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Open Access Publications from the University of California

First Detection of Huanglongbing and Implementation of its Mitigation Efforts in Texas


After six years of intensive statewide surveys, Huanglongbing (HLB) was first detected in two adjacent commercial groves in Texas in 2012, and Candidatus Liberibacter asiaticus (CLas) was found associated with the disease. Assessment of affected trees within the two infected groves was made by visual inspection of foliage and PCR-testing of symptomatic tissue.  HLB-infected trees exhibited an aggregated distribution and a strong perimeter effect in the two groves. While in one grove (sweet orange), more qPCR positive trees were observed in the south-eastern side of the grove, in the other (grapefruit) more HLB-infected were found on the western border, adjacent to the sweet orange grove suggesting movement of infected psyllids between the two groves. The Asian psyllid vector, Diaphorina citri Kuwayama, known vector of CLas, reported for the first time in 2001, is widespread in Texas. In an effort to reduce the risk of HLB in Texas, a proactive area-wide psyllid control program was initiated in 2010 which has contributed to significant reduction of psyllid populations in Texas. The detection of HLB has led to an intensification of psyllid control measures in groves within a mile radius of the HLB-positive sites, both in commercial and residential settings. All known infected trees have been removed and a five mile-radius quarantine has been put in place to regulate movement of all Rutaceae plants and to ensure safe harvesting of citrus.

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