Evaluation of some bioagents and botanicals in in vitro control of Colletotrichum destructivum

Abstract

Collectotrichum destructivum has not been effectively controlled. This led to trials on the use of bioagents and botanicals to control the pathogen. The bio-agents such as Pseudomonas fluorescens,
Bacillus subtilis, Trichoderma harzianum and Trichoderma pseudokoningii were inoculated as dixenic culture with the pathogen to monitor antagonistic effect. In another experiment, botanicals of tobacco (Nicotiana tabacum) and castor plant (Ricinus communis) were incorporated as poison in a growth media. Of all the four bio-agents used, only P. fluorescens was able to inhibit the growth of the pathogen
mycelia significantly by 52%. Though B. subtilis also inhibited the growth of the pathogen, the effect on the pathogen was not significant when compared with that of P. fluorescens. The extracts of R.
communis at higher concentration acted as growth “promoter” to the pathogen; its mycelia had a better sporulation and fluffiness than that of the controlled plate. The extract of N. tabacum significantly controlled the growth of the pathogen at the highest concentration when compared with other extracts and the control. In comparison, bio-agents were found to have better control of the pathogen than the botanicals. P. fluorescens was the best bio-agent in the control of C. destructivum.