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

Plant Disease ◽  
2000 ◽  
Vol 84 (6) ◽  
pp. 644-648 ◽  
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.

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.

scholarly journals Seed Treatment Using Pre-infiltration and Biocontrol Agents to Reduce Damping-off of Corn Caused by Species of Pythium and Fusarium

Plant Disease ◽  
1998 ◽  
Vol 82 (3) ◽  
pp. 294-299 ◽  
Author(s):  
W. Mao ◽  
R. D. Lumsden ◽  
J. A. Lewis ◽  
P. K. Hebbar
Keyword(s):  
Disease Control ◽  
Plant Height ◽  
Root Rot ◽  
Seed Treatment ◽  
Pythium Ultimum ◽  
Biocontrol Agents ◽  
Infested Soil ◽  
Damping Off ◽  
Fresh Weight ◽  
Inoculum Rate

Bioassays were conducted in a greenhouse at 18°C to determine the effectiveness of a seed treatment used in combination with biocontrol agents for the reduction of corn damping-off caused by species of Pythium and Fusarium. Corn seeds were infiltrated with tap water, drained, air-dried, and then coated with biomass of an antagonistic fungus, Gliocladium virens isolate Gl-3, or an antagonistic bacterium, Burkholderia cepacia isolates Bc-B or Bc-1, or a combination of Gl-3 with each of the bacterial isolates. A nonsterile field soil was infested with a combination of pathogens: Pythium ultimum, P. arrhenomanes, and Fusarium graminearum at 2 inoculum rates (1× and 4×). Pre-infiltration enhanced (P ≤ 0.05) disease control with most treatments at both inoculum rates. Treatments with biocontrol agents alone or in combination, as well as the fungicide captan, effectively reduced the disease at a pathogen inoculum rate of 1×, resulting in greater (P ≤ 0.05) seedling stands, plant height, and fresh weight, and lower (P ≤ 0.05) root rot severity compared with untreated seeds in infested soil. At a pathogen inoculum rate of 4×, stands were lower (P ≤ 0.01) and root-rot severity was higher (P ≤ 0.01) compared to those at 1× for all treatments. Nevertheless, coating seeds with all biocontrol agents (alone or in combination), except with Bc-1 alone, reduced disease (P ≤ 0.05) compared to untreated seeds in infested soil. At both inoculum rates of 1× and 4×, coating seeds with Gl-3 + Bc-B was more effective (P ≤ 0.05) in disease control than any other treatment, resulting in stands, growth rate (plant height and fresh weight), and root rot severity similar to plants from untreated seeds in noninfested soil. In addition, when the exudate from a 2-h infiltration of corn seed was added to the seeds during seed coating, seedling stand was often lower and root rot severity was often higher than those from infiltrated seeds (P ≤ 0.05). These results indicated that the infiltration process removed certain exudates, including nutrients and/or stimulants (not detected in this study) that might be utilized by pathogens to initiate seed infection. A thin-layer chromatography (TLC) profile of the exudates showed the presence of eight amino acids and three major carbohydrates.

scholarly journals Plug Source and Growth Retardants Affect Finish Size of Bedding Plants

HortScience ◽  
2001 ◽  
Vol 36 (2) ◽  
pp. 321-323 ◽  
Author(s):  
Jeff S. Kuehny ◽  
Aaron Painter ◽  
Patricia C. Branch
Keyword(s):  
Plant Species ◽  
Catharanthus Roseus ◽  
Plant Size ◽  
Antirrhinum Majus ◽  
Trimethylammonium Chloride ◽  
Growth Retardants ◽  
Bedding Plants ◽  
Salvia Splendens ◽  
Bedding Plant ◽  
Significant Difference

Eight bedding plant species were grown from plugs obtained from two sources. The plugs were transplanted into jumbo six packs and sprayed with a solution of chlormequat/daminozide with concentrations of 1000/800, 1250/1250, or 1500/5000 mg·L-1 when new growth was ≈5 cm in height or width. Three different species were grown in the fall (Dianthus chinensis L., `Telstar Mix', Petunia ×hybrida Hort. Vilm.-Andr., `Dreams Red', and Viola ×wittrockiana Gams., `Bingo Blue'), winter [Antirrhinum majus L., `Tahiti Mix', Matthiola incana (L.) R. Br., `Midget Red', and P. × hybrida, `Dreams Mix'], and spring [Catharanthus roseus (L.) G. Don, `Cooler Pink', Salvia splendens F. Sellow ex Roem. & Schult., `Empire Red', and Begonia ×semperflorens-cultorum Hort., `Cocktail Mix']. The treatments significantly reduced finished plant size of all species for each season. There was a significant difference in finish size between sources for Dianthus, Antirrhinum, Matthiola, Catharanthus, Salvia, and Begonia. The efficacy of chlormequat/daminozide also differed for each source of Dianthus, Matthiola, and Begonia, but the treatments minimized the differences in finish size between sources for Petunia and Viola. Chemical names used: (2-chlorethyl) trimethylammonium chloride (chlormequat); (N-dimethylaminosuccinamic acid) (daminozide).

