Temporal Progress of Huanglongbing Epidemics and the Effect of Noncommercial Inoculum Sources on Citrus Orchards in Sao Paulo State, Brazil

Author(s)

Pazolini, Kelly ^[1] ; Arruda, Josiclea H. ^[1] ; Chinelato, Gressa A. ^[1] ; Bergamin Filho, Armando ^[1] ; Belasque, Jose ^[1]

Affiliation

^[1] Univ Sao Paulo, Luiz De Queiroz Coll Agr, Plant Pathol Dept, BR-13418900 Piracicaba, SP - Brazil

• Document type: Journal article
• Source: PLANT DISEASE; v. 105, n. 9, p. 2472-2483, SEP 2021.
• Web of Science Citations: 1

Abstract

Huanglongbing (HLB) incidence is increasing and threatening citrus production in Sao Paulo State, Brazil, despite multiple efforts to control the disease and its vector, the Asian citrus psyllid (ACP) (Diaphorina citri). The objective of this research was to study the temporal dynamics of HLB epidemics, under intensive disease management, in 177 individual commercial citrus blocks on a single property in Sao Paulo State. The effect of internal and external sources of HLB-associated bacteria and its vector were explored based on the disease epidemics and vector dynamics in the studied area. To manage HLB, the property owner used healthy nursery plants, eradicated symptomatic trees, and used insecticides to control ACPs. Logistic and Gompertz models were fitted to the data to describe dynamics of HLB incidence for all blocks. The average number of ACPs per yellow sticky trap was determined for the same blocks for a period of four consecutive years. Both logistic and Gompertz models described the HLB epidemics well, although the Gompertz model provided a slightly better fit. Disease progress rates, HLB incidences, and average ACP count per trap in the 177 blocks were low compared with reports in the literature. HLB incidence and number of ACPs per trap were higher (P <= 0.05) in some citrus blocks located on the periphery of the property. A large number of noncommercial trees were found near the property and were a potential primary inoculum source of HLB-associated bacteria, accounting for the higher incidence of HLB and ACPs per trap in blocks located on the periphery of the property. These results support the recommended preventive measures to HLB management and the necessity of external actions, to include trees in commercial orchards, and noncommercial trees located near commercial citrus properties, in an attempt to maximize the effectiveness of these preventive measures. (AU)

• FAPESP's process: 13/20296-1 - Spatial and temporal dynamics of Huanglongbing (HLB) and its vector Diaphorina citri in commercial citrus orchards: tools for disease management and sampling methods
• Grantee: José Belasque Junior
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/01796-1 - HLB management enhancement employing the spatio-temporal epidemiology of the disease and its vector (Diaphorina citri)
• Grantee: Kelly Pazolini
• Support Opportunities: Scholarships in Brazil - Doctorate