The ear blighting of rice plant is the phenomenon which shows the dark brown coloured and blighted symptoms at panicle branch, kernel and neck. It is caused by various kinds of fungi except Pyricularia oryzae. It is called panicle blast, when the causal fungus is Pyricularia oryzae.
The panicles showing the symptoms of ear blighting were collected from various paddy fields located near Tsu-city and examined for the causal fungi. Pyricularia oryzae was commonly found affecting the diseased panicle branches and Cochliobolus miyabeanus showed also a common occurrence. In most cases, Pyricularia oryzae was found in susceptible varieties to panicle blast. Rice plants which showed severe infection of brown spot lesions on the leaf blade was also infected by Cochliobolus miyabeanus at the panicles. Cercospora oryzae was found at the panicle branches of the rice plant which was affected with the causal fungus on the leaf blade and leaf sheath.
A positive relationship between brown spot lesions on the leaf blade and the incidence of ear blighting was observed in the field survey and also in our experimental studies. A closer relationship was also observed between the brown spot lesions on leaf blades and on the incidence of the panicle infection by Cochliobolus miyabeanus.
Spore trapping work was carried out during the course of panicle ripening in the paddy field where the panicle infection by Cochliobolus miyabeanus was predominent. The amount of conidia of Cochliobolus miyabeanus dispersed at the early stages of panicle ripening was very much less compared to the heavy amount of conidia dispersed during the harvesting stage. Conidia dispersing at the level of 40 cm height in the paddy field was more than at the level 80 cm height (at the same level of panicle growth) for the periods between flowering to soft dough.
The larger sized lesions having the ability for conidia production on the leaves were less and distributed only in the lower leaves during the early stages of panicle ripening. During the later stages the lesions increased and was distributed not only in the lower leaves but also in the upper leaves.
Infection by Cochliobolus miyabeanus on the panicle branches occurred almost near harvesting stage of the crop.
The transition and distribution of the conidia dispersion in the field and the large size of lesions on the leaves coincided with the time of the outbreak of panicle branch infection by Cochliobolus miyabeanus.
Therefore it appears that the inocula of the panicle branch infection by Cochliobolus miyabeanus came from brown spot lesions on the leaves of the rice plant, even though the kernel infection occurred only during the early stages of panicle ripening due to the limitation of fungal penetration to the kernel at this stage.

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1. The kind and frequency of causal fungi responsible for ear blighting of rice plant were examined at some localities in Shizuoka Prefecture from 1967 to 1970. The results showed that the most important pathogen of ear blighting was Helminthosporium oryzae (=Cochliobolus miyabeanus). In some instances, Fusarium nivale was also found to be responsible for ear blighting.
2. The relationship between severity of ear blighting and that of Helminthosporium leaf spot on leaf blade was investigated under various field conditions. In the plots of a field test for fungicidal effect, correlation coefficient was as high as 0.695*** to 0.796*** between the number of leaf spots and the percentage of diseased necks, panicle branches or kernels. In the fields different in variety, locality or transplanting time, high correlation coefficient of 0.792*** was obtained only between the number of leaf spots and the percentage of diseased kernels, while no significant correlation was found between the number of leaf spots and the percentage of diseased necks or panicle branches.

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The present study was conducted to identify the causal fungi of ear blighting of rice plant, to make clear the relation between leaf blade infection and ear blighting, and to determine the proper timing of EDDP application for the control of ear blighting.
1. A large number of ear blighting samples were collected to determine the kind of causal fungi throughout Aichi Prefecture from 1967 to 1970. Main species detected were Helminthosporium sp., Cladosporium sp., Pyricularia sp., Cercospora sp., etc. Helminthosporium sp. and Cladosporium sp. were generally found on almost all the samples, while Pyricularia sp. and Cercospora sp. varied in their incidence with the locality or with the year. Cladosporium sp. has not been recognized to be pathogenic to rice plant. It is supposed, therefore, that Helminthosporium sp. is the most important causal fungus of ear blighting in Aichi Prefecture.
2. Distinct correlation was not found between the leaf blade infection with Helminthosporium oryzae and the incidence of ear blighting under the field condition. In the concrete pot experiment, however, both leaf and ear infection with Helminthosporium oryzae was increased with the decrease of root vitality induced by the reductive condition of soil.
3. The ear blighting was effectively controlled by the application of EDDP spray from full heading stage to dough-ripe stage.

