Abstract Detail

Biological Control of diseases and weeds (CFBC)

Wylie, Andrew C. [1], Nasir, Atta-ul [1], Punja, Zamir K. [1].

Assaying the efficacies of a fungal and a bacterial biocontrol agent in the presence of a microbial background.

Biological control of greenhouse plant diseases in soil-based growth media frequently used in organic production differs from that in hydroponic systems because soil contains a concentrated microbial population that the biocontrol organism is inoculated into. It has been demonstrated that populations of soil microbes can exhibit general suppression of plant diseases, and that biocontrol organisms can control plant diseases through specific suppression, but to our knowledge it has not been demonstrated how resident soil microbes suppress or enhance the ability of a biocontrol agent to control plant diseases. We are investigating whether biocontrol organisms can reduce the growth of plant pathogenic microorganisms in the presence of a background population of soil microbes: we describe an assay designed to determine this ability. The microbial population used in these trials was derived from vermicompost which was tested using PCR-DGGE to determine that a consistent microbial community was present. The assay itself measures the growth of a plant pathogenic fungus on a petri dish containing half-strength PDA, a lawn of organisms derived from a vermicompost tea extract, and a lawn of biological control agent, with associated control treatments. We tested the assay with the biocontrol agents Bacillus subtilis strain QST 713 (Rhapsody) and Clonostachys rosea f. catenulata (Gliocladium catenulatum) strain J1446 (Prestop), and the plant pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (FORC). Both the vermicompost and Bacillus were antagonistic to FORC individually; in combination they were not any more effective. Clonostachys and vermicompost were also antagonistic to FORC individually, but in combination they were better than vermicompost alone and slightly better than Clonostachys alone. The assay will next be scaled up to include plants and test whether the effects observed here are reflected in an actual reduction in disease. This assay provides an expedient, reproducible technique for screening biological agents for antagonism against plant pathogens in systems that utilize soil-based media such as found in intensive organic greenhouse vegetable production.

1 - Simon Fraser University, Biological Sciences, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada

Keywords:
biological control
vermicompost
greenhouse vegetable production
organic.

Presentation Type: Oral Paper:Papers for Topics
Session: 75
Location: Salon 2/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 4:15 PM
Number: 75003
Abstract ID:789
Candidate for Awards:CPS Best Student Presentation Awards