Biocontrol of Damping-off Diseases Caused by Rhizoctonia solani and Pythium ultimum with Alginate Prills of Gliocladium virens, Trichoderma hamatum and Various Food Bases

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.

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Biocontrol of cotton damping-off caused by Rhizoctonia solani in the field with formulations of Trichoderma spp. and Gliocladium virens

Crop Protection ◽

10.1016/s0261-2194(06)80031-1 ◽

1991 ◽

Vol 10 (5) ◽

pp. 396-402 ◽

Cited By ~ 23

Author(s):

J.A. Lewis ◽

G.C. Papavizas

Keyword(s):

Rhizoctonia Solani ◽

Damping Off ◽

Trichoderma Spp ◽

Gliocladium Virens

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Biocontrol of Damping-off of Catharanthus roseus Caused by Pythium ultimum with Trichoderma virens and Binucleate Rhizoctonia Fungi

Plant Disease ◽

10.1094/pdis.2000.84.6.644 ◽

2000 ◽

Vol 84 (6) ◽

pp. 644-648 ◽

Cited By ~ 24

Author(s):

J. R. Burns ◽

D. M. Benson

Keyword(s):

Plant Species ◽

Catharanthus Roseus ◽

Pythium Ultimum ◽

Biocontrol Agents ◽

Trichoderma Virens ◽

Damping Off ◽

Binucleate Rhizoctonia ◽

Biocontrol Efficacy ◽

Bedding Plant ◽

Gliocladium Virens

Four isolates of Trichoderma (Gliocladium) virens (G-45, G-65, G-85, and G-93) and two isolates of binucleate Rhizoctonia spp. (BNR621 and P9023) were evaluated for biocontrol of preemergence damping-off of Catharanthus roseus (vinca) caused by Pythium ultimum. Putative biocontrol agents were amended to a soilless mix 1, 3, or 6 days prior to seeding and pathogen infestation to determine if colonization of the mix before infestation was important for biocontrol efficacy. Biocontrol of preemergence damping-off of vinca with the four isolates of T. virens was variable. Only isolate G-93 gave control of preemergence damping-off (10 to 18% disease) regardless of the length of time the mix was amended prior to seeding and infestation compared to the infested control (43% disease). In contrast, preemergence damping-off was 10 to 15% with SoilGard (based on isolate GL-21 of T. virens). For isolate G-65, preemergence damping-off of vinca was 0% in lots of mix amended 1 day prior to seeding, but over 60% in lots of mix amended 6 days prior to seeding, compared to 43% in the infested control. With the exception of isolate G-65 in the lot amended 6 days before seeding, the isolates of T. virens were as effective as metalaxyl (19% damping-off) for control of P. ultimum in lots of mix amended 1 to 6 days before seeding. In contrast to T. virens, biocontrol efficacy of isolates BNR621 and P9023 of binucleate Rhizoctonia spp. in a Pesta formulation improved as lots of mix were amended up to 6 days before seeding and infestation. As length of initial amendment increased from 1 to 6 days, preemergence damping-off decreased from 37 to 16% for BNR621, and from 42 to 22% for P9023. Preemergence damping-off was observed in vinca in control treatments with only the putative biocontrol agents (BNR621, 14% disease and P9023, 19.6%); therefore, additional bedding plant species were evaluated for susceptibility to the BNR isolates. In the absence of P. ultimum, isolates BNR621 and P9023 in a Pesta formulation caused an average 82.5, 56.5, and 5.8% damping-off of snapdragon, petunia, and impatiens, respectively. Our results suggest that binucleate Rhizoctonia isolates, although effective for biocontrol of P. ultimum on vinca, should be evaluated for pathogenicity on a crop by crop basis before use on other crops.

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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

Canadian Journal of Microbiology ◽

10.1139/m94-018 ◽

1994 ◽

Vol 40 (2) ◽

pp. 113-119 ◽

Cited By ~ 34

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.

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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

Phytopathology ◽

10.1094/phyto-95-0306 ◽

2005 ◽

Vol 95 (3) ◽

pp. 306-315 ◽

Cited By ~ 94

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.

