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Citrus Canker in Australia

Citrus Canker in Australia explained for Australian readers, with local season, shopping, growing, recipe, nutrition, or industry context.

By Mandarins.com.au Editorial Updated 1 June 2026

Citrus canker is a bacterial disease that causes scabby, raised lesions on the leaves, fruit, and stems of citrus plants. It is caused by the bacterium Xanthomonas citri subsp. citri. There is no cure. Infected trees must be destroyed.

Australia has successfully eradicated citrus canker multiple times. The most recent outbreak, detected in Darwin in April 2018 and later found in Kununurra and Wyndham in Western Australia, was officially declared eradicated in April 2021 after a three-year national response program. As of June 2026, Australia is citrus canker free.

What it is

Citrus canker is a highly contagious bacterial disease that affects all citrus species including mandarin, orange, lemon, lime, grapefruit, kumquat, and native citrus such as finger lime. It is not a risk to human health.

Infected plants display lesions on leaves, fruit, and stems that:

  • Start as small yellow marks roughly the size of a pin head
  • Develop into raised, spongy, tan to brown spots over several months, often 5 to 10 mm across
  • Are rough to the touch and surrounded by a yellow halo
  • Can develop a crater-like centre on older lesions
  • Cause leaves to drop, fruit to fall early, and young trees to be stunted

The disease is most active in hot, wet weather. It spreads rapidly in tropical and subtropical climates.

Australian outbreak history

Australia’s history with citrus canker goes back to 1912, when the first recorded outbreak occurred in the Northern Territory. That outbreak took 11 years to fully eradicate and resulted in the destruction of every citrus tree north of latitude 19 degrees south.

Subsequent outbreaks:

  • 1984: Thursday Island, Queensland. Eradicated by 1988.
  • 1991 and 1993: Lambells Lagoon, NT. Eradicated 1995.
  • 2004: Emerald, Queensland. A major outbreak that wiped out millions of dollars worth of citrus crops in the Central Burnett region.
  • 2018 to 2021: Darwin NT and Kununurra and Wyndham WA. The response involved more than 270 workers, 6,192 host plants removed, and cost-sharing between federal, state, and territory governments and industry.

The Queensland government (Business Queensland) notes that the national citrus industry is valued at more than $977 million for the year ending June 2023, with exports of 231,301 tonnes worth $441 million. Citrus canker would severely damage Australia’s access to international markets if it became endemic.

How to identify it

Look for:

  • Raised, rough, tan-coloured lesions on leaves, with a yellow ring or halo around each spot
  • Similar scabby lesions on fruit rind and stems
  • Lesions that feel rough or corky, not smooth
  • Clusters of lesions where water pools on leaves (along leaf margins or tips)
  • Abnormal leaf drop and poor tree condition

Citrus canker can follow the feeding tracks of citrus leaf miner, as the wounds provide entry points for the bacteria. In Queensland, the presence of citrus leaf miner damage alongside canker-like lesions is a known risk pattern.

Citrus canker may be confused with lemon scab (Elsinoe fawcettii), which also causes scab-like lesions, mainly on lemons in coastal regions. Lemon scabs look drier and do not have a yellow halo.

How to report

If you suspect citrus canker anywhere in Australia, do not touch the plant or move any material. Report it immediately.

  • Exotic Plant Pest Hotline: 1800 084 881 (free call, available nationally)
  • Biosecurity Queensland: 13 25 23
  • DPIRD Western Australia: contact through MyPestGuide or your local office

The Australian Department of Agriculture (DAFF) manages import controls and national biosecurity for citrus canker. The disease is listed as a prohibited matter under biosecurity legislation in Queensland and other states.

What home gardeners must do

Under Australian biosecurity law, everyone has a general biosecurity obligation to take all reasonable steps to prevent the introduction or spread of plant pests.

If you see lesions that look like citrus canker:

  1. Take a clear photo of the affected leaves, fruit, or stems.
  2. Do not touch or disturb the plant material.
  3. Do not move any plant material off the property.
  4. Wash your hands, clothing, and footwear before leaving the area.
  5. Call the Exotic Plant Pest Hotline on 1800 084 881.

Why imported trees and plant material are a risk

Most of Australia’s citrus canker outbreaks have been linked to illegally imported plant material or to travellers bringing citrus items from affected countries. The Torres Strait is a known pathway for the disease to enter from PNG and Indonesia, where citrus canker is common.

The Department of Agriculture (DAFF) notes that authorities regularly intercept citrus canker-infected material in passenger baggage from Asia at Brisbane, Sydney, and Melbourne airports, as well as in postal items.

To reduce risk:

  • Only source citrus planting material from reputable Australian nurseries.
  • Do not bring citrus plants, fruit, leaves, or cuttings into Australia from overseas.
  • Do not accept citrus cuttings or seeds from overseas sources through the mail.
  • Citrus Australia recommends sourcing budwood only from suppliers who use certified material through Auscitrus.

Travelling between states

While Australia is currently citrus canker free, state quarantine rules for citrus plant material (as distinct from fruit) still apply in some circumstances. Check the Australian Interstate Quarantine website before moving citrus plants between states.