Bananas Are Dying!

The Tropical Race 4 (TR4) is a strain of a fungus that kills banana plants by choking them of water and nutrients. In addition, the Taiwanese pathogen is immune to pesticides. Yikes! Thankfully, the pathogen only affects one type of banana - the Cavendish. However, this particular banana variety makes up almost the entire export market, which accounts for 47 per cent of all global production of the fruit:  

But the Cavendish has no defence against TR4. When Ploetz first encountered the new pathogen, there had been just a handful of suspected infections reported. In 1992, Ploetz received packages containing TR4 from plantations in Indonesia and Malaysia. “At the time all we knew was that it was a new pathogen,” he says. “We didn’t know what to expect as far as its broader implications. The more samples we got from these export plantations, the more we began to realise that this was a bigger issue than we had ever anticipated,” he recalls. His prediction proved to be eerily accurate.

In 2013, TR4 was found for the first time in Mozambique. Ploetz thinks it had been carried on the boots and equipment of banana planters from southeast Asia. The pathogen has now travelled to Lebanon, Israel, India, Jordan, Oman, Pakistan and Australia. In 2018, it was found in Myanmar. “Then in southeast Asia,” Ploetz says. “It’s everywhere.”

When TR4 hits, the destruction is near-total. “It looks like somebody’s gone to the plantation with a herbicide,” [Randy] Ploetz says. “There are big areas that no longer have any plants at all.” The fungus, which can live undetected in the soil for decades, enters banana plants through their roots and spreads to the water- and nutrient-conducting tissue within, eventually starving the plant of nourishment. Two to nine months after being infected, the plant – hollowed out from the inside – collapses in on itself. The soil it grew in, now riddled with the fungus, is useless for growing bananas.

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