Candidatus Liberibacter asiaticus
(Citrus Greening (Huanglongbing) ) |
||
|
Class: Alpha Proteobacteria Order: Rhizobiales Family: Phyllobacteriaceae Synonym(s): |
|
Description: Huanglongbing (HLB) in Chinese literally translates to Yellow Dragon Disease and it is caused by phloem-limited bacterium. That means that this bacterium attacks the phloem system of plants which is like the circulatory system in animals. This bacterium is carried to host plants by an insect vector, for Huanglongbing it is the psyllid insect Diaphorina citri.
Symptoms: Host(s): Citrus (lemon, lime, orange, grapefruit, kumquats etc.) In Texas, we are most concerned about the threat to Citrus plants both in our backyards and those used for commercial production. History: HLB is one of the most devastating diseases of citrus and since its discovery in Florida in 2005, citrus acreage in that state has declined significantly. In April 2012, after about a week of testing, the California Department of Food and Agriculture (CDFA) removed a pumelo tree with a lemon graft from Los Angeles County after the tree and an Asian citrus psyllid found on the tree both tested positive for Huanglongbing. In late 2012, the presence of HLB was confirmed in south Texas, where some orchards are now quarantined to prevent the infection from spreading. In just 7 short years this disease has spread to 7 states, including Texas, California and Florida that are crucial for the citrus industry.
Biology: The psyllid Diaphorina citri, transmits the bacteria when they feed on an infected plant and then feed on an uninfected citrus plant. The bacteria can be acquired by the insects in the nymphal stages and the bacteria may be transmitted throughout the lifespan of the psyllid. Ecological Threat: There are three forms of greening that have been described. The African form produces symptoms only under cool conditions and is transmitted by the African citrus psyllid Trioza erytreae, while the Asian form prefers warmer conditions and is transmitted by the Asian citrus psyllid Diaphorina citri. The American form (discovered first in Brazil) originated in China, so symptoms show under warmer conditions and it is transmitted by Diaphorina citri. HLB is known to occur in Florida, Louisiana, South Carolina, Texas and Georgia. HLB has caused a loss of 100.000 citrus acres in its first year (2005-2006) in Florida alone. For Florida, almost the entire state has established infection of Huanglongbing. As of 2021 in Texas, this disease has been detected in several areas throughout the state. The Texas Department of Agriculture (TDA) has instituted citrus quarantines to prevent the spread. Quarantined areas include: counties throughout Coastal Bend, Laredo, Rio Grande Valley and Gulf Coastal areas including Houston metroplex. For more information on the Asian Citrus Psyllid (Diaphorina citri) click here US Habitat: Where citrus trees grow, in states that are subtropical and maintain humidity levels above 50%. Distribution
Resembles: The yellowing of leaves can also be caused with over-watering of Citrus. However, if fruit production becomes asymmetrical and sour that is a strong indicator of Citrus Greening. Management: Informed citizens who adhere to citrus quarantines are necessary to stop the spread of Citrus Greening and Asian Citrus Psyllid to more counties throughout our state.
References
Data Source
Last Updated: 2024-02-01 by Ashley Morgan-Olvera, Texas Invasive Species Institute |
||
|