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Reference: Use of Chitosan and Other Natural Compounds Alone or in Different Strategies with Copper Hydroxide for Control of Grapevine Downy Mildew
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Grapevine downy mildew (GDM) is one of the most serious diseases of grapevines. Limitations for the use of copper-based products in organic agriculture according to EU Regulation EU/2002/473 and the later EU Commission Implementing Regulation 2018/1981 has promoted a search for alternatives. This 5-year field trial evaluated the effectiveness against GDM of several strategies using different chitosan-based formulations and application rates in comparison with other natural compounds, with these applied individually or with copper hydroxide. Trials were run in commercial vineyards, with different environmental conditions and grapevine cultivars. For the natural compounds applied as individual treatments, a 0.5%/0.8% chitosan formulation provided the best protection against GDM, with the other compounds and formulations less effective. When copper hydroxide use was halved by combination with these natural compounds according to three different strategies, GDM incidence, severity and McKinney Index were reduced, in particular for copper hydroxide applied in combinations with the 0.5%/0.8% chitosan formulation, rather than with a mixture of laminarin and Saccharomyces spp. extract. The 0.5%/0.8% chitosan formulation alone and with copper hydroxide provided good protection against GDM for both high-pressure and low-pressure disease seasons. Chitosan thus represents a good alternative to copper formulations for control of GDM for both organic and integrated disease management.

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Publication Details

Published: 2020
Publication: Plant Disease
Issue: 2020 Online November 2020
Author: Romanazzi G 2020


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