Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Volume 36 , Issue 4
Showing 1-16 articles out of 16 articles from the selected issue
  • Toshio KIKUMOTO, Masayuki SAKAMOTO
    1970 Volume 36 Issue 4 Pages 207-213
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The present investigation was undertaken to demonstrate the relationship between soft-rot bacteria (Erwinia sp.) and soil structure. The distributions actinomycetes, and fungi within soil aggregates were examined by the serial washing and sonic vibration method designed by Hattori. Microbial cells in the aggregates were thus fractionated into those in inner and outer parts.
    1. It was found that the number of soft-rot bacteria in individual fractions of aggregates isolated from the soil in contact with midribs of chinese cabbage in late stages of its wrapping, designated as phyllosphere soil, was almost equal. On the contrary, the numbers of other organisms increased up to 150 percent with the decrease in the size of aggregates of the fractions.
    2. When these fractions of aggregates were exposed to sonic treatment for three minutes, an increase in the numbers of microorganisms with the exception of soft-rot bacteria was observed.
    3. Soft-rot bacteria were detected by dilution plating in 29 of 46 soil aggregates, their numbers ranging from 12 to 1, 600. There was no correlation between the numbers of soft-rot bacteria and of dye-tolerant bacteria in individual soil aggregates (2.00-0.84mm).
    4. It was found that 90 percent or more cells of soft-rot bacteria resided in the outer part of soil aggregates collected from the rhizosphere and phyllosphere of chinese cabbage.
    5. The rhizosphere effect of chinese cabbage on bacterial flora in the soil aggregates was more pronounced in the outer part than in the inner part.
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  • Toshihiko KUSABA, Aki TOYAMA
    1970 Volume 36 Issue 4 Pages 214-222
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Two-rowed barley plants grown on autoclaved soil showed infection when mechanically inoculated on leaves with soil-borne barley yellow mosaic virus. Test seedlings grown on this soil or autoclaved soil containing the roots of these infected plants failed to produce infection.
    A drench of Dexon** at a concentration of 70-140ppm on drill furrows of infected fields immediately before sowing brought about a considerable decrease in the disease incidence. On the other hand, the infectivity of diseased leaf juice was not affected by the addition of Dexon to the juice at concentrations of 50-200ppm in mechanical inoculations.
    Naturally infected roots were homogenized and filtered through 325 mesh screen. The filtrate was found to contain a high concentration of resting spores of Polymyxa graminis Led., and showed infectivity when inoculated to soil. The infectivity was lost at a dilution of 1:102.
    Naturally infected roots stored in refrigerator (4°C) for 4 months were immersed in tap water in petri dishes at 13-15°C. The water was changed daily. Infectivity of this water was tested by soaking germinated barley seeds in it, and was found to be infective from the 4th day after root immersion. A considerably high infectivity persisted until the 15th day. The infectivity of the water became higher when infected roots were kept in wet soil at 23°C for more than two weeks before immersion.
    The number of zoospores mostly of P. graminis released on successive days after the roots were immersed was found to be closely correlated with the infectivity of the water.
    From these results, P. graminis is suspected to be a vector of this virus.
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  • Aki TOYAMA, Toshihiko KUSABA
    1970 Volume 36 Issue 4 Pages 223-229
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Roots of two-rowed barley plants naturally infected with yellow mosaic virus were homogenized, after being stored in a refrigerator for 4 months, and filtered successively through 100-. 200-, and 325-mesh screens. The final filtrate was repeatedly centrifuged at 100 and 600 (or 500) rpm for 5-6 minutes alternately and a suspension of fungal spores was obtained. The majority of the fungal spores were resting spores of Polymyxa graminis Led.
    Autoclaved soil was inoculated with the fungal spore suspension and barley seeds were sown. More than half of the seedlings became infected showing mosaic symptom. Infection was not obtained when a spore suspension taken from the roots of healthy plants was used.
    Barley seedlings were grown on autoclaved soil inoculated with a resting spore suspension of P. graminis obtained from healthy barley roots and the leaves were mechanically inoculated with the virus. The roots of these seedlings showed infectivity. No infectivity was detected in the roots of seedlings grown on soil not inoculated with spore suspension.
    Roots of naturally infected barley plants differed in infectivity according to the time of sample collection. The roots of plants showing pronounced mosaic symptom from middle of March to early April showed low infectivity. The roots of plants having obscure symptoms after middle of April showed high infectivity.
    The time when the infectivity of the roots increased coincided with the time when P. graminis matured and formed abundant resting spores in the root tissues.
