Biosecurity advice update - Citrus Canker WA detection

Xanthomonas citri Citrus Canker
May 2018
Northern Territory and Western Australia

Current Situation
• There is a confirmed case of Citrus canker on citrus plant in three properties in Western Australia including two retail businesses in Kununurra and one property at Wyndham
• This detection follows tracing and testing of nursery plants imported from Darwin.
• In April this year, citrus canker was found at two retail outlets in Darwin.
• The disease is limited to nurseries and residential properties. Surveillance of citrus production areas so far, has not detected citrus canker.
• 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.
• This response plan will be revised following this detection in Western Australia.
• The Department of Primary Industries and Regional Development, Western Australia and the Northern Territory Department of Primary Industry and Resources are working together, along with their local industry and communities to contain, and prevent further spread of the disease.
• The other states and territories are also conducting surveillance and tracing activities. At this stage the disease has not been found in any other jurisdiction.
• 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.
• Residents who have citrus plants in Western Australia’s north, and throughout the Northern Territory, need to check them for signs of citrus canker. Plants that were purchased this year are of concern. Photos of citrus canker symptoms and further information can be found at
• 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.
• Citrus canker does not affect human health, animals or other plants, and infected fruit remains safe to be consumed.

Background to the incident
• Citrus canker was detected in early April 2018, when plants showing signs of infection were found at two retail outlets in Darwin and Palmerston.
• Three citrus plants are understood to have been sold from the Darwin retailer, and three from the Palmerston retailer, before the symptoms were noticed.
• In Darwin, the disease was detected on a variety of West Indian lime.
• All citrus products in the Northern Territory have been removed from the affected retail outlets and have been disposed of under strict biosecurity procedures.
• The source of the disease is not known at this stage.

Biosecurity and reporting
• Early detection, reporting and not moving infected plants is vital, and will give us the best chance of eradicating this disease.
• You should not collect a sample or move the suspect plant.
• Signs of infection can look like 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 sourced citrus plants from the Northern Territory or Kununurra WA please contact the Exotic Plant Pest Hotline on 1800 084 881. This will put you in touch with the department of primary industries or agriculture in your state or territory.
• Most states have an app or mechanism for submitting 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. For WA this can be found at MyPestGuide Reporter
• 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 on the Interstate Quarantine website which is

About the disease
• Citrus canker is a contagious disease caused by the bacteria Xanthomonas citri sub species citri which can affect all citrus plants. There are also non-citrus hosts for this disease.
• Citrus canker is native to South East Asia. It infects a plant through wounds and natural openings on leaves, stems, thorns and fruit.
• The disease 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.

Further information can be found at:
WA Dept. of Agriculture -
NT Dept. of Primary Industries and Resources -
Australian Commonwealth -

• The Department of Agriculture and Water Resources has notified the International Plant Protection Convention. This is in line with international reporting requirements when an emergency plant pest or disease is confirmed.
• While there are no international trade implications at this time, 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 to minimise any risk of spread.

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.
• 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.

Response arrangements
• The Consultative Committee on Emergency Plant Pests provides technical and scientific advice in response to exotic plant pest and disease outbreaks. The Committee is chaired by Australia’s Chief Plant Protection Officer and comprises the Chief Plant Health Managers from each state and territory, other specialists from government, Plant Health Australia, and representatives from affected industries that are signatories to the Emergency Plant Pest Response Deed.
• The National Management Group (NMG) consists of Chief Executive Officers from government agencies responsible for agriculture and affected industry organisations, including NGIA, that are signatories to the Emergency Plant Pest Response Deed. It is chaired by the Secretary of the Australian Government Department of Agriculture and Water Resources. Plant Health Australia is a non-voting member.
• NMG makes decisions on whether to support national eradication programs for emergency plant pest outbreaks under the deed. NMG considers recommendations provided by the consultative committee before making decisions on whether an emergency plant pest is technically feasible to eradicate.
• The Emergency Plant Pest Response Deed is a formal legally binding agreement between Plant Health Australia, the Australian, state and territory governments, and national plant industry bodies representing specific cropping sectors. The deed covers the management and funding of nationally agreed responses to emergency plant pests.