A number of citrus plants showing signs of the disease were removed from nurseries in Darwin and Palmerston.

Although citrus canker does not affect human or animal health and are safe to eat, the disease is contagious to other citrus plants and can cause significant costs to the industry.  

Officials said it was likely three citrus plants were sold from a Darwin nursery and three sold from a Palmerston nursery.

DPIR’s chief plant health officer Sarah Corcoran said the department had strong evidence to suggest the plants were infected with citrus canker.

“Early detection, reporting and not moving infected plants is vital, and will give the department the best chance of eradicating this disease,” she said.

“The disease is a serious disease of citrus and was detected on a species of West Indian lime and samples collected from grapefruit, Kaffir lime and Tahitian lime are also being tested.”

The symptoms of citrus canker include blister-like lesions and causes the leaves to drop and fruit to fall to the ground before it ripens.

Previous outbreaks have resulted in substantial economic losses to citrus industries across the globe. 

Citrus canker was last detected in Emerald, Queensland, in May 2005 and after large costs to the industry, Australia was declared free of the disease in 2009.

Ms Corcoran said it was unknown at this stage how the disease entered the Northern Territory, and all options were being investigated to determine its origin.

“We are currently asking all Territorians with citrus plants to please urgently check them for symptoms, not to move the plants and to contact the department if you think it may be infected with the disease.

“Bio security is everyone’s business and we need to work together to manage the risk and eradicate citrus canker. Government and industry are taking this extremely seriously and are working together to manage this situation,” Ms Corcoran said.

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

Officials said plants that were purchased over the past 12 months are of particular concern.

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

When phoning the hotline you can arrange to submit a photo for preliminary diagnosis, but do not collect a sample or move the suspected plant.