Laboratory evaluation of botanical extracts, microbial culture filtrates and silver nanoparticles against Botrytis cinerea

Abstract

In an attempt to find alternatives to fungicides, the efficacy of crude extracts of seven plant species (Cassia senna, Caesalpinia gilliesii, Thespesia populnea var. acutiloba, Chrysanthemum frutescens, Euonymus japonicus, Bauhinia purpurea and Cassia fistula), three microbial culture filtrates (Epicoccum nigrum, Bacillus subtilis and Bacillus pumilus) and silver nanoparticles were evaluated against Botrytis cinerea, the causative fungus of rot, under laboratory conditions. All tested materials were evaluated alone and combined with tolclofos-methyl, the recommended fungicide against B. cinerea. Gas chromatography–mass spectrometry analysis was performed to identify the possible biologically active components of the most effective plant extract and culture filtrate against B. cinerea. The results showed that Euonymus japonicus was the most effective plant extract and Bacillus subtilis was the most effective culture filtrate against B. cinerea. In addition, silver nanoparticles showed a high efficacy against B. cinerea. Combining each of the microbial culture filtrates, plant extracts and silver nanoparticles with the tolclofos-methyl improved the efficacy of the fungicide against B. cinerea. These non-traditional control methods can be regarded as providing effective control against B. cinerea, but their practical application and effect on human health need to be evaluated. If a combination of one or more of the tested materials and tolclofos-methyl were to reduce the amount of fungicide required to control B. cinerea, the adverse side effects of this fungicide on human health and the environment would also be reduced.