For decades, farmers have turned to synthetic pesticides as the first line of defence against the diseases and pests that threaten global food production. But this reliance has come with mounting costs. Pesticides can linger in soil and waterways, harm pollinators, disrupt ecosystems, and even pose health risks to humans. Research has linked long-term exposure to problems such as hormonal disruption, respiratory illness, and neurological damage.
Despite their short-term effectiveness, many chemical sprays are a double-edged sword, undermining the very soil health that crops depend on. Particularly the overuse of fungicides, which are chemicals designed to kill fungi that cause crop disease, has led to the rise of resistant pathogens and reduced diversity in the microorganism environment in agricultural soils. With tighter regulations and growing demand for sustainable farming, scientists have been seeking natural alternatives that could offer protection without pollution.
Now, new research from Rothamsted, in collaboration with the Universities of Warwick and Exeter, suggests that the answer may already be underfoot in the soil itself!
The study has revealed that a common soil fungus, Trichoderma hamatum, naturally produces volatile organic compounds (VOCs) — tiny airborne molecules that can reduce and overall inhibit the growth of major crop diseases. In plants, VOCs help to attract pollinators or repel insects; in fungi, they can act as communication tools or defensive agents. Due to their small nature, they evaporate easily and can travel through air or soil, allowing organisms to influence each other without direct contact.
The Trichoderma genus is already well-known in agriculture for their beneficial roles: they colonise plant roots, boost nutrient uptake, and even stimulate plant immunity. But this new research uncovers another weapon in their arsenal, an ability to ‘fumigate’ nearby pathogens through chemical signals released in the air.
Credit: Gareth A. Thomas @ Environmental Microbiology Reports
In the lab, researchers co-cultured Trichoderma hamatum with Sclerotinia sclerotiorum, a mould that causes rot in crops like lettuce and oilseed rape. T. hamatum rapidly overgrew the pathogen, visibly suppressing its spread. Chemical analysis showed that the beneficial fungus released a distinct mix of VOCs when grown alongside the pathogen. One of these, 1-octen-3-one, powerfully inhibited S. sclerotiorum and also suppressed other crop diseases in lab tests.
The findings suggest that T. hamatum can boost its natural chemical defences in response to threats, a mechanism that could inspire new, environmentally friendly antifungal treatments.
Such approaches are increasingly important as Europe and the UK move to restrict chemical pesticide use. In recent years, several commonly used fungicides have been banned due to environmental persistence or potential human toxicity. Yet farmers still need reliable ways to keep crops healthy.
That’s where T. hamatum and its natural vapours could come in. Instead of synthetic chemicals that linger in the environment, fungal VOCs break down quickly, leaving minimal residue. Their ability to target a range of pathogens also means they could help reduce the overall chemical load in farming systems.
“Further work is needed to understand how these fungal VOCs operate in real-world farming conditions, and whether they can be harnessed effectively at scale”, said Dr Jozsef Vuts, co-author of the study. “But the discovery offers fresh hope for greener crop protection at a time when agriculture is under pressure to cut chemical inputs.”
This isn’t the first time that Trichoderma fungi have shown promise in sustainable agriculture. They’re already used in some bio-control formulations, particularly in horticulture and seed coatings. What makes this study different is its focus on the airborne communication between fungi, and how these invisible exchanges could be leveraged for pest control.
As researchers dig deeper into the chemistry of soil ecosystems, discoveries like this underscore how much nature has already solved. The soil beneath our feet teems with organisms locked in constant competition — plants, fungi, and bacteria that have evolved intricate strategies to defend their turf. By tapping into these natural systems, agriculture may be able to shift from a model of domination to one of cooperation.
