Comparative studies on myceliogenic germination of tan sclerotia of Sclerotinia sclerotiorum and Sclerotium rolfsii

1989 ◽  
Vol 67 (5) ◽  
pp. 1395-1401 ◽  
Author(s):  
H. C. Huang ◽  
S. K. Sun
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Room Temperature ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Time Lapse ◽  
Potato Dextrose Agar ◽  
Damping Off ◽  
Seed Rot ◽  
Myceliogenic Germination ◽  
Exogenous Nutrients

Tan-colored sclerotia of Sclerotium rolfsii and of an aberrant strain of Sclerotinia sclerotiorum that were freshly harvested from 5-week-old cultures on potato dextrose agar or stored at room temperature in paper bags for 4 weeks germinated myceliogenically on moist field soil without exogenous nutrients. A comparative study by time-lapse photomicroscopy revealed similarity in the mode of myceliogenic germination of sclerotia of the two species. The germination appeared to be of the hyphal type in both species and was characterized by the emergence of individual hyphae through the rind. There was no evidence of eruptive type of germination in any of the strains tested. Although several hyphae often emerged through the same spot of the rind, these hyphae emerged singly, and the time-lapse photomicrographs showed no evidence of eruptive germination. While most of the germinated sclerotia of S. rolfsii developed into colonies within 4 days of incubation on moist soil, the development of colonies from germinating sclerotia of S. sclerotiorum appeared to be slow, taking up to 28 days. Results of the inoculation studies showed that mycelia from the germinated sclerotia of S. rolfsii were able to infect and cause seed rot and damping-off of canola and alfalfa, which were planted near the soil surface at a distance of at least 15 mm from the sclerotium, without providing exogenous nutrients.

scholarly journals First Report of Sclerotium rolfsii on Sunflower in Italy

Plant Disease ◽  
1997 ◽  
Vol 81 (8) ◽  
pp. 960-960 ◽  
Author(s):  
A. Infantino ◽  
G. Di Giambattista ◽  
S. Socciarelli
Keyword(s):  
Crop Rotation ◽  
Room Temperature ◽  
Peat Soil ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Potato Dextrose Agar ◽  
Soil Mixture ◽  
First Report ◽  
Rainy Period ◽  
Stem Segments

During June 1996, 1-month-old sunflower plants (Helianthus annuus. L.) of the cvs. Blue Mix and Romsun × 590, grown at the experimental farm of the Istituto Sperimentale per la Nutrizione delle Piante (Montelibretti, Rome), showed symptoms of wilting, and then gradually dried out. Discolored areas were observed on the crown, where whitish, fan-shaped mycelia were occasionally present. A fungus was isolated on potato dextrose agar from surface-disinfested, diseased stem fragments. It also developed from diseased stem segments incubated in moist chambers. In both cases, round sclerotia developed after 9 days at room temperature. The fungus was identified as Sclerotium rolfsii Sacc. The fungus has been deposited in the ISPaVe collection (no. ER 883). To test pathogenicity, 20-day-old sunflower seedlings of the cvs. Blue Mix and Romsun × 590 were grown singly in an autoclaved peat/soil mixture in 20-cm-diameter plastic pots in a greenhouse at 30 ± 3°C. Plants were inoculated by placing five sclerotia of isolate ER 883 near the crown of each plant about 5 mm below the soil surface. For each cultivar, 10 plants were inoculated and 10 were left uninoculated. Wilting symptoms and stem discoloration appeared after 12 days. Sclerotia were produced at the stem base of some inoculated plants. All inoculated plants died after 20 days. S. rolfsii was consistently reisolated from all the inoculated plants, while no symptoms or signs were observed on the uninoculated plants. This is the first report of S. rolfsii on sunflower in Italy and has important implications for the use of sunflower in crop rotation. An unusual rainy period delayed planting of sunflowers by 1 month in 1996 and this could have favored the disease.

