Mechanism of disease suppression by plant products have proved that, the active principles present in them and/or induce systemic resistance in host plants. In the present investigation we studied the expression of induced systemic resistance in banana fruits upon treatment with plant extracts. Banana fruits are dipped in 10 per cent of leaf extracts of Solanum torvum, Zimmu and Allium alliaceum for five minutes and inoculated with conidial suspensions (106/ml) of Colletotrichum musae by pin prick method. The changes in the induction of defence mechanism of the inoculated fruits, inoculated fruits dipped in leaf extracts and uninoculated control are analyzed separately both in peel and pulp 2, 4, 6, 8 and 10 days after treatment. The Peroxidase(PO), Polyphenol oxidase(PPO) and Phenylalanine ammonia-lyase(PAL) activity was significantly increased both in peel and pulp of the inoculated fruits dipped in leaf extracts as compared to inoculated fruits alone. Activity of defense enzymes are highest at six day after inoculation and decline in subsequent days.
