Biocontrol of Plant Diseases Using Glycyrrhiza glabra Leaf Extract.

The growing concern regarding the potential risks of pesticides and their impact on nontarget organisms stimulates the development and application of alternative, environmentally friendly products. It seems necessary to develop alternatives for conventional products and for those already widely used in organic agriculture, e.g., copper. Very importantly, such alternative products should not limit the productivity and profitability of agriculture. In this study, we examined the efficacy of licorice (Glycyrrhiza glabra) leaf extract as such an alternative. We tested its impact on the virulence of Pseudomonas syringae toward the model plant Arabidopsis thaliana and the crop plant tomato (Solanum lycopersicum) as well as of Clavibacter michiganensis, Xanthomonas campestris, and Phytophthora infestans toward tomato, at multiple levels. We demonstrate that licorice leaf extract acts as a direct fungicide and bactericide. Moreover, it acts against a metalaxyl-resistant P. infestans strain. In addition, the extract from licorice leaves influences the plant immune system, modulating the plant responses to the challenge with pathogen(s); this involves both salicylic acid and ethylene-based responses. Our results show that in addition to the well-known use of licorice root extract in medicine, the leaf extract can be an effective alternative in organic and integrated farming, contributing to copper reduction and resistance management.[Formula: see text] Copyright © 2022 The Author(s). This is an open-access article distributed under the CC BY 4.0 International license.

Reducing copper use in the environment: the use of larixol and larixyl acetate to treat downy mildew caused by Plasmopara viticola in viticulture.

BACKGROUND: Plant extracts might provide sustainable alternatives to copper fungicides, which are still widely used despite their unfavourable ecotoxicological profile. Larch bark extract and its constituents, larixyl acetate and larixol, have been shown to be effective against grapevine downy mildew (Plasmopara viticola) under semi-controlled conditions. The aim of this study was to reduce the gap between innovation and the registration of a marketable product, namely to develop scalable extraction processes and to evaluate and optimise the performance of larch extracts under different conditions. RESULTS: Toxicologically and technically acceptable solvents like ethanol were used to extract the active compounds larixyl acetate and larixol from bark in sufficient amounts and their combined concentration could be increased by up to 39% by purification steps. The combined concentration of larixyl acetate and larixol from larch turpentine could be increased by up to 66%. The Minimal Inhibitory Concentration (MIC100 ) against P. viticola in vitro (6-23 µg mL-1 ) and the Effective Concentration (EC50 ) in planta under semi-controlled conditions (0.2-0.4 mg mL-1 ) were promising compared with other plant extracts. In vineyards, efficacies of larch extracts reached up to 68% in a stand-alone strategy and 84% in low-copper strategies. CONCLUSION: Larch extracts represent valid candidates for copper reduction in organic vineyards, and their development into a sustainable plant protection product might be feasible. © 2017 Society of Chemical Industry.