Infection of different plant parts of soybean seedlings by southern Diaporthe phaseolorum and its role in the development of stem canker symptoms

1987 ◽  
Vol 65 (10) ◽  
pp. 2104-2108 ◽  
Author(s):  
R. C. Ploetz ◽  
F. M. Shokes
Keyword(s):  
Southeastern United States ◽  
Stem Canker ◽  
Relative Importance ◽  
Symptom Development ◽  
Canker Disease ◽  
Soybean Seedlings ◽  
Plant Parts ◽  
Diaporthe Phaseolorum ◽  
Leaf Infection ◽  
Positive Correlations

Leaves, petioles, petiole bases, and stems of 'Hutton' soybean seedlings (V5-V6) were inoculated with ascospores and α-conidia of southern Diaporthe phaseolorum to determine the relative importance of these plant parts as infection sites. This objective was accomplished in two experiments either by removing certain plant parts after inoculation and incubation for infection (48 h) or by protecting plant parts from infection during inoculation and incubation of plants. In both cases, plant parts were assayed for infection 48 h after inoculation and after plants had reached the R3 growth stage (66 and 56 days after inoculation for experiments 1 and 2, respectively); symptom development was rated at the end of each experiment. Significant, positive correlations were detected between the incidence and severity of symptoms and the infection of either stems 48 h after inoculation (P < 0.01 and 0.05, respectively) or petiole bases at the end of the experiments (P < 0.001 and 0.01, respectively). Development of symptoms was not significantly correlated (P ≥ 0.05) with infection of petioles, petiole bases, or leaves 48 h after inoculation. These results suggest an important and causal role for infection of petiole bases and stems in the development of the symptoms of this disease. Leaf infection appears to be unimportant in the stem canker disease cycle in the southeastern United States.

scholarly journals Histopathology of Macrophomina Stem Canker Disease in Pigeonpea (Cajanus cajan L.)

2013 ◽  
Vol 2 (3) ◽  
pp. 187-192
Author(s):  
Sandeep K. Maurya ◽  
Surinder Kaur ◽  
Vijay B. Chauhan
Keyword(s):  
Trypan Blue ◽  
Infected Plant ◽  
Stem Canker ◽  
Macrophomina Phaseolina ◽  
Post Inoculation ◽  
Canker Disease ◽  
Plant Parts ◽  
Entire Plant ◽  
Serious Disease ◽  
Growth Of Seedlings

Macrophomina phaseolina, causal agent of stem canker disease has recently emerged as an agriculturally important plant pathogen. Macrophomina stem canker disease (MSD), caused by Macrophomina phaseolina is a potentially serious disease in pigeonpea that occurs when reaches physiological maturity i.e., during flowering. The fungus incites necrotic lesions on stem and girdles the plant at the base leading to premature flower drop leading to complete witling and finally death of the entire plant. The mechanisms of infection remain to be fully elucidated. The present study investigated histopathology of MSD caused by M. phaseolina in pigeonpea seed and seedlings using light microscopy. Pigeonpea variety ‘Bahar’ was used in this study. Histopathological sections of seed, stem, root, and leaves were prepared and stained with safranin and trypan blue. Histopathology of the infected plant parts showed the presence of intercellular mycelia and microsclerotia in the cortex and vascular tissues. The germ tube colonized the plant with growth of seedlings following seed coat, cotyledon, stem, root and leaves. According to the results, the pathogen can penetrate and invade the seeds within 24 h post inoculation.

A method for screening soybean seedlings for resistance to northern stem canker caused by Diaporthe phaseolorum var. caulivora

2007 ◽  
Vol 87 (2) ◽  
pp. 443-447 ◽  
Author(s):  
K. Thickett ◽  
J. VanDerWal ◽  
L. Lovett-Doust ◽  
T. R. Anderson
Keyword(s):  
Screening Method ◽  
Stem Canker ◽  
Susceptible Variety ◽  
Lesion Length ◽  
Resistance Screening ◽  
Soybean Seedlings ◽  
Diaporthe Phaseolorum ◽  
The Mean ◽  
Canker Development ◽  
Cut Surface