scholarly journals Formulation of Binucleate Rhizoctonia spp. and Biocontrol of Rhizoctonia solani on Impatiens

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1241-1248 ◽  
Author(s):  
E. W. Honeycutt ◽  
D. M. Benson
Keyword(s):  
Rhizoctonia Solani ◽  
Shelf Life ◽  
Rice Flour ◽  
Trichoderma Virens ◽  
Damping Off ◽  
Salt Solutions ◽  
Binucleate Rhizoctonia ◽  
Controlled Atmospheres ◽  
Plastic Bags ◽  
Over Time

Isolates BNR621 and P9023 of binucleate Rhizoctonia spp. (BNR) in Pesta and rice flour formulations were evaluated for control of preemergence damping-off of impatiens caused by R. solani. Amendment of a soilless potting mix with the formulations at 0.47% (vol:vol) 3 days prior to seeding and infesting did not improve control compared to amendment 1 day prior to seeding and infesting regardless of whether the moistened amended potting mix was stored in closed plastic bags or in plug trays under a mist system. BNR fungi were no more effective in biocontrol of R. solani in formulations amended at 0.9%. Control of damping-off was comparable but not consistent between formulations of BNR fungi and the fungicide thiophanatemethyl. Damping-off was controlled better with formulations of BNR fungi than with SoilGard based on Trichoderma virens. Shelf life of Pesta and rice flour formulations at 4°C was determined by assessing viability of BNR isolates over time. Viability of the BNR isolates, measured as CFU/g of formulation, declined to approximately 68 to 79% of the original propagule concentration after 6 months in Pesta and rice flour formulations, with the greatest decline in the first 2 months. Shelf life of BNR isolates in formulation significantly affected control of preemergence damping-off but was isolate dependent. Preemergence damping-off was only 5 to 7% with fresh formulations but increased to 30 to 50% with 4-month-old formulations. Controlled atmospheres, maintained with saturated salt solutions, were established to measure the effect of water activity on shelf life of formulations. Water activities (aw) of 0.12 and 0.33 aw enhanced BNR survival in formulations by approximately 2 to 3 months compared with aw of 0.53 and 0.75 aw. Storage of Pesta and rice flour formulations at 4°C significantly improved BNR survival by 4 to 5 months compared with storage at 25°C. These results suggest that improved shelf life of BNR isolates is needed before formulated products can be developed for biocontrol of preemergence damping-off.

scholarly journals Seed-Colonizing Microbes from Municipal Biosolids Compost Suppress Pythium ultimum Damping-Off on Different Plant Species

2008 ◽  
Vol 98 (9) ◽  
pp. 1012-1018 ◽  
Author(s):  
M.-H. Chen ◽  
E. B. Nelson
Keyword(s):  
Plant Species ◽  
Pythium Ultimum ◽  
Disease Suppression ◽  
Microbial Consortia ◽  
Damping Off ◽  
Microbial Species ◽  
Pathogen Suppression ◽  
Municipal Biosolids ◽  
Leaf Compost ◽  
Biosolids Compost

Composts are known for their suppressive properties toward many different seed- and root-infecting pathogens and diseases. Although disease and pathogen suppression induced by composts is believed to be mediated by microbial activities, the nature of the microbial species and processes responsible for suppressiveness remain unknown. We demonstrated previously that seed-colonizing microbial consortia from leaf compost could explain the observed levels of Pythium ultimum-induced damping-off suppression on cotton. The aim of the present work was to determine whether seed-colonizing microbial consortia could explain Pythium damping-off suppression in municipal biosolids compost on three different plant species. Significant levels of disease suppression were observed on cucumber, wheat, and pea at water potentials of –2 kPa. The suppression of damping-off on cucumber and wheat could be eliminated by autoclaving the compost prior to sowing. High levels of suppressiveness were expressed both on cucumber and on wheat seed surfaces within 8 h of sowing. However, the expression of damping-off suppression on the surface of pea seeds was inconsistent and highly variable. Our results demonstrate that compost-induced suppression of P. ultimum damping-off of cucumber and wheat can be explained by the microbial consortia colonizing seeds within 8 h of sowing. These results further suggest that disease suppression in composts is related to microbial species that interact with the pathogen in its infection court and not in the bulk compost.

