Researchers in Australia and around the globe are trying to breed new varieties of Cavendish in a bid to protect supply of the world's most popular banana as the threat of a damaging fungus spreads.

Key points: Race is on globally to find effective resistance to TR4, head of Banana Plant Protection Program says

Race is on globally to find effective resistance to TR4, head of Banana Plant Protection Program says Researchers fast-tracking development of new varieties using "mutation breeding" technique

Researchers fast-tracking development of new varieties using "mutation breeding" technique Plants showing improved resistance will be put into further breeding trials

Cavendish bananas are highly susceptible to a fungus referred to as Panama Tropical Race 4 (TR4), which has spread throughout Asia, Africa and the Middle East.

In 2015 it spread to a single property in north Queensland, risking the state's $600 million banana industry.

Professor Andre Drenth, head of the Banana Plant Protection Program, a collaboration between the University of Queensland and the Northern Territory and Queensland governments, said the race was on to find TR4-resistant bananas.

"The race is clearly on, not just in Australia, the race is on globally to find effective resistance to TR4, and we need to win the race otherwise Cavendish is in serious trouble," he said.

"There are solutions in the form of tolerant banana varieties, but a truly resistant variety I have not seen yet.

"I have seen things that are resistant but they are small bananas, thin-skinned bananas, and small plants [which are] probably not as productive."

Professor Drenth also said the varieties that have shown some resistance are not adequate commercial substitutes for the Cavendish, which accounts for over 90 per cent of, not only the Australian banana market, but also the total global banana export trade.

It has made limiting the impact of TR4 on these bananas a critical priority for the industry.

'Mutation breeding' to fast-track research

Cavendish affected by TR4 in China were replaced by dragon fruit crops. ( Supplied: Andre Drenth )

Queensland Department of Agriculture's Sharon Hamill said researchers were fast-tracking the development of new varieties that suit conditions in Australia using a technique called "mutation breeding".

"What we'll be doing is getting some of the cultivars that already have improved tolerance [to TR4] and putting them through mutation breeding," she said.

Sharon Hamill analyses one of the banana plants being raised under tissue culture. ( ABC News: Marty McCarthy )

This involves exposing banana plants to radiation, as a way to stress the plant to create a "mutant" with a particular trait — in this case disease resistance.

Dr Hamill said the process of exposing the plants to radiation helped the plants produce mutants quicker, but was quick to point out it was not genetic modification.

"We're not adding anything, we're just putting stresses on the plant to make it adapt and make its own changes," she said.

After mutation breeding the plants are sent to the NT's Coastal Plains Horticulture Research Station for testing.

Goldfinger 'highly resistant' to the disease

The Northern Territory has been infected with TR4 since 1996, and is therefore a good trial site for the plants.

The NT Department of Primary Industry's Bob Willian's said they are interested in the disease resistant qualities of the Honduran-bred Goldfinger banana.

The Goldfinger is resistant to TR4, but it does not have the same commercial qualities as a Cavendish.

"The Goldfinger is already highly resistant or tolerant to the disease but the bunch characteristics, or the fruit characteristics, are not commercially acceptable," Dr Williams said.

"So let's see if we can jiggle the genes around a bit and see if we can get good tolerance to the disease, good bunch characteristics but then improve flavour for the consumer.

"We may not end up with a variety that can last 20 years but we may end up with a variety that can last five to seven rotations, which under North Queensland production systems is better than nothing at all."

Farmers hoping to pre-empt any further development of TR4

Chinese Cavendish plants have been destroyed by TR4. ( Supplied: Andre Drenth )

Northern Territory researchers have been trialling different banana varieties for the past four months.

"We don't anticipate seeing any symptoms for about another month-and-a-half when the plants start to come into the hot season and get hot stress," Dr Williams said.

The plants that show improved resistance will be put into further breeding trials, to try to isolate their disease resistance traits.

"This is going to be ongoing for the next four or five years where we look at the mutated material … pick out the best of that and evaluate it more strongly," Dr Williams said.

He said farmers and the industry were waiting anxiously to see the results.

"They are screaming out for this type of information so that they can pre-empt any further development of TR4 in a very good production region," he said.

"It is of great importance to Queensland growers as it is to the Northern Territory."

Watch Landline's story on the science behind TR4 on ABC TV at midday on Sunday.