Attack of the Clones - What do Apples, Oranges and Avocados all share with Bananas?
By Oscar Lozada
What do all these foods have in common with bananas?
Aside from them all being fruits, of course! It’s something much less obvious, yet pervasive and potentially disastrous.
Basically, all these fruits are clones - not of each other of course, that would be silly, but of themselves. On this site we’ve talked a lot about bananas being clones - that’s kind of a core element of our project, trying to make people aware of this, and the cliff-edge it places the entire global banana industry on. But accompanying the banana on its road of perpetual replication are several other exceedingly familiar fruits to us consumers in Europe and North America, including Granny Smith apples, navel oranges, the Hass avocado and several cultivars of wine-producing grapes.
Very long story short, the familiar, inescapable sweet bananas we all know and love are all identical; they are called Cavendish bananas, after Duke William Cavendish who first had them brought to Britain in 1834. Cavendish bananas don’t have seeds and cannot reproduce naturally, so to satisfy the relentless demand, banana farmers divide the roots of a plant and producing cuttings, which they then plant, cloning the same plant over and over and over again, perpetuating their sweet taste we've come to know and love. Similarly, navel oranges have no natural seeds, so a process called grafting (attaching the cuttings of the desired plant to the roots of another plant) is the only way to propagate the trees, ensuring the constant supply of this sweet, juicy and easy-to-peel orange. Of course, Granny Smith apples and Hass avocados do have seeds, but the plants that emerge from these are genetically ‘variable’ so the familiar crisp, juicy crunch and tart acidic flesh of a Granny Smith, or the soft smooth of a Hass avocado may not be present. So to preserve the exact, quintessential ‘Granny Smith’ or ‘Hass’, grafting and cuttings must be used.
Basically, the system is designed to discourage and suppress genetic diversity at all stages. What this means, then, is that every single example of these fruits are virtually genetically exactly the same as each other, as they’ve barely had any opportunity to diversify. The banana you ate today is virtually genetically identical to the banana you ate yesterday. Every navel orange found in a Colorado Walmart is almost genetically identical to every navel orange in a UK Tesco’s. Every Granny Smith apple you eat in the 21st century is more or less identical to the apples first grown by old Maria ‘Granny’ Smith in Sydney in 1868. Etc, etc.
This is nothing new of course; countless plants trees, vines, ferns and shrubs all utilise cloning as a form of reproduction - it’s called “vegetative reproduction” or “apomixis”, or ‘grafting’. Bananas bud off of new plants at the base of an existing trunk, grapevines in contact with the ground will sprout roots and form a new plant, the list goes on. Horticulturalists cottoned onto this thousands of years ago, discovering that desirable plants (for aesthetic, vigour or deliciousness of fruit) must be propagated by cloning (such as rooting, grafting, or budding), so have been doing so ever since.
As a result, countless plant cultivars of today are clones - derived from a single individual, multiplied over and over again for thousands of years. Only last year, a brand new study found that the Savignan grape vine (used today to produce the famed vin jaune wine of Eastern France) was genetically identical to a grape pip from 1100AD - meaning that this variety has been cut, grafted and cloned over and over again for over 900 years. What’s more, the team also found suggestions that humagne blanche (a white grape grown today in the Swiss Alps), was directly related to grapes grown in southern France by the Romans - so it may be 2000 years old!
So it appears that cloning of plants works, and has done so in nature for thousands of years, right? However, that was before the 20th century when monoculture plantations exploded across the world.
Perhaps the great problem of cloning is that it greatly diminishes the genetic variation of the tree population - whether an orchard, vineyard, agroforest or banana plantation. So when disease strikes, there’s no variation in susceptibility vs resistance to help weather the storm. This is precisely what happened 100 years ago to the world’s most popular banana at the time, the Gros Michel (aka "Big Mike"), but we wrote a whole article on the disaster that ensued already so check that out for the story!
Now, it looks like history could be repeating itself. Tropical race 4 (TR4) is the new strain of Panama disease for the modern world, that now infects our ubiquitous Cavendish. As you read this, it is currently spreading, slowly but surely, around the world. Having emerged in South-East Asia in the 1990s, by the 2010s it had spread to almost all banana-producing countries in Asia. By 2013 it had spread to West Africa. And in October 2019, it was first sighted in Colombia. Now, it is possible we are teetering on the edge of the Cavendish’s extinction. Farmers and scientists alike are hard at work searching for a solution, but without genetic variation, this cloned fruit is as susceptible to disease as its predecessor Gros Michel. Finding (or genetically engineering) a new variety to succeed Cavendish (like how Cavendish replaced Gros Michel) is an option (a last-resort option I should add), but to successfully replace Cavendish on the global market this new variety needs to taste good, be easy to grow in industrial quantities, ripen in a predictable amount of time and be capable of long-distance transport undamaged. And even if we did find this magical new-Cavendish, we’d simply be repeating the course of history, and in a few decades’ time may face the exact same cyclical problem again.
What’s more, this same susceptibility is faced by other cloned fruits. Navel orange trees for instance suffer severely from viral and bacterial infections like citrus stubborn disease (CSD), which requires diligent and endless control of the beet leafhoppers that transmit the offending bacteria. The relentlessly cloned Granny Smith apples may be hardy, but if an Apple Scab, Powdery mildew and Cedar Apple Rust infection is strong enough they may too succumb. At the time of writing, no strains of these diseases have emerged that are nearly as virulent or destructive as the banana’s Panama disease (CSD for instance can only tolerate Mediterranean climates, being ill-suited to navel oranges in tropical or subtropical zones), but given the lack of genetic variation in these fruits, a global infection like Panama disease cannot be ruled out.
So the reality is we could very soon find ourselves with no Cavendish bananas at all. And what with the weighing of our global fruit industry on clones, it’s not impossible that we could one day find ourselves without many of our favourite fruits and fruit products entirely. Of course, it’s not just consumers that would be affected. The Cavendish for instance amounts to almost 50% of the entire global banana production - an industry upon which the livelihoods of millions of people around the world depend. So a worldwide collapse could amount to millions if not billions of people affected - consumers and producers alike.
Right now, the banana seems to be one of the first global-scale casualties of this inherent genetic susceptibility, but the others may not be far behind. It’s tough enough to try to imagine a world without the world’s favourite fruit (bananas), but a world without apples? Or oranges? Or avocados? Or wine? Of course, I’d be doom-mongering if I said that any of this was any more than unlikely, but with the 2019 appearance of TR4 in South America, and the steady capitulation of Cavendish, perhaps it’s not so outlandish a possibility?
In light of all this, maybe we should have called this documentary Fruitageddon. Or Fructageddon? Either way, try to get your 5-a-day in while you can.