Potential use of Siparuna guianensis essential oil for the control of Moniliophthora roreri in cacao

Abstract

Cacao (Theobroma cacao L.) is a crop of globally importance on whose production around 20 million people depend directly. The crop is threatened due to the incidence of diseases caused by phytopathogenic fungi such as Moniliophthora roreri, causing losses of more than 80 % of the annual production. For this reason, in this study, a natural product such as the essential oil (EO) obtained from Siparuna guianensis was evaluated as a control alternative. The chemical composition of the EO, as well as the antifungal effect in vitro and in vivo on M. roreri, the causal agent of moniliasis frosty pod rot, were determined in the cacao pods located in a commercial plantation in southern Huila, Colombia. 28 compounds were detected, predominating: D-Germacrene (26.5 %), (E)-nerolidol (21.5 %), β-caryophyllene (9.3 %), elemol (8.0 %), bicyclogermacrene (7.5 %), δ-elemene (3.5 %), β-elemene (3.0 %), and α-pineno (2.4 %). At a concentration of 1000 μg ml-1 of EO in vitro, an inhibitory effect of 98 % on the mycelial growth of M. roreri was obtained. In the in vivo test at concentrations of 1000 μg ml-1 and 750 μg ml-1, a direct relationship in the decrease of the incidence, external gravity, and internal gravity of M. roreri in cocoa pods was observed, using EO as fungicide. It was concluded that S. guianensis EO represents a great potential for the control of frosty pod rot.