Smarter fungicides: Fighting infection while protecting soil health

25-03-2026

Copper nanoparticles could lead to less polluted soils in vineyards, according to a study published in Environmental Science: Nano. The researchers came to the ESRF’s ID21 to track how copper behaved in grapevines plants inoculated with a fungus.

Copper-based pesticides have been used around the world vineyards to keep fungal diseases at bay for more than a century in the form of Bordeaux mixture. Whilst it has proven to be extremely effective, copper is a metal and accumulates over time. Bordeaux mixture has a low affinity to plant leaves. When it rains, it washes it off the plants onto the soil, where it can harm earthworms, beneficial microbes and long-term soil health, which can lead to less productive soil in the long run.

Winemakers, particularly in the organic sector, where copper remains one of the few approved fungicides, face a difficult question: how can they protect their vines without poisoning their soils? With the aim of pushing more environmentally friendly practices, European regulators are increasingly limiting the amount of copper to be used in grapevines.

“We wanted to test whether copper nanoparticles (copper oxide) could be as reactive as the traditional sprays but using much less quantity”, explains Astrid Avellan, CNRS researcher and corresponding author of the publication.

The idea was that the nanoforms of copper would adhere to the leaves better. But copper oxide in its nanoform is not very toxic to the fungi: It would need to dissolve and release ionic copper to be efficient. The team, with scientists from the Universidade de Aveiro in Portugal and the ESRF, didn’t know how the nanoparticles would behave at the plant surface. Would they remain untransformed? Would they dissolve in the presence of fungal spores to release the antifungal ionic copper?

Astrid Avellán preparing the samples in the lab at the ESRF's ID21. Credits: D. Salvador.

They came to the ESRF’s ID21 beamline to analyse several vineyard plants that had conventional Bordeaux Mixture and various copper nanoparticles applied to them, on which they had inoculated fungal spores. They used micro X-ray fluorescence and X-ray absorption spectroscopy (XANES) to track for the copper distribution and transformations on and in the leaves. “Analysing plant tissues at ID21 is possible thanks to our dedicated cryogenic sample environment tailored for this kind of studies; this is in addition to the high sensitivity for copper and the outstanding nano-beam stability allowing to perform XANES on nanomaterials”, explains Hiram Castillo, scientist on ID21.

They noticed that when copper sits undisturbed on a leaf, it largely stays put. It does not move into other parts of the plant, remains at the leaf surface and does not transform.

Fungus switches fungicide on

But when fungus such as Botrytis cinerea, the fungus responsible for grey mould, reaches the leaves, it releases small molecules, including organic acids and sulphur-containing compounds that chemically transform the copper. These fungal metabolites dissolve the copper particles and bind to the released copper ions, effectively activating the metal at the site of infection. In other words, the pathogen itself helps switch the fungicide on.

The impact of climate change

The implications of this study are particularly interesting at a time when climate change is triggering fungal presence in vineyards due to warmer and more humid conditions. Equally, consumers and regulators are after more sustainable practices for the long run. Sonia Rodrigues, assistant professor in the Universidade de Aveiro and part of the team, explains: “There is genuine urgency in the field: producers are actively seeking alternatives to conventional copper treatments that will deliver effective disease control without the long-term cost to soil health and biological function that accumulation of copper compounds entails. This study speaks directly to that need."

The next step for the researchers is to study the actual fungal protection these treatments could lead to, in more realistic conditions, instead of a controlled environment like the lab.

Lightning questions

CÁTIA PINTO - Innovation catalyst at National Confederation of Agricultural Cooperatives and Agricultural Credit of Portugal (CONFAGRI)

Is there an increase of fungi in the grapevines?

Yes. Climate is changing and with this we have a disturbance in the microbial communities, and the environmental pressures may result in new diseases caused by pathogens such as fungi. Some of the problems or threats lies primarily in the emergence of new strains or new diseases, as well as in their prediction.

What is the situation like in Europe?

In Europe, some active substances in plant protection products are being withdrawn from the market and other are considered as candidates for substitution, so it is also necessary to learn to adapt to more sustainable strategies, increasingly avoiding dependence on these products.

Do you think that the findings from this paper could be used to implement new antifungal strategies?

The use of nanoparticles as fungicides is an important milestone for the sustainability of plant treatments: as it will allow for greater effectiveness, less waste, and a slower and more efficient release of active substances. This work will open many doors for the development of innovative treatments for plant protection, including the application of future biological control agents (BCAs).

Are there changes that have already been implemented in the vineyards to better preserve soils, whilst still effectively getting rid of fungi?

Yes, fortunately, agricultural production is becoming increasingly aware of the importance of soil biology, and there is a growing number of producers opting for more careful, sustainable management with regenerative techniques. The European Parliament has effectively approved the Soil Monitoring and Resilience Directive (or Soil Monitoring Act), which aims to establish a harmonized framework for monitoring and ensuring that all European soils are healthy by 2050. This is a very important milestone and we have a lot of work to do!

Reference:

Salvador, D. et al, Environ Sci Nano. 2026 Feb 24;13(3):1485–1498. doi: 10.1039/d5en01102g

https://doi.org/10.1039/D5EN01102G

Text by Montserrat Capellas Espuny

Top image: Grapevines in France. Credit: M. Wagner.