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Latest News / February 8, 2019

Simon Cook’s Nuffield Thoughts: Part 9

Banana Panama – Queensland

The final visit of my Nuffield was to tropical North Queensland. I had headed to Queensland to look at Tropical race 4 or TR4. TR4 is a devastating soil borne fungal disease affecting bananas and is often referred to as Banana Panama disease. Tropical race 1 the first variety of the disease was first described at the Brisbane botanical gardens back in the late 1800’s.

In the 1950’s almost all bananas produced worldwide were of the Gros Michel variety. TR1 disease began to spread to all the banana producing areas of the world, slowly wiping out plantations worldwide. A desperate search for a solution led to the Cavendish variety which had tolerance to the TR1 strain. Cavendish plant material was quickly spread amongst all banana producing countries to replace the dying Gros Michel. Today almost all bananas grown worldwide for human consumption are of the Cavendish cultivar. In the Philippians another Tropical race, now designated as race 4, had developed alongside the native seeded banana cultivars. Because they have developed over time together, they have developed a natural symbiosis or tolerance and could happily live together. When Cavendish was planted in an area where native bananas had previously grown, Cavendish suddenly came into contact with the native TR4 for the first time, to which it had no natural tolerance. The result, Cavendish plants were overcome by the disease and started dying. Unfortunately overtime TR4 has since been spread by humans from its native location in the Philippians and is now devastating Cavendish plantations around the world. It is not feasible to sterilise soil infected with TR4, which is thought to last in excess of 40 years in soil, without any host material. The upshot is once an area is infected it will be impossible to grow the current variety of Cavendish in that area for the foreseeable future.

TR4 was first detected in Australia in 1997 near Darwin. It then proceeded to effectively wipe out the production of Bananas in that area. The next area in Australia to have TR4 identified was Tully in Northern Queensland in March 2015, almost 20 years later. The Tully area is the largest banana growing area in Australia. Despite knowing the risk of TR4 and knowing an area in Australia had already been infected, the growers in Tully were totally unprepared for the arrival of TR4.

One of the initial problems faced be the first orchard in Tully to be diagnosed with TR4 was the immediate shutdown of its operations. Banana growers are able to stagger their production so they harvest and sell bananas 52 weeks of the year. When TR4 hit Biosecurity Queensland (BQ) they immediately put movement controls on the property so no plant material or soil were able to be removed. Initially this also included the bananas themselves meaning the plantation was unable to sell any of the bananas as they ripened and were forced to destroy and dispose of them instead. This meant an immediate halt to any income for the operation as well. BQ then worked through a process with the plantation owner to allow bananas to be moved off the property. Banana bunches do not carry the disease and it is only located in soil and lower down an infected trunk. The plantation owner suddenly had to put in place sufficient hygiene and biosecurity controls to satisfy BQ that the risk of moving TR4 was negligible. During this period, they were unable to move any bananas off the orchard so lost a significant amount of income, highlighting the importance of having industry incursion plans prepared and market access negotiated before a pest arrives.

The peak body in Australia for banana growers is the Australian Banana Growers Council (ABGC). The ABGC decided the best course of action was to try and stop the disease in Tully by buying the infected plantation, destroying any plants on it and trying to seal it off as best as possible. The idea was to try to eliminate the risk of any transfer of material off the property. The negotiation to buy the property was lengthy and difficult and required funds to be gathered from growers all around Australia, not just those close by, to complete the sale. Unfortunately, shortly after the orchard was removed a second site nearby had a positive test for TR4. A short time later a third neighbouring orchard also had a positive test. Both those plantations have killed off any plants in the blocks that had plants with positive tests but continue to farm other blocks following the implementation of strict hygiene practices approved by BQ.

The two main vectors for the transfer of TR4 are infected plant material or infected soil. As well as by people and machinery, soil can also be transferred by animals such as pigs and the movement of other plant material. Another significant risk facing Queensland growers is soil runoff following heavy rain, an all too frequent occurrence in a tropical region. All farms now have fences and traps to try and exclude wild pigs in an effort to mitigate this vector. There have also been attempts to reduce wild pig populations by shooting from helicopters in an effort to cull numbers.

The focus in Queensland now is on aggressive containment with on farm biosecurity at the forefront of the battle. Every plantation I visited had biosecurity signs up at the gate requiring any vehicles entering properties to go through some form of wash procedure. A number of these were 1000L IBC pods filled with a sanitiser solution and fitted with some sort of petrol or battery powered pump to enable vehicles entering to sterilise tyres. The most extreme of these was a large scale operation that a had fully automated drive through bath and spray system capable of handling trucks and buses.

