scholarly journals Biological and Application-Oriented Factors Influencing Plant Disease Suppression by Biological Control: A Meta-Analytical Review

2006 ◽  
Vol 96 (11) ◽  
pp. 1168-1174 ◽  
Author(s):  
P. S. Ojiambo ◽  
H. Scherm
Keyword(s):  
Biological Control ◽  
Effect Size ◽  
Untreated Control ◽  
Plant Disease ◽  
Biocontrol Agent ◽  
Disease Suppression ◽  
Effect Sizes ◽  
Biological Control Agents ◽  
Control Effect ◽  
Soilborne Diseases

Studies to evaluate the effectiveness of biological control in suppressing plant disease often report inconsistent results, highlighting the need to identify general factors that influence the success or failure of biological control in plant pathology. We conducted a quantitative synthesis of previously published research by applying meta-analysis to determine the overall effectiveness of biocontrol in relation to biological and application-oriented factors. For each of 149 entries (antagonist-disease combinations) from 53 reports published in Biological & Cultural Tests between 2000 and 2005, an effect size was calculated as the difference in disease intensity expressed in standard deviation units between the biocontrol treatment and its corresponding untreated control. Effect sizes ranged from -1.15 (i.e., disease strongly enhanced by application of the biocontrol agent) to 4.83 (strong disease suppression by the antagonist) with an overall weighted mean of 0.62, indicating moderate effectiveness on average. There were no significant (P >0.05) differences in effect sizes between entries from studies carried out in the greenhouse versus the field, between those involving soilborne versus aerial diseases, or among those carried out in conditions of low, medium, or high disease pressure (expressed relative to the disease intensity in the untreated control). However, effect sizes were greater on annual than on perennial crops, regardless of whether the analysis was carried out for all entries (P = 0.0268) or for those involving only soilborne diseases (P = 0.0343). Effect sizes were not significantly different for entries utilizing fungal versus bacterial biocontrol agents or for those targeting fungal versus bacterial pathogens. However, entries that used r-selected biological control agents (i.e., those having short generation times and producing large numbers of short-lived offspring) were more effective than those that applied antagonists that were not r-selected (P = 0.0312). Interestingly, effect sizes for entries that used Bacillus spp. as biological control agents were lower than for those that applied other antagonists (P = 0.0046 for all entries and P = 0.0114 for soilborne diseases). When only aerial diseases were considered, mean effect size was greater for entries that received one or two sprays than for those that received more than eight sprays of the biocontrol agent (P = 0.0002). This counterintuitive result may indicate that investigators often attempt unsuccessfully to compensate for anticipated poor performance in antagonist-disease combinations by making more applications.

scholarly journals Mechanistically Compatible Mixtures of Bacterial Antagonists Improve Biological Control of Fire Blight of Pear

2011 ◽  
Vol 101 (1) ◽  
pp. 113-123 ◽  
Author(s):  
V. O. Stockwell ◽  
K. B. Johnson ◽  
D. Sugar ◽  
J. E. Loper
Keyword(s):  
Biological Control ◽  
Plant Disease ◽  
Fire Blight ◽  
Biological Control Agent ◽  
Field Trials ◽  
Control Agent ◽  
Extracellular Protease ◽  
Peptide Antibiotics ◽  
Biological Control Agents ◽  
Control Activity

Mixtures of biological control agents can be superior to individual agents in suppressing plant disease, providing enhanced efficacy and reliability from field to field relative to single biocontrol strains. Nonetheless, the efficacy of combinations of Pseudomonas fluorescens A506, a commercial biological control agent for fire blight of pear, and Pantoea vagans strain C9-1 or Pantoea agglomerans strain Eh252 rarely exceeds that of individual strains. A506 suppresses growth of the pathogen on floral colonization and infection sites through preemptive exclusion. C9-1 and Eh252 produce peptide antibiotics that contribute to disease control. In culture, A506 produces an extracellular protease that degrades the peptide antibiotics of C9-1 and Eh252. We hypothesized that strain A506 diminishes the biological control activity of C9-1 and Eh252, thereby reducing the efficacy of biocontrol mixtures. This hypothesis was tested in five replicated field trials comparing biological control of fire blight using strain A506 and A506 aprX::Tn5, an extracellular protease-deficient mutant, as individuals and combined with C9-1 or Eh252. On average, mixtures containing A506 aprX::Tn5 were superior to those containing the wild-type strain, confirming that the extracellular protease of A506 diminished the biological control activity of C9-1 and Eh252 in situ. Mixtures of A506 aprX::Tn5 and C9-1 or Eh252 were superior to oxytetracycline or single biocontrol strains in suppressing fire blight of pear. These experiments demonstrate that certain biological control agents are mechanistically incompatible, in that one strain interferes with the mechanism by which a second strain suppresses plant disease. Mixtures composed of mechanistically compatible strains of biological control agents can suppress disease more effectively than individual biological control agents.