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The present paper deals with investigation on the causal fungi of ear blighting of rice plant in Gifu Prefecture.
1. Many species of fungi, such as Helminthosporium oryzae, Cercospora oryzae, Pyricularia oryzae, Cladosporium sp. and Alternaria sp. were detected from a number of samples of ear blighting collected from various parts of Gifu Prefecture. Among them, Helminthosporium oryzae was usually found to be most popular.
2. Helminthosporium oryzae was detected from the samples at every stage after heading, while Cercospora oryzae was detected only from the samples at the ripening stage.
3. The frequency of Helminthosporium oryzae or Cercospora oryzae on the diseased ear was variable with the position on the ear as well as with the variety of rice plant.

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A survey was conducted on the causal fungi of rice ear blighting in Shiga Prefecture during three years from 1967 to 1969. The samples were collected from 67 or 78 locations throughout the Prefecture and the fungi found on their necks and panicle branches were identified by microscopic observation.
The fungi found on the samples were Pyricularia oryzae, Helminthosporium oryzae, Cladosporium cladosporioides, Cercospora oryzae, Nigrospora oryzae, Curvularia lunata, Rhynchosporium oryzae, Fusarium sp., Alternaria sp., Penicillium sp., Aspergillus sp., Epicoccum sp., etc. Some samples were found to be contaminated with two or three species of those fungi.
The most prevalent and widely distributed species were Cladosporium cladosporioides and Pyricularia oryzae, both of which were found on the samples more than 40% and from the locations more than 90%. Helminthosporium oryzae was next to them, and Cercospora oryzae was also widely distributed but with rather low frequency. Curvularia lunata was not popular in its frequency nor distribution.
The panicles infected with Pyricularia oryzae should not be called ear blighting but panicle blast. Cladosporium cladosporioides is known to be non-pathogenic to the panicles of rice plant. Helminthosporium oryzae, therefore, is considered to be the major pathogen of ear blighting in Shiga Prefecture, and Cercospora oryzae, Curvularia lunata and Rhynchosporium oryzae are also concerned with the disease in some occasions.

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The relation between the incidence of Helminthosporium leaf spot on leaf blade and that of ear blighting of rice plant was examined in the experimental field at the Kyoto Prefectural Agricultural Experiment Station as well as in the farmers' fields covering 20 ha at Yagi Town of the Prefecture.
The fungi found on the samples of ear blighting of many varieties with different heading data were Helminthosporium oryzae, Pyricularia oryzae, Cladosporium sp., Alternaria sp., etc. and, among them, Helminthosporium oryzae was supposed to be the most important pathogen of the disease.
In the experimental field, the number of lesions of Helminthosporium leaf spot at the milky stage showed positive correlation with that at the ripening stage (r=0.606), and the latter was highly related with the percentage of diseased panicle branches at the ripening stage (r=0.695). In the farmers' fields, however, the correlation coefficient was as low as 0.448 between the lesion number of Helminthosporium leaf spot and the percentage of diseased panicle branches. This may be due to the lack of uniformity in cultivation methods, especially in fertilization.

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The species of causal fungi of rice ear blighting and the relationship between ear blighting and Helminthosporium leaf spot were investigated in Nara Prefecture for two years extending from 1969 to 1970. The results are summarized as follows.
1. The rice ear blighting was found to be prevalent in the hilly regions northwest of Nara-City, in the regions around Mt. Ikoma and Mt. Kongo, and in the “akiochi” regions along the riversides of Yoshino. The outbreak of ear blighting in these regions was generally more frequent than in the others, though local outbreak may occasionally be observed in the latter.
2. The fungi detected from the neck of diseased ears were Cladosporium, Helminthosporium, Fusarium, Alternaria, etc. Ear blighting in most cases was likely the symptom of the mixed infection with these fungi.
3. Helminthosporium was detected with high frequency from the necks of diseased ears collected from the fields where Helminthosporium leaf spot was prevalent, while Cladosporium was frequently found on the samples from the fields with less incidence of Helminthosporium leaf spot. The species of major causal fungi may sometimes be varied year by year.
4. Any significant correlation was hardly found between the severity of Helminthosporium leaf spot and that of ear blighting. In the fields, however, where Helminthosporium leaf spot was prevalent, the heavy incidence of the leaf spots on the 3rd leaf from the top was presumed to be somewhat related to the infection of panicle branches.

