Sally Musungu, Research Postgraduate on the Science and Solutions for a Changing Planet Doctoral Training Partnership, is studying the impact of climate change on banana crops. Earlier this year, she delivered a talk about her research at the Grantham Institute’s Climate Friendly Pop-Up Kitchen and served a selection of raw and cooked bananas to Great Exhibition Road Festival visitors. In this blog, she discusses why bananas are at risk, and how to help future-proof one of the world’s favourite fruits.
Bananas are one of the most widely consumed fruits in the world – a household staple that is popular in breakfast smoothies, fruit bowls and lunch boxes. Based on production quantities alone, the banana ranks as the most popular fresh fruit worldwide. They are one of five fruits recommended to meet micronutrient requirements, such as potassium, and are also a source of protein.
Bananas are grown in Africa, South America, the Caribbean and Asia. There are over 150 varieties of bananas, including plantain, red bananas and the matooke, but the global market is dominated by one: the Cavendish.
Bananas at risk
Banana crops are sensitive to temperature, which makes them vulnerable to human-caused climate change. Temperature rises above a certain threshold will mean certain areas are no longer suitable for banana production. This could devastate farmers and global food supplies, and leave populations in parts of the Global South, who depend on bananas as a primary source of calories, facing starvation.
Cavendish bananas in the UK are sourced mainly from Latin America. To meet demand for these they have been intensively farmed as a monoculture. However, growing crops in this way is risky, and might not sustain future banana supplies – especially during a climate crisis.
In the 1950s, another variety of banana, the Gros Michel, was grown as a monoculture. It was wiped out by the Panama disease, caused by the soil-borne fungus Fusarium oxysporum f. sp. Cubense. Now, the beloved Cavendish is facing a similar threat: a strain of Panama disease known as the Panama Tropical Race 4 or TR4. The TR4 is a devastating fungus that blocks the plant’s tissues that carry water and nutrients, eventually killing it. It can pose a threat to all bananas, but Cavendish are at particular risk as they are farmed so intensively as a monoculture.
The prevalence of TR4 has led to substantial economic losses in banana-producing countries. Although Cavendish farmers are working around the clock to prevent the spread of TR4 and ensure you get your bananas, there are no robust management measures in place. The risk of extinction of the Cavendish banana by TR4 is real. And because the Cavendish variety dominates global banana supplies, the TR4 fungus could severely undermine the banana industry.
Other banana varieties are vulnerable to disease too, including a leaf spot disease called Black Sigatoka, and pests like the nematode parasites and the banana weevil. The risk of pests like this will be magnified as global temperatures rise. That’s why growing a diverse range of banana crops is so essential. Crop biodiversity ensures a broad genetic base, which makes the crop more productive, resistant to pests and diseases, and resilient to climate change.
A wide variety of bananas is essential for food security
Different banana varieties play essential roles in food security in different countries. For instance, the East African Banana (EAHB), also known as matooke, is widely cultivated in many African countries. The matooke is a primary source of calories to about 25 million people in East Africa, but is less known on a global level since it is mostly consumed in producing countries. As a result, the crop has little impact on the global economy and there is less investment in it. However, this could have negative impact on national food supplies and ultimately global food security.
Some of these less well-known banana varieties are essential to improve the resilience of the banana industry. The matooke hybrid, for example, has certain climate resilient traits: it matures early, and can withstand drought and certain diseases. These traits could contribute to breeding more robust banana crops in future. Similarly. of recent interest to scientists is Ethiopia’s ‘ensete’, a close relative of the banana, which has drought-tolerant traits and can withstand higher global temperatures caused by climate change.
There are also technologies, such as gene editing and genetic engineering, that can transfer genes responsible for certain traits in ensete crops to banana crops. This could, for example, help scientists to develop drought-tolerant bananas. These interventions would allow farmers to adapt to rising temperatures more quickly than through conventional breeding programs, which can take up to 20 years to yield results – time we do not necessarily have given the pace of the climate emergency.
Disrupting the monoculture
Diversifying banana consumption is critical to sustain global banana supplies in future. There may be 150 varieties of banana, but as a consumer, it can be hard to find them. Street markets, health food shops and greengrocers often have diverse bananas and can help consumers change their habits. In so doing, they can contribute to disrupting the banana monoculture system.
By getting information about alternative bananas, consumers also gain insights about their relative importance in producing countries. The plantain is widely available in London and is delicious fried or baked. It is protein rich and can be a great side dish or compliment to curries and stews. You can often find sweet baby bananas here too, which are particularly delicious.
I hope this has convinced you to go in search of some different sorts of bananas! For even more information I recommend Banana Link.
Sally is investigating how temperature fluctuations linked to climate change will affect crop supplies and food security in East Africa. She is mapping banana pest hotspots and assessing the effectiveness of current pest adaption technologies to guide farmers and help them identify suitable production areas and robust pest adaption technologies. Her findings will help farmers maintain the matooke biodiversity and improve household food security in future climates.
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