Inhibition of Colletotrichum gloeosporioides (Penz) Sac. causal organism of rubber ( Hevea brasiliensis Muell. Arg.) leaf spot using plant extracts

Abstract

In vitro and in vivo antifungal evaluations were carried out on twenty-one plants selected from fourteen families on a folial pathogen of para rubber, Colletotrichum gloeosporioides (Penz). Sac. Extracts of Ocimum basilicum L. and Allium sativum L. exhibited total inhibitory effects on the mycelial growth of C. Gloeosporioides. An evaluation of concentration effects was carried out using four concentrations of five selected plants: A. sativum, Jatropha curcas, O. Basilicum, Vernonia amygdalina and Ageratum conyzoides. A. sativum and O. basilicum totally inhibited conidial germination 24 h after inoculation, and conidial germination in liquid amended media was recorded only in the A. conyzoides amended liquid media. An in vivo evaluation showed that treatment with 100% O. basilicum resulted in disease index (D.I) of 31.7% which was significantly lower than the control 65% D.I at 5% level of probability.