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  • Masaya SHIRAISHI, Masao FUKUTOMI, Shigeyasu AKAI
    1970 Volume 36 Issue 4 Pages 230-233
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The present paper dealt with the mycelial growth, sporulation, conidium germination and appressorium formation of Botrytis cinerea in relation to the incubation temperature and spore age. The optimum temperature for mycelial growth on PSA medium was in the range of 24-28°C, and the maximum and minimum temperature seemed to be at 0° and 35°C, respectively (Fig. 1).
    The sporulation was observed on PSA medium at 24°C and on sponge matrices which had been incubated in a moist chamber at 24°C after shake-culturing for 4 days in PS medium (2% sucrose) with sponge matrices. On the sponge matrices, conidia were produced synchronously about 24 hours after transferring to moist chamber (Fig. 3). Sporulation on PSA medium, however, was initiated 3 days after inoculation and reached the maximum from 4th to 6th day after the inoculation (Fig. 2).
    Young conidia, in general, germinated well at 20°C comparing with old conidia. Eighty seven per cent of germination was secured of the conidia produced synchronously on the sponge matrices. However, rapid reduction in germination of conidia occurred with the elapse of time, and after 3 days incubation germination fell down to less than 50 per cent. After 6 days incubation almost no germination of conidia took place in water (Fig. 3). Most of the conidia germinated, however, were capable of forming appressoria at the tip of the germ tube.
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  • Masaya SHIRAISHI, Masao FUKUTOMI, Shigeyasu AKAI
    1970 Volume 36 Issue 4 Pages 234-236_2
    Published: September 30, 1970
    Released: April 03, 2009
    JOURNALS FREE ACCESS
    Effects of temperature upon the conidium germination and appressorium formation of Botrytis cinerea Pers. were investigated on glass slides.
    1) Conidia of this fungus were able to germinate in the range of 5-32°C. At 10°C, however, germination was so much delayed that only 60 per cent of conidia germinated within 48 hours.
    2) The optimum temperature for the conidium germination was between 20 and 30°C, and the maximum temperature was 35°C. The minimum temperature seemed to be lower than 5°C.
    3) Appressorium formation occurred between 10 and 30°C, the optimum temperature being in the range of 15-20°C. Appressoria were formed fairly well even at 10°C, despite the delay of conidium germination. At 25°C or above, both the germination and germ tube elongation were favored, but appressorium formation was poorly detected.At 30°C the germ tube elongation was markedly accelerated, but no formation of appressoria was recognized.
    4) Young conidia, 2 days after their formation, commenced to germinate after 2 hours at 20°C on glass slides. Most of the conidia formed an appressorium at the tip of the germ tube after 4-6 hours of incubation. After 8-12 hours of incubation, most of the appressoria thus formed germinated again with elongating hyphae which branch ed during further incubation.
    5) At 15°C, conidia germinated well, but elongation of hyphae and appressorium formation were not conspicuous within 24 hours. Appressoria were formed after 48 hours. At 20°C, conidia germinated well and the elongation of germ tubes was vigorous accompanying marked formation of appressoria. At 25°C, two germ tubes sometimes protruded from a single conidium. In this case, appressorium was usually formed only on one of the germ tubes, while the other elongated as a vegetative hypha. The germ tube elongation was most prominent at 25°C. At 30°C, conidia germinated usually without forming appressoria.
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  • Tsuneo TSUCHIZAKI, Kiyoshi YORA, Hidefumi ASUYAMA
    1970 Volume 36 Issue 4 Pages 237-242
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Relations between seed transmission and gamete infection were studied on cowpea and azuki bean plants inoculated with seed-borne viruses. Virus-host combinations tested were, (1) azuki bean mosaic virus (AzMV)-azuki bean, (2) cowpea aphid-borne mosaic virus (CAMV)-cowpea, (3) cucumber mosaic virus (CMV)-azuki bean, (4) subclover mottle virus (SMV, a strain of broad bean wilt virus)-cowpea, and (5) CAMV-azuki bean. Seed transmission occurs in the former two combinations, but does not occur in the remaining three combinations, as described in a previous paper (Tsuchizaki et al., 1970). Seed transmission through either pollen or ovule of infected plants occurred only in the case of virus-host combinations that were seed transmitted. CAMV was recovered from pollen, anthers, and ovaries, of CAMV-infected cowpea plants, whereas SMV was recovered from anthers and ovaries, but not from pollen, of SMV-infected cowpea plants. No correlation between virus concentration in floral parts and seed transmission was found in virus infected cowpea or azuki bean plants, although the virus concentration was generally lower in pistils than in petals or leaves. Virus concentration was higher in anthers, but lower in ovaries, in CAMV-infected cowpea plants than in CAMV-infected azuki bean plants. Cowpea plants were inoculated with CAMV in their flowering time. The mature seeds producted on them were collected separately according to their flowering days, and transmission of CAMV through the seeds were examined. The result showed that seed transmission occurred only when the mother plants were inoculated with CAMV at least 20 days before the flowering day, while CAMV was recovered from pollen only when the mother plants were inoculated at least 17 days before the flowering day. From these results it was concluded that seed transmission of a virus depended largely on gamete infection by the virus.
