15/09/2024
Food for thought
If you’ve been wondering why banana prices are so stubbornly high: bananas in North Queensland – actually, worldwide – are under threat from a soil-borne fungus called Panama TR4 disease. Over the past nine years, this fungus has been detected in eight North Queensland farms. (In the late 1990s, the same disease wiped out the banana industry in the Northern Territory).
When TR4 attacks a banana tree, it dies: the fungus blocks the plant's vascular system preventing movement of water and nutrients. The plant literally starves, wilts and dies within a week. As this happens, the fungus produces more spores that can spread the disease. It takes only 1 microscopic spore to infect a new banana plant.
In other words, once a farm is infected, it can try and isolate the infected patch – but eventually it spreads.
We’ve seen this movie before: in the early 1900s, most banana-growing regions were cultivating a single variant called the Gran Michel. This variety turned out to be susceptible to Panama disease TR1, and within a few decades it was wiped out. The industry en masse moved across to the Cavendish, which was resistant to TR1. Today 97% of bananas grown world-wide – including in Australia – are Cavendish, even though there are literally over 1000 known banana varieties. And what’s unique to bananas is that they don’t reproduce sexually: every single banana tree around today is the offspring of a slice of the plant’s suckers growing below ground. This means it has no way of evolving, so it can’t adapt to new threats that arise in the environment.
In other words: our insistence on monoculture is seriously threatening our food security, and it’s not just bananas: coffee harvests are under threat from global warning as we rely on just 2 heat-sensitive varieties: arabica and robusta.
There are 7000 known edible plants, yet the world relies for 75% of its food on only 12 plants and 5 animal species. It’s this lack of (genetic) biodiversity that is threating our food supply, and reversing this is gong to be a massive task.
Meanwhile, Qld University of Technology has been working on a genetically modified Cavendish – which is TR4 resistant - for the past 20 years, and it’s getting close: it was granted final approval for human consumption by the Australian government in April, but commercialisation will take a few years. However, even the scientist who led the project concedes that this is a stop-gap: eventually this GMO variety will fall victim to the next version of Panama disease.
