Óleos essenciais de citros no controle do crestamento bacteriano do feijoeiro

Abstract

Essential oils are derived from plants that may have different biological activities. This work aimed to evaluate essential oils from different citrus species in the control of bacterial blight of common bean, caused by Xanthomonas axonopodis pv. phaseoli. Essential oils of Citrus sinensis, C. limon and C. nobilis were evaluated, as well as the surfactant Tween 20 and the water control. In in vitro conditions, the antimicrobial effect on the bacteria was evaluated. The protective effect of 0.25% essential oils on common bean plants was also evaluated, with application of essential oils 72 hours before or after inoculation with the pathogen, as an indicator of the preventive or curative effect, respectively. The incidence and severity of the disease were evaluated. The essential oils of C. nobilis, C. limon and C. sinensis, as well as Tween 20, showed inhibitory action when in direct contact with Xanthomonas axonopodis pv. phaseoli. Treatments with citrus essential oils did not reduce the severity of bacterial blight, but in general the preventive application showed lower incidence and severity when without wounds in relation to the curative application. The results demonstrate the effect of citrus essential oils on X. axonopodis pv. phaseoli, mainly due to its preventive and direct action on the pathogen.