The news that Panama Disease Tropical Race IV (TR4) has been detected on Australia's largest banana operation was a heavy blow for the industry, and the pressure is on to find a replacement for the predominant Cavendish variety. In northern New South Wales (NSW), an industry and government-funded project acts as an "ongoing revolving door" for trialing varieties from around the world, and some are showing great potential. 

"This year for example there are six varieties coming in from the French program put in what we call the "killing fields", the contaminated site, to see how they handle the Race I Panama Disease," says David Peasley of Peasley Horticultural Services.

This earlier strain is actually what sparked the worldwide adoption of Cavendish, replacing the Gros Michel variety that used to be mainstream but has since been relegated mostly to mountainous areas of the Latin American tropics. 

Another variety susceptible to the earlier disease strain is Lady Finger, a popular banana in Australia.

"Growers on Lady Finger plantations now are feeling very threatened," says Peasley, who is heading up the project in Duranbah in the Tweed Valley. 

An off-chance find in a Queensland field, FLF shows good potential as a replacement for the Lady Finger variety, according to researcher David Peasley.

"In fact a lot of growers think that in five years there will not be any Lady Fingers left."

Hence the term "killing fields" for the site, which may be far from plantations infected by TR4 in the Northern Territory and northern Queensland, but the first strain's fungus has lingered for decades.

"We've selected this trial block on a farm that had Lady Finger bananas growing on it 35-40 years ago but they were wiped out by Panama Disease Race I," says Peasley.

The researchers put Lady Fingers back in the ground to test whether the disease was still there, and sure enough it bore its ugly head.

The fungus was then isolated and has been artificially placed under every tree planted from overseas breeding programs and domestic one-off selections. 

"We know that Race I Panama acts in a similar way to Tropical Race IV, so any variety that’s going to be resistant to Race I is going to be worth testing against Tropical Race IV.

"It’s a matter of when that disease spreads and not particularly if it spreads."

He adds different varieties are being tested in TR4-infected areas in the Northern Territory as well, but it is still early days.

"It's in a commercial plantation. The commercial plantations were eradicated in the Northern Territory, but TR4 actually appeared in nursery banana plants so it’s pretty widespread up there.

"So the only way out for the Northern Territory industry is through the very strict quarantine of vehicles and footwear going into the plantation, but the ultimate test or solution lies in resistant varieties."

The scientist adds the varieties tested in Duranbah have also undergone resistance testing for TR4 in the Netherlands under glasshouse conditions.

"While that’s not definitive about how they’ll perform in the field, it does give us an indication of their resistance levels."

Possible bananas for the future

Out of all the varieties brought to the test plot from around the world - Guadeloupe, Taiwan, Mexico, Israel and elsewhere - four have so far passed the taste test for potential economic viability, and these will be tested in the next phase.

Two are from Honduras, one is from South Africa, and the fourth was found by chance over the border in Queensland. 

Somewhat more similar to the common Cavendish variety, PKZ from South Africa is also promising.

One of the victims that didn't make it was the High Noon. Peasley finds it "very tasty" but as it's only moderately resistant to TR1, it's "not going to survive under heavy disease pressure".

The first of the selected cultivars is called "FLF", named after Lady Finger banana grower Bill Freeman.

"He’s over 90 years old and I was up there about seven years ago on his plantation when I just noticed this one plant that looked pretty promising," says Peasley.

"I asked old Bill what variety is that?"

At the time Freeman wasn't happy with the plant as he'd ordered ordered Lady Finger bananas and this one was different.

"But it's turned out to be a winner as far as disease resistance goes so he’s quite chuffed about it," Peasley says.

He says the FLF fruit is a "local somaclonal variant" of the Honduran Foundation for Agricultural Research-developed FHIA 18, with "extremely good resistance to the disease, very good bunching and resistance to leaf disease".

"It's a beautiful fruit to eat and it’s looking to be a replacement for the Lady Finger variety, and it’s very similar to Lady Finger in flavor," he says.

The second variety is called "PKZ", named after Peter Knight who found it in South Africa, and is primarily oriented towards replacing Cavendish someday.

"They won’t be given marketing names until later, but it’s a beautiful variety - it’s quite shorter than the normal Cavendish, but very cylindrical, with a beautiful bunch and very sturdy plant," Peasley says.

David Peasley with Honduran-developed cooking bananas.

Even in the absence of TR4, the researcher believes a move into potential Cavendish-replacing varieties like PKZ is necessary in his part of the country.

"Here in the subtropics we don’t have ideal conditions for growing Cavendish which is a tropical variety – over the winter time the fruit gets quite dull," he says.

"While excellent eating quality, the appearance is not as good as North Queensland where they can produce the bananas better looking and with longer fruit suitable for the supermarkets.

"But a lot of people are saying there’s more than having a banana that looks good and lasts a long time; it has to taste good."

The other two selected varieties, both from the FHIA, aren't intended for the fresh market. 

"The third one we had to look for a variety that suited the processing market for making jams or drying or cooking banana - the plantain types - and it’s a variety from Honduras," he says.

"It’s a FHIA 17 and it’s a very large bunch – it grows up to 65-70 kilos in weight, it’s very resistant to leaf disease, and it’s not bad eating also.

"The last one is called FHIA 25 and we’re looking at that as a replacement for potatoes – its starch qualities are suitable for people with dietary problems – they might be gluten-intolerant people. It has a very big bunch as well."

Little Gem

Peasley highlights another variety that hasn't been chosen yet for the next phase with the FHIA, PKZ and FLF cultivars, but looks like it could have great commercial success for Australian growers. 

"Just by keeping your eyes out these things come up occasionally in the field," he says.

"There's another one in New South Wales which a local grower Tim Johnson has found - it's an exceptional banana and he’s called it Little Gem.

"It’s a somaclonal variant of the Goldfinger banana (FHIA-01) and it’s on the market now. There's tremendous interest in that."

He says the Little Gem is smaller, very tasty and doesn't go soft when it ripens.

"It’s got beautiful flavor but there’s just not enough of it on the market," he says.

"There are a couple of growers who are growing it under contract at the moment, so there are some exciting things coming in the future for the Australian consumers, and it’s about time.

He says there was "no infection at all" when Little Gem was put in the killing fields.

"It’s completely resistant to Race I – it’s going to be trialed up in Northern Territory for Tropical Race IV, so it looks pretty exciting from that point of view as well," he says.

More gems on the horizon

The research program - funded by levies paid by members of the Australian banana industry, Horticulture Innovation Australia,and  the Queensland, New South Wales and Federal governments - may have three years yet before anything is released commercially, says Peasley.

"They've got to go through the post-harvest research and consumer testing, and we’ve got to work out the plant spacing we recommend to growers and a management program to make sure those varieties are economically viable.

"It’s an ongoing program of testing and release, but as we test that there will be an ongoing revolving door and hopefully we’ll come up with sweeter varieties that are suitable for the Australian consumer market and also economically viable for growers.

"What we want to do with bananas is to provide a greater variety of high quality bananas in terms of flavor, size and appearance that consumers simply haven’t had in the past. Tropical Race IV has forced us into that situation.

"We’ve got a fair range of varieties now to cover for the future but we’re not stopping there."

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