Effect of temperature during sclerotial formation, sclerotial dryness, and relative humidity on myceliogenic germination of sclerotia of Sclerotinia sclerotiorum

1998 ◽  
Vol 76 (3) ◽  
pp. 494-499 ◽  
Author(s):  
H C Huang ◽  
C Chang ◽  
G C Kozub
Keyword(s):  
Relative Humidity ◽  
Sclerotinia Sclerotiorum ◽  
Hyphal Growth ◽  
Effect Of Temperature ◽  
Limited Growth ◽  
Moist Sand ◽  
Sclerotial Formation ◽  
Seed Rot ◽  
Myceliogenic Germination ◽  
Exogenous Nutrients

A study was conducted to determine the effect of sclerotial dryness, temperature during sclerotia formation, and relative humiditiy during incubation on myceliogenic germination of sclerotia of two isolates of Sclerotinia sclerotiorum (Lib.) De Bary. In the absence of exogenous nutrients, sclerotia germinated more readily at 100% RH than at 95% RH or lower. Desiccation of sclerotia is an important factor affecting myceliogenic germination and hyphal growth. At high humidity, either in an atmosphere with 100% RH or on moist sand, desiccant-dried sclerotia germinated readily and produced vigorous hyphal growth that often developed into colonies. On the other hand, fresh, untreated sclerotia germinated less readily and produced limited growth of hyphae that rarely developed into colonies. There was generally no effect of temperature at which sclerotia formed on germination. The incidence of seed rot and seedling wilt of sunflower was significantly (p < 0.05) higher when desiccant-dried sclerotia were used as inoculum rather than fresh sclerotia.Key words: Sclerotinia sclerotionum, sclerotia, myceliogenic germination, sclerotinia wilt of sunflower, relative humidity.

scholarly journals First Report of Sclerotium rolfsii on Jerusalem Cherry (Solanum pseudocapsicum) in Europe

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 1048-1048
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
The United States ◽  
Northern Italy ◽  
Ornamental Plant ◽  
Potato Dextrose Agar ◽  
First Report ◽  
Initial Symptoms ◽  
Stem Necrosis

Jerusalem cherry (Solanum pseudocapsicum) has recently become popular as a potted ornamental plant in Italy. During the summer of 1999, a sudden wilt of 60-day-old plants was observed in the Albenga region (Northern Italy), an area of intensive floriculture. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Necrotic tissues were covered with whitish mycelium that differentiated into reddish brown, spherical (1 to 2 mm diameter) sclerotia. Sclerotium rolfsii was consistently recovered from the surface of symptomatic stem sections that were disinfected for 1 min in 1% NaOCl and then plated on potato-dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Pathogenicity of three S. rolfsii isolates was confirmed by inoculating 90-day-old S. pseudocapsicum plants grown in pots. Inoculum consisted of mycelium and sclerotia of the pathogen placed on the soil surface around the base of each plant. Noninoculated plants served as controls. All plants were kept in a growth chamber at 18 to 28°C and RH > 85%. Inoculated plants developed symptoms within 7 days, while control plants remained symptomless. Sclerotia developed on infected tissues and S. rolfsii was reisolated from symptomatic tissues. The disease has been observed in the United States (1), but this is the first report of stem blight of S. pseudocapsicum caused by S. rolfsii in Europe. Reference: (1) S. A. Alfieri, Jr., K. R. Langdon, C. Wehlburg, and J. W. Kimbrough, J. W. Index Plant Dis. Florida Bull. 11:215, 1984.

scholarly journals Stem Blight of Eustoma grandiflorum Caused by Sclerotium rolfsii

Plant Disease ◽  
2000 ◽  
Vol 84 (4) ◽  
pp. 490-490 ◽  
Author(s):  
R. J. McGovern ◽  
H. Bouzar ◽  
B. K. Harbaugh
Keyword(s):  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Potato Dextrose Agar ◽  
Eustoma Grandiflorum ◽  
Disease Symptoms ◽  
Central Florida ◽  
Stem Blight ◽  
Symptomatic Tissue ◽  
Stem Necrosis ◽  
Maximum Temperatures