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A joint study on ear blighting of rice plant was conducted by seven Agricultural Experiment Stations located in seven Prefectures of Tokai-Kinki Region from 1969 to 1971. The obtained results are reported in this volume by the investigator (s) of every Prefecture. The results of the joint study are summarized as follows:
1. Helminthosporium oryzae (=Cochliobolus miyabeanus) was found to be the most prevalent causal fungus of rice ear blighting in Tokai-Kinki Region. Cercospora oryzae (= Sphaerulina oryzina) and Fusarium nivale were also found to be the major pathogen in some locations or in a certain year. Mixed infection with two or more of those pathogenic fungi including Pyricularia oryzae was often observed. Helminthosporium sigmoideum var. irregulare attacked the uppermost internode only in special occasion. Alternaria sp., Cladosporium sp., Curvularia sp., Epicoccum sp., Fusarium sp., Nigrospora sp. and Phoma sp. were also seen on the samples of ear blighting, but they are not considered to be the essential cause of the disease because of the lack of distinct pathogenicity.
2. There was high correlation in some cases, while low or no correlation in other cases between the grade of leaf blade infection and panicle infection with Helminthosporium oryzae. The results were variable especially in the farmers' fields covering large area, where the cultivation practices were different in many aspects. The pot tests indicated, however, that the rice plants liable to leaf blade infection with H. oryzae were also liable to panicle infection with the fungus. It may be said, therefore, the counterplan should be considered against ear blighting when the leaves are severely attacked by H. oryzae by the time of heading.

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The epidermis-stripped primary leaves of two varieties of barley (Hordeum vulgare L.) (var. Russian 74 and H. E. S. 4) were inoculated with conidia of a race of Erysiphe graminis hordei, H_r74 (affinitive to Russian 74 and non-affinitive to H. E. S. 4) in order to clarify if the causal fungus can form haustoria only in the epidermis and to analyse the direct affinitive and non-affinitive reactions to the mesophyll cells in response to the fungal invasion. The conidia germinated on the exposed mesophyll surface and the hyphae elongated into the mesophyll. Within 48 hours after inoculation, a number of mycelial aggregates were formed in the mesophyll cells. The intercellular hyphae were visible at the same time. These fungal developments were observed in both affinitive and non-affinitive host-parasite combinations; however, the numbers of the mycelial aggregates and intercellular hyphae were extremely restricted in the non-affinitive combination. Densely stained materials were deposited on the outermost cell wall of exposed mesophyll cells which were inoculated with the non-affinitive fungal conidia. They seemed to be associated with the extreme restriction of the fungal development in the non-affinitive host mesophyll.

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Submerged application of IBP (O, O-diisopropyl-S-benzylthiophosphate) granules in irrigation water, 3-6Kg per 10 ares, showed that the culm length of rice plants became shortened, the lower internodes growing shorter than those of the control plants.
IBP gave more shortening effect against the culm length in application 6 kg than 3 kg per 10 ares, and the most from the most active-tillering stage to the young panicle formation stage. The load of culm base at breaking-point was also apt to be increased owing to shortening of culm length.
It was observed in field.s that the greater the degree of shortening of culm length, the less the degree of lodging. IBP application showed the increasing of the number of cilicified cells in a leaf blade of the rice plants.
On the one hand, IBP was the most effective for control of neck rot, in application 6 Kg per 10 ares, 10 days before heading (88% disease control) and still effective at the maximum tiller number stage (81% disease control).
From these results, it seems that submerged application of IBP in irrigation water, 6 Kg per 10 ares, at the maximum tiller number stage can be practically used for both prevention of lodging and control of neck rot of rice plants.

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The authors give a list of the flower-visiting insects in citrus orchards with special consideration on scarring of fruit surface at Wakayama, southwest Japan in 1968-1972. These comprised of 64 species belonging to 9 orders as shown in Table 1. Notes are given on their relative abundance, behaviours on citrus flowers and relations to scarring of fruit surface.

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We have studied on the uptake of γ-BHC by fungal mycelium. In this experiment, the uptakes of α-, β-, and δ-BHC by fungus were studied, and it was clear that the maximum uptaken weights of α-, β-, andδ-BHC by Fusarium roseum were repsectively 0.049, 0.033, and 0.055,μg/mg of fresh mycelial weight.
The weight of α- and δ-BHC uptaken by Aspergillus oryzae, Cochliobolus miyabeanus and Fusarium roseum from the medium containing these BHC-isomers were calculated. The weight of δ-BHC uptaken by every fungus used in this experiment was greater than one of a-BHC. On the other hand, in the case of using of another medium containing α- and γ-BHC, the mycelia of C. miyabeanus uptook γ-BHC more than α-BHC, and it was opposite result on the uptake of the isomers by mycelia of A. oryzae and F. roseum from the medium.

