ISOLATION OF MICROBIAL ANTAGONISTS FOR BIOCONTROL OF GREY MOLD DISEASE OF STRAWBERRIES

A screening programme is described for the assessment of the potential of biocontrol agents to control grey mould of strawberries caused by Botrytis cinerea. Bacteria were isolated from strawberry fruits, leave s and flowers from a commercial field site and screened for antagonism towards B. cinerea using two vitro and one in vivo screening techniqu es. From 559 microorganisms isolated, 108 inhibited pathogen growth on agar plates and 27 of these prevented spore germination on Cellophane membranes. The ability of these 27 isolates to inhibit infection of y oung strawberry leaves by B. cinerea on whole plants under glass was t hen tested. Seven isolates reduced grey mould development and were sub sequently assessed in a field trial. Two isolates, one of Bacillus pum ilus and one of Pseudomonas fluorescens, were as effective or more eff ective than standard dichlofluanid sprays and may therefore be of pote ntial value as antagonists of B. cinerea.