Practice

Practice

Vitifutur aims at bringing research and practice together. How can we translate the knowledge generated through research into specific applications? This is our main goal in the project, because it is the only way to give relevance to this knowledge. This conversion has many facets; for instance, our research findings form an integral part of the recommendations on cultivation of grape vine. This enables us to face the spread of pathogens more efficiently and to prevent the development of resistance.

However, we always keep the general public in mind. After all, what is the use in all our efforts for a more sustainable viticulture, if no one wants to buy the product in the end? As a consequence, a scientific evaluation of the general public’s opinion of sustainable viticulture is an integral part of Vitifutur.

Piwi Marketing

The breeding of fungi-resistant grape varieties (Piwis) is a scientific success story. The smart use of natural biodiversity enabled us to create new varieties that require the use of very little or even no pesticides at all.

Of course, the greatest invention has little value if no one buys the final product. The history of Piwis is one of many political and legal obstacles: during National Socialism it was prohibited to perform research on those varieties, because European varieties were distorted with “American blood”. In the 1970s it was established Europe-wide that quality wine may only be produced from the variety Vitis vinifera; in some counties the cultivation of Piwis was even banned. It was not until 2008 that France relaxed this general ban and approved 20 new varieties.

Ultimately, the view that these grape varieties, who’s DNA often consists of 90% or more of the DNA of Vitis vinifera, are actually to be considered Vitis vinifera prevailed.

However, the acceptance of Piwi varieties is still an issue, as many consumers prefer traditional varieties and are initially skeptical about new varieties and names.

Events such as „The Best of Piwis“, which is organized by the project partner WBI, help to improve the acceptance of Piwi varieties among the general public, and at the same time provide a picture on how the consumers evaluate these wines. Anonymous wine tastings may reveal interesting trends – those who are not very fond of Pinot noir, judge the Piwi Cabenet cortis as the finer (and more expensive) variety. A strategy that uses these individual differences can certainly help to tap into new markets, especially among younger people.

The first step to developing new marketing strategies for Piwi varieties is a scientific evaluation of the consumers’ acceptance of Piwis. As a start, it is evaluated how widespread Piwi varieties are in the Upper Rhine region in the first place and in what form they are marketed. In a second step, hypothesis that are based on this newly-gained knowledge are tested empirically in interviews with experts from the wine industry. The results of these surveys give important clues for successful marketing strategies of Piwis.

Viticulture with resistant grape varieties

Vine varieties (Vitis vinifera), which have been cultivated in Europe for thousands of years, are infected time and again by highly specialized pathogens, causing considerable losses of quality and yield. Among these pathogens, the vine peronospora (Plasmopara viticola), also known as downy mildew of the grapevine, stands out for its distinct virulence. High average temperatures and frequent rainy periods foster the rapid spread of the pathogen. In some years, these epidemics, which are difficult to control, have occurred as early as spring. The climate-change related increase of warm periods and heavy rainfall events enhance the risk of serious epidemics with considerable economic damage. In light of the highly susceptibility of the classical European vine varieties to peronospora, and the increasing frequency of epidemics, innovative methods to secure quality and yield are urgently needed. One way to achieve this is by cultivating grape varieties that are highly resistant to vine peronospora. In this subproject, several research institutions are working together to promote viticulture with resistant grape varieties through scientific work, practical innovations and transfer of knowledge.

Our research aims at getting a deeper understanding of resistance mechanisms in grape vine. This newly-gained knowledge consequently serves as basis for breeding work. For this purpose, early stages of infection of the vine peronospora at potential crossing partners are characterized and the interaction of the pathogen with its host plant is analysed. The dynamics and effectiveness of the resistance mechanisms are evaluated in the laboratory and under practical conditions. A close cooperation between the partners from basic university research and applied viticultural research allows the use of the latest microscopic, biochemical and molecular biological methods. Our research will help to identify grape vine strains with improved resistance to vine peronospora as candidates for breeding work, while maintaining high standards of product quality.

The cultivation of resistant grape varieties requires new management systems. It is particularly important to protect the quality and yield of the vine from infestion with peronospora under conditions of high infestation pressure caused by specific weather conditions. Furthermore, there is a risk of resistance erosion during extensive epidemics. Therefore, novel crop protection strategies need to be developed and evaluated. The evaluation of these sustainable management systems as well as plant protection strategies of sustainable crop protection strategies with resistant vine varieties is carried out in close cooperation with the wine-growing industry. In order to do so, yield vineyards with resistant varieties are used to determine the level of resistance, the health of the foliage wall and grapes, as well as yield and quality. The data will be scientifically analyzed and results regarding management systems and strategies will be presented to the wine-growing industry.

