Fungi are a major threat to crops around the world, scientists warn in a new review, and are increasingly becoming “disasters” in our food supply.
We tend to worry more about pathogens that directly infect humans, especially viruses and bacteria. But even corn and stem rust cannot scare us like Ebola or E. colimaybe they should.
These fungi are already devastating, with farmers worldwide losing 23 percent of their crops to fungal diseases every year. They also add that the mushroom is 10 to 20 percent after harvesting.
Because of its effects on the world’s five most powerful crops – rice, wheat, corn, soybeans, and potatoes – the fungus currently destroys enough food to provide 2,000 calories per day for one year to between 600 million and 4 billion people.
And it’s increasing because of a “perfect storm” of inputs that are leaving many gardens vulnerable to the fungus, according to University of Exeter botanist Sarah Gurr.
Although they can’t turn into zombies, like the fictional fungus (or slime mold) does to humans in the HBO drama. The Last of Us, these mushrooms are not dangerous, Gurr warns. Also, they are real.
“Although the story is science fiction, we warn that we may see a global crisis due to the global spread of fungal diseases as they become more widespread in a warming world,” he says. “The immediate danger here is not about zombies, but about global hunger.”
Farmers have been fighting fungi for years, but not like this, writes Gurr and co-author Eva Stukenbrock, an ecologist at the Christian-Albrechts University of Kiel.
Climate change is one important factor because increased temperatures help fungi to multiply (among other problems), including species that threaten large crops.
Humans have challenged the problem in other ways, the researchers wrote, such as planting more genetically identical crops, which are particularly susceptible to fungal diseases.
And although fungicides have helped farmers deal with these plagues in recent generations, fungi are finding ways to protect against even the most powerful defenses, Gurr and Stukenbrock explain.
Many fungicides work by targeting only one cellular pathway, allowing the fungus to evolve its resistance – an opportunity that the fungus seems eager to seize.
When fungicides begin to work on newly challenged fungi, frustrated farmers sometimes respond by using the same fungicide, making the situation worse.
Due to rising temperatures, pesticide failures, and major crop varieties being unprotected from fungi, our crops are like sitting ducks.
And with more than 8 billion people now living on Earth – many of whom are already food insecure, often due to some of the effects of climate change – now is not a good time for fungi to destroy food sources, Stukenbrock notes.
“As the world’s population is expected to rise, people are facing unprecedented challenges in food production,” he says. “We’re already seeing massive crop damage from fungal diseases, which can affect millions of people every year.”
The damage is already a problem that needs international attention, but this new review aims to shed light on how the situation has become and how it could become even more serious.
“These concerns are likely to worsen as a warming world increases the prevalence of fungal diseases in European crops, and they continue to develop resistance to antifungals,” says Stukenbrock. “This will be dangerous for developing countries and will have a major impact on the West.”
Since humans helped create this mess, however, we have the power to fix it, Gurr and Stukenbrock argue.
Apart from the obvious but impossible goal of reducing the emissions that cause climate change, which is very important for other reasons, there are several ways to effectively protect our crops from fungi in the near future.
Researchers at the University of Exeter have developed new methods that will help the current class of fungicides target multiple cell systems, Gurr and Stukenbrock note, which make it difficult for fungi to mutate.
Research shows that this type of antifungal can work against several pathogens, he adds, including corn smut, rice blast, and the fungus that causes fusarium wilt in bananas.
Even without better fungicides, we can reduce the risk of the fungus spreading by adopting better agricultural practices, Gurr and Stukenbrock show, pointing to Denmark’s successful fight against fungal diseases by planting a variety of mixed crops.
“Fungal diseases are threatening our most important crops, from potatoes to beans and bananas,” Gurr said. “We are already seeing huge losses, and this is threatening to become a global disaster because of the population growth.”
The review was published in Nature.