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

Phytopathology ◽

10.1094/phyto.2003.93.9.1115 ◽

2003 ◽

Vol 93 (9) ◽

pp. 1115-1123 ◽

Cited By ~ 52

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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Dried powders of velvetbean and pine bark added to soil reduce Rhizoctonia solani-induced disease on soybean

Fitopatologia Brasileira ◽

10.1590/s0100-41582006000300004 ◽

2006 ◽

Vol 31 (3) ◽

pp. 261-269 ◽

Cited By ~ 1

Author(s):

Luiz E. B. Blum ◽

Rodrígo Rodríguez-Kábana

Keyword(s):

Rhizoctonia Solani ◽

Pine Bark ◽

Soybean Plant ◽

Pueraria Lobata ◽

Damping Off ◽

Alternative Control ◽

Trichoderma Hamatum ◽

The World ◽

Pinus Spp ◽

Hydrolysis Of

Diseases induced by Rhizoctonia solani, like damping-off and root and stem rot on soybean (Glycine max), are a serious problem around the world. The addition of some organic material to soil is an alternative control for these diseases. In this study, benzaldehyde and dried powders of kudzu (Pueraria lobata), velvetbean or mucuna (Mucuna deeringiana), and pine bark (Pinus spp.) were used in an attempt to improve soybean plant growth and to reduce the disease R. solani (AG-4) causes on soybean. Benzaldehyde (0.1-0.4 mL/kg of soil) and velvetbean (25-100 g/kg) significantly (P < 0.05) reduced mycelial growth of R. solani in laboratory tests. In greenhouse experiments, the percentage of non-diseased plants was higher in treatments with pine bark and velvetbean (50-100 g/kg). In soil treated with kudzu (r²=0.91) or velvetbean (r²=0.94), increasing rates of these amendments tended to increase plant fresh mass. In microplot field conditions, soil amended with velvetbean (r²=0.85) and pine-bark (r²=0.61) significantly reduced disease on soybean. Numbers of Bacillus megaterium (r²=0.87) and Trichoderma hamatum (r²=0.92) and hydrolysis of fluorescein diacetate (r²=0.91) were higher in soil amended with increasing rates of velvetbean, indicating an increase in microbial activity. From this study it is concluded that dried powders of velvetbean and pine bark added to soil can reduce Rhizoctonia-induced disease on soybean.

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A Formulation of Trichoderma and Gliocladium to Reduce Damping-off Caused by Rhizoctonia solani and Saprophytic Growth of the Pathogen in Soilless Mix

Plant Disease ◽

10.1094/pdis.1998.82.5.501 ◽

1998 ◽

Vol 82 (5) ◽

pp. 501-506 ◽

Cited By ~ 34

Author(s):

J. A. Lewis ◽

R. P. Larkin ◽

D. L. Rogers

Keyword(s):

Rhizoctonia Solani ◽

Population Increase ◽

Acid Activation ◽

Dilute Acid ◽

Damping Off ◽

Trichoderma Spp ◽

Gliocladium Virens ◽

Aseptic Conditions ◽

Biocontrol Fungi

Commercially manufactured cellulose granules (Biodac) were mixed with a sticker and fermentor-produced biomass of isolates of Trichoderma spp. and Gliocladium virens to produce a formulation in which chlamydospores in the biomass were “activated” with dilute acid. Activation resulted in the formation of young, actively growing hyphae of the biocontrol fungi within a 2- to 3-day period under no special aseptic conditions. Activated Biodac with biomass of isolates Gl-3, Gl-21, and Gl-32 of G. virens and isolate TRI-4 of T. hamatum applied to soilless mix at a rate of 1.5% (wt/wt) reduced damping-off of eggplant caused by Rhizoctonia solani (R-23) and resulted in stands comparable to that (88%) in noninfested soilless mix. Saprophytic growth of the pathogen was also reduced. The application of either of two activated Biodac formulations to provide the same amount (1.5% with 9.4 mg of biomass per g of Biodac or 0.2% with 75.0 mg of biomass per g of Biodac) reduced preemergence damping-off as well as saprophytic growth of R-23. Also, there was about a 103-fold population increase of Gl-3 and TRI-4 in the soilless mix at the time of plant harvest compared with that provided to the soilless mix at the time of formulation addition. Activated Biodac of Gl-3 also reduced the spread of R-23 in soilless mix when the pathogen was applied at specific foci rather than evenly distributed. The inhibition of pathogen spread significantly reduced the postemergence damping-off of cucumber, eggplant, and pepper seedlings.

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