During a 4-week period in May through June 1996, 15% of 50 mature lisianthus (Eustoma grandiflorum) ‘Maurine Blue’ and ‘Maurine White’ plants exhibited stem blight in a landscape planting in west-central Florida. Initial disease symptoms included stem necrosis at the soil line, and yellowing and tan discoloration of leaves. As blighting of the stem progressed, infected plants wilted and died. Symptomatic stem sections from three plants were surface-disinfested in 0.5% NaOCl and placed on acidified 25% potato dextrose agar (APDA). Sclerotium rolfsii Sacc. was isolated from all three diseased stems. Pathogenicity of each of three S. rolfsii isolates was confirmed using two lisianthus ‘Flamenco Blue’ plants grown in 10.2-cm-diameter plastic pots containing a peat-based medium. Sclerotia produced on APDA were sprinkled on the soil surface around each plant base; 50, 100, and 5 sclerotia from isolates A, B, and C, respectively, were used (isolate C grew more slowly and produced fewer sclerotia than either A or B). Two noninoculated lisianthus served as controls. Plants were maintained in a greenhouse at minimum and maximum temperatures of ≈24 and 35°C, respectively. Plants inoculated with sclerotia from isolates A and B developed blight symptoms within 6 days. One of two plants inoculated with isolate C developed blight symptoms within 17 days, and the other remained symptomless, as did the control plants. Infection by S. rolfsii was confirmed by reisolation from symptomatic tissue. This is the first report of stem blight of lisianthus caused by S. rolfsii.

Effect of temperature on melanization and myceliogenic germination of sclerotia of Sclerotinia sclerotiorum

1989 ◽  
Vol 67 (5) ◽  
pp. 1387-1394 ◽  
Author(s):  
H. C. Huang ◽  
E. G. Kokko
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Cell Walls ◽  
Potato Dextrose Agar ◽  
Effect Of Temperature ◽  
Brown Pigment ◽  
Normal Strain ◽  
Color Intensity ◽  
Electron Dense Material ◽  
Moist Sand ◽  
Myceliogenic Germination

While sclerotia of the normal strain of Sclerotinia sclerotiorum produced on potato-dextrose agar at 7, 16, and 30 °C were black, the color of sclerotia of the aberrant strain was light brown, brown or tan, and dark brown or greyish black under 7, 16, and 30 °C, respectively. In the normal strain, deposition of melanin substance was heavy both on the surface and inside the cell walls of the rind of black sclerotia formed at 16 and 30 °C, but in sclerotia formed at 7 °C, many of the rind cells were unmelanized or partially melanized. In sclerotia from the aberrant strain, an electron-dense material, smaller than the melanin particles of the black sclerotia, was present in trace amounts or absent in light-brown sclerotia formed at 7 °C, but it was more abundant in dark-brown or greyish black sclerotia formed at 30 °C. Despite marked differences in color, sclerotia of the aberrant strain produced at the three temperatures were capable of undergoing myceliogenic germination on moist sand. It is concluded that temperature affects cell wall melanization during sclerotial morphogenesis, and that myceliogenic germination of sclerotia of S. sclerotiorum was affected by the black pigment but was unaffected by the color intensity of the brown pigment.

scholarly journals First Report of Damping-off Caused by Alternaria japonica on Chinese Cabbage Seedlings in China

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1378-1378 ◽  
Author(s):  
X. X. Ren ◽  
G. Z. Zhang ◽  
W. A. Dai
Keyword(s):  
Chinese Cabbage ◽  
Brassica Campestris ◽  
Morphological Characteristics ◽  
Soil Surface ◽  
Potato Dextrose Agar ◽  
Universal Primers ◽  
Damping Off ◽  
First Report ◽  
Tibet Autonomous Region ◽  
The Tibet Autonomous Region

