IN VITRO EVALUATION OF ANTI FUNGAL ACTIVITY OF SOME MEDICINAL PLANTS AGAINST HELMINTHOSPORIUM ORYZAE, THE INCITANT OF BROWN SPOT DISEASE OF PADDY

Brown spot of rice incited by Helminthosporium oryzae is a serious disease and cause considerable yield loss. Several fungicides have been reported to control the disease effectively. With the increase in awareness on the toxic hazards of chemicals to crops, consumers and environment, the importance of indigenous natural products in plant disease control has been recognized. In the present investigation, four medicinally important plant species were screened for fungitoxicity against H. oryzae. Among the plant species assayed, crude extracts of garlic bulb (20%), Lawsonia inermis(80%) and Vinca rosea (100%) lesves recorded complete inhibition of mycelial growth and are on par with Hinosan (0.1%) and neem leaf extract recorded 85% reductin in mycelial growth over control at 80 % concentration . Since garlic was found to be more effective than other plant extracts, a detailed in vitro screening study was conducted to find out the effective concentration.