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  • Nobuyuki ISHIZAKA, Kohei TOMIYAMA
    1970 Volume 36 Issue 4 Pages 243-249
    Published: September 30, 1970
    Released: April 03, 2009
    JOURNALS FREE ACCESS
    Observations were made on the processes of (1) wound periderm formation, (2) lignification (with phloroglucine-HCl), and (3) suberification (with Sudan III) of cut tuber surfaces of the highly resistant potato cv. Rishiri (R1) either inoculated with race 0 (incompatible) or race 1 (compatible) of Phytophthora infestans or non-inoculated. All experiments were conducted at 19-20°C. With cut tissue (control, noninoculated), renewed cell division first appeared on the surface two days after cutting, with subsequent cell division progressing toward inner tissue. Cell division occurring in a few cells located in succession from the cut surface toward the inner tissue resulted in the formation of a periderm. When the cut surface was inoculated with an incompatible race just after cutting, cell division was delayed, and the thickness of the periderm was reduced. In tissue inoculated with a dilute zoospore suspension, cell division first occurred in the cell directly adjacent to the browned cell, thereafter progressing toward the inner tissue. When inoculated with a concentrated zoospore suspension, cell division first occurred in the third cell away from the browned cell. Usually no cell division occurred in the second cell (the cells directly adjacent to the browned cell). The rapidity and extent of lignification and suberification also were reduced by infection with an incompatible race. Infection by a compatible race strongly inhibited the development of wound periderm structure.
    Evidence was presented that the infection by the incompatible race itself can cause the formation of the periderm.
    With aged tubers, the brown lesion progressed inward more deeply. The formation of the periderm was delayed and its extent also was reduced, as compared with fresh tubers. In extreme cases no periderm developed, even though the lesion has stopped developing.
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  • Tsutomu SAKUMA, Tadayuki SHIMANUKI
    1970 Volume 36 Issue 4 Pages 250-253
    Published: September 30, 1970
    Released: April 03, 2009
    JOURNALS FREE ACCESS
    Observation on the process of infection of red clover by Kabatiella caulivora was made to compare the response of resistant and susceptible clones of host plant.
    Conidial germination by germ tube formation on the epidermal tissues began 16 hours after inoculation, and actual penetration was observed 48-72 hours after inoculation. Appressoria were not detected.
    There was no difference in percentages of conidial germination on the epidermal tissues between resistant and susceptible clones. Hyphae were found to penetrate through cuticular layer. In the case of the resistant clones, cells at the infection site were not killed in the early stage of infection.
    Growth of the fungus within the host tissue was as follows: hyphae 2.5-4.0μ in diameter elongated in the intercellular space and reached phloem but no haustorium was observed within the cells. The hyphae did not penetrate into the xylem, but into the phloem. In the phloem, hyphae increased from 2.5-4.0μ to 8.0-12.5μ in diameter and formed abundant branches and septa. Finally the phloem collapsed.
    The difference in the hyphal growth and symptom development between the tissue of both clones was as follows. Symptoms: elongated lesions about 20mm in length, having water-soaked appearence, appeared on the petioles of the susceptible clone 6 days after inoculation; conversely, there were minute black flecks on those of the resistant clone 7 days after inoculation. Sometimes lesions with black margin appeared on the petiolules of the resistant clone 9 days after inoculation. Hyphal growth: microscopical observation was made on transverse sections of young lesions 7 days after inoculation. Degenerated cells, showing a slight browning, extended to the phloem in the susceptible clone. These degenerated cells finally collapsed. Conversely in the resistant clone, degeneration of the infected tissue showing deep browning was limited to 2-3 cell layers. These cells were found to be coagulated.
    Regardless of the water-soaked type or the minute black fleck type of lesions, hyphae were observed in the intercellular space of tissues around the lesions.