Five soybean varieties, Williams, Harosoy, AC Hime, Coles and Leo were inoculated 2 and 4 wk after planting with Diaporthe phaseolorum var. caulivora to determine if differences in resistance to stem canker could be detected in the early stages of plant development. Seedling stems were severed above the unifoliolate leaves and inoculum was applied to the cut surface. Stem lesion lengths were measured at 1, 2 and 3 wk following inoculation. The mean lesion length on seedlings inoculated 2 wk after planting (27.2 mm) was significantly less than seedlings inoculated 4 wk after planting (44.5 mm). Based on mean lesion length, Williams was the most susceptible variety followed by Harosoy. AC Hime, Coles and Leo were equally resistant. Stem canker development measured at 2 and 3 wk following inoculation was negatively correlated with stem moisture at the time of inoculation suggesting that stem moisture is important in the development and severity of stem canker. Key words: Diaporthe phaseolorum var. caulivora, Glycine max, inoculation method, northern stem canker, resistance, screening method

Evidence for homothallism and vegetative compatibility in southern Diaporthe phaseolorum

1986 ◽  
Vol 64 (10) ◽  
pp. 2197-2200 ◽  
Author(s):  
R. C. Ploetz ◽  
F. M. Shokes
Keyword(s):  
Southeastern United States ◽  
Lima Bean ◽  
Stem Canker ◽  
Potato Dextrose Agar ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Diaporthe Phaseolorum ◽  
Compatibility Group ◽  
Cornmeal Agar ◽  
Group 1

Twenty-nine vegetative compatibility groups (vcgs) were identified among 297 isolates of the fungus causing soybean stem canker in the southeastern United States (southern Diaporthe phaseolorum). Of the isolates characterized, 79% were from one of the vcgs described (group 1). Barrage zones formed between isolates from different vcgs when grown on potato dextrose agar, and also formed, but not always distinctly, on cornmeal agar, Czapek-Dox agar, lima bean agar, and malt agar; barrages did not form on Sach's agar or water agar. Two types of evidence suggested that southern D. phaseolorum is homothallic. Perithecia and viable ascospores were produced by single ascospore isolates, and ascospores produced by mass isolates were always of the same compatibility group as the parental mass isolate.

scholarly journals First Report of Soybean Stem Canker Caused by Diaporthe phaseolorum var. caulivora in Argentina

Plant Disease ◽  
2001 ◽  
Vol 85 (1) ◽  
pp. 95-95 ◽  
Author(s):  
R. N. Pioli ◽  
E. N. Morandi ◽  
V. Bisaro
Keyword(s):  
Disease Incidence ◽  
Low Frequency ◽  
Principal Component ◽  
Stem Canker ◽  
Morphological Characters ◽  
Santa Fe ◽  
First Report ◽  
Soybean Seedlings ◽  
Diaporthe Phaseolorum ◽  
Soybean Plants

A soybean stem canker (SSC) outbreak caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández was reported in Santa Fe, Argentina, in 1997 (3). In 1999 an isolate, which was morphologically distinct from D. phaseolorum var. meridionalis, was obtained from stems of field-grown soybean plants exhibiting SSC symptoms, at Oliveros, Santa Fe, Argentina (Lat. 32° 33′S, Lon. 60° 51′W). Disease incidence was 76% in the field where samples were collected. The pathogen was isolated in darkness at 25°C on potatoglucose agar acidified with 0.2% lactic acid (3). The isolate produced white colonies with compact and tufted mycelium that changed to yellow and light tan with age. Stromata and pycnidia were not produced. After 35 days in culture, clustered perithecia were frequently observed on stem segments. Fifty asci, five from each of 10 perithecia, and bicellular, biguttulated ascospores were measured. Ascus mean length was 26.9 ± 2.5 μm and width was 5.3 ± 0.5 μm; ascospore mean length was 8.3 ± 0.6 μm and width was 2.6 ± 0.1μm. Based on these features, the new isolate was classified as D. phaseolorum var. caulivora Athou & Caldwell (1). To further compare the new isolate with previous identified ones, a principal component analysis (PCA, SAS Systems) was performed using seven isolates of D. phaseolorum var. meridionalis, three isolates of D. phaseolorum var. sojae, and two isolates of Phomopsis longicolla. Seventeen morphological characters, all related with the color and texture of the colonies, the presence and shape of the pycnidia and conidia, the presence and type of stromata and perithecia, and the length of the asci, were compared. According to the PCA analysis, the principal characters that discriminated SSC producing isolates (D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora) from non-SSC producing ones (D. phaseolorum var. sojae and P. longicolla) were the development of perithecia (r = 0.98) and low frequency stromata (r = 0.98) in D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora isolates. The principal components that discriminated SSC producing isolates were the more compact and tufted aspect of the mycelia (r = 0.95) and the shorter length of the asci (r = 0.83) in D. phaseolorum var. caulivora compared with D. phaseolorum var. meridionalis. Pathogenicity trials were performed under greenhouse conditions by inoculating D. phaseolorum var. caulivora mycelia in hypocotyls of soybean seedlings by the toothpick method (2). Typical SSC symptoms were observed on susceptible plants and the pathogen was re-isolated and identified from stem portions of the first internode above the inoculation point. Pathogenicity trials were repeated twice with similar results. This is the first report of D. phaseolorum var. caulivora in Argentina and, as far as we know, in all of South America. References: (1) F. A. Fernández et al. 1999. Stem canker. Pages 32–35 in: Compendium of Soybean Diseases, 4th ed. APS Press, St. Paul, MN. (2) B. L. Keeling. Phytopathology 72:807–809, 1982. (3) R. N. Pioli et al. Plant Dis. 81:1215, 1997.

