Determination of antibiotic activity on plasmids from fluorescent pseudomonads isolates CW2, WB15 and WB52 against pre-emergence damping-off caused by Pythium ultimum and Rhizoctonia solani in cucumber

2010 ◽  
Vol 53 (2) ◽  
pp. 161-167 ◽  
Author(s):  
M. Salman
Keyword(s):  
Rhizoctonia Solani ◽  
Pythium Ultimum ◽  
Antibiotic Activity ◽  
Fluorescent Pseudomonads ◽  
Damping Off

Gliovirin, a new antibiotic from Gliocladium virens, and its role in the biological control of Pythium ultimum

1983 ◽  
Vol 29 (3) ◽  
pp. 321-324 ◽  
Author(s):  
Charles R. Howell ◽  
Robert D. Stipanovic
Keyword(s):  
Pythium Ultimum ◽  
Similar Efficacy ◽  
Antibiotic Activity ◽  
Infested Soil ◽  
Damping Off ◽  
Potato Dextrose Broth ◽  
Seedling Disease ◽  
X Ray ◽  
Gliocladium Virens ◽  
Induced Mutant

A compound with antibiotic activity toward Pythium ultimum was isolated from potato dextrose broth shake cultures of Gliocladium virens, a common soil mycoparasite known to inhibit but not parasitize P. ultimum. The mass spectrum and an X-ray crystallograph of the purified antibiotic indicated that it was a new diketopiperazine, and we have given it the trivial name gliovirin. Gliovirin is highly toxic to P. ultimum but is inactive against other fungi associated with cotton seedling disease. The antibiotic does not persist in nonsterile soil where it is apparently inactivated by the soil microflora.An ultraviolet light induced mutant of G. virens deficient for gliovirin production was overgrown by P. ultimum in culture and did not protect cotton seedlings from damping-off in P. ultimum infested soil. A mutant with enhanced gliovirin production was more inhibitory to P. ultimum in culture than the parent isolate and showed similar efficacy as a seedling disease suppressant, even though its growth rate was reduced when compared to the parent isolate. These results indicate that gliovirin may be important to the antagonist–pathogen interaction.

Relationship between in vitro growth inhibition of pathogens and suppression of preemergence damping-off and postemergence root rot of white bean seedlings in the greenhouse by bacteria

1994 ◽  
Vol 40 (2) ◽  
pp. 113-119 ◽  
Author(s):  
M. S. Reddy ◽  
R. K. Hynes ◽  
G. Lazarovits
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Fusarium Solani ◽  
Root Rot ◽  
Culture Media ◽  
Pythium Ultimum ◽  
Damping Off ◽  
Bacterial Strains ◽  
White Bean

One hundred and twenty diverse bacterial strains were screened under greenhouse conditions for their ability to protect white bean seedlings from preemergence damping-off caused by Pythium ultimum and Rhizoctonia solani and postemergence root rot by Fusarium solani f.sp. phaseoli. Preemergence mortality or root rot increased with an increase in the inoculum concentration of fungal isolates. For further testing, 200 propagules/g soil of P. ultimum, 3 propagules/g soil of R. solani, and log 3 conidia/g vermiculite of F. solani f.sp. phaseoli were used, as these rates provided an optimal level (approximately 50%) of disease severity. Bacterial strains suspended in sterile distilled water were added to pathogen-amended soil or vermiculite at log 7 colony-forming units/g soil or vermiculite prior to seeding. Final healthy stand and root rot were recorded 4 weeks after planting. Nine bacterial strains on P. ultimum, five on R. solani, and nine on F. solani f.sp. phaseoli provided significant (P = 0.05) suppression of disease severity compared with the nonbacterized control. Bacterial strains were also tested in vitro against the mycelial growth of the fungi on solid and liquid media. There was no relationship between the ability of bacterial strains to inhibit fungal vegetative growth on solid culture media and their ability to suppress pathogen activity in the greenhouse, but, for a few strains, the reduction in disease was linked to reduced growth of the pathogens in liquid media.Key words: White bean, damping-off, root rot, Pythium ultimum, Rhizoctonia solani, Fusarium solani f.sp. phaseoli.