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Radioactive mycelia of Pythium aphanidermatum were prepared by growing the fungi on an agar plate containing³²P-orthophosphate (10_μCi/ml). The growth of radioactive mycelia on agar plates without the isotope was detected by autoradiography. Radioactive zoospores were obtained from the radioactive mycelia grown on V8 juice agar plates. Behavior of the radioactive zoospores inoculated to cucumber seedlings was also traced by autoradiography.

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Pysicai experiments with the mixtures of pesticides were conducted on the relations between the surface tension of fungicidal suspension and the deposition of the fungicides on the citrus leaves. The results of these experiments are summarized as follows;
1. High correlation was recognized between the surface tensions of various kinds of fungicides and its deposition upon citrus leaves. This correlations are shown by following formula.
y=0.2313x-7.5743
(y: weight of deposit on the 500cm² citrus leaves in gram., x: surface tension of fungicidal suspensions in dyne/cm²)
2. When fungicides were mixed with insecticides or spreader the surface tension of the fungicidal suspensions became almost equal to that of pesticides or spreaders.
3. The relation between surface tension of insecticidal suspensions or spreader and the deposition of fungicides upon leaves are shown by the following formula;
y=0.236x-7.541
4. In case of the mixtures of Dithane M-45 with insecticides their surface tension (72.5dyne/cm²) went down to that of other suspensions or emulsions mixed, and consequently the fungicidal deposit decreased on citrus leaves. These relations are indicated as the following formula;
y=0.2287x-7.02
5. The spraying of fungicides mixed with insecticides or spreaders reduced the fungicidal deposit on citrus leaves compared with the fungicide alone. The quantity of fungicidal deposit is the more variable when the surface tension of fungicides the higher or that of the additives the lower.

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The author previously reported that the decrease of surface tension of fungicidal suspensions is parallel to the deposit of fungicide on leaf surface. In the present paper the author reports on the influence of the quantity of the deposit of fungicide upon the control of citrus melanose.
1. Mixing Elsan, Vinyphate, Spracide, Azomite, and Citrazone with Dithane M-45 decreased its deposit on the leaves and reduced the effect for the control of melanose.
2. Mixing of various insecticides with M-Diphur also decreased its deposit on the leaves, showing 21.04r/2cm² of M-Diphur alone, and 3-10r/2cm² of the various mixtures. On the other hand, its mixture with Summer Oil showed much more deposit even 39 days after spraying. Effectiveness for the control of melanose seemed to be parallel to the quantities of the fungicidal deposit. And its mixture with Summer Oil showed the highest effect of all combination and superior to even Diphur alone.
3. For the purpose of compensating the decrease of fungicidal deposit of the mixtures, the concentration of Dithane M-45 in the mixture was increased as following dilutions: 1/360 in the mixture with Dimethoate, 1/240 in Supracide, 1/180 in Elsan, 1/180 in Citrazone, 1/120 in Vinyphate, 1/60 in Amiphos and Santokuten. All those mixtures proved higher effect than Dithane alone. While the mixture with Microdenapon or Eraditon showed less effect than the alone.
4. Adding the wettable spreader to Dithane M-45 or Dithane Z-78 showed much less effect than the alone for the control of citrus melanose.

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When Phytophthora capsici infect a cucumber fruit, several kinds of bacteria are induced to grow associating with the fungus and develop in the lesion. After several days, these bacteria occupy the place of the fungus on the fruit, but have no pathogenicity to cucumber. In this paper the contribution of these bacteria to tissue softening and cell degradation were investigated and discussed.
The macerating and pectolytic activities of the extracts of the lesion in which P. capsici and the association bacteria coexist are in same grade as that of the lesion which is invaded by P. capsici alone. Both activities of the culture fluid of these bacteria are extremely low as compared with those of P. capsici culture. Cellulase activities of these bacteria are low too.
On the contribution of these non pathogenic bacteria to lesion development on cucumber fruit, it is considered that these bacteria increased in number depending on exduate from the degraded host tissue after invasion of P. capsici, although they have little amount of enzymes regarding to softening of the tissue as described above. Then pH of the tissue are shifted to the optimum for macerating action of P. capsici depending on the increase of these bacteria and decomposition of the tissue by the fungus.
Strong pectolytic activity of Erwinia carotovora suggests that the host infected together by P. capsici and E. carotovora results in severe damage.

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[in Japanese]

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