A prerequisite for a successful sustainable viticulture with resistant grape varieties is that these new varieties are accepted by the wine industry as well as wine consumers. In order the wine industry to decide to cultivate these varieties, the most important criteria are reliable resistance, stable yields and high quality as well as marketing potential. Only if wine consumers accept and demand resistant varieties, it will be possible to establish the cultivation of these varieties in the wine industry. Therefore, scientifically based surveys in the wine industry on the acceptance of resistant grape varieties create the preconditions for the introduction of the varieties into practice and their placement on the market.

Viral Deseases

Virus diseases - who does not think of smallpox, Ebola, HIV, influenza or other serious, as well as minor but unpleasant diseases, such as colds? Not only humans, but also plants are affected by these pathogens and can be more or less severely damaged. Viruses are parti-cles of mysterious appearance that stand between living organisms and inanimate, complex nanoparticles. They use the cell apparatus of their host plant to reproduce and spread in plant tissue. Outside their host cell, viruses are in a dormant state in which they cannot ac-tively spread, as they depend on vectors for the infection of their host plant. They are injected directly into the plant cells by their vectors, in most cases plant-sucking insects, mites or nematodes (threadworms), during the sucking process. Like the vast majority of cultivated plants, grapevine is also infected by viruses. Virus diseases, however, very often recede behind other diseases such as the vine peronospora, powdery mildew and botrytis, and in the everyday life of the winegrower they are more rarely perceived as the cause of diminishing vitality of the grapevine. Nevertheless, viruses are of great importance for viticultural practice, as they can cause considerable damage. In Alsace, Baden, Palatinate and Switzerland, viral diseases of the vine spread increasingly and affect the yield, quality and longevity of the vines.


Viruspartikel-ARMV

Particle of the Arabis Mosaik virus (ArMV), Icosaeder with a diametre of 28 nm.


Bild: © WBI


Viruspartikel-GLRAV1

Particles of vine leaf roll virus type 1 (GLRaV 1) with a filamentous structure, a length of about 1,800 nm and a diameter of 12 nm.

Bild: © WBI


The vine is the host plant of very different virus species, which all impair the vitality and life span of the plant. Out of the many viruses found in grapevines, the brushwood disease and the leaf roll disease are of particular importance to viticultural practice.

The brushwood disease manifests itself with a number of symptoms, which can vary depending on the variety, location and annual weather conditions. What all varieties have in common is that the vitality of diseased plants decreases, with some varieties reacting very sensitively to virus infestation, while others are affected to a lesser extent. Shrunken shoots with short distances between leaves (shortened internodes), reduced leaf area and sprinkled grapes are the result.

This decline in vigour shows clear differences between the varieties Gewürztraminer and Trollinger, which are more pronounced than, for example, the Riesling variety. Other symptoms of the brushwood disease can also develop very differently, such as leaf discolouration (adulteration). Depending on the weather, parts of the leaves turn golden yel-low and form patterns that form more or less large spots, sometimes in the form of rings. In some cases, untypical allocations or adhesions of the shoots also occur. The brushwood disease is caused predominantly by the virus of the brushwood disease (GFlV), but also by the Arabismosaik virus (ArMV), more rarely by the raspberry ring-spot virus (RRV). The viruses mentioned are almost round particles of approx. 28 nm in diameter, which are composed of 20 surfaces (eggosahedron). They are transmitted by migratory, root-sucking nematodes (threadworms). Because of these properties, this virus group is called nepo viruses (nematode-transferable poolytic viruses). To feed, the virus-transmitting nematodes prick the fine roots of the vine and suck at the cells in the root cylinder. During this process, they take up the virus particles from infected plants and can release them back into the cells of the root during the next sucking cycle on an uninfected plant. In this way, the viruses of the brushwood disease spread throughout the entire stock in the form of a herd from individual or a few infected plants.

