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

Changes in Norisoprenoid Levels with Long-term Nitrogen Fertilisation in Different Vintages of Vitis vinifera var. Riesling Wines

C13-norisoprenoids were measured in Riesling wines produced from the 1996, 1997 and 2003 vintages within thescope of a long-term nitrogen (N) fertilisation experiment. The wines were made from treatments of 0, 60 and 150kg N/ha; each treatment was repeated four times and arranged in a completely randomised design. N fertilisationled to lower TDN (1,1,6-trimethyl-1,2-dihydronaphthalene) concentrations, whereas the trend was for actinidol andß-damascenone to increase with increasing fertilisation and vitispirane was not affected by fertilisation. Yield,which was affected by N fertilisation, showed negative correlations with norisoprenoids in 1996 and 1997.Vitispirane, actinidol and TDN increased with storage time. The colder year, 1996, which had fewer sunshine hours,resulted in higher concentrations of ß-damascenone and lower concentrations of the norisoprenoids vitispirane,actinidol and TDN compared with 1997

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

Geostatistical Analysis and Scaling of Grapevine Root Distribution

Geostatistical analysis was conducted for the root distribution of Vitis berlandieri x Vitis riparia using dispersionindex, fractal dimension, autocorrelation and semivariance. The data were derived from the observation of rootsof six 12-year old Riesling/5C vine plants in a field experiment using minirhizothron technique. The dispersionindex (DI) indicated the clustering of roots. Autocorrelation as a function of the distance lag showed that a higherDI was related to higher autocorrelation at small lags. Small scale (< 3cm) spatial analysis using variograms,showed a clustering of roots at short distances (< 6cm), but also a periodicity at greater distances (16cm) with holeeffects in the variograms. The spatial variance for small scale was 60-85% within a range of 5-8cm. At mediumscale (5-10cm) the spatial variance decreased to 0-20%. Geostatistical analysis is a useful tool to demonstratevariation in root distribution at plant level and to improve root sampling. Although the different geostatisticaltools were related, it was not possible to deduce one result from the other quantitatively

Effect of different N fertilization of vine on the tryptophan, free and total indole-3-acetic acid concentrations

The compound responsible for UTA (untypical ageing off-flavour) in wines is o-AAP (o-amino acetophenone). It is formed from IAA (indole-3-acetic acid), triggered by sulfurylation. The aim of this study was to evaluate the effect of different N fertilizer supply on this precursor in must and wine, making use of a long-term nitrogen fertilization experiment. Trp (Tryptophan) as well as free and conjugated IAA were determined in musts and wines produced from grapevines supplied with 0, 30, 60, 90 or 150 kg N ha-1 year-1. IAA concentrations in musts and wines varied highly over years (1994-1999), wines containing about half of the total IAA of musts. The IAA concentration in must was positively correlated with the concentration of amino acids in must, however, nitrogen supply did not have any effect, neither on Trp nor on IAA concentrations

Investigation of grapevine root distribution by in situ minirhizotron observation

Root observations of Vitis berlandieri x Vitis riparia were conducted in two experimental sets using minirhizotron technique. Experiment 1 was a field experiment carried out on a 12 years old Riesling/5C vineyard. On six plants three minirhizotrons were installed at different angles (90°, 60°, 45°) and two directions per tube were used for observation. The maximum of root length density (RLD) was found in soil depths of 600-800 mm with high variation mainly due to plant x angle interaction. Observation direction did not influence the estimates of RLD. The installation angle of the tubes did not lead to any consistent effect on root observation. Experiment 2 was a pot trial of six pots with four vines each. Tubes were installed horizontally. RLD in the pot experiment according to the monolith method and the estimated RLD according to the minirhizotron method did not correlate, so the quantification of Vitis RLD distribution using minirhizotron is difficult.

Einfluss verschiedener weinbaulicher Bewirtschaftungssysteme auf die photosynthetische Leistung der Rebe (Vitis vinifera ssp. Riesling)

Based on a field trial, the impact of three different viticultural management practices on photosynthetic activity of Vitis vinifera cv. Riesling were compared. The vines were planted in 1991 at Geisenheim (Rheingau, Germany) and the different management practices i.e. integrated (good agricultural practice), organic (EU VO 834/07 and ECOVIN standard) und biodynamic (EU VO 834/07 and DEMETER standard) were established in 2005. Even though all treatments received the same level of nutrients and water the initial measurements of photosynthetic activity differed tendentially. The integrated and biodynamic treatment showed a slightly higher degree of light saturation, as well as photosynthetic activity, compared to the organic treatment

Root dynamics and pattern of 'Riesling' on 5C rootstock using minirhizotrons

Root length density (RLD) in the years from 1994-1997 was estimated using minirhizotrons. The field experiment was conducted on six 'Riesling' vines in Rheingau (Germany). The majority of root distribution was found in soil depths of 60-100 cm with considerable variations between the plants. Roots dynamics showed a periodicity with one or two maxima, depending on year and vine plant. The first peak of RLD was observed around veraison, the second peak appeared after harvest. The rate of root length death was estimated. In the deeper layer the turnover of roots was 60% of the total RLD every year.

