SHELF-LIFE IMPROVEMENT IN PINEAPPLES BY USING PLANT EXTRACTS TO CONTROL CERATOCYSTIS PARADOXA.

Abstract

Ceratocystis paradoxa, a fungus causes soft-rot of pineapples. The high temperature and humid condition prevailing during the peak fruiting season (June-July) promote infection by pathogenic microorganisms. In the recent past, angiospermic plants have proved to be useful sources of fungitoxic substances that are rather harmless compared to synthetic chemical fungicides which often impose undesirable side effects. The present investigation also reveals that plant extracts can be used in controlling C. paradoxa. Xanthium strumarium was the most effective in inhibiting mycelial growth in vitro. The effectiveness of various extracts against C. paradoxa was in the decreasing order of Phlogacanthus thyrsiflorus, Toona ciliata, Vitex negundo, Azadirachta indica, Eupatorium birmanicum, Ocimum sanctum and Leucas aspera. Extracts of Gynura cusimba and Ocimum canum showed poor fungitoxicity. Millipore filter-sterilized extracts had a more inhibitory effect on the fungus than the autoclaved sample.If pineapple juice was added to the medium, the growth of C. paradoxa increased with increasing concentration of the juice. Xanthium extract also inhibited the growth of the fungus in this case. Treatment of pineapple fruits with X. strumarium extract reduced the severity of the disease. Since the extract has significant preventive activity against soft-rot disease in pineapples, there is possibility of using such an extract as a fungitoxic agent in post-havest fruit technology development.