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  • Kiyoshi OSAWA, Akira YAMAGUCHI
    1970 Volume 36 Issue 4 Pages 254-259
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Multiplication of tobacco mosaic virus within the inoculated leaves of four local lesion hosts and the quality of necrotic lesions on the leaves of these hosts were compared.
    First recovery of virus from the inoculated leaves preceded the lesion appearance in all hosts used: Nicotiana glutinosa, Datura stramonium, Nicotiana tabacum var. Samsun NN, and Phaseolus vulgaris. It is concluded that virus multiplication occurred first in leaf cells to which virus was introduced and then necrotization of these cells followed. This confirmed the idea of Dr. Yoshii that necroic reaction in local lesion host to virus infection was completely different from the “hypersensitive reaction” that was given first to the phenomenon of cell death of hypersensitive wheat variety against incompatible race of Puccinia graminis.
    From the interval between first virus recovery and lesion appearance, these hosts were divided into two groups. In N. glutinosa, D. stramonium, and N. tabacum var. Samsun NN the interval was long, while it was short in P. vulgaris.
    Virus multiplication curve within the inoculated leaves of these hosts was divided into 2 types. Type A has no plateau after lesion appearance but simply shows a sigmoid curve, which is similar to the case in the systemic host, N. tabacum var. Samsun. Type B has a clear plateau after lesion appearance. N. tabacum var. Samsun NN and D. stramonium showed type B or sometimes type A in replicated trials. N. glutinosa and P. vulgaris always showed type B. The plateau in virus multiplication curve was seen during 20-40 hours after lesion appearance, while number and size of lesions were. still increasing. It was supposed that the limiting mechanism of virus multiplication and movement connected with the browning of infected cells is intensively operating during this period.
    After this period, virus multiplication still continues for a while. This seems to proceed with the increase of lesion size, especially in the case of N. tabacum var. Samsun NN and D. stramonium. Necrotization of infected cells then overcomes the spread of virus, and eventually virus multiplication ceases.
    The intervals between first virus recovery and lesion appearance and the type of virus multiplication curve within the inoculated leaves correspond with the color, size, and shape of lesions on different local lesion hosts. The lesion color, size, and shape also reflect on maximum yield of virus 100 hours after inoculation.
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  • Kazuo ABIKO, Hiroshi KITAJIMA
    1970 Volume 36 Issue 4 Pages 260-265
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    Blister canker, a new disease of peach tree was found in 1965 in Kanagawa Prefecture and also, in Gunma, Shizuoka, and Okayama Prefectures. The disease is caused by a fungus belonging to the genus Physalospora which produces both perithecia and pycnidia in infected bark tissues. The newly invaded bark tissue swells up and finally shows rough appearance, resembling blisters. In later stages, gum oozes out from these blisters, and infected twigs finally die.
    The fungus shows the following morphological characteristics: perithecia mostly scattered, partly imbedded, black, globose to subglobose, ostiolate, about 150-290μ in height and 170-340μ in diameter; asci 8-spored, clavate, wall thick especially at the apex, hyaline, 57.5-87.5×12.5-22.5μ; paraphyses erect, filamentous; ascospores nonseptate, hyaline to slightly tinted, ellipsoid, 15.0-32.5×5.0-12.5μ; pycnidia (Macrophoma) scattered, partly imbedded, black, globose to conical, about 240-440μ in height and 240-590μ in diameter; pycnospores hyaline, non-septate, fusiform elliptical, 20.0-35.0×5.0-12.5μ and produced on conidiophores about 20μ long. The inoculation test indicated that the fungus is pathogenic only to peach.
    Since no fungus corresponding to the Physalospora here described can be found in the literature, this fungus is treated as a new species, Physalospora persicae Abiko et Kitajima.
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  • Tetsuo TAMADA
    1970 Volume 36 Issue 4 Pages 266-274
    Published: September 30, 1970
    Released: February 19, 2009
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    A virus diseaase of soybeans, characterized by a rugosity of leaves and a dwarfing of plants, has been found in Hokkaido District since about 1952. The disease causes a severe damage to soybean crops. This virus, designated as soybean dwarf virus (SDV), was transmitted by the aphid, Aulacorthum solani (Kaltenbach), but not by sap inoculation nor through seeds. Of 43 species of plants in 10 families, which were inoculated by the aphids, 13 leguminous species were found to be infected with the virus. All soybean varieties tested were susceptible, though they differed in their symptom expression. The aphid was able to acquire the virus by feeding on infected soybean plants for 30-60min, and viruliferous aphids reared on source plants could transmit the virus to healthy soybean seedlings during a period of 10-30min. The longer the periods of acquisition and inoculation feedings, the higher was the transmission rate. The minimum latent period in the aphid vector was between 15 and 27hr. In serial transmission tests, the aphids retained their infectivity through molting and for periods of up to 21 days, but most of them lost infectivity in the later transfers. Although the transmission pattern of SDV is quite similar to that of other circulative aphid-borne viruses, SDV differs from any previously described virus on the basis of host range, symptoms, and vector species.
