8. Activity of four plant leaf extracts against three fungal pathogens of rice.
Trop. Agric. (Trinidad), 68, 4, 1991, pp. 373-375
With a view to countering obvious pollution problems in the environment and avoiding the toxic effects of synthetic chemicals on non-target organisms, investigations on exploiting pesticides of plant origin are becoming increasingly important in the field of plant pathology.
Fresh leaves of P. betle, O. sanctum, N. arbor-tristis and C. limon were collected, washed thoroughly in tap water and sterile distilled water, oven dried at 45 _ 2 C and ground to obtain 1 kg dry powder from each.
Each powder was extracted with 95% ethanol and concentrated through a rotary vacuum pump flash-evaporator to a syrupy form weighing 130 g from each powder.
The plants were selected for the present study to screen against the major fungal pathogens of rice in vitro and in vivo.
The leaf extracts were effective in reducing the radial in vitro growth was found to be the best, followed of the pathogens and in checking the spread of blast, brown spot and sheath blight diseases of rice in vivo.
Though the leaf extracts from the other two plant species tested (N. arbor-tristis and C. limon) reduced the radial growth of the pathogens in vitro at a higher concentration, they failed to check their spread effectively in the glasshouse. P. betle and O. sanctum could be used as source of a pesticide of plant origin to combat the above three pathogens of rice in the field.
This is the first record for the control of three rice diseases in vivo using P. betle or O. sanctum leaf extracts.
Much of the plant kingdom still remains unexplored for possible exploitation against major fungal pathogens.
1202 92 - 10/129
Study, cassava, pathogens, biocontrol, CIAT
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