In vivo Testing of Plant Extracts in Controlling Rice Brown Spot Disease Through Folia Application

Abstract

Background: Rice brown spot disease is caused by the fungus Bipolaris oryzae (Breda de Haan), which is one of the most significantly devastating diseases in rice. Nowadays, biological control agents and plant extracts as botanical fungicides are used to develop an alternative method to control this disease and reduce the use of synthetic fungicides. Therefore, the efficacy levels of Hydnocarpus anthelminthicus Pierre ex Laness., Crateva magna (Lour.) DC., Caesalpinia sappan L., Xanthophyllum lanceatum J. J. Sm. and Carallia brachiata (Lour.) Merr. crude extracts were tested in vitro against B. oryzae and their control of rice brown spot disease under greenhouse conditions. Methods: Five plants namely; H. anthelminthicus, C. magna, C. sappan, X. lanceatum and C. brachiata were cleaned with tap water and air dried at 28±2°C then cut into small pieces and ground into fine powder and stored at 4°C until used. Plant crude extracts was prepared using ethanol as solvent. Result: The results showed that the H. anthelminthicus crude extract showed the best antifungal activity against B. oryzae at the highest dose tested, causing 93% mycelial growth inhibition. Under greenhouse testing, the application of the H. anthelminthicus, X. lanceatum, C. brachiata, C. magna and C. sappan crude extracts at a concentration of 50,000 ppm effectively suppressed and reduced rice brown spot incidence caused by B. oryzae when applied once 30 days after transplanting (DAT). Interestingly, the H. anthelminthicus crude extract at a concentration of 10,000 ppm displayed the greatest suppression of the development of rice brown spot disease in terms of disease incidence when applied twice 30 DAT and 45 DAT compared with unprotected control. The results of this study indicated that H. anthelminthicus could provide botanical fungicide protection against rice brown spot disease to reduce the use of synthetic fungicides © 2023, Indian Journal of Agricultural Research.All Rights Reserved.