Abstract
In organic viticulture, copper-based fungicides are commonly used to suppress Downy Mildew infection, caused by the oomycete Plasmopara viticola. However, the frequent and intensive use of such fungicides leads to accumulation of the heavy metal in soil and nearby waters with adverse effects on the ecosystem. Therefore, alternative, organic fungicides against Downy Mildew are urgently needed to reduce the copper load in vineyards. In this study, the use of Warburgia ugandensis Sprague (Family Canellacea) leaf and bark extracts as potential fungicides against Downy Mildew were evaluated. In vitro (microtiter) and in vivo (leaf discs, seedlings) tests were conducted, as well as field trials to determine the efficacy of the extracts against Downy Mildew. The results revealed an MIC100 of 500 µg/mL for the leaf extract and 5 µg/mL for the bark extract. Furthermore, experiments with leaf discs and seedlings demonstrated a strong protective effect of the extracts for up to 48 h under (semi-) controlled conditions. However, in field trials the efficacy of the extracts distinctly declined, regardless of the extracts’ origin and concentration.
Highlights
Downy Mildew (DM) of grapevine, caused by the oomycete Plasmopara viticola, is one of the most threatening and harmful diseases in viticulture
Protective measures were urgently needed in the second half of the 19th century to control this disease, and it was a coincidence that led to the first plant protection product (PPP) against DM, the Bordeaux mixture [3]
The phytochemicals with the highest contribution to the antifungal properties of WU extracts belong to the group of sesquiterpenes; polygodial, warburganal and muzigadial [33,40]. Their ability to inhibit the fungal growth could be demonstrated for Candida utilis and Saccharomyces cerevisiae, among others [50]
Summary
Downy Mildew (DM) of grapevine, caused by the oomycete Plasmopara viticola, is one of the most threatening and harmful diseases in viticulture. The continuous and intensive application of Cu-based fungicides leads to an accumulation of the heavy metal in agricultural soils and nearby waters and as a result negatively affects the ecosystems [2,7,8,9,10]. In organic viticulture, this problem is even more severe since alternatives with comparable efficacies to copper are rare presently or even non-existing since the ban of phosphonates [11]. More PPPs are strongly needed to extend the “toolbox” for protection against DM and with that, reducing the cooper input in the environment [12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
