Effect of aqueous extracts of some medicinal plants on in vitro growth of <i>Botryodiplodia theobromae pat.</i>

Abstract

The development of Botryodiplodia theobromae Pat, was evaluated in chloramphenicol potato dextrose agar (cPDA) medium amended with aqueous extracts of eight plants used in Nigerian ethnomedicne. Linear mycelial growth in media containing unautoclaved or autoclaved extract was measured at 12 h interval for 48 h, while dry weight was determined after 48 h of incubation. Stroma production was determined after 7 days of incubation. Cassia alata was most inhibitory to the fungus and was followed by Azadirachta indica, Alchornea cordifolia and Baphia nitida respectively. Cyathula prostrata, Vernonia amygdalina, Euphorbia hirta and Zingiber officinale promoted radial mycelial growth of the pathogen. Autoclave heat treatment did not affect the inhibitory action of C. alata on the linear growth but reduced the efficacy of the leaf extract on dry weight and stroma production. Autoclaved extracts of A. cordifolia, A. indica, E. hirta and C. alata supported more stroma production, heat treatment did not stimulate production of more stroma on media containing extracts of C. alata, V. amygdalina and Z. officinale.. The inhibition of mycelial growth and stroma production by unheated aqueous extracts of some of the test plants suggests that effective control of the pathogen with extracts of medicinal plants is possible. Keywords:Botryodiplodia theobromae, medicinal plants, aqueous extracts, in vitro growth inhibition. [Global Jnl Agric Res Vol.2(1) 2003: 17-24]