ABSTRACT
The southern red mite, Oligonychus ilicis (McGregor) (Acari: Tetranychidae) can cause a significant reduction in the photosynthesis potential and the growth of new coffee plants (Coffea spp., Rubiaceae). Studies suggest that the leaf spraying of silicon (Si) leads to increase plants resistance in order to reduce infestations of insect pests such as herbivores, borers, sucking insects and mites. The objective of this study was to evaluate the effect of leaf spraying of potassium silicate (K2SiO3) to control the southern red mite in coffee plants. Experiments were conducted in coffee plants (Coffea arabica L.), grown in a greenhouse, by means of completely randomized design with six treatments: Dose 0 (control), 2, 4, 6, 8 and 10 liters of silicate potassium ha-1 and five replications. Plants treated with potassium silicate, regardless of the applied dose, had a lower O. ilicis infestation compared to the control, not allowing the population increase, thus a smaller damage in coffee leaves. The silicon content in leaves was higher in plants treated with the highest dose of potassium silicate. It was observed that there was induction of defense molecules such as tannins and lignin in plants sprayed with potassium silicate. It was concluded that the potassium silicate applied in leaf spraying had positive effect on reducing O. ilicis attack in coffee plants, even being a dicot. Therefore, the applications of potassium silicate by leaf spraying can be used in programs of integrated management of the southern red mite in coffee, with a view to sustainable management and environmental protection.