In May 2011, samples of Chinese cabbage (Brassica campestris L. subsp. chinensis Markino) seedlings at the two-to four-leaf stage with damping-off symptoms were collected from greenhouses in the Tibet Autonomous Region of China. Infected stems of the seedlings were constricted at or near the soil surface. On diseased stems, a light to dark brown coloration was demarcated from healthy tissue. Damping-off and death of seedlings occurred as the lesions enlarged, resulting in a significant reduction of seedlings. Diseased stems were cut into 3-mm-long segments, surface-sterilized with 3.5% sodium hypochlorite for 1 min, and rinsed in sterilized water three times before being placed on water agar. A fungus frequently isolated from diseased plants was hyphal tipped under a dissecting microscope and transferred onto potato dextrose agar (PDA) to obtain a pure culture. The isolate grew slowly on PDA at 25°C with a 12-h photoperiod. The colony was white at first and gradually turned gray or grayish-green. No conidia or chlamydospores developed. However, conidia were produced on potato-carrot agar. Conidia were yellow-brown, obpyriform or obpyriform with beaks, had two to eight transverse septa, one to three vertical or oblique septa, and were produced solitarily or often in chains of two or three and measured 43.5 to 85.2 × 21.5 to 28.0 μm. A few conidia without beaks were also present and were nearly round and slightly smaller than the conidia with beaks. Several adjacent chlamydospores with thickened walls were often intercalary. The isolate was tentatively identified as Alternaria japonica based on its morphological characteristics (1,2). For molecular analyses, the internal transcribed spacer (ITS) regions of ribosomal DNA from the isolate were amplified with universal primers ITS1 and ITS4. The resulting sequence (Accession No. JN654465) submitted to GenBank had a 99% identity to that of A. japonica (Accession No. AY154703.1) isolated from leaves of Raphanus sativus. To confirm the pathogenicity of A. japonica, nine healthy 10-day-old Chinese cabbage seedlings were inoculated at the stem base with one PDA plug from a 6-day-old culture, with nine noninoculated (PDA plus only) seedlings serving as controls. Two days after inoculation, symptoms similar to those on the naturally infected plants developed on the inoculated seedlings. No symptoms developed on the controls. The pathogen was reisolated from the stems of inoculated and diseased seedlings. To our knowledge, this is the first report of A. japonica leading to damping off on Chinese cabbage seedlings in China. References: (1) M. P. Corlett and M. E. Corlett. Can. J. Plant Pathol. 21:298, 1999. (2) T. Y. Zhang. Flora Fungorum Sinicorum: Alternaria (in Chinese) Vol. 16. Science Press, Beijing, 2003.

scholarly journals First Report of Petiole Rot of Pulmonaria longifolia Caused by Sclerotium rolfsii var. delphinii

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 313-313 ◽  
Author(s):  
B. A. Edmunds ◽  
M. L. Gleason
Keyword(s):  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Potato Dextrose Agar ◽  
Pathogenicity Test ◽  
First Report ◽  
Plastic Bags ◽  
Affected Tissue ◽  
Pathogenicity Tests ◽  
The Media ◽  
Herbaceous Perennial

Sclerotium rolfsii var. delphinii was isolated from the bases of discolored petioles on wilted, yellow leaves of Pulmonaria longifolia (cultivar unknown), an herbaceous perennial growing in a landscape planting in Ames, IA. White mycelia and brick red, 2- to 3-mm-diameter sclerotia were found on affected tissue and nearby soil. The isolates were identified as S. rolfsii var. delphinii based on the formation of dark red, irregularly shaped, >2.0-mm-diameter sclerotia on potato dextrose agar (PDA) around the edge of the culture (1,2). Pathogenicity tests were conducted by inoculating 5-month-old P. longifolia cv. E. B. Anderson growing in 20-cm-diameter pots in a greenhouse at 25 to 30°C. Inoculum was produced by transferring plugs from a 1-week-old culture of the S. rolfsii var. delphinii isolate on PDA to autoclaved carrot disks. After 2 days of incubation, a mycelium-infested carrot disk was placed on the soil surface at the base of each plant. Six plants were inoculated and six plants served as uninoculated controls. All plants were enclosed in plastic bags to maintain high humidity. The pathogenicity test was repeated once. All inoculated plants developed characteristic symptoms within 10 days, whereas all control plants remained symptomless. Sclerotia developed on infected tissue and the media surface, and S. rolfsii var. delphinii was reisolated on PDA from symptomatic petioles. To our knowledge, this is the first report of petiole rot of P. longifolia caused by S. rolfsii var. delphinii. References: (1) Z. K. Punja. Annu. Rev. Phytopathol. 23:97, 1985. (2) Z. K. Punja and A. Damiani. Mycologia 88(5):694, 1996.

scholarly journals Application of Bio-Friendly Formulations of Chitinase-Producing Streptomyces cellulosae Actino 48 for Controlling Peanut Soil-Borne Diseases Caused by Sclerotium rolfsii

