Potencial fungitóxico do óleo essencial de Lippia gracilis (Schauer) in vitro sobre fitopatógenos.

Abstract

Pre and post-harvest diseases caused by phytopathogenic fungi have a significant impact on agriculture worldwide, leading to reductions in profit due to significant losses during all stages of production. This study evaluates the in vitro effect of the essential oil of Lippia gracilis on phytopathogenic fungi aiming to provide a environmentally safe product for the control of plant diseases. The experiment was carried out in a completely randomized experimental design with eight treatments in five replicates each. The essential oil was incorporated into the PDA culture medium (Potato-Dextrose-Agar) and poured into Petri dishes. The treatments comprised different concentrations of the oil (0.0125, 0.025, 0.05, 0.1, and 0.2%), a negative control (0.0%), and two positive controls supplemented with commercial fungicides. The plates were inoculated with the fungi Colletotrichum gloeosporioides, C. musae, C. fructicola, C. asianum, Alternaria alternata, A. brassicicola, Fusarium solani, F. oxysporum f. sp. cubense, and Lasiodiplodia theobromae and incubated for seven days at 27±2°C. To verify the difference among treatments, we measured the following variables: percentage of mycelial growth inhibition (PGI) and index of mycelial growth speed (IMGS). All the oil concentrations of L. gracilis inhibited the mycelial growth of the evaluated fungi. The complete inhibition occurred at concentrations from 0.0125 to 0.1%. The treatments with oil had similar or higher efficiency than commercial fungicides.