Bioactivity of certain selected composites on fungal pathogens
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Date
2004-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Mounting pressure of teeming population and shrinking land resources have necessitated the production of more food per unit area. Synthetic pesticides have played a major role in restricting pest problems and ensuring an increase in food grain production. However, the indiscriminate use of synthetic pesticides have created several problems of pest resistance, food contamination by toxic residuce (Subash Chander and Munshi, 1995) environmental pollution, pest resurgence and resistance (Schumtterer et al., 1990). Recently, the use of bioactive products of plants is being popularized to control the pests, as these are safer, cheaper and their crude extracts are quite easy to prepare. In the present study, an attempt is being made to screen five different members of family Compositae (Asteraceae) for their antifungal efficacy, by „Paper-Disc‟ agar method, in different organic solvents (methanol and acetone) and aqueous extracts at different concentrations (1000 g ml-1), and time intervals. The results obtained showed that the extracts of the selected composites inhibited the growth of one or the other fungus, in different extracts to certain degrees at different time intervals and concentrations except the aqueous extracts of Ageratum conyzoides and Tagetus erecta that has no effect on Fusarium oxysporum and Alternaria heterosporus respectively. Acetone extract of T. erecta was the most effective in inhibiting the growth of Alternaria heterosphorus, followed by the acetone extract of Cirsium arevensis and methanol extract of Parthenium hysterophorus. The methanol extract of A. conyzoides was the most active against Fusarium oxysporum. Rhizoctonia solani was most inhibited by the methanol extract of A. conyzoides, followed by acetone extract of C. arvensis. The acetone extract of A. conyzoides proved to be highly effective in inhibiting the growth of Sclerotium rolfsii followed by acetone extract of T. erecta. Thus, the above mentioned results clearly indicate that there is a vast potential in the botanicals to be used safely against pests.
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