2021 ◽  
Vol 7 (3) ◽  
pp. 167
Author(s):  
Gaber Abo-Zaid ◽  
Ahmed Abdelkhalek ◽  
Saleh Matar ◽  
Mai Darwish ◽  
Muhammad Abdel-Gayed
Keyword(s):  
Open Field ◽  
Biocontrol Agent ◽  
Sclerotium Rolfsii ◽  
Dry Weight ◽  
Culture Broth ◽  
Field Conditions ◽  
Damping Off ◽  
Mycelium Growth ◽  
Particle Size Analyzer ◽  
Cell Pellet

Of ten actinobacterial isolates, Streptomyces cellulosae Actino 48 exhibited the strongest suppression of Sclerotium rolfsii mycelium growth and the highest chitinase enzyme production (49.2 U L−1 min−1). The interaction between Actino 48 and S. rolfsii was studied by scanning electron microscope (SEM), which revealed many abnormalities, malformations, and injuries of the hypha, with large loss of S. rolfsii mycelia density and mass. Three talc-based formulations with culture broth, cell-free supernatant, and cell pellet suspension of chitinase-producing Actino 48 were characterized using SEM, Fourier transform infrared spectroscopy (FTIR), and a particle size analyzer. All formulations were evaluated as biocontrol agents for reducing damping-off, root rot, and pods rot diseases of peanut caused by S. rolfsii under greenhouse and open-field conditions. The talc-based culture broth formulation was the most effective soil treatment, which decreased the percentage of peanut diseases under greenhouse and open-field conditions during two successive seasons. The culture broth formulation showed the highest increase in the dry weight of peanut shoots, root systems, and yielded pods. The transcriptional levels of three defense-related genes (PR-1, PR-3, and POD) were elevated in the culture broth formulation treatment compared with other formulations. Subsequently, the bio-friendly talc-based culture broth formulation of chitinase-producing Actino 48 could potentially be used as a biocontrol agent for controlling peanut soil-borne diseases caused by S. rolfsii.

Biological control of seed rot and preemergence damping-off of chickpea with fluorescent pseudomonads

1989 ◽  
Vol 21 (2) ◽  
pp. 269-273 ◽  
Author(s):  
W KAISER ◽  
R HANNAN ◽  
D WELLER
Keyword(s):  
Biological Control ◽  
Fluorescent Pseudomonads ◽  
Damping Off ◽  
Seed Rot

Responses of soil microorganisms to volatile exudates from germinating pea seeds

1985 ◽  
Vol 63 (6) ◽  
pp. 1040-1045 ◽  
Author(s):  
J. M. Norton ◽  
G. E. Harman
Keyword(s):  
Soil Microorganisms ◽  
Sclerotium Rolfsii ◽  
Hyphal Growth ◽  
Soil Microbial Activity ◽  
Soil Microflora ◽  
Natural Soil ◽  
Soil Microbial ◽  
Aged Seed ◽  
Seed Rot ◽  
Pea Seeds

Responses of soil microorganisms to volatile exudates from germinating pea seeds of differing quality were determined. Germination of sclerotia of Rhizoctonia solani and Sclerotium rolfsii and subsequent hyphal growth were stimulated by exposure to volatiles from aged but not nonaged pea seeds. Hyphae grew preferentially toward aged seeds. In natural soil, bacterial and fungal populations showed significant increases after exposure to volatiles from aged seed. For example, Fusarium spp. and Pseudomonas spp. showed increases of 79 and 2200%, respectively, over their original population levels after a 48-h exposure to volatiles. Conversely, Pythium populations and associated seed-rotting potential of soil decreased in natural soils exposed to volatiles. In autoclaved soils infested with P. ultimum (PHP4), Pythium populations increased dramatically after exposure to volatiles from aged pea seeds. In soils infested with either soil fungi or bacteria in addition to P. ultimum, Pythium levels remained constant or decreased, respectively, with time of exposure. Exposure to the volatiles from aged pea seeds stimulated soil microbial activity. These results suggest that Pythium germlings, when unable to reach a host, are subjected to microbial antagonism in the presence of the native soil microflora. A decrease in cucumber seed rot coincided with decreases in Pythium numbers.

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