Inhibition of Corynespora cassiicola With Extracts and Fractions of Exotic and Amazonian Plants

Abstract

The control of the disease by plant extracts is a financially and ecologically feasible alternative for tomato small holders in Amazonas. Extracts and fractions of P. sprucei, C. cajucara, P. marginatum and C. zedoaria were evaluated in vitro and in vivo on tomato plants against the pathogen C. Cassiicola pathogen. The aqueous plant extracts at concentrations of 0%, 10%, 20%, 30%, 40% and 50%, and the effect of the hexanic, ethyl acetate and methanolic fractions, were evaluated on mycelial growth, sporulation and conidium germination of the fungus. Direct bioautography was performed and the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined. Aqueous extracts of P. marginatum were used to evaluate the reduction of disease symptoms in tomato seedlings. The hexane and ethyl acetate fractions of P. marginatum reduced mycelial growth, spore formation and conidium germination. In direct bioautography, zones of mycelial growth inhibition were observed in the hexane and ethyl acetate fractions of P. marginatum, with MIC of 2.5 mg mL-1. P. marginatum extract reduced disease severity in tomato seedlings, but was not effective in controlling the pathogen as a single management procedure.