Algorithmen für Matchingprobleme in speziellen Graphklassen

Das Matching- oder Korrespondenzproblem gehört zum Gebiet der Graphentheorie. Zielsetzung ist es, in einem Graphen mit n Knoten und m Kanten effizient ein maximales Matching, d.h. eine möglichst große Menge disjunkter Kanten zu finden. In dieser Arbeit stellen wir hierzu mehrere neue Algorithmen vor: Erstens geben wir zwei Methoden an, um mit Hilfe von Graphenkompression, aber ohne Transformation in ein Flussproblem, ein maximales Matching in Zeit O(n^(0,5)m(log(2n^2/m)/log(n))) zu finden. Die eine Methode erlaubt einen einfachen Beweis ihrer Korrektheit, die andere ist aufgrund kleinerer Konstanten bei der Laufzeit eher zur Implementierung geeignet. Zweitens präsentieren wir einen Algorithmus, der in einem bipartiten Graphen, der n^(0,5)o^3 disjunkte perfekte Matchings enthält, ein einzelnes maximales Matching in Zeit O(n^(0,5)m/o) findet. Durch Kombination der beiden Verfahren können wir im zweiten Fall für spezielle Graphklassen noch weitere Verbesserungen erzielen

Ökologischer Weinbau in Deutschland - Feldversuche und praktische Erfahrungen zur Kupferreduzierung

Ableitend aus dem aktuellen Kenntnisstand, den vorgestellten Ergebnissen und vielfältigen Erfahrungen aus der Praxis muss festgestellt werden, dass derzeit keine praxisreifen Kupferersatzstoffe aus den Bereichen anorganische Salze, Pflanzenextrakte und biologische Antagonisten zur Verfügung stehen. Die im Rahmen der vorgestellten Versuche mit einem unformulierten Präparat des biologischen Antagonisten von Plasmopara viticola, Erwinia herbicola, erzielten Ergebnisse machen den Forschungsbedarf in diesem Sektor deutlich. Die Wirkungspotentiale von Erwinia herbicola konnten mit dem unformulierten Versuchsprodukt bei gleichzeitig starkem Infektionsdruck und den realisierten Applikationsintervallen nicht ausgeschöpft werden. Gute Ergebnisse beim Einsatz von Erwinia herbicola Anfang der 90er Jahre belegen die Wirksamkeit dieses Antagonisten, wobei besonders durch entsprechende Formulierung Wirkungssteigerungen erreicht wurden. Um die Existenz des europäischen Bioweinbaus sicherzustellen ist der Erhalt bestimmter Kupferverbindungen im Anhang II der EU-VO 2092/91 derzeit unverzichtbar. Weiterhin ist aufgrund der klimatisch bedingten, an Stärke zunehmenden Infektionsereignisse durch Plasmopara viticola eine Reduzierung der Aufwandmengen unter 3 kg/ha und Jahr in der Praxis nicht vorstellbar. Möglichkeiten zu einer weiteren nationalen Reduzierung des Kupfereinsatzes (< 3 kg/ha) bei hohem Befallsdruck wären derzeit nur nach einer Wiederzulassung von phosphithaltigen Präparaten durch die BBA (Ökofluid-P und Robus sind derzeit nicht als Pflanzenstärkungsmittel registriert) gegeben und im Sinne der Praxis verantwortbar, wobei die Akzeptanz dieser Präparate durch die Bioanbauverbände gegeben sein müsste. Bei einer Eingruppierung als Pflanzenschutzmittel wäre eine Aufnahme in den Anhang II der EU Verordnung zu beantragen. Bereits bekannte Ergebnisse aus den 90er Jahren und aktuelle Untersuchungen zu Phosphonatrückständen in den Weinen aus den vorgestellten Versuchen sowie weiteren Proben aus der Praxis belegen die bestehende Rückstandsproblematik. Aktuell laufende Untersuchungen weisen jedoch darauf hin, dass dieser Problematik durch eine Begrenzung des Einsatzes bis in den Bereich des Entwicklungsstadiums „Erbsengröße“ (BBCH 75) sowie den Einsatz von Präparaten mit geringerer Phosphonatkonzentration deutlich entgegengewirkt werden kann. Die Untersuchungen hierzu sind noch nicht abgeschlossen und werden fortgesetzt