Huanglongbing of Citrus

Abstract

Huanglongbing (Chinese for yellow dragon disease or yellow shoot disease, abbreviated as HLB) also known as citrus greening, is a lethal, fast-spreading bacterial disease of citrus. HLB is the worst disease of citrus trees worldwide. HLB was first described in China in the early 1900s. It has since been reported in the citrus-producing regions of 45 countries worldwide except in Australia and in the Mediterranean Basin (da Graça et al. 2016). Wherever HLB has occurred, citrus production has been greatly reduced with the loss of millions of trees worldwide. The consequences of HLB are reduced yields, higher tree maintenance costs and potential tree death, all of which have negative impacts on profitability. HLB was first detected in the U.S. in Florida in 2005 and has since affected all of its citrus-producing areas, leading to a 75 percent decline in Florida’s $9 billion citrus industry (Hodges and Spreen 2012). Fifteen U.S. States or territories, including Arizona are under full or partial quarantine due to the presence of the Asian citrus psyllid (ACP), the vector of HLB-associated bacterium (USDA-APHIS-PPQ 2018).