An ecological solution against pathogenic fungi

Synthetic fungicides are commonly used to control harmful fungi in conventional agriculture, but they have various drawbacks. Researchers from the University of Neuchâtel, HE-Arc Ingénierie and FiBL are therefore developing an alternative control strategy against certain fungal diseases. In the Enhance project, they are focusing on microcapsules containing a combination of microorganisms.

Microscopic view of a bacterial colony (colored purple) on fungal hyphae (yellow). (Photo: University of Neuchâtel, Saskia Bindschedler)

Fungal pathogens cause 13 percent of agricultural losses worldwide every year. In conventional agriculture, synthetic fungicides are used to combat them, but these have drawbacks, including the development of resistance and negative effects on ecosystems and human health. In addition, the demand for pesticide-free food is increasing. The Enhance project is looking for innovative and environmentally friendly control strategies against certain fungal diseases. With a budget of CHF 1.9 million, the research will run for four years from January 2025. The project is supported by the Swiss National Science Foundation SNSF.

The research is primarily focused on methods to combat Rhizoctonia solani. This fungal pathogen attacks lettuce and endive and causes the disease called bottom rot which causes losses of up to 100 per cent. Over the course of the project, other target diseases will be added, which will be selected in dialogue with farmers to meet their needs. 

Fungal-highways

But how do you go about combating the pathogenic fungi? The first step is to identify a suitable active mixture of beneficial bacteria. A new discovery offers a clever solution for delivering the bacteria to the right place: Fungal-highways. Fungi form widely branched networks of root-like structures called hyphae. Certain bacteria can use this network to move around. By leveraging these fungal highways, beneficial bacteria can be transported directly to roots of plants, where they provide protection. 

In practice, the beneficial bacteria, in association with a fungus-highway, are enclosed in a microcapsule, which allows for their preservation until both are delivered to their target environment. Once in the soil, the fungus will be able to break the barrier of the microcapsule and spread its hyphae, creating a bridge for the bacteria to actively reach their target.

Testing phase

Once the microcapsules have been successfully developed and suitable fungus-bacteria combinations have been isolated, the practical testing phase begins. This is being led by soil scientist Natacha Bodenhausen in collaboration with the Office Technique Maraîcher (OTM) consultancy and the Fondation rurale interjurassienne (FRI). The effectiveness and environmental friendliness of the new biofungicides will be tested in pot trials and in the field.