A finding that a North Queensland banana farm tested positive to Panama Disease Tropical Race IV (TR4) in early April has been reversed, with quarantine measures now lifted on the property.

In a release, the Australian Banana Growers Council (ABGC) said the final TR4 result on the Mareeba property came up negative, which was excellent news for the grower and his family.

The now overturned detection was the second to hit the Queensland industry, after the disease was found on a plantation in Tully in mid-March.

"The announcement that the Mareeba farm has had its initial TR4 diagnosis overturned and its quarantine lifted is great news for that farm's grower and his family and for the banana industry," ABGC chairman Doug Phillips said in the release.

"However, growers need to remember there is still one case of TR4 on a Tully Valley farm and this result has been confirmed using the highest level of TR4 testing available.

"Growers need to remain vigilant and continue with their on-farm biosecurity measures."

The state's Acting Chief Biosecurity Officer Malcolm Letts said the initial positive result from a PCR (polymerase chain reaction) test was a 'false positive'.

"Since the initial positive result in early April, we have been conducting further surveillance and testing samples from the property. This has been a complex process, but the final definitive vegetative compatibility group (VCG) test result is negative for tropical race 4," Letts said.

"Extensive investigative work by the diagnostic team involved in the testing indicates that the particular PCR test used isn't reliable. To our knowledge this is the first time there has been evidence of a problem with this diagnostic test anywhere in the world."

He said consultancy firm Deloitte had been appointed to conduct an independent review of the Panama disease testing procedures used by Biosecurity Queensland and the University of Queensland.

"That work has commenced and is expected to be completed next month.

"When dealing with exotic diseases Biosecurity Queensland must always take a precautionary approach. If we believe a serious risk exists, as we did in this case based on the initial positive result, we will quarantine properties to control the risk of spread.

"It is better to have to revoke a quarantine than to hesitate at the outset and potentially place an entire industry at risk.

Letts said the government had made a commitment to reimburse the net revenue forgone for the period in which each of the quarantined properties was unable to trade.

"We still have a confirmed case of Panama disease tropical race 4 at Tully and growers should continue strengthening their on-farm biosecurity practices to protect their businesses," he said.

"We don't yet know if Tully is the index case, and there may still be other infected properties yet to be identified. Panama disease tropical race 4 can live in the soil for decades and it can be a number of years before symptoms become apparent in plants."

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