|    Asiatic citrus canker is a widespread
  bacterial disease in Asia and in certain other citrus-growing regions of the
  world.  It was eradicated from the
  United States after its introduction in the early part of this century.  New infestations of true Asiatic citrus
  canker have been recently detected in Florida, suggesting that the
  introduction of this serious pathogen may continue to be a threat.
          Strains
  of Xanthomonas axonopodis pv.
  citri vary in aggressiveness, but typically cause raised, corky lesions on
  fruit, stems, and leaves.  Under
  conditions favorable to the pathogen, severe branch die back and even death
  of trees can occur.  In most cases,
  younger leaves are considered to be most susceptible to infection, and damage
  caused by citrus leaf miner larvae (Phyllocnistis
  citrella) can be sites for infection to occur.  Within a controlled laboratory setting,
  symptoms can appear in 14 days following inoculation into a susceptible host.
  In the field environment, the time for symptoms to appear and be clearly
  discernible may be on the order of several months after infection.  Lower temperature prolongs appearance of
  the disease.  Citrus canker bacteria
  can stay viable in old lesions and other plant surfaces for several
  months.  The drier conditions of
  California are generally considered to be less conducive to the establishment
  and spread of bacterial diseases such as citrus canker, which depend on
  wind-driven rain and high humidity for initial infection.  But, University of California researchers
  recently discovered an avocado branch and trunk canker disease caused by
  another strain of Xanthomonas that
  is widespread in coastal counties of California.  This demonstrates that bacterial diseases of this type can
  persist in our climate on subtropical tree crops.          Between
  1915 and 1933, more than $6 million was spent in Florida alone on the first
  eradication effort for citrus canker in the southeastern United States.  In the more recent eradication effort in
  the 1980s, over 20 million trees were burned in Florida at a cost of nearly
  $94 million.  The bacterium is spread
  locally by wind-driven rain.  In
  Florida, over 16 million trees have been destroyed in an attempt to eradicate
  the disease after the current outbreak started in 1995.  It is now in 24 counties resulting in the
  entire state being placed under a USDA quarantine which prohibits shipment of
  citrus from Florida to any citrus-producing states.  The 2004-05 hurricanes spread the disease so far that in 2006,
  the USDA determined that eradication is no longer possible and ceased the
  tree removal program.  To protect from
  potential loss of citrus quality and productivity regulatory restrictions
  should be applied on the shipment of fruit from regions infested with citrus
  canker.   REFERENCES:   Bock, C .H., P. E. Parker & T. R. Gottwald.  2005. 
  The effect of simulated wind-driven rain on duration and distance of dispersal
  of Xanthomonas axonopodis pv. citri from canker infected citrus
  trees.  Plant Disease. 89:  71-80.   Cubero, J., J. H. Graham, T. Gottwald & T.
  Riley.  2000.  Quantitative PCR method for the diagnosis
  of citrus bacterial canker.  Applied
  and Environmental Microbiology 67: 
  2849-2852.   Gottwald, T. R., J. H. Graham & D. S. Egel.  1992.  Analysis of foci of infection of Asiatic
  citrus canker in a Florida citrus orchard. 
  Plant Disease 76:  389-396.   Gottwald, T. R., T. R. Graham & T. S.
  Schubert.  1997.  An epidemiological analysis of the spread
  of citrus canker in urban Miami, Florida, and synergistic interaction with
  the Asian citrus leafminer.  Fruits 
  52:  383-390.   Gottwald, T. R., J. H. Graham & T. S. Schubert.  2002.   Citrus Canker: The pathogen and its
  impact.  Plant Health Progress 2002.   Gottwald, T. R., G. Hughes, J. H. Graham, X. Sun
  & T. Riley.  2001.  The citrus canker epidemic in Florida –
  the scientific basis of regulatory/eradication policy for an invasive plant
  pathogen.  Phytopathology  91: 
  30-34.   Gottwald, T. R., X. Sun, T. D. Riley, J. H. Graham,
  F. Ferrandino & E. L. Taylor. 
  2001.  Geo-Referenced,
  Spatiotemporal Analysis of the Urban Citrus Canker Epidemic in Florida.  Phytopathology  92:  361-377.   Gottwald T. R & L. W. Timmer. 1994. The efficacy
  of windbreaks in reducing the spread of citrus canker caused by Xanthomonas campestris pv. citri. 
  Tropical Agriculture  72:  194-201.   Graham, J. H. & T. R. Gottwald.  1997. 
  Research perspectives on eradication of citrus bacterial diseases in
  Florida. Plant Dis. 75:  1193-1200.   Graham, J. H., T. R. Gottwald, J. Cubero & D.
  Achor.  2004.  Xanthomonas axonopodus
  pv. citri: Factors affecting
  successful eradication of citrus canker. 
  Molecular Plant Pathology 
  5:  1-15.   Graham, J. H., T. R. Gottwald, T. D. Riley, & M.
  A. Bruce.  1992.  Susceptibility of citrus fruit to
  bacterial spot and citrus canker. 
  Phytopathology  82:  452-457.   Leite Jr., R. P. & S. K. Mohan.  1990. 
  Integrated management of citrus bacterial canker disease caused by Xanthomonas campestris pv. citri in the state of Paraná,
  Brazil.   Crop Protection 9:  3-7.   Reedy, B. C. 
  1984.  Incidence of bacterial
  canker of citrus in relation to weather. 
  Geobios New Reports 3:  39-41.   Schubert, T .S., J. W. Miller, & D. W. Gabriel.  1996.  Another outbreak of bacterial canker of
  citrus in Florida.  Plant Dis. 80:  1208.   Schubert, T. S., S. A. Rizivi, X. Sun, T. R. Gottwald, J.
  H. Graham  & W. N. Dixon.  2001.  Meeting the challenge of eradicating
  citrus canker again in Florida.  Plant
  Disease  85:  340-356.   Stall, R. E. & E. L. Civerolo.  1991. 
  Research relating to the recent outbreak of citrus canker in
  Florida.  Annual Rev. Phytopathol.  29: 
  399-420.   Sun, X., R. E. Stall, J. Cubero, T. R. Gottwald, J. H.
  Graham, W. N. Dixon, T. S. Schubert, P. H. Chaloux, J. B. Jones, V. K.
  Stromberg, G. H. Lacy  & B. D.
  Sutton.  2001.  Detection and characterization of a new
  strain of citrus canker bacteria from key/Mexican lime and alemow in
  Florida.  Plant Disease 88:  1179-1188.   Verniere, C. J., T. R. Gottwald & O.
  Pruvost.  2002.  Disease development and symptom expression
  of Xanthomonas campestris pv. citri in various citrus plant
  tissues.  Phytopathology  93: 
  832-843     Wilson, M., S. S.
  Hirano  &  S. E. Lindow.  1999.  Location and
  survival of leaf-associated bacteria in relation to pathogenicity    and potential for growth within the
  leaf.  Appl. Environ. Microbiol.
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