Helping nature fight back:
How biocontrol and biofumigation support safe, climate-smart vegetable production
– 18 December 2025 –
As countries across Africa and Asia face rapidly intensifying pest and disease pressures as a result of climate change, vegetable crops are increasingly at risk in the field and after harvest. These threats often push farmers toward heavier use of chemical pesticides, creating risks for human health and the environment.
With funding support from the Australian Centre for International Agricultural Research (ACIAR), the World Vegetable Center (WorldVeg) is generating evidence to help countries adopt safer, more sustainable ways to grow vegetables despite the pressures from pests and diseases. Two of the most promising approaches are biocontrol and biofumigation – powerful tools that can improve soil health, reduce dependence on chemical pesticides, and lower risks along the vegetable value chain.
Biocontrol – sending nature’s bodyguards into action
Biocontrol uses living organisms – like beneficial insects, fungi, or bacteria – as a form of crop protection, to keep harmful pests and diseases in check. To support its use in vegetable production, the WorldVeg Plant Protection team has characterized promising microbial strains to compile the WorldVeg Beneficial Microbe Bank. This is a catalog of microbial isolates and their assessed traits to support research, product development, innovation, and sustainable crop protection. Several strains have already shown outstanding potential in laboratory, greenhouse, and field evaluations.
A colony of Trichoderma virens DM5 (green culture) at the WorldVeg virology laboratory in Taiwan. The fungus protects plant roots, and has been shown to significantly reduce infestations of southern blight – a highly destructive soil-borne disease affecting many vegetable crops in Africa and Asia. Pic by Neil Palmer (WorldVeg).
Among them is Trichoderma virens DM5, a kind of fungal bodyguard that protects plant roots. It was shown to reduce infestations of southern blight – a highly destructive soil-borne disease affecting many vegetable crops in Africa and Asia – by a remarkable 95%. Lab tests also showed it suppressed Fusarium wilt, Phytophthora blight, and bacterial wilt – major diseases that invade a vegetable plant’s vascular system or roots, blocking water flow and causing rapid wilting, collapse, and often total crop loss. In addition, it promoted seedling vigor. Field trials from Taiwan to Benin are evaluating Trichoderma virens DM5 under heat stress and real-world production constraints.
As part of research with South Korea’s Rural Development Administration (RDA), greenhouse trials involving another beneficial microbe, Streptomyces canus B4S, provided almost total control of Phytophthora blight – a major pathogen that affects production of peppers, eggplants, tomatoes, cucurbits, beans, and more. In addition, in collaboration with Taiwan’s National Chung Hsing University, researchers showed that Beauveria isolate 157 – a strain of a naturally occurring insect-killing fungus – demonstrated vigorous activity against thrips, aphids, and whiteflies, tiny sap-sucking insects that feed on vegetable plants, spread diseases, and damage leaves, flowers, and fruits. At a concentration of one million spores per milliliter, it killed half of the test insects within a week.
(Top left): Juan Li-Wen from the WorldVeg virology team with a yeast control sample; (Top right): Chiu Ming-Hsueh, Lorena Arone Maxwell, Chang Hung-Chia, Su Mei-Lien discuss fungal spores; (Bottom left) a petri dish containing a colony of Southern blight, a highly destructive soil-borne disease affecting many vegetable crops in Africa and Asia; (Bottom right) a colony of entomopathogenic fungus Metarhizium anisopliae isolate MA69 (NCHU) featured in the WorldVeg Beneficial Microbe Bank. Pics by Neil Palmer (WorldVeg).
These biocontrol agents have been integrated into Integrated Pest Management (IPM) packages. These combine biologicals (natural, science-based tools such as beneficial microbes or plant-derived compounds that protect crops by suppressing pests and boosting plant health), resistant crop varieties, and plant activators (substances that switch on a plant’s natural defense systems) to offer farmers robust, non-chemical options for suppressing crop diseases. In addition, through the newly launched WorldVeg Biologicals Consortium, the Center expects to partner with research institutes, farmers, and industry to accelerate the development, formulation, and adoption of the most effective biocontrol agents through coordinated trials and joint innovation.
“Replacing synthetic pesticides with science-based biological alternatives is essential if we want safer vegetables, healthier soils, and more resilient farmers,” said Dr. Lourena Maxwell, Scientist–Plant Pathologist at WorldVeg. “Our work with biocontrols and our collaboration through the WorldVeg Biologicals Consortium will give farmers new tools that work with nature, not against it.”
Wallace Chen checks a plot of tomatoes treated with biocontrol agents. Pics by Neil Palmer (WorldVeg).
Biofumigation – bringing out the Brassica brigade
Biofumigation involves growing certain plants – especially Brassicas such as mustard, pak-choi, and radish – that accumulate glucosinolates (GSLs), a group of sulfur-rich compounds that play a central role in plant defense. When the crop is finely mulched and incorporated into the soil, plant cells rupture and release the glucosinolates, acting as natural fumigants that suppress a wide range of soilborne pathogens and pests, reducing the need for chemical fumigants.
Irrigation or rolling immediately after incorporation seals the soil surface, maximizing gas retention and pathogen suppression. In addition, all biofumigant crops contribute to enhanced soil health, including improved organic matter, better soil structure, and increased beneficial microbial activity.
WorldVeg’s multi-season trials show that pak-choi (Brassica chinensis) is one of the most effective species for reducing populations of Ralstonia, soilborne pathogens that cause bacterial wilt in several crops, offering farmers a reliable rotation or intercropping option for suppressing the disease in tropical production systems. Biofumigation complements other regenerative practices, such as the use of green manure and reduced tillage, that WorldVeg is promoting across ACIAR-supported projects.
Together, biocontrol and biofumigation create a powerful ecosystem-based approach to restoring soil function while reducing farmers’ dependence on pesticides and supporting the supply of safe vegetables. Through regional workshops, hands-on training, and co-development of diagnostics and field protocols, WorldVeg is equipping stakeholder researchers with skills to identify, screen, and formulate biocontrol agents, diagnose pathogens, and integrate biologicals and biofumigation into local IPM programs, promoting food safety and environmental protection in vegetable value chains.
“Biocontrol and biofumigation represent a new generation of sustainable crop protection,” said Wallace Chen, who has worked for more than 20 years in the WorldVeg Plant Pathology research unit and serves as Specialist and Senior Assistant in the Mycology Laboratory, testing biocontrols and integrating them into crop management solutions. “Whether it’s microbes acting as bodyguards or Brassicas cleaning the soil, these tools give farmers real alternatives that boost resilience and safeguard vegetable production.”
Brassicas growing at WorldVeg for use in biofumigation (left) and incorporating Brassica biomass into the soil during rototilling. This process activates the glucosinolate–myrosinase reaction in the plants that releases biofumigant compounds.
