Status of Huanglongbing (HLB) outbreaks in Florida, California and Texas

Abstract

Nowhere in the U.S. is Huanglongbing (HLB) under adequate control due to the lack of effective tools to reduce spread of the vector, Diaphorina citri (Asian citrus psyllid), and transmission of the associated pathogen, Candidatus Liberibacter asiaticus, in the absence of disease resistance in commercial citrus varieties. In Florida, Asian citrus psyllid was well established by the time of HLB discovery and growers did not remove trees to eliminate inoculum, so there was no chance of controlling the epidemic. Based on the Florida experience, Texas proactively controlled the vector by implementing area-wide management and disease spread was slower than in Florida, however, they also did not remove infected trees. California controlled both ACP and tree inoculum and have delayed the development of an epidemic in the Central Valley. This situation is aided by topographic isolation from the Los Angeles basin where ACP and HLB are endemic and a climate distinctly different from other citrus growing regions in the U.S.