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Exotic plant pests - citrus canker
Have you seen citrus with these symptoms?
Be on the lookout for these symptoms and report them to DPI&F. Early detection and reporting of symptoms are the key to controlling this disease.
Do not touch the lesions or move plant material off your property - this can spread the disease.
Call QPIF 13 25 23
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- Leaf lesions can vary in appearance depending on age, environment, and host species, but are typically raised and can be seen on both sides of the leaf.
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- Irregular shaped lesions may form around areas of damage, including damage caused by insects or human activity or the tree itself.
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- Fruit lesions are scab-like or corky; the yellow halo may not be obvious on yellow or orange fruit.
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- Stem lesions often indicate that infection has been present for a long time.
General information
Citrus canker is a contagious disease of citrus (and some other plant species of the Rutaceae family) caused by the bacteria Xanthomonas axonopodis pathovar citri. Infected trees display unsightly lesions which can form on leaves, fruit and stems.
Trees infected with the disease may suffer from low vigour and a reduction in fruit quality and quantity. Citrus canker is a serious disease impacting on citrus production and is the subject of a number of control and eradication programs around the world.
Overview
| Symptoms |
The bacterium enters the plant tissue and causes the development of blister-like formations (lesions). Lesions are usually raised, coloured tan to brown, surrounded by an oily, water-soaked margin and a yellow ring or halo. Large or older lesions may have a crater-like appearance. Leaf, fruit and stem tissue may be infected. Leaf tissue offers more opportunity for infection and as such typically displays the most numerous lesions over time. It is unusual to see multiple lesions on fruit or stems if lesions are not present on leaves. |
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| What to do if you find symptoms |
Phone DPI&F on 13 25 23 for advice. Do not touch the lesions or move plant material off your property - this can spread the disease. |
| Susceptible plants (hosts) |
A number of plant species within the Rutaceae family, including:
Note: Mock orange (Murraya paniculata Exotica and Min-a-min) is a member of the Rutaceae family however it is not considered a host of citrus canker. |
| Infection and spread |
Lesions ooze bacterial cells when wet, which creates an inoculum mixture capable of infecting new sites. Splash caused by rain or overhead irrigation systems is a common mechanism of short distance disease spread. Spread over longer distances can occur during severe weather events where strong winds and rain are present. People may also contribute to disease spread by moving infected plants, or plant parts. The movement of contaminated equipment, vehicles, tools, gardening equipment or people (hands, shoes and clothing) also poses a risk of spreading the disease. |
| Distribution |
Widespread in many tropical and subtropical citrus growing areas of the world. Outbreaks in Australia are rare. The last detection of citrus canker in Australia was in Emerald, Queensland, in May 2005. |
| Significance |
Serious economic disease affecting the citrus industry. |
| Human health |
Citrus canker is a plant disease. It is not harmful to people or animals. |
Further information
See also:
For more information, contact:
- QPIF Business Information Centre
- your local DPI&F inspector.
Author: Grant Telford
Page maintained by Grant Telford
Last updated 13 January 2009