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  • Keiichi TOMARU, Yoichi TAKANAMI, Akira UDAGAWA
    1970 Volume 36 Issue 4 Pages 275-282
    Published: September 30, 1970
    Released: April 03, 2009
    JOURNALS FREE ACCESS
    Isolates of tobacco rattle virus obtained from naturally infected tobacco plants in Japan were separated into two groups on the basis of their symptoms on aster plant, serological reaction and particle-length distribution. HSN group (HSN and IH isolates) gave systemic necrosis on aster plant, while MD-1 group (MD-1, TH, UD, CH-2, CH-3 and MH isolates) produced yellow rings and mottle. In serological tests, these two groups gave cross reactions. Differences were observed in agar geldiffusion tests and in titers in micro-droplet precipitin tests. Similarly, differences were also noted in particle-length distribution; HSN group gave a bimodal distribution with 180-190mμ and 70-80mμ particles, while MD-1 group was characterized by shorter particles having a length of 40-60mμ.
    Among Nicotiana spp. tested with the different isolates, no immune plant was observed, though there were differences in susceptibility of the different species and cultivars. Vinca rosea appeared to be a good reservoir host of the virus.
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  • Masaki YAMAMOTO
    1970 Volume 36 Issue 4 Pages 283-285
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The cell wall of midrib epidermis of potato leaves was labeled with the fluorescent dye, Calcofluor white M2, for 3 hours, and the zoospores of Phytophthora infestans were inoculated on the epidermis. After 3 and 18 hours, the fluorescence was observed under fluorescence microsope (Olympus HLS) with 320-400mμ U.V. through DV-1 and BG-12 filters. Just after labeling the cell wall with the dye, equally intense fluorescence was recognized around the healthy cell wail both in resistant and susceptible varieties. No fluorescence was observed on hypersensitive flecks in the resistant variety caused by the invasion of an incompatible race nor on susceptible lesions caused by the invasion of a compatible race of Phytophthora infestans. Sometimes, strong and clear fluorescence appeared in the cell wall around hypersensitive flecks in the resistant variety.
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  • Michio MASUKO, Hiroshi EGAWA, Akinori UEYAMA, Koichi KOSHIMIZU, Kin-ic ...
    1970 Volume 36 Issue 4 Pages 286-288
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • T.K. NARIANI, S.P. RAYCHAUDHURI
    1970 Volume 36 Issue 4 Pages 289-290
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
  • Kadzunori TATSUYAMA, Kazuo JIKIHARA
    1970 Volume 36 Issue 4 Pages 290-294
    Published: September 30, 1970
    Released: February 19, 2009
    JOURNALS FREE ACCESS
    The effects of herbicides on the growth of soi-lborne plant pathogens and on the occurrence of damping-off of cucumber seedlings inoculated with the causal fungi were studied.
    Among ten sorts of herbicides used, dinoseb, pentachlorophenol, linuron, and chloropropham inhibited the mycelial growth of Fusarium oxysporum, Rhizoctonia solani and Pythium aphanidermatum on culture medium, while 2, 4-D, MCPA, prometryne, and simazine seemed to promote the development of aerial hyphae of R. solani or P. aphanidermatum.
    The effect of antifungal herbicides among above-described on the occurrence of pre- or post-emergence damping-off in cucumber was examined. Pythium+dinoseb, Pythium+linuron, and Fusarium+dinoseb combinations resulted in the increase in healthy seedlings compared with Pythium or Fusarium alone. This is probably due to the antifungal effect of herbicides. Rhizoctonia+dinoseb, Rhizoctonia+linuron, Pythium+pentachlorophenol, and Rhizoctonia+pentachlorophenol combinations, however, resulted in an appreciable reduction in cucumber stand due to damping-off compared with Rhizoctonia or Pythium alone. At present, it is not clear whether the herbicides acted on the pathogens or on the host.
    It is possible that the herbicides affected the physiology of host plant, so that the susceptibility of emerging seedlings to the pathogens increased. The results may suggest the importance of secondary effects of herbicide.
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