidia to the pressure seemed to be largest in C. miyabeanus, though tolerance is variable with spore individuals. The conidia of P. oryzae, however, were found to be lowest in pressure tolerance among the fungi employed, and variation in tolerance due to spore individual was also restricted.
3. Elongation of the germ-tubes of the conidia of C. miyabeanus and P. oryzae was restricted in parallel with increase of pressure.

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Pentachlorobenzylalcohol (PCBA) is a new fungicide remarkably effective against rice blast caused by Piricularia oryzae Cavara. It is known that PCBA has many desirable characteristics as a rice blast fungicide; for example, nonphytotoxicity for every variety of plants tested and extremely low toxicity for the rat, mouse and small carp. One of the most striking characteristics of PCBA in comparison with the organic mercury fungicides is the excellent residual effect. However the antifungal activity in vitro of PCBA against rice blast fungus is too weak to be regarded as the origin of the efficacy.
To know the physiological function of PCBA on the rice plant, the influence of PCBA on the constituents of nitrogen and carbohydrate in the rice plant was studied. The change of the ratio of these organic constituents of the PCBA-sprayed rice plant and the unsprayed has been traced at successive growth stages.
The results obtained was summarized as follows:
1. Spraying of PCBA on the rice plant appeared to cause the decrease of the ratio of total nitrogen in the leaf blade. In ripening stage, however, the ratio of total nitrogen was estimated in higher level in the PCBA-treated plant than in the untreated.
2. Concerning water soluble- and protein-nitrogeous fractions the results showed the similar tendency to that of the total nitrogen ratio. The compounds with amino radicals, especially glutamic acid and aspartic acid, decreased considerably after the treatment of PCBA, and were maintained in relatively low level till the later growth stage.
3. In the carbohydrate fractions, the ratio of crude starch estimated in the lower sheath of the rice plant sprayed with PCBA was much higher than that of the unsprayed plant. There was also appreciable difference in the accumulation of crude starch in the ear between the PCBA-sprayed plant and the unsprayed.

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As has previously been reported, the symptom of dwarf-diseased mulberry tree at Taimei town, Tamana county, Kumamoto Prefecture is more severe than that at Kikuchi city, Kumamoto. At Taimei town crinkled leaves appear before the cutting back of mulberry trees in June, but at Kikuchi city, on the other hand, they do not appear before the cutting back, but they are recognized on the newly grown shoots after cutting back in June. Further information has been obtained as follows: these symptoms were not influenced by natural circumstances, but seemed to be the essential characteristics. Therefore, the virus of dwarf disease of mulberry tree was classiffied into two strains, one is the Tamana severe strain and the other is the Kikuchi mild strain.

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Mexican lime seedlings were grafted with buds from the following Hassaku plants suspected to carry tristeza virus.
A) Two nursery plants, apparently healthy, one of which was supposed not to be pitted (M1) and the other severely pitted (S2), although both had been propagated from the same mother tree.
B) Hassaku-dwarf-affected trees (S0, S1).
C) An old, apparently healthy but slightly pitted tree (M2).
All the lime seedlings used for the experiments were kept in a screened greenhouse for observation for 7 to 11 months.
1) When Mexican lime seedlings were grafted with buds from S0, S1 or S2, they developed severe symptoms of vein clearing, vein corking, stem pitting, stunting, etc. On the contrary, when grafted with buds from M1 or M2, only mild symptoms of vein clearing, stem pitting, etc. were observed on the grafted lime seedlings. The symptoms in this case ceased to develop any more.
2) Inoculation with leaf pieces from those diseased lime seedlings caused same reactions on other batches of lime seedlings as did the original grafting, viz. inoculation with leaf pieces from the seedlings with mild symptoms caused mild symptoms; inoculation with severe ones caused severe symptoms on the second batch of lime seedlings.
3) When Mexican lime seedlings were grafted first with buds from M1 or M2, and then, one or two months later, grafted with buds from S0, S1, or S2, they showed milder symptoms than those on seedlings grafted with buds of latter group alone.
4) Considering from these results, the plants M1 and M2 seem to be infected with a mild strain of tristeza virus, and S0, S1, and S2 with a severe strain.

