Citrus greening disease
Citrus greening disease or yellow dragon disease (calque of Chinese: 黃龍病; pinyin: huánglóngbìng abbr. HLB) is a disease of citrus caused by a vector-transmitted pathogen. The causative agents are motile bacteria, Liberibacter spp. The disease is transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae, also known as the two-spotted citrus psyllid. It has no known cure. It has also been shown to be graft-transmissible.
| Citrus greening disease | |
|---|---|
Citrus greening disease on mandarin oranges | |
| Common names | HLB, citrus vein phloem degeneration (CVPD), citrus greening disease, yellow shoot disease, yellow dragon disease, leaf mottle yellows in the Philippines, citrus dieback in India |
| Causal agents | Liberibacter spp. (L. asiaticus, L. africanus, L. americanus) |
| Hosts | citrus trees |
| Vectors | Diaphorina citri, Trioza erytreae |
| EPPO Code | 1LIBEG |
| Distribution | Asia, Africa, United States |
Three different types of HLB are currently known: the heat-tolerant Asian form, and the heat-sensitive African and American forms. The disease was first described in 1929 and first reported in South China in 1943. The African variation was first reported in 1947 in South Africa, where it is still widespread. Eventually, it affected the United States, reaching Florida in 2005. Within three years, it had spread to the majority of citrus farms. The rapid increase in this disease has threatened the citrus industry not only in Florida, but the entire US. As of 2009, 33 countries have reported HLB infection in their citrus crop.