Copper replacement in organic viticulture - state of the art in legislation and research

In European viticulture, downy mildew (Plasmopara viticola (Berk. & Curt.) Berl. & de Toni) is one of the most dangerous diseases affecting grapes, causing significant damage and severe decreases of product quality. European organic viticulture is predominantly based on copper applications to control this disease. Due to environmental problems incurred by copper applications, the European Commission decided to limit the use of certain copper products in organic viticulture. This should be achieved by the year 2002 (cf. EC 1488/97). Therefore, the Commission recommends testing alternative strategies in downy mildew control in line with EC 2092/91. In the last decade, specific actions were realized to investigate, apply and support alternative control measures. These are based on microbial antagonists, plant extracts and inorganic, naturally occurring compounds. Studies on modes of action should help to characterize markers indicating effective resistance inducers. Apart From the introduction of newly developed control agents, field trials focused on copper reduction strategies and new products with extremely low copper concentrations. Nevertheless, a multidisciplinary approach is highly recommended in order to help solving one of the major problems of organic viticulture

Using Copper in Organic Viticulture: Doing it best with less?

For many years, applications of copper fungicides have been used to control downy mildew on grapes. Nowadays, its intensive use is under consideration due to ecotoxicological aspects, especially in organic viticulture. As a result, this project made allowance for consumer perception about organic viticulture and is seeking suitable alternatives. The project includes an association of six research facilities, four organic wineries, several consultant agencies for organic viticulture as well as SME (small and medium-sized enterprise) partners, which are working together in four work packages. The aim of this work is to obtain an array of products that provide sufficient control of Plasmopara viticola with the lowest possible input of copper. As a longterm intention, copper-containing products should be totally replaced by other effective agents. Progress to-date suggests that some non-copper products and several copper-based products using less than 3 kg/(ha*a) have potential to effectively control the disease with less ecological residue

Kupferersatz/-minimierung im ökologischen Weinbau – erste Ergebnisse aus dem laufenden BÖL-Verbundprojekt

The project examines the control of downy mildew (Plasmopara viticola) in organic viticulture based on copper replacement and copper reduction strategies, respectively. The replacement agents or the new copper formulations with minimised copper dose will be integrated into the “organic standard” strategy, which additionally aims at the control of other pests and diseases. The following agents were tested: plant strengtheners, plant extracts and stone meals. Despite unclear situations regarding commercialisation and registration purposes, respectively, bacterial antagonists and phosphoric acid were also included. After a screening on potted vines, agents were tested in the test-vineyards of six different research stations for viticulture and plant protection. The last step should be the application on four pilot sites under practical conditions. Based on the results of the first growing period (2004), agents and strategies could be selected for large scale and practical use by organic vinegrowers. Algae products and new copper formulations have been proven to be highly effective against P. viticola in the greenhouse as well as in the field

Early remote detection of downy mildew on grape vine by fluorescence methods

Pathogenic fungi severely threatens the annual yield of grapes in quantity and quality. Therefore, viticulture requires intensive fungicide applications, compared to other crops. Aimed at a reduction of fungicide input, different techniques and combined strategies are applied in viticulture. To successfully reduce losses in yields, early detection techniques are required. In this work we present premeasurements to remotely detect a pathogenic fungus on the leaves of Vitis vinifera (Müller-Thurgau). We were able to detect a leaf infection with Plasmopara viticola (causal agent of downy mildew) on potted vines within the first week after inoculation. Our results could be reproduced over multiple samples and different methods. Fluorescence mapping was used to monitor the blue-green fluorescence and chlorophyll fluorescence behaviour over a wide area of excitation wavelengths. Based on this, spectral data of fluorescence emission was recorded via fluorometric measurements with excitation at different wavelengths in the visible and UV range. Furthermore, we used laser-induced fluorescence (LIF) and hyperspectral imaging to verify our results. Additionally, we combined hyperspectral imaging with LIF. The evaluation was based on the ratio of blue fluorescence to far-red fluorescence (BFRR_UV) and normalized difference vegetation index (NDVI), which represent an established method in many agricultural applications. Eventually, we evaluated the scalability of our methods for long term measurements. Our results form a fundamental approach for the design of a laser-based stand-off detection system for the practical application in vineyards. Such a system can serve as a model technology for early detection of pathogenic diseases and opens a window for early countermeasures. As mildew infection is considered the most damaging disease in European viticulture, these early countermeasures could greatly reduce the environmental and economic cost associated with fungicide application

