Atividade do óleo volátil, fases e extrato etanólico de Piper aduncum L. contra Corynespora cassiicola (Berk. e M.A. Curtis) C.T. Wei, agente causal da mancha-alvo do tomateiro (Lycopersicon esculentum Mill.)

Abstract

The dark-brown spot is a disease that occurs in the leaves of the tomato tree and is caused by the fungus Corynespora cassiicola. The fungus is considered cosmopolitan and nonspecific because of the wide host range and geographical distribution. Due to the absence of resilient and grow commercial chemicals registered in Brazil to control the disease the same is done with the use of alternative products so healing. This paper reports the in vitro antifungal effect of the ethanol extract phases and volatile oil from Piper aduncum and prophylactic and curative effect of aqueous extract of P. aduncum in tomato seedlings. The aqueous extract was obtained by macerating 300 g of fresh leaves in 2 L of water, ethanol extract by means of cold maceration of leaves with ethanol, the essential oil obtained by the method of hydrodistillation of the dry leaves, the the hexane, chloroform, N-butanol and hydroalcoholic through the fractionation of the ethanol extract by the process of liquid-liquid partition. For in vitro assays were performed in petri dishes, the antifungal effect of the ethanol extract phases and volatile oil of P. aduncum on mycelial growth, and germination of conidia blades while in vivo via inoculation of conidia suspension of 104 conidia mL-1 in tomato seedlings of the cultivar Santa Cruz Kada, the analyzes were done before and after treatment with aqueous extract, evaluations of prophylactic and curative effect, respectively. The volatile oil of P. aduncum showed no inhibition on the mycelial growth of C. cassiicola concentrations tested. The ethanol extract, the hexane and chloroform showed antifungal effect in 10000 μg.mL-1 concentration on mycelial growth and spore germination. The minimum inhibitory concentration on the mycelial growth was in 2000 μg.mL-1 of the hexane phase, this same concentration was found for the germination of conidia in the ethanol extract. The aqueous extract of P. aduncum the test of curative effect at dosages 1:1 and 1:2, showed significant effect in reducing the severity of the disease. The calculation of AUDPC confirming curative effect at all doses tested. In testing the prophylactic aqueous extract showed no effectiveness in controlling the disease