Queensland banana growers have avoided a serious biosecurity risk with the Northern Territory today officially declared banana freckle free.
The successful eradication follows a five year joint effort between the Australian, state and territory governments and the banana industry.
Banana freckle is a pest of banana leaves and fruit caused by a fungal pathogen.
Federal agriculture minister David Littleproud said the announcement would boost confidence for Queensland growers and the $1.2 billion Australian banana industry.
“Eradication is a tough business so this is a big win for some 700 banana growers across the country,” Littleproud said.
“Growers were staring down the barrel of up to $24 million a year in additional management costs.
“The disease posed a real threat to the livelihoods of many banana growers but swift action saw it contained to the Northern Territory before it was eradicated.”
The fungal disease isn’t a health risk but does stunt the growth of the plant and causes spotting on the fruit, making it less appetising and harder to sell, Littleproud said.
“Had the disease spread to Queensland strict controls would have been put in place and no fruit would have been able to leave the region to be sold to supermarkets across Australia,” he said.
The federal government contributed $6 million to the national response program led by the Northern Territory and assisted with surveillance, monitoring and response planning.
“The partnership between the Northern Territory and the Australian Banana Growers Council was an essential component of the eradication program. The efforts of banana growers who participated in the program in the Northern Territory should also be commended,” Littleproud said.
“Queensland is the powerhouse of the Australian banana industry. In 2016–17 North Queensland produced 94 per cent of Australia’s banana production for the year.”
Researchers from QUT have developed a golden-orange fleshed banana, rich in pro-vitamin A which could save the lives of thousands of children who die each year from a deficiency of the vitamin.
According to QUT’s Professor James Dale, who lead the research, an estimated 650,000-700,000 children world-wide die each year with a further several hundred thousand going blind because of this problem.
The decade-long research, which has been published in the Plant Biotechnology Journal, involved extensive laboratory tests at QUT as well as field trials in north Queensland.
Professor Dale said the genetic modification process had resulted in the identification and selection of banana genes that could be used to enhance pro-vitamin A in banana fruit.
The research backed with close to $10 million from the Bill & Melinda Gates Foundation, ultimately aims to improve the nutritional content of bananas in Uganda, where the fruit is the major staple food in their daily diet.
Professor Dale describes the development of the biofortified banana as a significant humanitarian project.
“The East African Highland cooking banana is an excellent source of starch. It is harvested green then chopped and steamed,” Professor Dale said.
“But it has low levels of micronutrients particularly pro-vitamin A and iron. The consequences of vitamin A deficiency are severe.”
Professor Dale explained that the researchers took a gene from a banana that originated in Papua New Guinea and is naturally very high in pro-vitamin A but has small bunches, and inserted it into a Cavendish banana.
“Over the years, we’ve been able to develop a banana that has achieved excellent pro-vitamin A levels, hence the golden-orange rather than cream-coloured flesh.
“Achieving these scientific results along with their publication, is a major milestone in our quest to deliver a more nutritional diet to some of the poorest subsistence communities in Africa.
“Our science works,” Professor Dale said, “and it’s technology that was developed here at QUT.
“We tried and tested hundreds of different genetic variations here in our lab and in field trials in Queensland until we got the best results.
“These elite genes have been sent to Uganda in test tubes where they have been inserted into Ugandan bananas for field trials there.”
Professor Dale said another really pleasing aspect of the project was the fact that young Ugandan students, who came to QUT to undertake their studies, had now completed their PhDs and were overseeing the research and field trials in Uganda.
The familiar bright yellow Cavendish banana is ubiquitous in supermarkets and fruit bowls, but it is in imminent danger. The vast worldwide monoculture of genetically identical plants leaves the Cavendish intensely vulnerable to disease outbreaks.
Fungal diseases severely devastated the banana industry once in history and it could soon happen again if we do not resolve the cause of these problems. Plant scientists, including us, are working out the genetics of wild banana varieties and banana pathogens as we try to prevent a Cavendish crash.
The cautionary tale of ‘Big Mike’
One of the most prominent examples of genetic vulnerability comes from the banana itself. Up until the 1960s, Gros Michel, or “Big Mike,” was the prime variety grown in commercial plantations. Big Mike was so popular with consumers in the West that the banana industry established ever larger monocultures of this variety. Thousands of hectares of tropical forests in Latin America were converted into vast Gros Michel plantations.
But Big Mike’s popularity led to its doom, when a pandemic whipped through these plantations during the 1950s and ‘60’s. A fungal disease called Fusarium wilt or Panama disease nearly wiped out the Gros Michel and brought the global banana export industry to the brink of collapse. A soilborne pathogen was to blame: The fungus Fusarium oxysporum f.sp. cubense (Foc) infected the plants’ root and vascular system. Unable to transport water and nutrients, the plants wilted and died.
Fusarium wilt is very difficult to control – it spreads easily in soil, water and infected planting material. Fungicide applications in soil or in the plant’s stem are as of yet ineffective. Moreover, the fungus can persist in the soil for several decades, thus prohibiting replanting of susceptible banana plants.
But the Cavendish unfortunately has its own weaknesses – most prominently susceptibility to a disease called Black Sigatoka. The fungus Pseudocercospora fijiensis attacks the plants’ leaves, causing cell death that affects photosynthesis and leads to a reduction in fruit production and quality. If Black Sigatoka is left uncontrolled, banana yields can decline by 35 to 50 percent.
