CORONA — A Southern California quarantine zone has been expanded in an effort to stop the spread of a disease that threatens the state’s multi billion-dollar citrus industry.
Hein Gerber and Christine Spreeth
First Fruits Consulting
Citrus greening disease takes two forms: Huanglongbing (HLB), the devastating Asiatic strain of citrus greening disease caused by the bacterium Candidatus leberibacter asiaticus and African greening disease, caused by the bacterium Candidatus lebiribacter africanus. Both forms can be spread by infected plant material or by citrus psyllid vectors, namely Diaphorina citri (Asiatic greening) and Trioza erytreae (African greening) (Gottwald et al., 2007). When a vector is carrying the bacteria, it is called a ‘hot vector’ (Jansen, 2019). The psyllid vectors transfer the disease-causing pathogens when they feed on plant sap from citrus leaves (Grafton-Cardwell et al., 2006).