Assessing aerated vermicompost tea (ACT) combined with microbial biological control agents for suppression of Fusarium and Rhizoctonia

2020 ◽  
Author(s):  
Andrew C. Wylie ◽  
Zamir K. Punja
Keyword(s):  
Biological Control ◽  
Plant Diseases ◽  
Disease Suppression ◽  
Biocontrol Agents ◽  
Background Suppression ◽  
Biological Control Agents ◽  
Vitro Assay ◽  
Vermicompost Tea ◽  
The Impact ◽  
Better Than

Biological control of plant diseases is important in organic greenhouse vegetable production where fungicide use is limited. Organic producers employ microbially-diverse substrates, including composts, as media for plant growth. Previous research into the impact of vermicompost on the efficacy of applied biocontrol agents is limited. An in vitro assay was developed to test the efficacy of two biological control agents in a competitive microbial background. Suppression of the pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (Forc) by Clonostachys rosea f. catenulata (Gliocladium catenulatum strain J1446 (Prestop®) and Bacillus subtilis strain QST 713 (Rhapsody®), was assessed on agar media amended with aerated vermicompost tea (ACT). Pathogen growth was reduced more by C. rosea than ACT alone and C. rosea was equally effective when combined with ACT. In contrast, B. subtilis reduced pathogen growth less than ACT, and when combined, reduced pathogen growth not more than ACT alone. Both biocontrol agents were similarly tested with ACT against Forc and Rhizoctonia solani on cucumber and radish. Additive, neutral, and antagonistic responses, depending on host, pathogen, and biocontrol agent, were observed. ACT alone provided more consistent disease suppression on cucumber compared with B. subtilis or C. rosea. In combination, disease suppression was most often better than each biocontrol alone but not better than ACT alone. ACT had antagonistic or additive interactions with C. rosea in the radish/R. solani pathosystem, depending on the experiment. The specific and general suppression of plant diseases by biological control agents in microbially-rich environments is variable and requires further study.

scholarly journals Control of Fire Blight by Pseudomonas fluorescens A506 and Pantoea vagans C9-1 Applied as Single Strains and Mixed Inocula

2010 ◽  
Vol 100 (12) ◽  
pp. 1330-1339 ◽  
Author(s):  
V. O. Stockwell ◽  
K. B. Johnson ◽  
D. Sugar ◽  
J. E. Loper
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Field Trials ◽  
Disease Suppression ◽  
Biological Control Agents ◽  
Population Sizes ◽  
Mixed Inocula ◽  
Pantoea Vagans

The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in 10 field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to blossoms influenced establishment of the pathogen and the efficacy of biological control. Pantoea vagans C9-1 suppressed fire blight in all five trials in which the pathogen was applied as lyophilized cells but in none of the trials in which the pathogen was applied as freshly harvested cells. In contrast, Pseudomonas fluorescens A506 reduced disease significantly in only one trial. A mixture of the two strains also suppressed fire blight, but the magnitude of disease suppression over all field trials (averaging 32%) was less than that attained by C9-1 alone (42%). The two biological control agents did not antagonize one another on blossom surfaces, and application of the mixture of A506 and C9-1 to blossoms resulted in a greater proportion of flowers having detectable populations of at least one bacterial antagonist than the application of individual strains. Therefore, the mixture of A506 and C9-1 provided less disease control than expected based upon the epiphytic population sizes of the antagonists on blossom surfaces. We speculate that the biocontrol mixture was less effective than anticipated due to incompatibility between the mechanisms by which A506 and C9-1 suppress disease.