scholarly journals Suppression of Seedling Damping-Off Caused by Pythium ultimum, P. irregulare, and Rhizoctonia solani in Container Media Amended with a Diverse Range of Pacific Northwest Compost Sources

2005 ◽  
Vol 95 (3) ◽  
pp. 306-315 ◽  
Author(s):  
Steven J. Scheuerell ◽  
Dan M. Sullivan ◽  
Walter F. Mahaffee
Keyword(s):  
Rhizoctonia Solani ◽  
Pacific Northwest ◽  
Large Degree ◽  
Pythium Ultimum ◽  
Biological Properties ◽  
Peat Moss ◽  
Damping Off ◽  
Diverse Range ◽  
Sphagnum Peat Moss ◽  
Qualitative Index

Suppression of seedling damping-off disease caused by Pythium spp. and Rhizoctonia solani is a potential benefit of formulating soilless container media with compost. Thirty-six compost samples from Pacific Northwest commercial composting facilities were analyzed for a number of physical, chemical, and biological properties, including suppression of damping-off caused by Pythium ultimum, P. irregulare, and R. solani. The samples were produced from diverse feedstocks and composting technol ogies; this was reflected in a large degree of variability in the measured properties. When mixed with sphagnum peat moss and inorganic aggregates, 67% of the compost samples significantly suppressed P. irregulare damping-off of cucumber, 64% suppressed P. ultimum damping-off of cucumber, and 17% suppressed damping-off of cabbage caused by R. solani. Suppression of Pythium damping-off was related to the potential of compost to support microbial activity and a qualitative index of ammonia volatilization. Suppression of Rhizoctonia damping-off was not related to any one compost factor. Currently available compost products potentially could provide commercially acceptable control of damping-off caused by Pythium spp., but it is necessary to fortify composts with microbial antagonists for the control of R. solani.

scholarly journals Suppression of Rhizoctonia solani on Impatiens by Enhanced Microbial Activity in Composted Swine Waste-Amended Potting Mixes

2003 ◽  
Vol 93 (9) ◽  
pp. 1115-1123 ◽  
Author(s):  
H. G. Diab ◽  
S. Hu ◽  
D. M. Benson
Keyword(s):  
Rhizoctonia Solani ◽  
Microbial Activity ◽  
Microbial Biomass Carbon ◽  
Pythium Ultimum ◽  
Population Diversity ◽  
Disease Suppression ◽  
Peat Moss ◽  
Biomass Carbon ◽  
Damping Off ◽  
Carbon And Nitrogen

Peat moss-based potting mix was amended with either of two composted swine wastes, CSW1 and CSW2, at rates from 4 to 20% (vol/vol) to evaluate suppression of pre-emergence damping-off of impatiens (Impatiens balsamina) caused by Rhizoctonia solani (anastomosis group-4). A cucumber bioassay was used prior to each impatiens experiment to monitor maturity of compost as the compost aged in a curing pile by evaluating disease suppression toward both Pythium ultimum and R. solani. At 16, 24, 32, and 37 weeks after composting, plug trays filled with compost-amended potting mix were seeded with impatiens and infested with R. solani to determine suppression of damping-off. Pre-emergence damping-off was lower for impatiens grown in potting mix amended with 20% CSW1 than in CSW2-amended and nonamended mixes. To identify relationships between disease suppression and microbial parameters, samples of mixes were collected to determine microbial activity, biomass carbon and nitrogen, functional diversity, and population density. Higher rates of microbial activity were observed with increasing rates of CSW1 amendment than with CSW2 amendments. Microbial biomass carbon and nitrogen also were higher in CSW1-amended mixes than in CSW2-amended potting mixes 1 day prior to seeding and 5 weeks after seeding. Principal component analysis of Biolog-GN2 profiles showed different functional diversities between CSW1- and CSW2-amended mixes. Furthermore, mixes amended with CSW1 had higher colony forming units of fungi, endospore-forming bacteria, and oligotrophic bacteria. Our results suggest that enhanced microbial activity, functional and population diversity of stable compost-amended mix were associated with suppressiveness to Rhizoctonia damping-off in impatiens.

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