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The mechanism of fungitoxicity of higher alkylphenols upon mycelia of Piricularia oryzae, a pathogen of rice blast, was investigated comparing with the action of another phenolic fungicide, pentachlorophenol (PCP), and other chemicals.
Fungitoxicity of PCP was shown to be due to the uncoupling of oxidative phosphorylation in the fungous cells, but the uncoupling action of higher alkylphenols could not act as a primary factor of fungitoxicity. Higher alkylphenols inhibited uptake of glucose and glutamate into the cells, and removed ninhydrin-positive substances from the cells at and beyond the minimum growth-inhibitory concentration. This disturbance of the function of cell membrane may be caused by the absorption or distribution of a certain quantity of the phenol to the lipoidal layer of the cell membrane, and causes death of the fungi.

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Incidence of leaf spot disease of turmeric (Curcuma longa L.) incited by Taphrina maculans Butler has been demonstrated to be influenced by the amount of soil-borne inoculum as well as prevailing environmental conditions. Age of the host leaves becomes inconsequential, since they remain susceptible to infection over a long period until moisture remains available. Early appearance and severity of disease are conditioned by the concentration of effective inoculum in the soil. Moist cloudy weather with a temperature of 25-30°C (30-25°C from August to September) prevalent in this area is conducive to disease incidence in severe form.

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The present report describes the application of the immunofluorescent staining to the detection and the counting of Erwinia aroideae in the presence of other bacteria.
Immunofluorescent staining was performed by indirect method. The time required for staining was 10-15 minutes. 1:100 to 500 and 1:32 dilutions of anti-E. aroideae 1068 serum and of labelled goat anti-rabbit globulin respectively were adequate for the staining of used bacterium. 2 strains of E. aroideae and 3 strains isolated from soft rotted carrots showed positive staining reactions with the foregoing antisera, while 30 strains of E. aroideae and 27 strains of bacteria belonging to 12 genera gave negative reactions under the same conditions.
In impression smears from the leaves of Chinese cabbage previously sprayed with E. aroideae 1068, a number of fluorescent bacterial cells and colonies were recognized mainly along the joint regions of the epidermal cells.
E. aroideae could be detected using the microcolony technique in the soil suspensions containing as few as 52 cells per ml. With specimens containing smaller numbers of E. aroideae, some of the promising combined methods for the calculation of this pathogen are discussed.

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The isolation of nuclear fraction from tobacco leaves and the extraction of histones from the isolated nuclei were investigated. A fairly pure nuclear fraction, freed from chloroplasts and other cellular organelles, was obtained by the combined method of differential centrifugation and density gradient centrifugation. Histones extracted by 0.25N HCl from isolated nuclei contained 2 main components as revealed by electrophoresis using cellulose acetate film (Separax). Tobacco nuclear histones seemed to be composed of small amount of arginine-rich histone and large amount of lysine-rich histone.

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In a previous paper (Ann. Phytopath. Soc. Japan 25: 187, 1960), the writer reported a virus obtained from cabbage and rape plants showing mosaic symptom, and identified it as cauliflower mosaic virus (CAMV) described by Tompkins (1937). Electron microscopic examination of partially-purified virus preparations revealed two kinds of spherical particles differing in size, about 10∼13mμ and about 50mμ in diameter, respectively. As the larger particles were thought to be the aggregates of the smaller particles, the virus was reported to be spherical particle of about 10∼13mμ in diameter. In the same year, however, Day and Venables (1960) and Pirone et al. (1960) reported that CAMV was a spherical particle of about 50mμ in diameter. As it seemed likely that the writer's former conclusion was in error, re-examination using more purified preparation was made.
Preparation made by the purification method already reported was further purified by sucrose density gradient centrifugation after Day and Venables and Pirone et al. Examination of the tube after density gradient centrifugation showed a distinct opalescent band in the middle and a barely discernible opalescent band near the top. The band at the top contained only smaller particles and was noninfectious. In inoculation tests, the middle band showed high infectivity, and electrom microscopic examination revealed the presence of uniformly-sized spherical particles of approximately 50mμ in diameter. The virus was therefore considered to be the spherical particles of about 50mμ, and the writer corrects his mistake in identification of the virus particles reported in his previous paper.

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