Lessons from a case of successful eradication of citrus canker in a citrus-producing farm in São Paulo State, Brazil

Asiatic citrus canker (ACC), caused by the bacterium Xanthomonas citri subsp. citri, is one of the most serious diseases affecting citrus worldwide. In areas under quarantine/eradication, such as São Paulo state (SPS), Brazil, the impact of ACC is related to the production costs for inspections and tree removal. Several protocols for eradication were adopted in SPS since the first detection of ACC in 1957. Among these, the one carried out from 1999 to 2009 was the most effective for maintaining the disease at a very low level throughout the state. That protocol mandated periodic inspections and removal of symptomatic and asymptomatic trees based on disease incidence in the block. After 2009 the eradication protocols were less stringent and ACC incidence continued to increase. This study aimed at identifying the key factors for the successful eradication of ACC in a farm located in SPS. Data on the outbreaks from 2006 to 2010 were collected and the related control measures adopted. The farm remained under quarantine from July 2006 to March 2010. Twelve disease foci were detected from July 2006 to January 2008 and incidence of symptomatic tress ranged from 0.05% and 0.43%. The successful eradication of ACC in this farm is attributed to the relatively low number of diseased trees in all foci detected in the course of frequent and well-executed inspections. The results of this case study may be used to guide containment protocols in other citrus production areas of Brazil or countries where ACC is either absent or has a low incidence.