Citrus canker
Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit.Citrus canker is mainly a leaf-spotting and rind-blemishing disease, but when conditions are highly favorable, it can cause defoliation, shoot dieback, and fruit drop.A number of types of citrus canker diseases are caused by different pathovars and variants of the bacterium:[4] Plants infected with citrus canker have characteristic lesions on leaves, stems, and fruit with raised, brown, water-soaked margins, usually with a yellow halo or ring effect around the lesion.Also, damage caused by citrus leaf miner larvae (Phyllocnistis citrella) can be sites for infection to occur.In the field environment, the time for symptoms to appear and be clearly discernible from other foliar diseases varies; it may be on the order of several months after infection.The effector interacts with host machinery to induce transcription for genes that regulate plant hormones such as gibberellin and auxin.Pruning or hedging can cut open mesophyll tissues, creating wounds through which the plant may be directly infected.Additional diagnostic tests (antibody detection), fatty-acid profiling, and genetic procedures using polymerase chain reaction can be conducted to confirm diagnosis and may help to identify the particular canker strain.Quarantine measures are implemented in areas where citrus canker is not endemic or has been obliterated to prevent the introduction of X. axonopodis.For example, areas with strong wind are avoided to decrease the dispersal of bacterial inoculum to the susceptible citrus trees.[8][4] Once citrus canker is introduced into a field, removal of the infected trees is enacted to halt further spread of the bacteria.[14] In the process, the infected trees are uprooted and burned, as the bacteria can survive on the lesions of woody branches for years.As a sanitation measure, the workers in citrus orchards are required to do thorough decontamination of personnel and equipment to prevent the spread of bacteria from the infected areas.Because of its rapid spread, high potential for damage, and impact on export sales and domestic trade, citrus canker is a significant threat to all citrus-growing regions.Eradication was successful, with permission to replant being granted to farmers by the biosecurity unit of the Queensland Department of Primary Industries in early 2009.Despite eradication attempts, by late 2005, the disease had been detected in many places distant from the original discovery, for example, in Orange Park, 315 miles (500 km) away.
EPPO CodeCitrusXanthomonasSoutheast AsiaScientific classificationBacteriaPseudomonadotaGammaproteobacteriaXanthomonadalesXanthomonadaceaeBinomial nameC H HasseSynonymsGram-negativegenomebase pairspathovarskey limebitter orangepomeloSaudi Arabiahurricanesstomatabiofilmxanthantranscriptional activator-like (TAL) effectorstype III secretion systemgibberellinpolymerase chain reactionClara H. HassefungoidbacterialGrapefruitKaffir limetrifoliate orangetangerinestangorstangelosC. sinensisC. aurantiumCitronMandarinsCalamondinkumquatIntegrated Pest Managementnursery treesCentral AfricaMiddle EastBangladeshPacific IslandsFloridaNorthern Territorycentral QueenslandC. glaucaEmeraldQueensland Department of Primary IndustriesWestern Australiastate of São PauloGeorgiaDade CountyGulf statesSouth CarolinaMiami-Dade County, FloridaOrange ParkBacterial blight of cassavaWayback MachineUnited States National Agricultural LibraryspeciesAustralian and Papuan wild limes groupIchang papedaKumquats groupMandarin orangeMangshanyeganMountain citronRyukyu mandarinhybridsOrangesweet orangecultivarsAlemowAmanatsuAssam lemonBergamot orangeBizzarriaBlood limeBlood orangeByeonggyulBiasongCam sànhCara Cara navel orangeCitrangeCitrumeloClementineCoorg orangeDaidaiDekoponEncoreFairchild tangerineFlorentine citronForbidden fruitGinger limeHarukaHassakuHebesuHeen naranHyuganatsuImperial lemonIndian wild orangeIyokanJabaraJaffa orangeJamaican tangeloKabbadKabosuKaji NemuKakadu limeKanpeiKawachi bankanKhasi papedaKinkoji unshiuKinnowKishu mikanKiyomiKobayashi mikanKomikanLaraha