scholarly journals Differential Inactivation of Seed Exudate Stimulation of Pythium ultimum Sporangium Germination by Enterobacter cloacae Influences Biological Control Efficacy on Different Plant Species

2003 ◽  
Vol 69 (2) ◽  
pp. 1114-1120 ◽  
Author(s):  
Koji Kageyama ◽  
Eric B. Nelson
Keyword(s):  
Biological Control ◽  
Plant Species ◽  
Enterobacter Cloacae ◽  
Pythium Ultimum ◽  
Damping Off ◽  
Control Efficacy ◽  
Stimulatory Activity ◽  
Seed Exudate ◽  
Pea Seeds ◽  
Stimulation Of

ABSTRACT This study was initiated to understand whether differential biological control efficacy of Enterobacter cloacae on various plant species is due to differences in the ability of E. cloacae to inactivate the stimulatory activity of seed exudates to Pythium ultimum sporangium germination. In biological control assays, E. cloacae was effective in controlling Pythium damping-off when placed on the seeds of carrot, cotton, cucumber, lettuce, radish, tomato, and wheat but failed to protect corn and pea from damping-off. Seeds from plants such as corn and pea had high rates of exudation, whereas cotton and cucumber seeds had much lower rates of exudation. Patterns of seed exudation and the release of P. ultimum sporangium germination stimulants varied among the plants tested. Seed exudates of plants such as carrot, corn, lettuce, pea, radish, and wheat were generally more stimulatory to P. ultimum than were the exudates of cotton, cucumber, sunflower, and tomato. However, this was not directly related to the ability of E. cloacae to inactivate the stimulatory activity of the exudate and reduce P. ultimum sporangium germination. In the spermosphere, E. cloacae readily reduced the stimulatory activity of seed exudates from all plant species except corn and pea. Our data have shown that the inability of E. cloacae to protect corn and pea seeds from Pythium damping-off is directly related to its ability to inactivate the stimulatory activity of seed exudates. On all other plants tested, E. cloacae was effective in suppressing damping-off and inactivating the stimulatory activity of seed exudates.

scholarly journals Aluminum Amendment of Potting Mixes for Control of Phytophthora Damping-off in Bedding Plants

HortScience ◽  
1995 ◽  
Vol 30 (7) ◽  
pp. 1413-1416 ◽  
Author(s):  
D.M. Benson
Keyword(s):  
Catharanthus Roseus ◽  
Aluminum Sulfate ◽  
Seedling Emergence ◽  
Antirrhinum Majus ◽  
Damping Off ◽  
Madagascar Periwinkle ◽  
Bedding Plants ◽  
Host Pathogen Interaction ◽  
Bedding Plant ◽  
Exchangeable Aluminum

Control of preemergence damping-off caused by Phytophthora parasitica Dastur was investigated on three bedding plant species in a 1 peat: 1 vermiculite medium (v/v) limed at 3 kg·m–3 and drenched with aluminum at 10, 25, or 50 meq Al/100 cm3 medium. Aluminum as Al2(SO4)3 was applied as a drench at 0.75, 1.9, or 3.75 g/150 ml water to the surface of infested medium in 650-cm2 plug trays (1300-cm3 tray volume). All concentrations of aluminum were effective in controlling preemergence damping-off of snapdragon (Antirrhinum majus L.) and vinca (Catharanthus roseus G. Don, Madagascar periwinkle), but only 50 meq Al+3/100 cm3 medium was effective for petunia (Petunia ×hybrida Hort. Vilm.-Andr.). At 4 days after seeding and drenching with aluminum sulfate, exchangeable aluminum was 0, 0.5, and 2.03 meq Al+3/100 g medium, respectively, for the three concentrations used. Control of damping-off of snapdragon and vinca with 10 meq Al+3/100 cm3 medium with no detectable exchangeable aluminum 4 days after application suggests that P. parasitica was suppressed by aluminum early in the host–pathogen interaction, whereas petunia was susceptible to damping-off for a longer period before seedling emergence. Aluminum was not phytotoxic to vinca, snapdragon, or petunia grown in a limed medium.

Effects of photoperiod on leaf greenness of four bedding plant species

2003 ◽  
Vol 78 (3) ◽  
pp. 400-404 ◽  
Author(s):  
F. A. Langton ◽  
S. R. Adams ◽  
K. E. Cockshull
Keyword(s):  
Plant Species ◽  
Bedding Plant ◽  
Leaf Greenness
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