Cavendish growers currently manage Black Sigatoka through a combination of pruning infected leaves and applying fungicides. Yearly, it can take 50 or more applications of chemicals to control the disease. Such heavy use of fungicides has negative impacts on the environment and the occupational health of the banana workers, and increases the costs of production. It also helps select for survival the strains of the fungus with higher levels of resistance to these chemicals: As the resistant strains become more prevalent, the disease gets harder to control over time.
To further aggravate the situation, Cavendish is also now under attack from a recently emerged strain of Fusarium oxysporum, known as Tropical Race 4 (TR4). First identified in the early 1990s in Taiwan, Malaysia and Indonesia, TR4 has since spread to many Southeast Asian countries and on into the Middle East and Africa. If TR4 makes it to Latin America and the Caribbean region, the export banana industry in that part of the world could be in big trouble.
Cavendish varieties have shown little if any resistance against TR4. Growers are relying on temporary solutions – trying to prevent it from entering new regions, using clean planting materials and limiting the transfer of potentially infected soil between farms.
Black Sigatoka and Panama disease both cause serious production losses and are difficult to control. With the right monitoring in place to rapidly intervene and halt their spread, the risks and damage imposed by these diseases can be considerably reduced, as has been recently shown in Australia. But current practices don’t provide the durable solution that’s urgently needed.
Getting started on banana genetic research
If there’s a lesson to be learned from the sad history of Gros Michel, it’s that reliance on a large and genetically uniform monoculture is a risky strategy that is prone to failure. To reduce the vulnerability to diseases, we need more genetic diversity in our cultivated bananas.
Over a thousand species of banana have been recorded in the wild. Although most do not have the desired agronomic characteristics – such as high yields of seedless, nonacidic fruits with long shelf life – that would make them a direct substitute for the Cavendish, they are an untapped genetic resource. Scientists could search within them for resistance genes and other desirable traits to use in engineering and breeding programs.
To date, though, there’s been little effort and insufficient funding for collecting, protecting, characterizing and utilizing wild banana genetic material. Consequently, while almost every other crop used for food production has been significantly improved through plant breeding over the last century, the banana industry has yet to benefit from genetics and plant breeding.
Researchers now have the tools to identify resistance genes in wild bananas or other plant species. Then they can use classical plant breeding or genetic engineering to transfer those genes into desired cultivars. Scientists can also use these tools to further study the dynamics and evolution of banana pathogens in the field, and monitor changes in their resistance to fungicides.
Availability of the latest tools and detailed genome sequences, coupled with long-term visionary research in genetics, engineering and plant breeding, can help us keep abreast of the pathogens that are currently menacing the Cavendish banana. Ultimately we need to increase the pool of genetic diversity in cultivated bananas so we’re not dependent on single clones such as the Cavendish or the Gros Michel before it. Otherwise we remain at risk of history repeating itself.
Recent trials by CHEP Australia in the use of reusable plastic crates as an alternative to cardboard cartons for the banana industry have returned positive results for growers and other members of the supply chain.
Early estimates show a 10 to 15 per cent cost saving, while also reducing damage to the fruit when using crates compared with cartons.
In early 2015, more than 200 crates were used to pack bananas at a trial site in northern NSW, with wholesaler PW Chew managing transport, ripening and distribution. A combination of Lady Finger and Cavendish bananas were used in the trial. Fruit sizes ranged from 15kg XL, 13kg XL and 13kg large.
PW Chew Operations Manager, Mark Bradshaw, says the ability to cross-stack crates and the greater crate integrity over cartons are huge bonuses for the banana industry.
“The greater stability that is available in cross-stacking has shown to be of great benefit to the integrity of the bananas. By the time they were ripened for retail, the initial trials indicated that there was less rub marking, bruising due to movement and neck damage in comparison to the same fruit packed in cartons from the same district,” Mr. Bradshaw said.
“Cooling and ripening of the fruit was far more efficient too with the crates as you are not cooling the cardboard as well as the fruit. As a result, airflow, temperature and humidity are more consistent around the ripening room, which means we save nearly a day in ripening.”
Pooled solutions provider, CHEP Australia, has been developing and trialing a reusable plastic crate in collaboration with the Australian banana industry over the past three years. The current design features smooth walls and a waved base to minimise damage to bananas, improved ventilation and a footprint to suit Australian pallets with six crates per layer.
The CHEP pooling system also allows for crates to be returned for washing – to a HACCP level if required – giving a hygienic solution for the industry and less overall wastage in cardboard.
CHEP Australia Business Development Manager, Nick Jones, said, “The trial gave all parties involved an opportunity to learn from each other to find the best packing methodology, supply chain logistics and retail requirements.
“The structural integrity of a plastic crate means that the weight bearing of a stacked pallet is through the crate, not a carton so it won’t compress.
￼“Compression damage to fruit from cartons is a major problem for the industry. Very early on in the trial, it became evident that the use of a slitted liner would be beneficial. The combination of plastic crates and liner bags allow for gases to flow through the bag giving a more consistent ripening colour.
“From a ripening perspective we found the crates delivered consistent half-colour ripening to levels between stage three and four, compared with cardboard. One retailer commented that if they could have consistent colour at stage 3.5, then they will be able to increase their rate of sales.”
The next phase in the trials of the plastic crates will be to conduct studies in northern Queensland to assess the crate performance over longer distances to the major capital cities.