Climate Change

Fungal flood: Increasing disease, aided by climate change, risk to global food security

Practising monoculture in modern agriculture provides ideal grounds for fungi

By Himanshu Nitnaware
Published: Friday 05 May 2023
Higher temperatures encourage the development of new fungal pathogen variants. Representative photo: iStock.
Higher temperatures encourage the development of new fungal pathogen variants. Representative photo: iStock. Higher temperatures encourage the development of new fungal pathogen variants. Representative photo: iStock.

A rapid surge in fungal attacks on the world’s most important crops, worsened by climate change, could become a “catastrophe” for the world’s food supply, scientists have warned.

Growers across the globe have already lost 10-23 per cent of crops to fungal diseases, the researchers wrote in a paper published in journal Nature on May 3, 2023.

The losses amount to 2,000 calories every day for a year, enough food to meet the hunger requirements of 600 million-four billion starving people, the researchers from the University of Kiel, Germany and the University of Exeter in the UK, wrote in their study.

Also read: Quarter of a billion people are facing acute hunger: Report

The five most important crops for humanity — rice, wheat, maize, soyabeans and potato — are vulnerable to fungal diseases such as rice blast fungus, wheat stem rust, corn smut, soybean rust and potato late blight, all caused by water mould oomycete.

The Food and Agricultural Organization has identified hundreds of fungal diseases that affect 168 crops crucial to provide nutrition to humans. The devastating impact of fungal diseases will worsen due to climate change, the researchers pointed out.

The rising temperatures are causing fungal infections to move steadily towards the poles, about seven kilometres a year. Citing an example, they said wheat stem rust infections, usually reported in tropical countries, have been found in England and Ireland.

Fungus, which is primarily a pathogen, produce massive amounts of spores which can remain active in the soil for up to 40 years, they added.

Higher temperatures encourage the development of new fungal pathogen variants. Extreme weather conditions such as storms or tornados can spread the spores in wider geographic ranges, they stated. For instance, wheat stem rust produces airborne spores that can travel across continents.

The scientists further claimed that practising monoculture in modern agriculture had become ideal grounds for fungus to feed on entire crops and breed. Such cropping patterns have enabled the fungus to quickly evolve and develop resistance to the fungicides. 

The use of antifungals has spiked in agriculture, leading to more fungicide-resistant pathogens. Between 2021 and 2028, the fungicide market will grow around 4.9 per cent annually, especially in low-income countries, they said.

The researchers expressed fears that increasing temperatures due to global warming will change the relationship between plants and microbiomes, including the endophytic fungi and organisms that co-exist in a single host plant. However, these can develop into fungi as a response to environmental stresses.

The fungus can threaten food security as the pressure on food systems increases with the growing human population. The global population is estimated to grow to 9.7 billion in the next 30 years.

Despite the threats, the researchers hope to battle the situation by moving away from a single-target site fungicide approach to developing compounds that fight multiple pathogens.

Read more: UN Food Systems Summit: Sanctioning the status quo

In 2020, researchers at the University of Exeter presented a compound that targets several fungi and protects wheat, rice and banana.

Introducing plant diversity and seed mixtures with multiple resistance against pathogens can reduce fungus evolution, the scientists suggested. In 2022, Denmark demonstrated it successfully, where 25 per cent of total wheat production used mixed cultivars. The move helped reduce the severity of yellow and brown rust and septoria tritici blotch in mixed cultivars without affecting the yield.

The researchers also recommend collaborating with farmers and using technologies such as AI and remote sensing to monitor and manage pathogens early.

More focus should be made on increasing research towards the fungal diseases in crops, the study stated. The UK Research and Innovation Council, for instance, spent Rs $686 million between January 2020 and 2023 on COVID-19 research to publish 225,000 papers globally. But at the same time, the council allocated $30 million to fungal crop research and generated 4,000 research papers.

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