scholarly journals Using Pseudomonas spp. for Integrated Biological Control

2007 ◽  
Vol 97 (2) ◽  
pp. 244-249 ◽  
Author(s):  
Virginia O. Stockwell ◽  
James P. Stack
Keyword(s):  
Biological Control ◽  
Pseudomonas Syringae ◽  
Environmental Protection Agency ◽  
Plant Disease ◽  
Fire Blight ◽  
Disease Suppression ◽  
Model Organisms ◽  
Bacterial Disease ◽  
Multiple Production ◽  
Pseudomonas Spp

Pseudomonas spp. have been studied for decades as model organisms for biological control of plant disease. Currently, there are three commercial formulations of pseudomonads registered with the U.S. Environmental Protection Agency for plant disease suppression, Bio-Save 10 LP, Bio-Save 11 LP, and BlightBan A506. Bio-Save 10 LP and Bio-Save 11 LP, products of Jet Harvest Solutions, Longwood, FL, contain Pseudomonas syringae strains ESC-10 and ESC-11, respectively. These products are applied in packinghouses to prevent postharvest fungal diseases during storage of citrus, pome, stone fruits, and potatoes. BlightBan A506, produced by NuFarm Americas, Burr Ridge, IL, contains P. fluorescens strain A506. BlightBan A506 is applied primarily to pear and apple trees during bloom to suppress the bacterial disease fire blight. Combining BlightBan A506 with the antibiotic streptomycin improves control of fire blight, even in areas with streptomycin-resistant populations of the pathogen. BlightBan A506 also may reduce fruit russet and mild frost injury. These biocontrol products consisting of Pseudomonas spp. provide moderate to excellent efficacy against multiple production constraints, are relatively easy to apply, and they can be integrated with conventional products for disease control. These characteristics will contribute to the adoption of these products by growers and packinghouses.

scholarly journals Microbial Interactions Within Multiple-Strain Biological Control Agents Impact Soil-Borne Plant Disease

2020 ◽  
Vol 11 ◽  
Author(s):  
Ben Niu ◽  
Weixiong Wang ◽  
Zhibo Yuan ◽  
Ronald R. Sederoff ◽  
Heike Sederoff ◽  
...  
Keyword(s):  
Biological Control ◽  
Plant Disease ◽  
Microbial Interactions ◽  
Biological Control Agents

scholarly journals Searching for Novel Fungal Biological Control Agents for Plant Disease Control Among Endophytes

2019 ◽  
pp. 25-51 ◽  
Author(s):  
David B. Collinge ◽  
Hans J. L. Jørgensen ◽  
Meike A. C. Latz ◽  
Andrea Manzotti ◽  
Fani Ntana ◽  
...  
Keyword(s):  
Biological Control ◽  
Disease Control ◽  
Plant Disease ◽  
Biological Control Agents ◽  
Plant Disease Control

scholarly journals Biological Control of the Artillery Fungus, Sphaerobolus stellatus, with Trichoderma harzianum and Bacillus subtilis

2001 ◽  
Vol 19 (1) ◽  
pp. 21-23 ◽  
Author(s):  
Elizabeth A. Brantley ◽  
Donald D. Davis ◽  
Larry J. Kuhns
Keyword(s):  
Biological Control ◽  
Bacillus Subtilis ◽  
Trichoderma Harzianum ◽  
Biocontrol Agent ◽  
Biocontrol Agents ◽  
Biological Control Agents ◽  
Oatmeal Agar ◽  
Time Of Application ◽  
Bacterium Bacillus Subtilis ◽  
Bacterium Bacillus