Early remote detection of downy mildew on grape vine by fluorescence methods

Pathogenic fungi severely threatens the annual yield of grapes in quantity and quality. Therefore, viticulture requires intensive fungicide applications, compared to other crops. Aimed at a reduction of fungicide input, different techniques and combined strategies are applied in viticulture. To successfully reduce losses in yields, early detection techniques are required. In this work we present premeasurements to remotely detect a pathogenic fungus on the leaves of Vitis vinifera (Müller-Thurgau). We were able to detect a leaf infection with Plasmopara viticola (causal agent of downy mildew) on potted vines within the first week after inoculation. Our results could be reproduced over multiple samples and different methods. Fluorescence mapping was used to monitor the blue-green fluorescence and chlorophyll fluorescence behaviour over a wide area of excitation wavelengths. Based on this, spectral data of fluorescence emission was recorded via fluorometric measurements with excitation at different wavelengths in the visible and UV range. Furthermore, we used laser-induced fluorescence (LIF) and hyperspectral imaging to verify our results. Additionally, we combined hyperspectral imaging with LIF. The evaluation was based on the ratio of blue fluorescence to far-red fluorescence (BFRR_UV) and normalized difference vegetation index (NDVI), which represent an established method in many agricultural applications. Eventually, we evaluated the scalability of our methods for long term measurements. Our results form a fundamental approach for the design of a laser-based stand-off detection system for the practical application in vineyards. Such a system can serve as a model technology for early detection of pathogenic diseases and opens a window for early countermeasures. As mildew infection is considered the most damaging disease in European viticulture, these early countermeasures could greatly reduce the environmental and economic cost associated with fungicide application

Use of a Sapindus mukorossi-extract to regulate fungal pathogens on vines – an alternative strategy for organic grape protection?

Ein wässriger Extrakt von Schalen der Indischen Waschnuss (Sapindus mukorossi) hat in Gewächshausversuchen an Blättern von Vitis vinifera (L.) eine gute Wirksamkeit gegenüber Guignardia bidwellii (Erreger der Schwarzfäule an Weinreben) und Plasmopara viticola (Erreger des Falschen Rebmehltaus) gezeigt. Diese Wirkung bestätigte sich bezüglich G. bidwellii grundsätzlich auch an Beeren im Freiland. Im Falle zeitnah vor der Inokulation durchgeführter Applikationen wurden hohe Wirkungsgrade im Bereich der beiden Vergleichswirkstoffe aus dem ökologischen Weinbau (Netzschwefel) bzw. integrierten Rebschutz (Metiram) erzielt (75 bis 90%). Die Wirkungsdauer ist jedoch begrenzt. Im Freilandversuch mit siebentägigem Applikationsintervall betrug der Wirkungsgrad des Waschnuss-Extraktes rund 50%. Entgegen den Ergebnissen aus dem Gewächshaus konnte ein Wirkungspotential gegenüber dem Falschen Rebmehltau im Freilandversuch – zumindest bei geringem Befallsdruck (Versuchsjahr 2008) – nicht nachgewiesen werden.In greenhouse experiments on leaves of Vitis vinifera (L.) a water-extract of shells of the Chinese Soapberry (Sapindus mukorossi) indicated an excellent efficacy against Guignardia bidwellii (causal agent of black rot) and Plasmopara viticola (causal agent of downy mildew). Regarding G. bidwellii, this effect was principally confirmed on clusters in the field. Here, when application takes place immediately prior to inoculation the observed efficiency (75 to 90%) was comparable to standard products applied in organic viticulture (Thiovit Jet®, a.i. sulphur) or integrated grape production (Polyram® WG, a.i. metiram). However, the duration of activity in the vineyard seems to be limited. In a field trial with a seven day application interval the efficacy of the water-extract of Sapindus mukorossi reached around 50%. The control of Plasmopara viticola in the field was even more difficult. Contrary to the results in the greenhouse, the potential of a water-extract of Sapindus mukorossi to control Plasmopara viticola was – at least in the growing period 2008 with prevailing low disease pressure – not evident

Remote detection of fungal pathogens in viticulture using laser-induced fluorescence: an experimental study on infected potted vines

Introduction: Pathogenic fungi, such as Plasmopara viticola and Erysiphe necator, severely threaten the annual yield of grapes in both quantity and quality. In contrast to other crop production systems, fungicides are intensively applied in viticulture as a countermeasure. The goal of precision viticulture is to optimize vineyard performance as well as the environmental impact by reducing fungicides and applying different techniques and combined strategies. Therefore, new emerging technologies are required, including non-invasive detection, as well as monitoring and tools for the early and in-field detection of fungal development. Methods: In this study, we investigated leaves of potted vines (Vitis vinifera cv. ‘Riesling’) and traced the development of the inoculated leaves using our new remote detection system vinoLAS®, which is based on laser-induced fluorescence spectroscopy. We ran a measurement campaign over a period of 17 days. Results: We were able to detect a leaf infection with P. viticola, the causal agent of downy mildew, between 5 and 7 days after inoculation. Our results provide evidence for a successful application of laser-based standoff detection in vineyard management in the future. Thus, the vinoLAS system can serve as a model technology for the detection of pathogenic disease symptoms and thus monitoring complete vineyard sites. This allows for early countermeasures with suitable crop protection approaches and selected hot-spot treatments. Discussion: As P. viticola is considered one of the most damaging fungi in European viticulture, disease mapping via this monitoring tool will help to reduce fungicide applications, and will, therefore, support the implementation of the European Green Deal claims