Métodos de aplicação de óleos essenciais no controle da antracnose em frutos de bananeira Prata-anã

Abstract

To verify the effects in vitro and in vivo of the essential oils of clove, thyme, ginger and tea tree oil in the development of Colletotrichum musae, associates to two application ways, one by contact and another by fumigation, and later to evaluate the physical-chemical characteristics of the fruits, two experiments were carried out. In the first one, the objective was to evaluate the effect of the essential oils on the development of Colletotrichum musae in vitro and in vivo by the application method for contact. Solutions of four essential oils of the species clove (Eugenia caryophyllus), tea tree oil (Melaleuca alternifolia), thyme (Thymus vulgaris), ginger (Zingiber officinale) were used, in four concentrations: 2, 4, 6 and 8 overline mu*L * m * L ^ - 1 that were added to the culture media. It was adopted as control only the culture medium. The appraised variables were germination, mycelia growth and conidia production. For the experiment in vivo the fruits were immersed in solutions containing the different essential oils in the concentrations of 2, 4, 6 and 8 mu L. m * L ^ - 1 , the control consisted of the immersion just in water without the oil. Every 3 days it was evaluated incidence and severity of the anthracnose. The experiments were carried out in an entirely randomized design in a factorial scheme 4 * 4 + 1 The averages were submitted to Kruscal-Wallis no parametric statistical analysis. The concentration of 6mu*L / m * L of clove oil is the most efficient in controlling the mycelia growth, sporulation and germination of C. musae. In the experiment in vivo, the treatment by immersion of Prata-ana banana fruits in solution of essential oils is not recommended since causing phytotoxity. The second experiment aimed to determine the best concentration and essential oil to control the development of C. musae in vitro and in vivo and later to evaluate the physical-chemical characteristics of the fruits treated with essential oils by the fumigation method. To accomplish that method, dosages of essential oil were added in filter paper glued in the cover of each Petri plate at concentrations of 2, 4, 6 and 8mu*L The appraised variables were germination, mycelia growth and conidia production. For the experiment in vivo the fruits were wrapped in plastic sacks on a tray of expanded polyethylene together with pieces of filter paper measuring 3c * m ^ 2 containing dosages of the essential oils in the concentrations of 80, 160, 240 and 320 µL.mL¹, the control consisted of the addition of 80 µL of distilled water on the filter paper and in the treatment with the Imazalil fungicide in the concentration of 2 mL/L. Every 3 days incidence and severity of the anthracnose was evaluated. To evaluate the physical-chemical characteristics of the fruits an experiment it was accomplished applying the essential oils in the concentration of 320 µL by fumigation. The experiments were in entirely randomized designs in factorial scheme 4x4+2. The averages were submitted to Kruscal-Wallis no parametric statistical analysis. The oils of tea tree oil and ginger controlled the incidence and the severity of the anthracnose in the fruits. The post-harvest characteristics of loss of fresh mass and coloration of the pericarp were maintained by the ginger and thyme oils.