Abstract Three strains of the fungus Trichoderma harzianum Rifai and two strains of the bacterium Bacillus subtilis (Ehrenberg) Cohn were evaluated for their ability to suppress colonization and sporulation of the artillery fungus (Sphaerobolus stellatus Tode:Pers.) on oatmeal agar. All five biological control agents inhibited growth of S. stellatus, but efficacy depended on time of application. Simultaneous inoculation of agar with S. stellatus and the biocontrol agents, as well as inoculation of biocontrol agents 14 days prior to S. stellatus, resulted in complete inhibition of S. stellatus. Inoculation of agar with biocontrol agents 14 days after inoculation with S. stellatus reduced, but did not completely suppress S. stellatus colonization and sporulation. In this experiment, gleba (spore masses) treated with all strains of T. harzianum and strain GBO3 of B. subtilis did not germinate, but 13% of gleba treated with strain MBI 600 of B. subtilis did germinate. Trichoderma harzianum was more effective than B. subtilis as a biocontrol agent.

scholarly journals Detection and identification of a selfintroduced parasitoid of the Acacia tortoise beetle

2010 ◽  
Vol 63 ◽  
pp. 282-282
Author(s):  
T.J. Murray ◽  
T.M. Withers
Keyword(s):  
Biological Control ◽  
New Species ◽  
New Zealand ◽  
Natural Enemies ◽  
Biocontrol Agent ◽  
Biological Control Agents ◽  
The Third ◽  
Acacia Melanoxylon ◽  
Detection And Identification ◽  
Tortoise Beetle

Dicranosterna semipunctata (Coleoptera Chrysomelidae) was detected in New Zealand in 1996 This Australian tortoise beetle has no specific natural enemies in New Zealand and has become a moderate pest of blackwood (Acacia melanoxylon) Although a number of potential biological control agents have been identified in Australia none has been intentionally introduced In January 2009 parasitised eggs of D semipunctata were found in Rotorua Comparison of the emergent parasitoids to hymenoptera held in the NZIC and ANIC confirm that the wasp is from the genus Neopolycystus The taxonomy of this genus is poorly resolved but there were three species of particular interest to which to compare the new specimens The first Neopolycystus sp nr insectifurax was introduced from Perth against Paropsis charybdis in 1989 but did not establish The second Neopolycystus sp was reared from D semipunctata eggs in NSW but was never imported into New Zealand as a biocontrol agent for D semipunctata The third N insectifurax Girault is selfintroduced since 2001 and is well established in New Zealand contributing significantly to the control of P charybdis The parasitoids reared from D semipunctata eggs in Rotorua were not analogous to any of these This new species Neopolycystus sp from Rotorua has since been recorded in the Northland Auckland Waikato and Bay of Plenty regions

scholarly journals Biological Control to Protect Watermelon Blossoms and Seed from Infection by Acidovorax avenae subsp. citrulli

2005 ◽  
Vol 95 (4) ◽  
pp. 413-419 ◽  
Author(s):  
A. Fessehaie ◽  
R. R. Walcott
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Disease Suppression ◽  
Biological Control Agents ◽  
Positive Bacterium ◽  
Control Seed ◽  
Bacterial Fruit Blotch ◽  
Feasible Option ◽  
Phosphate Buffered Saline ◽  
Seed Infestation

The efficacy of biological control seed treatments with Pseudomonas fluorescens (A506), Acidovorax avenae subsp. avenae (AAA 99-2), and an unidentified gram-positive bacterium recovered from watermelon seed (WS-1) was evaluated for the management of bacterial fruit blotch (BFB) of watermelon. In growth chamber and greenhouse experiments, seed treated with AAA 99-2 displayed superior disease suppression, reducing BFB transmission by 96.5%. AAA 99-2, P. fluorescens A506, and Kocide also suppressed the epiphytic growth of A. avenae subsp. citrulli when applied to attached watermelon blossoms 5 h prior to inoculation. Watermelon blossom protection reduced seed infestation by A. avenae subsp. citrulli. From blossoms treated with 0.1 M phosphate buffered saline (PBS), 63% of the resulting seed lots were infested with A. avenae subsp. citrulli. In contrast, for blossoms protected with WS-1, Kocide, P. fluorescens A506, and AAA 99-2, the proportion of infested seed lots were 48.3, 21.1, 24.1, and 13.8%, respectively. The effect of blossom treatments on seed lot infestation was statistically significant (P = 0.001) but WS-1 was not significantly different from PBS. These findings suggest that blossom protection with biological control agents could be a feasible option for managing BFB.

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