Asiatic citrus canker (canker A), caused by the bacterium Xanthomonas axonopodis pv. citri, is one of the most important diseases of citrus. The disease probably originated in Southeast Asia and continues to increase its geographic distribution around the world despite the quarantine regulations imposed by several countries. Citrus canker has been reported in almost all of the major citrus-growing areas of Southeast Asia, North America, and South America.1, 2 In general, the pathogen becomes established and disease may be severe in regions where temperatures and precipitation are high during the growing season.

Other forms of canker have been reported on citrus. Cancrosis B, caused by strain B of X. axonopodis pv. aurantifolii (= X. campestris pv. citri strain B), occurs on lemons in Argentina, Paraguay, and Uruguay.1 The disease also affects other Citrus spp., such as Mexican lime (C. aurantifolia), Pummelo (C. grandis), and sour orange (C. aurantium). Cancrosis B infects leaves, fruits, and twigs causing lesions similar to, but smaller than, those of canker A. Cancrosis C, caused by the strain C of X. axonopodis pv. aurantifolii (= X. campestris pv. citri strain C), was reported on Mexican lime in the State of So Paulo, Brazil.3 X. axonopodis pv. aurantifolii strain C is pathogenic only to Mexican lime and does not occur on other Citrus spp. Symptoms are identical to those of canker A. Atypical forms of canker A have been reported on Mexican lime in several countries in the Middle East.