Óleos essenciais no manejo da ferrugem na cultura do figo

Abstract

Rust fig (Ficus carica L) is caused by Cerotelium fici (Cast.) Arth., a disease that causes premature defoliation and significant damage to fruit production. The general objective is to study the epidemiology of C. fici, as well as disease control methods for the management in organic systems. We evaluated the best temperature and photoperiod for in vitro germination of C. fici urediniospores, through the use of temperatures of 10, 20, 23, 30 and 35 ° C, and the fotoperídos of 12-hours of light ou dark complete, in BOD with different amounts of spore suspension. The optimum temperature for germination of urediniospores was between 20 and 30 ° C. The 12-hour photoperiod provided smaller spore germination percentages than the continuous darkness. Germination of spores was favored by increasing the amount of suspension 0.5 mL to 1 mL, due to the suspension droplet drying while the amounts are smaller. Then, different concentrations of essential oils extracted from plants were tested for inhibition of germination of urediniospores in microtiter plates containing spores in this suspension concentration of 104 spores mL-1 and agar- water 2% culture. Concentrations of 1, 10, 100 and 1000 ppm of essential oil were evaluated, in two repeats of the experiment. Then we assessed concentrations of 5, 10, 15 and 20 ppm of these essential oils also into two repetitions of the experiment. The essential oils used were those of rosemary, lavender, chamomile, cinnamon, lemon grass, lemongrass, coriander, clove, lemongrass, fennel, eucalyptus, ginger, mint, orange, lime, basil, melaleuca, oregano and thyme. Using concentrations of 1-1000 ppm of each oil, stood out the cinnamon oil, oregano, rosemary, citronella, lemongrass, lavender, coriander and cloves with effects superior to others in inhibiting urediniosporal germination. Higher concentrations of essential oil have better control of germination of rust urediniospores. In concentrations of 5-20 ppm, better control of spore germination was found in cinnamon oil, followed by lemon grass oil and lavender, differing from basil oil, fennel, mint, cilantro, lime, chamomile, melaleuca, lemongrass, ginger and rosemary. Subsequently, we tested nine treatments for rust control in fig seedlings in the greenhouse (essential oils of rosemary, lavender, cinnamon, lemongrass, citronella, clove, coriander and oregano over the witness with application of water), in four concentrations (5, 10, 15 and 20 ppm) with two replications of the experiment. The severity of rust and calculated the area under disease progress curve were evaluated. The essential oils from cinnamon, lavender, lemon grass, rosemary, lemongrass, oregano, clove and coriander obtained results in the reduction of the fig tree rust severity, with the best results associated with cinnamon essential oil, followed by lavender oil, in higher concentrations. Increasing the concentration of essential oils from 5 to 20 ppm, showed linear trend of increment in controlling the disease