Uso de óleos essenciais no controle da fusariose do abacaxi

Abstract

Pineapple is a fruit of great economic importance, being grown in several countries with tropical and subtropical climate. One of the biggest obstacles in pineapple cultivation is fusariosis, a disease that is difficult to control and can lead to the total loss of a plantation. In this case, alternative control combined with other disease management practices is of fundamental importance; the use of essential oils is one of the most promising options for plant disease control. The essential oils of rosemary pepper (Lippia sidoides) and lemon grass (Cymbopogon winterianus), have in their composition substances capable of inhibiting fungal growth acting as a natural fungicide. In this context, the present work has the objective of evaluating different concentrations of the emulsified based on essential oils of L. sidoides and C. winterianus in the control of Fusarium guttiforme in vitro and in vivo. In the in vitro experiment, the following concentrations of the emulsifier (250, 500, 750, 1000 and 1250 µL. L-1) were tested, a control and a fungicide control, being evaluated for 15 days. The concentrations of (1000 and 1250 µL.L-1) of the emulsified agent significantly influenced the inhibition of mycelial growth.. In the inhibition of germination, the concentrations of the emulsifier (250, 500, 750, 1000 and 1250 µL.L-1) were tested, a control and a fungicide control, evaluated at 6 and 24 hours after incubation, in this experiment the 6 h inhibition in the concentration of 1250 µL.L-1 was 100% compared to the control. The fungitoxic effect of the emulsifier on the pathogen's structures was confirmed via scanning electron microscopy-SEM, evidencing the flattening of the hyphae and the rupture of the cell wall. In the in vivo experiment, the inoculation of asymptomatic fruits was carried out in three different points of the fruit and later applied the treatments with the concentrations of (750, 1000, 1250, 1500 and 2000 µL.L-1) a control (water) and a control fungal (fungicide). The size of the lesions at the inoculation points (width and length) were evaluated. In the in vivo control, there was no significant difference between the evaluated treatments. The in vitro and in vivo experiments evaluated the fungicidal potential of essential oils emulsified in the control of pineapple fusariosis. The emulsified oil based on essential oils was efficient in the in vitro control of F. guttiforme in the inhibition of growth and in the germination of conidia; it has bioactive components capable of causing damage to the fungal cell wall.