The Van Trump Report

World Food Supply at Risk from Expanding Fungal Infections

Fungal infections pose a significant and increasing risk to global food security, according to a recent warning by scientists in the journal Nature. Worldwide, producers lose between 10% and 23% of their crops to fungal infection each year, despite the widespread use of antifungals. An additional 10%-20% is lost post-harvest. Scientists predict those figures will worsen as a warming planet allows fungal pathogens to steadily move into new areas, which they say raises the risk of starvation worldwide.

Hundreds of fungal diseases affect the 168 crops listed as important in human nutrition by the Food and Agricultural Organization (FAO) of the United Nations. In a 2019 list of 137 pests and pathogens ranked according to impact, fungi dominate the first to sixth places for diseases affecting each of the world’s 5 most important calorie crops – rice, wheat, corn, soybeans, and potatoes. And losses from these fungi equate to enough food to provide as much as 4 billion people with 2,000 calories every day for one year.

The scientists note that fungi are extremely effective pathogens. They produce massive amounts of spores, some of which can persist in soil and remain viable for up to 40 years. In some species, airborne spores can disperse over distances ranging from a few feet to hundreds or even thousands of miles. Wheat stem rust, for example, produces airborne spores that can travel between continents, although many other fungi produce prolific numbers of spores more locally, promoting disease spread within and between adjacent fields.

The scientists say that it’s an open question how fungal diseases of crops will be affected by a changing climate. Co-author Eva Stukenbrock, a professor of Environmental Genomics at the Christian-Albrechts University of Kiel in Germany, says that many fungi proliferate in hot climates, such as tropical regions. But as global warming intensifies, fungal infections are moving toward the poles. For instance, stem rust infections that normally occur in the tropics have been reported in England and Ireland.

Increasing temperatures could also drive other threatening evolutions. For instance, harmless endophytic fungi (fungi that lives in plant tissues) could become pathogenic as temperatures change because plants themselves may change their physiologies in response to changes in the environment. The scientists suggest that higher temperatures could even lead to soil-dwelling pathogens adapting to new hosts, potentially affecting humans or animals.
Unfortunately, current fungicides may actually exacerbate the problem. That’s because many fungicides target only a single fungal cellular process, according to the scientists. Meaning that fast-mutating fungi can – and are – developing resistance. More than 77% of the market is dominated by just three fungicides (the azoles, the strobilurins, and the succinate dehydrogenase inhibitors) all of which are single target-site antifungals.

The scientists believe that protecting the world’s crops from fungal disease will require a much more unified approach than what’s been achieved so far. Their suggestions include initiatives to raise awareness about the signs of fungal infection and encourage farmers to report them, and the adoption of advanced tools like satellites and AI that could provide early warning systems. The scientists also urge moving away from single-target site fungicides and for industry to search for compounds that target multiple processes in the pathogen.

Other suggestions include the use of multiple “resistance genes, known as R-genes, that can be bred into plants to provide stacked protection. The scientists also note the growing use of biologics and crop biotics that could provide effective defenses against fungi. Strategies currently being explored include the exploitation of living antagonists of plant pathogens, such as the fungus Trichoderma spp., and spraying crops with natural antimicrobial compounds. The full article is available HERE.

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