Inhibition of Drechslera heveae (Petch) M. B. Ellis, causal organism of Bird’s eye spot disease of rubber (Hevea brasiliensis Muell Arg.) using plant extracts

Abstract

The in vitro and in vivo antifungal potency of twenty-one plant extracts selected from fourteen families were evaluated for their botanical fungitoxicants on Drechslera heveae. Extracts of Ageratum conyzoides, Allium sativum, Azadirachta indica, Jatropha curcas, and Ocimum basilicum were selected for evaluation of concentration effects on D. heveae. Treatment with Ocimum basilicum resulted in the lowest mycelial growth at 100% extract concentration.  The four concentrations (10%, 25%, 50% and 100%) of extracts of Ageratum conyzoides, Allium sativum and Ocimum basilicum gave total conidial inhibition of the pathogen in liquid media. Extracts of Allium sativum, and Ocimum basilicum at concentrations of 25% - 100% resulted in 100% conidial germination in the solid media. An in vivo  evaluation showed that treatment with 100% O. basilicum  gave disease index (D.I) of 33.33% which was significantly lower than the control 50% D.I at 5% level of probability