Lucius Tamm

Apple blotch (AB) is a major disease of apple in Asia and recently emerged in Europe and the United States. It is caused by the fungus Diplocarpon coronariae (formerly Marssonina coronaria; teleomorph: Diplocarpon mali) and leads to severe defoliation of apple trees in late summer, resulting in reduced yield and fruit quality. To develop effective disease management strategies, a sound knowledge of the pathogen's biology is crucial. Data on the early phase of disease development are scarce: No data on spore dispersal in Europe are available. We developed a highly sensitive TaqMan qPCR method to quantify D. coronariae conidia in spore trap samples. We monitored temporal and spatial dispersal of conidia of D. coronariae and the progress of AB in spring and early summer in an extensively managed apple orchard in Switzerland in 2019 and 2020. Our results show that D. coronariae overwinters in leaf litter, and spore dispersal and primary infections occur in late April and early May. We provide the first results describing early-season dispersal of conidia of D. coronariae, which, combined with the observed disease progress, helps to understand the disease dynamics and will be a basis for improved disease forecast models. Using the new qPCR method, we detected D. coronariae in buds, on bark, and on fruit mummies, suggesting that several apple tissues might serve as overwintering habitats for the fungus, in addition to fallen leaves. [ ] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Calls for supporting sustainability through more and better research rest on an incomplete understanding of scientific evidence use. We argue that a variety of barriers to a transformative impact of evidence arises from diverse actor motivations within different stages of evidence use. We abductively specify this variety in policy and practice arenas for three actor motivations (truth-seeking, sense-making, and utility-maximizing) and five stages (evidence production, uptake, influence on decisions, effects on sustainability outcomes, and feedback from outcome evaluations). Our interdisciplinary synthesis focuses on the sustainability challenge of reducing environmental and human health risks of agricultural pesticides. It identifies barriers resulting from (1) truth-seekers’ desire to reduce uncertainty that is complicated by evidence gaps, (2) sense-makers’ evidence needs that differ from the type of evidence available, and (3) utility-maximizers’ interests that guide strategic evidence use. We outline context-specific research–policy–practice measures to increase evidence use for sustainable transformation in pesticides and beyond.

The reduction of copper-based plant-protection products with the final aim of phasing out has a high priority in European policy, as well as in organic agriculture. Our survey aims at providing an overview of the current use of these products in European organic agriculture and the need for alternatives to allow policymakers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country, with statistics on organic area. In the 12 surveyed countries (Belgium, Bulgaria, Denmark, Estonia, France, Germany, Hungary, Italy, Norway, Spain, Switzerland, and the UK), we calculated that approximately 3258 t copper metal per year is consumed by organic agriculture, equaling to 52% of the permitted annual dosage. This amount is split between olives (1263 t y⁻¹, 39%), grapevine (990 t y⁻¹, 30%), and almonds (317 t y⁻¹, 10%), followed by other crops with much smaller annual uses (−1). In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27%, they use less than a quarter. At the time being, completely abandoning copper fungicides would lead to high yield losses in many crops. To successfully reduce or avoid copper use, all preventive strategies have to be fully implemented, breeding programs need to be intensified, and several affordable alternative products need to be brought to the market.

Although input use in organic agriculture is strictly regulated, and significantly less contentious inputs are applied in organic than in conventional farming systems, copper, mineral oil, external nutrient input, anthelmintics, antibiotics and vitamins are still commonly used among organic farmers in the EU, partly due to the scarce availability of alternative products and the difficulty of implementing preventive strategies. Moreover, besides the direction set by the European Commission’s organic regulation, only a handful of policy instruments exist at national levels to reduce the use of these contentious inputs. The purpose of this paper is to discuss the results of the RELACS EU-funded project about the current use of copper, mineral oils, external nutrient inputs, anthelmintics, antibiotics and vitamins in organic farming in the EU. The paper is based on six internal reports developed in RELACS which relied on international surveys, in-depth interviews, multiple case study methods, database-based calculations, secondary data sources, plus a survey independent from the reports to map existing policy instruments and voluntary initiatives in the EU aiming to reduce the use of the six input categories. As a result, the paper gives a comprehensive overview of the current consumption of the six contentious inputs within the organic sector, highlighting potential alternative strategies in the pipeline, available preventive measures and the willingness of farmers towards adopting these solutions. It also informs about specific policy instruments already in force, as well as about ongoing voluntary initiatives to reduce contentious inputs. Due to the current dependence of organic farming systems on the six categories of contentious inputs, any sudden phase-out or ban on their usage would do more harm than good to the organic sector. Therefore, gradual, data-driven reduction measures are needed, which require significant further investments in targeted research, and in policy support measures, with the active involvement of agricultural stakeholders.

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