Dinâmica populacional do psilídeo e incidência de hlb em laranja valência conduzida em diferentes porta-enxertos, espaçamentos e estratégias de controle do vetor

Abstract

Huanglongbing (HLB) is the most restrictive disease in citrus farming worldwide, requiring rigorous management of its insect vector, the psyllid Diaphorina citri. This study aimed to evaluate integrated management strategies for the vector and HLB in a young Valencia orange orchard under the influence of different rootstocks (citrandarins IAC 3155, Barretos, Itajobi, Santamélia and the citrumelo Swingle), planting spacings (1.5, 2.0, 2.5 and 3.0 m) and control strategies (physical barrier with processed kaolin and chemical control with thiamethoxam via drench). The experiment was conducted at the Sylvio Moreira Citrus Center in Cordeirópolis, SP, evaluating vegetative development, sprouting dynamics, psyllid population fluctuation, HLB incidence and severity, as well as the residual effect of the insecticide. The results demonstrated that vigorous rootstocks (IAC 3155 and IAC 3073 Barretos) induced greater canopy growth, while IAC 3026 Santamélia confirmed its dwarfing characteristic. Higher planting density (1.5 m between plants in the row) accelerated coverage in the planting row and reduced the total intensity of sprouting. A strong positive correlation was found between sprouting peaks and population outbreaks of D. citri, with the Swingle and IAC 3073 Barretos rootstocks favoring greater attraction of the vector. Fortnightly spraying with kaolin acted as an effective physical and visual barrier, reducing the insect population density by up to 72% during peaks. Although the incidence of HLB remained high (>90%) throughout the area, kaolin significantly reduced disease severity and symptom progression, with optimized protection in denser plantings. In chemical control, the rootstock variety did not influence the insecticide's efficiency, which showed excellent control and residual effect for 56 days, covering two reinfestation cycles. From the 57th day onwards, the depletion of the molecule's systemic protection in the plant reduced the product's effectiveness. It is concluded that the adoption of less vigorous rootstocks, combined with denser planting and the combination of kaolin with systemic insecticides, constitutes a strategy for mitigating the HLB-psyllid complex.