Each plantation tended to have its own packing facility as movement of bananas in bunches can result in significant physical damage, once packed tightly into a box it is much safer to transport them. The packing sheds I visited were all setup into hygiene zones, with different footwear for each zone. You would enter the packing facility from the road and remove your footwear. There would be a low brick wall which you could sit on then on the other side you would put on white gumboots for the clean packing facility. After putting on the white gumboots you still went through a foot bath before entering the shed. When you left the packing facility and entered the orchard you went through the same process transferring from the “clean area” white boots to the “dirty orchard area” and black gumboots. All packaging deliveries and load-outs to the shed are done through a dock so vehicles never leave the metal pad outside the packing facility. They had even setup a delivery system that allowed fertiliser to be dumped from a truck while it was still on the loading pad, with the fertiliser being dropped over a small boundary wall separating the farm from the road.

My very last visit of my Nuffield travels turned out to be my most rewarding. I met with a member of the family business who are the largest banana growers in Queensland. Being a very large, established grower, they run the business more like a commercial operation and have the ability to step back and think about the operation, as opposed to being on the ground fighting fires every day. The business was generational and their father who had been through the devastation TR1 had ingrained the importance of cleanliness and hygiene into the culture of the family business.

Before TR4 hit Queensland a member of the family had traveled to the Philippians to see first hand the damage the disease was causing in that area. In the Philippians they observed the stark difference in outcome between two neighbouring plantations, one who had engaged and invested in biosecurity practices and the other who had done nothing. The grower engaging in biosecurity practices had managed to slow the progression of the disease, and whilst suffering loss, was still in business whilst his neighbour’s plantation was effectively a write off.

Despite witnessing the devastation to Bananas in the Philippians and being aware that the disease could impact their own plantation to the same level, the penny still didn’t drop that this could actually happen and that they should prepare for it.

When the TR4 did finally appear in Queensland it was on a plantation almost neighbouring theirs. Whilst the visit to the Philippians hadn’t been enough to implement biosecurity practices, the minute TR4 was identified they were able to immediately implement the practices they had seen and then led their industry in adopting on-farm biosecurity practices. The disease has since been found in their plantation with all indications pointing to the spread occurring before those biosecurity practices were put in place. Their experience had taught them that biosecurity for TR4 was not about totally preventing the spread of disease, it was about controlling and slowing the spread. It was about buying time to prepare a long-term solution.

This triggered an interesting conversation about what happens next and what the long-term solution was for them. There is no cure for TR4 and it will survive for 40 plus years in the soil rendering it impossible to grow bananas in that area anytime in the foreseeable future. One obvious solution is to abandon the current site and move to fresh land where there is no disease and start again. This has been the model in China where the disease has slowly wiped out the areas that can support banana production. The problem in China was when an area became infected and they needed to relocate, machinery was taken from the infected area to establish the new area. Obviously, this had the effect of spreading the disease to the new area. The result now is that almost all land suitable for Banana production in China is now infected.

There are banana varieties that are tolerant to TR4, however they all are seeded and not suitable for retail consumption. You are left with the final option of trying to breed a version of Cavendish which is tolerant to TR4.

The family have decided to invest in developing a tolerant variety and are actively exploring 2 paths. The first is a natural breeding program based on propagating up individual plants that seem to show some tolerance and ability to survive in affected areas. They hope that this solution will provide them with a viable option, however they also understand that there are no guarantees. The second option they are pursuing is Genetic engineering using Crispa technology. This is definitely their least preferred option as it will result in uncomfortable discussions with markets that are philosophically opposed to genetic engineering. It is not unrealistic to think that they face a future of choosing between a genetically modified banana or no banana at all.

I saw distinct similarities between this situation and where we find New Zealand facing the threat of Kauri dieback. Both are soil borne disease that will continue to be spread not only by humans but also by weather, pigs and other wild animals. We are fighting a battle to slow the spread of Kauri dieback and buy time, but what are we doing with that time. I would like to think we are able to have a serious conversation about the possibility of using Crispa technology to save the Kauri tree in New Zealand. I know this will an uncomfortable conversation in parts of our society, but I also reflect back on the decision facing banana growers, is a GM Kauri better than no Kauri at all?