Abstract

José Baccarin, Jorge H. Ambrosio and Antônio Irineu Salles

The present study aimed to evaluate the toxicity and preventive action of essential oils in growth of cotton ramulosis, Colletotrichum gossypii var. cephalosporioides, in vitro and in vivo conditions. Six fungusisolates obtained from cotton belts, in Southern and Mid-West Brazilian regions were submitted to different oil concentrations in bioassays and inhibition of mycelia growth were evaluated during 7 days. Then, the selected oil was used in a preventive bioassay carried out in greenhouse using a susceptible cotton cultivar infected with fungus-conidia at 1.0 × 106 mL-1. Plants in greenhouse were daily evaluated during 30 days. Among all samples evaluated, clove oil at low concentration (500 ppm) provided best results as to fungusgrowth inhibition. The disease severity was reduced to 60% in relation to control (no-infected plants). These results mean an interesting alternative in the preventive control of cotton ramulosis, especially to small farmers which often have adopted an agro-ecological management for disease control of crops.