Antifungal activity of metal-based coatings on polytunnel surfaces

This study investigated the antifungal performance of copper-based antimicrobial coatings developed by Gencoa Ltd., previously validated against bacterial ESKAPE pathogens, alongside newly formulated titanium oxide coatings, against key agricultural fungal pathogens: Alternaria alternata, Botrytis cinerea, Cladosporium cucumerinum, and Fusarium oxysporum. Testing was conducted both in vitro and in field trials within an actively used polytunnel.

In vitro assays included a modified ISO 846 agar plate protocol and a six-well plate fungal colonization assay simulating high humidity conditions. Field trials assessed coating performance under real-world exposure. Copper-containing coatings: pure copper, copper oxynitride, and copper-doped titanium oxide, consistently demonstrated significant antifungal activity, effectively reducing spore germination and colonization. Titanium oxide coatings without copper showed minimal effect, performing similarly to uncoated polyethylene. While copper-based coatings were highly effective, some susceptibility to surface degradation under prolonged moisture was observed. However, antifungal activity often persisted in degraded areas of samples with high copper content.

Copper-based antimicrobial coatings offer strong potential for preventing fungal colonization on agricultural surfaces, outperforming titanium oxide formulations under both laboratory and field conditions. Optimization to enhance durability will further improve their suitability for long-term use in protected cultivation systems.