scholarly journals First Report of Diaporthe phaseolorum var. meridionalis on Soybean Seeds from Ghana

Plant Disease ◽  
1998 ◽  
Vol 82 (12) ◽  
pp. 1401-1401 ◽  
Author(s):  
S. N. A. Asante ◽  
H. Wolffhechel ◽  
E. de Neergaard
Keyword(s):  
African Country ◽  
Stem Canker ◽  
Potato Dextrose Agar ◽  
Soybean Seeds ◽  
Ecological Zones ◽  
Soybean Seedlings ◽  
Diaporthe Phaseolorum ◽  
Light Darkness ◽  
Blotter Paper ◽  
Agro Ecological Zones

Fifty-nine soybean samples (Glycine max) of various varieties, grown in various agro-ecological zones of Ghana, and harvested in 1995 and 1996, were collected during May through June 1996 and sent to Denmark for analysis. Seed samples were analyzed by the blotter method: seeds were placed on three layers of moistened blotter paper in petri dishes, 10 seeds per dish, 200 or 400 seeds per sample. The seeds were incubated for 7 days at 22 ± 2°C, exposed to alternating cycles of 12 h NUV-light and 12 h darkness. Subsequently, they were analyzed microscopically for fungal infection. Phomopsis spp. were detected in 68% of the samples, at infection levels ranging from 0.25 to 21.0% (mean 3.4%). One to five isolates of Phomopsis spp. were selected at random and cultured on potato dextrose agar acidified to pH 4.5 with 90% lactic acid (APDA) for identification to species. Isolates were cultured on APDA, with and without sterile soybean stem pieces, under either NUV-light/darkness or artificial daylight/darkness cycles. Of 103 isolates, 101 isolates produced only pycnidia and were identified as P. longicolla T. W. Hobbs based on the production of aggregated pycnidia with prominent beaks (2). Seventy-seven of these isolates produced only alpha conidia whereas 24 isolates produced both alpha and beta conidia, which differs from the description by Hobbs et al. (2). Two isolates from one seed sample produced perithecia but no pycnidia. Perithecia were evenly scattered in the colony, 200 to 350 × 250 to 400 μm, and had a beak of 900 to 1500 μm. Apical beak width was 60 to 110 μm, basal beak width 70 to 120 μm. Asci were 25.0 to 37.5 × 5.0 to 7.5 μm. Ascospores were two-celled, biguttulate in each cell, and 10.0 to 12.5 × 2.5 to 4.0 μm. Based on the description by Fernández and Hanlin (1), these isolates were identified as Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández (DPM), the causal agent of southern stem canker of soybean, which has not previously been reported from any African country. Ten 14-day-old soybean seedlings were inoculated with an isolate identified as DPM by the toothpick method (3) and two seedlings inoculated with sterile toothpicks served as controls. Local expanding lesions formed after 1 week on all plants at the point of inoculation with DPM; 2 weeks after inoculation, the pathogen was reisolated from all lesions by plating stem pieces, surface sterilized in 1% NaOCl, on APDA. In control plants no lesions were seen and no mycelial growth occurred from stem pieces plated on APDA. References: (1) F. A. Fernández and R. T. Hanlin. Mycologia 88:425, 1996. (2) T. W. Hobbs et al. Mycologia 77:535, 1985. (3) B. L. Keeling. Phytopathology 72:807, 1982.

