Your are here:

Citrus canker (canker A)

Scientific Name
Xanthomonas axonopodis pv. citri
Scientific Author
(Hasse 1915) Vauterin et al. 1995
Taxonomy
(Bacteria: Xanthomonadales)

Page menu options:

Diagnostic Images

Close
Caption
Source
Image Options
Close
Diagnostic Images (33)
Other Images (3)
Diagnostic Notes

Symptoms:

Citrus canker affects all aboveground plant parts, with initial symptoms on leaves appearing as tiny, slightly raised blister-like lesions. With time, foliar lesions turn grey, then tan/brown, a water soaked margin appears and the entire lesion is usually surrounded by a chlorotic margin. The centre of the lesion becomes characteristically raised, and spongy or corky. Lesions arising from stomatal infection are typically visible from both sides of the leaf (unlike these of scab – Elsinoe spp.). A shot-hole effect can also eventuate, after the centre of the lesion becomes crater-like and falls out. As the disease becomes more severe on foliage, defoliation generally occurs. A similar symptom to the above is observed on twigs and fruit, however chlorotic margins are not found on twig lesions. Severe infections can result in fruit abscission, and twig dieback due to girdling. Twigs not to be killed by girdling by the pathogen can harbour lesions for many years, with the old lesions tending to be raised corky patches in the otherwise smooth bark. Lesions can be associated with physical injuries to the host, in particular those caused by Asian citrus leaf miner (Phyllocnistis citrella Stainton) (Schubert et al. 2001).

 

The Bacteria:

The bacterium is an aerobic, gram-negative rod measuring 0·5–0·75 × 1·5–2·0 µm. It is motile by one polar flagellum. Carbohydrates are metabolised by oxidation. Growth on 2% sucrose-peptone agar is yellow and copiously mucoid. Gelatin, casein and starch are hydrolysed. Nitrite is not formed from nitrate, and aesculin is hydrolysed (Hayward and Waterston 1964).

 

More Information
Specimen Contact
Dr Jose R. Liberato
Author
Liberato JR, Miles AK, Rodrigues Neto J & Gambley C
Created
17/05/2006 01:53 AEST
Last Updated
21/10/2011 09:32 AEST
Citation
Liberato JR, Miles AK, Rodrigues Neto J & Gambley C (2006) Citrus canker (canker A) (Xanthomonas axonopodis pv. citri ) Updated on 10/21/2011 9:32:02 AM Available online: PaDIL - http://www.padil.gov.au.
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License

Loading