In vitro Bioprospecting of Botanicals Towards Inhibition of Microbial Pathogens of Rice (Oryza sativa L.)

The global call on the use of botanicals sequel to control of phytopathogenic microorganisms causing diseases of food crops most especially on rice has not been given attention in the tropics. A study was conducted to evaluate the antagonistic effect (in-vitro) of aqueous and ethanol extracts of Eucalyptus lameldulensis and Moringa oleifera leaves at different concentration (5, 10, 20, 40 and 160mg/ml) on fungal and bacterial pathogens affecting the aerial part of rice. The isolated fungal pathogens were Curvularia sp., Helminthosporium sp., Monascus rubber and Pyricularia grisea while that of bacterial pathogens were Xanthomonas oryzae and Corynobacterium xerosis. The aqueous extract from the botanicals showed less inhibition compared to the ethanol extract. All the tested concentration levels with respect to aqueous and ethanol extracts were significantly (p<0.05) effective on the fungal and bacterial pathogens. The highest inhibitory activity was observed on Curvularia sp. for fungi and Xanthomonas oryzae for bacteria. Eucalyptus lameldulensis and Moringa oleifera leaves extracts are therefore recommended for management of microbial pathogens of rice.