Variability among isolates of Diaporthe phaseolorum f.sp. meridionalis in different vegetative compatibility groups

1989 ◽  
Vol 67 (9) ◽  
pp. 2751-2755 ◽  
Author(s):  
R. C. Ploetz ◽  
F. M. Shores
Keyword(s):  
Growth Rates ◽  
Southeastern United States ◽  
Stem Canker ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Future Studies ◽  
Diaporthe Phaseolorum ◽  
Soybean Genotypes ◽  
Compatibility Group

Members of 1 of 29 previously described vegetative compatibility groups of Diaporthe phaseolorum f.sp. meridionalis (causal agent of soybean stem canker in the southeastern United States) predominated in epidemic populations from Alabama, Georgia, Florida, and Tennessee. Factors that might explain the prevalence of vegetative compatibility group (VCG) 1 were examined in studies with members of this and other VCGs of the pathogen. The virulence of isolates within six different VCGs on eight different soybean genotypes was similar, and variation among VCGs supported previous reports of diverse virulence in Diaporthe phaseolorum f.sp. meridionalis. Isolates within different VCGs also had similar in vitro growth rates and sensitivities to fungicides used either for controlling diseases of soybean in the Southeast (benomyl) or as an ingredient in a medium that is used to selectively isolate the pathogen (triadimefon). Since members of VCG 1 did not possess exceptional virulence, growth rates, or insensitivities to benomyl or triadimefon, the prevalence of VCG 1 could not be explained by these factors. However, relating these and other characteristics of Diaporthe phaseolorum f.sp. meridionalis to a biologically significant characteristic such as vegetative compatibility would provide a logical framework by which isolates and populations of the pathogen could be evaluated in future studies.

scholarly journals First Report of Stem Canker Disease of Pitaya (Hylocereus undatus and H. polyrhizus) Caused by Neoscytalidium dimidiatum in Taiwan

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 906-906 ◽  
Author(s):  
M. F. Chuang ◽  
H. F. Ni ◽  
H. R. Yang ◽  
S. L. Shu ◽  
S. Y. Lai ◽  
...  
Keyword(s):  
New York ◽  
Aerial Mycelium ◽  
Its Region ◽  
Stem Canker ◽  
Canker Disease ◽  
First Report ◽  
Neoscytalidium Dimidiatum ◽  
Succulent Plant ◽  
Sterile Medium ◽  
Hylocereus Undatus

Pitaya (Hylocereus undatus and H. polyrhizus Britt. & Rose), a perennial succulent plant grown in the tropics, is becoming an emerging and important fruit plant in Taiwan. In September of 2009 and 2010, a number of pitaya plants were found to have a distinctive canker on stems. The disease expanded quickly to most commercial planting areas in Taiwan (e.g., Pintung, Chiayi, and Chunghua). Symptoms on the stem were small, circular, sunken, orange spots that developed into cankers. Pycnidia were erumpent from the surface of the cankers and the stems subsequently rotted. After surface disinfestation with 0.1% sodium hypochloride, tissues adjacent to cankers were placed on acidified potato dextrose agar (PDA) and incubated at room temperature for 1 week, after which colonies with dark gray-to-black aerial mycelium grew. Hyphae were branched, septate, and brown and disarticulated into 0- to 1-septate arthrospores. Sporulation was induced by culturing on sterile horsetail tree (Casuarina equisetifolia) leaves. Conidia (12.79 ± 0.72 × 5.14 ± 0.30 μm) from pycnidia were one-celled, hyaline, and ovate. The internal transcribed spacer (ITS) region of ribosomal DNA was PCR amplified with primers ITS1 and ITS4 (2) and sequenced. The sequence (GenBank Accession No. HQ439174) showed 99% identity to Neoscytalidium dimidiatum (Penz.) Crous & Slippers (GenBank Accession No. GQ330903). On the basis of morphology and nucleotide-sequence identity, the isolates were identified as N. dimidiatum (1). Pathogenicity tests were conducted in two replicates by inoculating six surface-sterilized detached stems of pitaya with either mycelium or conidia. Mycelial plugs from 2-day-old cultures (incubated at 25°C under near UV) were inoculated to the detached stems after wounding with a sterile needle. Conidial suspensions (103 conidia/ml in 200 μl) were inoculated to nonwounded stems. Noninoculated controls were treated with sterile medium or water. Stems were then incubated in a plastic box at 100% relative humidity and darkness at 30°C for 2 days. The symptoms described above were observed on inoculated stems at 6 to 14 days postinoculation, whereas control stems did not develop any symptoms. N. dimidiatum was reisolated from symptomatic tissues. To our knowledge, this is the first report of N. dimidiatum causing stem canker of pitaya. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

Teratosphaeria stem canker disease on Eucalypt in Italy

2018 ◽  
Vol 153 (2) ◽  
pp. 503-515
Author(s):  
Salvatore Vitale ◽  
Laura Luongo ◽  
Etienne G. J. Danchin ◽  
Giovanni Mughini ◽  
Maria Gras ◽  
...  
Keyword(s):  
Stem Canker ◽  
Canker Disease
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