Epidemic Regularity and Control Effect of Huanglongbing （HLB） in Different Management Approaches

In order to reveal the epidemic regularity of Huanglongbing （HLB） in different management approaches, different citrus production areas were selected between 2002 and 2012 to compare epidemic regularity of different types and control effects of different management approaches with plant incidence rate. All survey data in 11 years were used to build a mathematical model, and epidemic evolution and control effects were quantitatively analyzed. The results indicated that diffusion and prevalence of HLB generally increased linearly. In naturally growing citrus orchards without artificial control, the annual diseased plant rate was 11.11%, and the epidemic diffusion model was y1 = 12. 24x - 1.382 8 （ n =9, r =0. 976 9 ＊ ＊ ）. Under general prevention and control conditions, the annual diseased plant rate was 4.69%, the epidemic diffusion model was Y2 = 5. 449 8x - 1.603 5 （ n = 11, r =0. 974 9 ＊ ＊ ）, and the control effect was 43.93% （22.93% - 55.04% ）. In citrus orchards with integrated prevention and control, the epidemic diffusion model was Y3 = 0. 366 3x - 0. 342 2 （ n = 11, r = 0. 989 8 ＊ ＊ ）, the control effect was 96.15% （94.95% -97.40% ）, and the annual diseased plant rate was 0.31%. Thus, HLB is preventable and controllable as long as integrated prevention and control work is implemented well.