Additive and synergistic antifungal effects of copper and phenolic extracts from grape cane and apples |
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Authors: | Paul Besrukow Frank Will Stefan Dussling Beate Berkelmann-Löhnertz Ralf Schweiggert |
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Affiliation: | 1. Department of Beverage Research, Geisenheim University, Geisenheim, Germany;2. Department of Crop Protection, Geisenheim University, Geisenheim, Germany |
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Abstract: | Background Organic viticulture seeks sustainable alternatives for eco-toxic copper fungicides to control downy mildew caused by Plasmopara viticola. (Poly)phenol-rich extracts of agricultural byproducts are known to possess antifungal activity, but high production costs often limit their actual implementation. Results We developed and produced novel ligninsulfonate-based grape cane extract (GCE) formulations and an apple extract on a pilot plant scale, including a detailed (poly)phenol characterization by high-performance liquid chromatography photodiode array mass spectrometry (HPLC-PDA-MS). Our GCE formulations alone reduced downy mildew disease severity in greenhouse trials by 29%–69% in a dose-dependent manner, whereas a standard application of the copper-based agent alone reached ~56%. When applied together, disease severity was diminished by 78%–92%, revealing a synergistic effect that depended on the mixture ratio. Combining GCE formulations with the apple extract, additive effects were found (80% disease severity reduction). Conclusion The studied plant extracts are proposed to both substitute for and synergistically reinforce copper fungicides in grapevine downy mildew control. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. |
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Keywords: | biocontrol biopesticides downy mildew natural products Plasmopara viticola polyphenols stilbenoids viticulture |
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