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Citrus greening, also called Huanglongbing or yellow dragon disease, is a bacterial disease that attacks the cascular system of plants. Once infected, there is no cure and can cause citrus trees to produce bitter and inedible fruit. The yellowing spreads, and trees decline and die.

DISEASE SYMPTOMS

  • Yellow shoots
  • Mottled leaves
  • Small fruit with poor juice quality

CAUSAL AGENT

In Florida, the disease is associated with Candidatus Liberibacter asiaticus, a bacterium that has not yet been cultured in the laboratory. In other parts of the world, this is disease is associated with Candidatus L. americanus and Candidatus L. africanus and may be spread by psyllids, which are insects that feed on plant juice.

HOST RANGE

Citrus species, and several other planbs that host the bacterium.

GEOGRAPHIC DISTRIBUTION

Citrus greening is present in all Florida counties with commercial citrus groves and has been found in other states including Texas and California. It is present in many citrus-producing counties in Asia, Latin America, and Africa.

SPREAD of the PATHOGEN and CONTROL OPTIONS

In Florida, this pathogen is pimarily spread from tree to tree by the Asican citrus psyllid (Diaphorina citri), a small insect, but can also be transmitted by grafting. Currently, spread of the disease is conrolled by insecticides. Novel methods to maintain health of infected trees and to prevent new infections are areas of of active research at the University of Florida.

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Information from Fresh From Florida and by Erica Goss, EPI and UF/IFAS Department of Plant Pathology.