Region-wide comprehensive implementation of roguing infected trees, tree replacement, and insecticide applications successfully controls citrus HLB.

Huanglongbing (HLB) is a devastating citrus disease worldwide. A three-pronged approach to controlling HLB has been suggested, namely, removal of HLB-symptomatic trees, psyllid control, and replacement with HLB-free trees. However, such a strategy did not lead to successful HLB control in many citrus producing regions. We hypothesize this is because of the small-scale or incomprehensive implementation of the program, conversely, a comprehensive implementation of such a strategy at regional level can successfully control HLB. Here we investigated the effects of region-wide comprehensive implementation of this scheme to control HLB in Gannan region, China, with a total planted citrus acreage of over 110,000 ha from 2013-2019. With the region-wide implementation of comprehensive HLB management, overall HLB incidence in Gannan decreased from 19.71% in 2014 to 3.86% in 2019. A partial implementation of such a program (without a comprehensive inoculum removal) at the regional level in Brazil resulted in HLB incidence increasing from 1.89% in 2010 to 19.02% in 2019. A dynamic regression model analyses predicated that in a region-wide comprehensive implementation of such a program, HLB incidence would be controlled to a level of less than 1%. Economic feasibility analyses showed that average net profits were positive for groves that implemented the comprehensive strategy, but negative for groves without such a program over a ten-year period. Overall, the key for the three-pronged program to successfully control HLB control is the large scale (region-wide) and comprehensiveness in implementation. This study provides valuable information to control HLB and other endemic diseases worldwide.