Citrus canker

Scientific name: Xanthomonas axonopodis pv. citri
Causal organisms: Bacteria

Host plants

Citrus

Affected plant stages

Seedling to reproductive stages

Affected plant parts

All above ground parts

Symptoms

Citrus canker is a bacterial disease of citrus that causes premature leaf and fruit drop.

A newly infected leaf has white spongy spots that will later turn gray or tan that finally erupt into a typical crater-like formation. The spots have oily margins or yellowish rings. The cankers can be seen on both sides of the leaf. Old cankers sometimes fall out, leaving behind a shot-hole effect.

On fruit, the cankers appear scab-like or corky but without the yellow halo (ring). Infected fruits are unlikely marketable.

Conditions that favor development

1. Strong winds and wind borne rain
2. Citrus psyllids, people, birds and animals, farm equipments that carry the bacteria
3. Movements of infected plants or plant parts

Preventive control

There is no effective control on citrus canker, except to pull out the infected tree and then burn it. Also, control citrus psyllids.

External links

• University of Florida. Citrus canker homepage. http://www.doacs.state.fl.us/pi/canker/

References

• Brooklyn Botanic Garden. (2000): Natural disease control: A common-sense approach to plant first aid. Handbook # 164. Brooklyn Botanic Garden, Inc. 1000 Washington Avenue, Brooklyn, NY.
• Gottwald, R.; McGuire, G.; Garran, S. (1988): Asiatic citrus canker: Spatial and temporal spread in simulated new planting situations in Argentina. Phytopathology 78: pp. 739-745.
• Thurston, D. (1998): Tropical plant diseases. Second Edition. APS Press. The American Phytopathological Society. St. Paul, Minnesota, USA.