The banana freckle outbreak in the Northern Territory is much bigger than first feared.
There are now 29 properties where the devastating plant disease has been found since it was discovered again in May.
The latest 12 confirmed infections are well outside the initial outbreak at Batchelor-Rum Jungle, to the south of Darwin.
Infections have now been confirmed at Marrakai (south-east of Darwin), Fly Creek (rural area south of Darwin), the Tiwi Islands (offshore from Darwin) and more cases in the original outbreak zone of Batchelor.
"The latest positive samples show that banana freckle is more widespread than was initially thought," the NT's chief plant health officer Dr Anne Walters said.
It now seems almost certain a national biosecurity response will be needed to eradicate the disease once again.
The Territory had hoped it had seen the last of the disease after a long and costly fight saw it declared banana freckle free early in 2019.
In 2013, the banana industry was systematically wiped out around Darwin to stop it spreading.
The banana freckle fungus cannot be eradicated by the use of chemicals, the banana plants have to be removed to get rid of it.
Banana plants around Darwin, Ramingining and the Tiwi Islands, were destroyed under the previous program, the largest plant pest eradication ever attempted in Australia.
More than 500,000 banana plants were destroyed on 9500 properties.
That previous response came in four phases.
The first phase involved destruction of host material; the second required a host-free period of at least six months, including a full wet season.
During the third phase sentinel disease-free banana plants were monitored for the disease; and proof of freedom occurred in phase four.
The eradication program coordinated by national biosecurity authorities cost an estimated $26 million.
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The NT has put on hold a federally approved Banana Freckle Response Plan after these latest 12 detections.
Biosecurity teams will continue surveillance "to better understand the extent of the spread and develop the best possible strategy for banana freckle".
That strategy will include input from the NT government, the banana and nursery industries, the Commonwealth, as well as other state and territory governments through national response arrangements.
The banana industry, which is centred in Queensland, is also battling Panama disease which has been found on a sixth commercial banana farm in the Tully Valley.
The national Consultative Committee on Emergency Plant Pests continues to meet in response to the banana freckle outbreak.
After the disease was surprisingly found last month at a government research farm at Middle Point, the committee still believed "banana freckle remains technically feasible to eradicate".
The "response plan" which was being considered in response to the outbreak has been put on hold.
Chief plant health officer Dr Walters said the public were being asked to inspect their plants and to let authorities know whether they show symptoms of banana freckle, or not.
"Staff from Biosecurity Northern Territory will continue to collect as much information as possible through continued surveillance about where banana freckle is being detected to try and establish how far the disease has spread.
"Our staff will continue to liaise with banana growers and industry groups to keep them informed on this evolving situation.
"The surveillance is an important part of our efforts to protect the Northern Territory's banana industry. We urge anyone who has a banana plant to contact the hotline. A healthy plant provides an important piece of information for our team," she said.
Banana growing states including Western Australia, New South Wales and Queensland, have prohibited banana fruit and/or banana plant material being brought in from the NT.
Australia's banana industry is valued at $600 million.