Citrus Huanglongbing: The Pathogen and Its Impact

Fig. 23. Diagram of a citrus tree divided into 8 sections and used for HLB disease severity estimation or 0 to 5, within each section. Method used for visual assay of individual trees on Reunion Island HLB epidemiology plot.



Image from Plant Health Progress article:
Citrus Huanglongbing: The Pathogen and Its Impact