Citrus canker
Xanthomonas axonopodis pv. citri
This disease is NOT in New Zealand.
Citrus canker is a Notifiable Organism
Report suspected sightings to hotline, ph 0800 809 966.
General Information
Citrus canker is a leaf and rind spotting disease of commercial citrus cultivars and some citrus relatives. The most serious and widespread strain of this disease (Asian or A-strain) is caused by the bacterium Xanthomonas axonopodis pv. citri.
Citrus canker is not in New Zealand. It would have a major economic impact on the country's citrus industry through loss of earnings due to the reduction of export and domestic fruit sales, as well as quarantine restrictions placed on growers and from the destruction of productive trees in attempts at eradication.
Citrus canker is thought to have originated in south-eastern Asia or India. It has been spread through much of Asia, to Japan, southern and central Africa, the Middle East, Australia, Pacific Islands, South America and the south-eastern United States.
Its international spread has been through infected nursery stock, diseased fruit and contaminated equipment. Short distance spread is via wind-driven rain, overhead irrigation, orchard workers' activities, clothing and equipment. Citrus trees within 600m of an infected source are likely to become infected.
Severe infections may cause defoliation, dieback, severely blemished fruit, reduced fruit quality and premature fruit drop. Symptoms of citrus canker can appear on all parts of the plant above the ground, including leaves, twigs and fruit and particularly young, actively growing parts.
On stems and fruit, canker lesions are raised and corky and surrounded by an oily or water-soaked margin. No yellowing (chlorosis) surrounds twig lesions, but it may be present around fruit lesions. Lesions may be irregularly shaped and sunken. Sunken craters can occur on fruit but the lesions do not penetrate deep into the rind.
There is no cure for citrus canker. The only effective means of control is to remove and burn infected trees.
Useful Resources
Page last updated: 19 June 2008