A new outbreak of Xanthomonas axonopodis pv. citri in Florida (US)
In Florida (US), a new outbreak of Xanthomonas axonopodis pv. citri (EPPO A1 quarantine pest) was discovered in late June 1998 in a commercial grapefruit orchard near Immokalee (Collier county). So far the disease has been found at moderate levels. The disease was found in one orchard (approximately 28 ha) and on 3 trees in an adjacent orchard. The affected orchard and surrounding trees are being destroyed.
A summary of the history of citrus canker in Florida is given on the Web site of the University of Florida, Gainesville. X. axonopodis pv. citri was introduced into Florida around 1910 and then into some other States (Alabama, Georgia, Louisiana, South Carolina, Texas) on Poncirus trifoliata material from Japan. It was eradicated from Florida in 1933 and from other States by 1947.
In June 1986, citrus canker was detected in residential citrus in Florida (Hillsborough, Pinellas, Sarasota, Manatee counties) and later in three commercial citrus groves (2 in Manatee and 1 in Highlands county). An eradication programme was applied and the disease was officially declared eradicated in 1994.
In September 1995, citrus canker was discovered for the third time in Florida in a residential area around Miami airport (EPPO RS 95/128, 97/129). It was found that the pathogen from this area was different from the archived isolates from the 1986-92 outbreak in West-central Florida. Despite eradication efforts, the disease spread predominantly northward from Dade into Broward county It must be noted that the area concerned by this particular outbreak is urban. A map shows its spread on Internet: http://doacs.state.fl.us/canker/miamimap.htm.
In May 1997, citrus canker was rediscovered in Manatee county in both commercial citrus groves and residential citrus. Genetic studies of the isolate present there showed close relationship with that of the 1986-92 outbreak (which may suggest that some infections remained undetected despite intensive inspections in that area). Finally, the last outbreak was found in June 1998 (see above).
Sources
ProMED posting from Schuber, T. Citrus canker – USA (Florida), 1998-08-06
http://www.healthnet.org/programs/promed.html
Web site of the University of Florida
http://www.ifas.ufl.edu/~entweb/cank377.html