Effects of Silicon On Pest Management and Productivity In Sugar Apple (Annona squamosa) Trees In Brazil

Sugar apple is an important fruit crop in Brazil grown commercially in semi-arid regions, with Bahia state being the largest producer. The cultivated area is estimated at 7,100 ha and almost all orchards have been established using seedlings. Silicon (Si) is involved in regulating physical functions of evapotranspiration and capable of forming a physical barrier to fungi, bacteria and insects. The objective of present work was to verify the effect of Si on pest management (fruit borer and mealy bugs) and productivity in sugar apple trees under irrigated conditions. The experiment was carried out at an experimental area of Unimontes, in Janaúba, Minas Gerais, Brazil. The experimental design consisted of randomized blocks with five treatments, five repetitions, and one plant per parcel. The following treatments were performed: control (No Si), 40, 80, 160, and 320 kg.ha^-1 SiO₂ (0.4, 0.8, 1.6, and 3.20 kg Si per plant, respectively). The product was applied directly to soil. The following characteristics were evaluated: physical and chemical characteristics of the soil, chemical analyses of the leaves, vegetative and reproductive characteristics of the plants, physical-chemical characteristics of the fruits and incidence of fruit borer and mealy bugs. The results were submitted to analysis of variance and regression analyzes. No significant differences were observed between the characteristics evaluated. Comparing the levels of Si in the soil before and after application, increments of 48.17% at the depth 0.0 – 0.2 m, and 67.31% at the depth 0.2 – 0.4 m were observed. The Si content in leaves and fruits was 0.52% and 0.50%, respectively. An average of 12kg of fruits per plant was observed, with a productivity of 11.41 tons per hectare. The maximum incidence observed for fruit borer was 13.33% and 14.39% for mealy bugs, respectively. Several factors are involved in pest management, such as the quantity of Si applied, physiology of the plant, and capacity of translocation and accumulation of this element to aerial parts.