Citrus canker

​The Northern Territory Department of Primary Industry and Resources is responding to citrus canker. This is a serious disease of citrus.

A nationally agreed response plan is in place with the aim of eradicating known infections, putting movement controls and quarantine measures in place, and determining the extent of the outbreak. These activities are underway while we gather information to determine if the disease can be eradicated.

Plants showing signs of infection were found at two retail outlets in Darwin and Palmerston. It has not been detected in citrus growing areas. However, surveillance in citrus growing areas is ongoing.

The Northern Territory Department of Primary Industry and Resources has been working with the retailers and production nurseries and other jurisdictions to undertake tracing activities.

Following tracing and testing of nursery plants imported from Darwin, there are confirmed and linked cases of citrus canker on three properties, two at Kununurra and one in Wyndham, in Western Australia’s north.

All infected and at risk plant material is being dealt with under strict biosecurity procedures.

All available evidence is that citrus canker is restricted to the home and garden sector. Surveillance of citrus production areas so far has not detected citrus canker.  

The Northern Territory’s Department of Primary Industry and Resources and Western Australia’s Department of Primary Industries and Regional Development are working together, along with their local industry and communities, to contain and prevent further spread of the disease.

Other states and territories are also conducting surveillance and tracing activities. At this stage the disease has not been found in any other jurisdiction.

The Consultative Committee on Emergency Plant Pests (CCEPP) continues to meet and discuss the response to this incident, and the response plan was recently endorsed by the National Management Group.

All leads are being investigated to determine its origin and how far it may have spread.

Citrus canker does not affect human health, animals or other plants, and infected fruit remains safe to be consumed.

Movement restrictions

The Northern Territory has special restrictions on the movement of host plants. The control area covers the greater Darwin area, south to Adelaide River, east to Kakadu and west to Dundee. 

See the Northern Territory’s Department of Primary Industry and Resources website for more information including maps.

The Western Australia Department of Primary Industries and Regional Development has issued a Quarantine Area notice for Kununurra and Wyndham and surrounding areas within 50 kilometres, to stop the movement of citrus fruit and plants which could harbour the disease.

Find out more about the WA Quarantine area including maps.

All jurisdictions have introduced domestic movement controls to prevent entry of citrus canker hosts and carriers, such as fruit, plants and plant material, soil, equipment and machinery, from the Northern Territory. Before moving any of these materials you should check Interstate Quarantine.

Biosecurity and reporting

Early detection, reporting and not moving infected plants is vital, and will provide the best chance of eradicating this disease.

You should not collect a sample or move the suspect plant.   

Signs of infection can look similar to other bacterial diseases that are known in northern Australia.  All suspected cases should be reported.

If you think you have a plant with citrus canker, or if you have recently bought citrus plants from a Darwin or Palmerston retail outlet, please contact NT’s citrus canker hotline on 1800 931 722.

When phoning the hotline you can arrange to submit a photo for preliminary diagnosis. The photo should be a clear image of the suspect plant, the disease symptoms and the plant’s label, if you still have it.

Detections outside of the Northern Territory can also be reported to the Exotic Plant Pest Hotline on 1800 084 881. This number will put you in contact with your state or territory department of agriculture or primary industries.

Interstate travellers also have a role in preventing the spread of pests and diseases. Do not take fruit, whole plants or plant cuttings into another state or territory without checking first.  You can do this by visiting interstatequarantine.org.au.

About citrus canker

Citrus canker is a contagious disease caused by the bacteria Xanthomonas citri sub species citri which can affect all citrus plants.

The disease is native to South East Asia. It infects a plant through wounds and natural openings on leaves, stems, thorns and fruit.

It presents as lesions or cankers at infection sites and severely impacts fruit quality and yield.

Symptoms are exacerbated by injury caused by feeding activity of the insect citrus leaf miner, which is the larvae of a small moth widely distributed in Australia.

The symptoms of citrus canker include blister-like lesions on both sides of the leaves that are raised, tan to brown in colour, and are surrounded by an oily, water-soaked margin and a yellow ring or halo. Large or older lesions may have a crater-like appearance.

Premature fruit drop can occur, along with defoliation, twig dieback and general tree decline. In severe cases, it can lead to tree death.

Citrus canker can be spread rapidly over short distances, particularly in tropical and subtropical climates by wind-blown rain.  Overhead irrigation systems can also spread the disease. Long distance spread occurs through flooding, cyclones, or by people moving infected plant material or equipment.

Plant Health Australia citrus canker fact sheet

National Diagnostic Protocol for Asiatic Citrus Canker

History of citrus canker in Australia

Citrus canker has previously been detected in Australia but has been eradicated in each instance.

The first recorded outbreak of citrus canker was in the Northern Territory in 1912.

The initial occurrence of the disease took 11 years to fully eradicate.

In 1984, a program was initiated to eradicate citrus canker from Thursday Island. Over a two year period a total of 10 citrus trees were found to have canker symptoms and were destroyed. No symptoms of citrus canker have been observed on Thursday Island since February 1986, and the disease was declared eradicated in September 1988.

Citrus canker was detected in the Northern Territory again in 1991 at Lambell's Lagoon, about 50 kilometres from Darwin, and affected a small number of pomelo citrus trees.

All affected trees were destroyed, and the area was intensively monitored for two years. Citrus canker was officially declared eradicated in the Northern Territory in 1995. The Department of Primary Industry and Resources has continued to undertake regular surveillance and testing since then to help ensure the Territory remained citrus canker free.

The disease was also detected on several commercial citrus orchards in Emerald, Queensland, in 2004.  Eradication of the outbreak and restoration of country freedom for the disease was declared in January 2009.

More information

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