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Volume 77 (2011)
- Issue 4 Pages 265-
- Issue 3 Pages 125-
- Issue 2 Pages 83-
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Volume 77, Issue 4
Displaying 1-6 of 6 articles from this issue
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Originals
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H. SAWADA, K. WATAUCHI, Y. KUNUGI2011 Volume 77 Issue 4 Pages 265-277
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSPolyphasic comparisons were carried out to characterize the pathogen of bacterial spot disease of grapevine (Xanthomonas arboricola) (Sawada et al., 2011) and that of bacterial spot diseases of stone fruits (X. arboricola pv. pruni) in detail. For that purpose, we isolated both pathogens in the area selected as a model, where the two diseases respectively occur annually in neighboring orchards, in Minami-Alps City, Yamanashi Prefecture in September 2010 to characterize them genotypically and phenotypically, to perform cross inoculation experiments, and to compare these results with those obtained from reference strains of X. arboricola pathovars. All strains of pv. pruni (1) are genetically highly uniform, (2) naturally infect peach, plum and apricot, (3) are highly virulent and stably pathogenic to peach, (4) do not naturally infect grapevine, and (5) are negative in the potato soft rot test. On the contrary, isolates causing bacterial spot disease of grapevine (1) are not genetically uniform and are scattered within the X. arboricola clade, interspersed with existing pathovars, in a gyrB phylogenetic analysis, (2) are weak, opportunistic pathogens, and only if the conditions are ideal, can they infect grapevine naturally, (3) do not naturally infect peach, plum or apricot, and (4) cause severe, rapid rot in the potato soft rot test. These results show that the latter pathogen should be regarded as a heterogeneous complex of genetically diverse, indigenous bacteria, although some phenotypes can be considered as common attributes. We concluded that it is inappropriate to propose a novel pathovar for the latter pathogen, until the pathovar of the genus Xanthomonas is further clarified and defined phenotypically and genotypically.
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Y. IWADATE, K. KATSUBE, S. HASE, T. NAMAI2011 Volume 77 Issue 4 Pages 278-286
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSBlack root rot of cucumber (Cucumis sativus) caused by Phomopsis sclerotioides is a serious greenhouse disease in many countries. Since 2001, the disease has been observed on outdoor-cultivated cucumber grafted on pumpkin rootstock in the Tohoku region of Japan, causing severe economic losses. We sought to establish control measures against black root rot of cucumber grafted on pumpkin rootstock caused by P. sclerotioides in outdoor culture in the Tohoku region of Japan. Soil fumigants chloropicrin (298.5 L a.i./ha), dazomet (294 kg a.i./ha), metham sodium (180 L a.i./ha), and fluazinam (15 kg a.i./ha) were evaluated for efficacy in naturally infested fields. Because it reduced sudden wilting, chloropicrin was selected for subsequent experiments to develop effective control. Partial fumigation (injection into polyethylene-mulched beds) gave adequate control, better than overall fumigation in fields. Partial fumigation significantly reduced sudden wilt incidence by 77% and 100% compared to untreated plots, and overall fumigation yielded 54% and 100% reduction in two experiments. For chloropicrin injection into polyethylene-mulched beds, a 90-cm width of the beds was better than the common practice of 60-cm width. Since the 90-cm width disinfested a wide area, we concluded that control was high (90-cm width significantly reduced sudden wilt incidence by 95% and 100% compared to untreated plots, and 60-cm width yielded 70% and 82% reduction in two experiments). However, these treatments did not completely control sudden wilt. Combining these treatments with the use of resistant rootstock C. ficifolia, which by itself suppressed disease from 56% to 100% in three experiments, reliably decreased the incidence of sudden wilt by 100% reduction in three experiments compared to the untreated plots. The efficacy of each control measure alone varied, so integrated methods are preferable.
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Short Communications
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K. TANINA, A. KAWAGUCHI2011 Volume 77 Issue 4 Pages 287-290
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSA method to isolate Clavibacter michiganensis subsp. michiganensis (Cmm) using ImmunoStripTMCmm (IS), a commercial strip to diagnose bacterial canker on tomato (Solanum lycopersicum) caused by Cmm, was developed. A distinct positive antigen-antibody reaction line developed for suspensions of Cmm over 2×105 cfu/ml. The Cmm-positive band on the IS was then cut from the strip, friction-ground in 0.1 ml sterilized distilled water, and a loopful of suspension was plated on potato semisynthetic agar for a fairly selective isolation of Cmm.
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Gilbertella stem rot of pitaya (Hylocereus undatus), a new disease caused by Gilbertella persicaria.S. TABA, M. NAKAZATO, K. NASU, T. TAKUSHI, Z. MOROMIZATO2011 Volume 77 Issue 4 Pages 291-294
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSAn unknown stem rot of pitaya (H. undatus; Cactaceae) was observed in orchards in Okinawa, Japan in 2005. A Gilbertella species was isolated from diseased stems, and typical symptoms were reproduced after inoculating wounded stems with isolates. The causal fungus was identified as G. persicaria (Eddy) Hesseltine on the basis of morphological characteristics, growth and germination temperature, and rDNA-ITS sequence homology. The name Gilbertella stem rot (Kukigusare byo) was proposed for this new disease.
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Y. IDE, T. NUNOKAWA, S. SHIMADA, K. NARAHARA, N. TASHIRO, F. KUCHIKI2011 Volume 77 Issue 4 Pages 295-298
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSHomogenization of plant tissue is an important process for various experiments with plants. Because the commonly used mortar and pestle is laborious and time-consuming, the Finger Masher, a new type of vessel made of flexible plastic with a rough interior surface, was developed by Mizuho-Medy Co. Ltd. for rapid, easy homogenizations. Hands become too fatigued, however, when many samples must be processed. Therefore, we developed an automatic macerating machine for the Finger Masher to handle many samples in a short time. ELISA values obtained for Apple stem grooving virus or Cucumber mosaic virus in plant samples extracted with the automatic macerating machine were similar to those obtained by conventional homogenization with a mortar and pestle. The time for sample preparation was also much shorter than for other methods.
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M. YAMAZAKI, H. MATSUOKA, K. YANO, Y. MORITA, S. UEMATSU, S. TAKEUCHI, ...2011 Volume 77 Issue 4 Pages 299-303
Published: 2011
Released on J-STAGE: December 09, 2011
JOURNAL FREE ACCESSIn 1997, Phytophthora rot caused serious losses to ginger (Zingiber officinale Rosc.) production in Kochi Prefecture, Japan. In the field in early summer and autumn, water-soaked rot on basal pseudostems and brown rot on rhizomes were first observed, then plants developed stem blight. The disease also developed on rhizomes stored at 15°C in the dark. A Phytophthora sp. was consistently isolated from the symptomatic lesions and caused the same symptoms after inoculation with the isolates. The identical Phytophthora sp. was then reisolated. White stellate colonies grew on PDA at a minimum temperature of 10°C, optimum of 23°C and maximum of 30°C. Sporangia were ovoid, ellipsoid, globose and distorted (variable) with one or two apices, noncaducous, 30–90 × 20–50 (average 50.0–56.1 × 25.0–32.6) μm, with a length to breadth ratio of 1.5–1.7:1. Nucleotide sequence of the r-DNA ITS regions agreed well with those of Phytophthora citrophthora (R. E. Smith and E. H. Smith) Leonian previously reported. Based on these results, the isolate was identified as P. citrophthora. This report is the first of a disease of ginger caused by P. citrophthora, and we propose the name “Phytophthora rot” for the disease.View full abstractDownload PDF (787K)
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