BIOLOGICAL CONTROL OF THE POST-HARVEST DISEASES OF COMMON VEGETABLES WITH A NATURAL ANTAGONIST
S PHILIP, RM ZACHRIAH and T RAJKUMAR
College of Agriculture, Kerala Agricultural University, Veilayani 695 522, Kerala, India
Background and objectives
Materials and methods
In vitro studies of the interactions of the epiphytic fungi to the pathogens were made using the dual culture technique  and the promising cultures were selected as antagonists. The selected antagonists were tested in vivo by blending and diluting with water at 2% concentration. The vegetables were dipped in this suspension and allowed to dry. After drying they were inoculated with their respective pathogens and stored under room temperature. The effect of the antagonist on the storage quality of vegetables in comparison to the control was studied.
Results and conclusions
in vitro studies on the type of interactions by the epiphytic fungi showed over growth, cessation of growth at the line of contact and inhibition. Fungi such as Botryodiplodia theobromae, Phoma sp., Pestalotia palmarum, Trichoderma viride, Aspergillus niger, A. flavus and A. terreus showed antagonisms to pathogens including F. soiani, R. solani and A. solani. T. viride alone was selected for further studies as it was an established antagonist. Inhibition of F. solani by T. viride was effected through coiling and penetration of hyphae, while with R. solani it was through coiling and disintegration of hyphae.
In vivo studies with all the vegetables also revealed the effect of T. viride as a biological antagonist. Vegetables treated with Trichoderma and inoculated with the respective pathogens registered a rotting of less than 50% on the 15th day of inoculation, while in control samples the rotting was 100%. Similarly Trichoderma-treated vegetables (without artificial inoculation by pathogens) retained their freshness and vigour upto 15 days after harvest at a room temperature of 28+2°C in contrast to control samples which showed symptoms of rotting.
The study thus indicates the immense possibilities of using Trichoderma formulations as biological antagonists, which can be adapted as an easy and eco-friendly technique for minimising the post-harvest spoilage of vegetables.References
1. Janisiewiez WJ, 1988. Phytopathology 78, 194-498.
2. Dennis C, Webster J, 1971. Transactions of the British Mycological Society 57, 41-48.