Overview of citrus huanglongbing spread and management strategies in Brazil

Huanglongbing (HLB) has been a serious threat to the citrus industry worldwide. After its first report in Sao Paulo State, the main citrus production area in Brazil, the disease spread to the States of Minas Gerais, Parana and Mato Grosso do Sul. Attempts to cure plants or remiss disease symptoms and damages have been evaluated and showed to be inefficient and nonviable. The development of resistant or tolerant varieties to the bacteria or its insect vector, the Asian citrus psyllid Diaphorina citri, is still a long term challenge. Earlier HLB management has been based on preventive measures such as planting of healthy nursery trees, elimination of diseased trees, and vector control. Supported by both research data and citrus grower experiences, HLB management in Sao Paulo and Triângulo/Sudoeste Mineiro citrus belt has been improved from measures individually applied only into the orchards to regional disease management, including differentiated psyllid control in the orchards based on tree location and shoot flushing, area-wide coordinated control of psyllids, and removal of inoculum sources in noncommercial properties in the vicinity of commercial orchards. In addition, the negative impact of HLB on orchard production and longevity has been reduced with wide adoption of better cultural practices such as high-density planting, irrigation, and adequate nutrition. Unlike in other countries where HLB reached epidemic levels, the management of HLB in Sao Paulo and Triângulo/Sudoeste Mineiro citrus belt has been considered a success case and has ensured the maintenance of citrus production and competitiveness of the Brazilian citrus industry while new, more durable, and sustainable measures are not yet available.