Leaves rolled downwards, which already turn yellow or red in late summer, depending on the variety, are the first sign of the leaf rolling disease. This also leads to a decline in the performance of the plant with the flowers trickling, small berries and compressed shoots. The leaf roll disease is caused by various types of leaf roll virus (GLRaV), whose particles resemble thin long threads. Under the climatic conditions in the wine-growing areas along the Rhine, the leaf roll disease is only spread through the use of infected scions or rootstocks. Therefore, with a few exceptions, the leaf roll disease can only be found scattered in vines. In warmer regions south of the Alps, various types of mealy bugs transfer the virus particles from infected to healthy vines during the sucking process. In the past, some grape varieties were almost completely infected by leaf roll disease. This was one of the reasons for the targeted selection of healthy and efficient clones.

Healthy plant material is the only way to prevent the spread of viral diseases. Therefore, only grafted vines produced from healthy rootstocks and scions are marketed. For this complex procedure, mother plants for rootstocks and scions are being tested with state of the art di-agnostic methods throughout Europe. However, a separate test procedure is required for each virus species and new, unknown viruses in the plant cannot be detected. In VITIFUTUR innovative methods are developed which allow the detection of a whole series of viruses in the parent plants in one process step. This means that newly immigrated viruses can also be detected in good time and their immigration by means of young plants can be prevented.

In most cases, both infected vines as well as the vectors of the viruses are present in infested vineyard areas. So far, there has been no way to prevent new infections and curb viral diseases. New rootstock varieties are now available that are resistant to virus-transmitting vectors. In VITIFUTUR these innovative rootstocks are tested under various climatic and soil conditions. The aim of this research and development work is to provide new types of rootstocks with high resistance to virus-infested vineyards.


Management of grapevine trunk diseases(such as Esca)

Grapevine trunk diseases, such as the Esca syndrome, have spread worldwidein the last years. In Baden, the Palatinate, the Alsace, and in Switzerland, these diseases have turned into an economic concern. While this syndrome has been known since the time of the Roman Empire, and has been described more than a century ago, it has been on the rise since the mid-1980s. Esca will sooner or later result in the complete breakdown of the plant. Early symptoms or the disease are loss of colour of the area between the leaf veins. These brightenedareas later turn necrotic until entire parts of the leaf die resulting in a loss of plant vigour. As a response, during later phases of the disease, only thin and stunted shoots are formed. It can take several years, until this final stage is reached after a long period of declining shoot formation, often accompanied with strong reduction of berry yield, grey-black discoloration, and shrinking of the berries. The economic damage of Esca is mainly due to the early death of the grape, because new grafted scions have to be purchased, planted, and raised to compensate for the loss. If the vineyard is already older, and the number of dead or dying grapes high, it may be more economic to replace the entire plot by a new planting. Of course, this precocious replacement means considerable costs that would have been avoided without Esca.

Esca

So called tiger stripes on the leaves are symptoms for the chronical progression of the Esca syndrome.

Bild: © WBI


Esca is caused by a complex of different wood-decaying fungi that colonise the trunk, often in succession. In the Upper Rhine region, the fungi Fomitiporiamediterranea, Phaeomeniellachlamydospora, Diplodiaseriata and Neofusicoccumparvum are found in the wood of grapes that show symptoms. Recently, additional fungi were discovered. Whether these fungi are causing the disease, is far from understood. In addition, the pathogen responsible for eutypiosis (Eutypalata) can be detected.

Often, different fungi can be seen in different regions of diseased trunks: Brown spots in the wood that appear as stripes in longitudinal sections contain Phaeomoniellachlamydospora, Diplodiaseriata, and Neofusicoccumparvum, fungi that colonise wood fibres and vasculature. They propagate through spores that are formed in the vascular bundles. How these spores spread and how they infect the trunk is not well known. The Esca symptoms seen in leaves and berries are most probably caused by toxins secreted by these fungi and travel to the foliage by the water transport.

Infection with Fomitiporiamediterranea causes a completely different appearance of wood sections. Here, the structure of xylem is completely dissociated leading to a cotton like tissue instead of the solid wood, delineated by dark-brown lines from the healthy wood. This so called White Rot is caused by many wood-decaying fungi (such as Fomitiporiamediterranea) by degradation of lignin in the wood fibres and the water-conducting trachea. In the cross-section, the progression of White Rot from large pruning wounds at the trunk head is evident, indicative of wounds as entry points for the fungus. The fungus propagates by spores released from the trunk throughout the year, even during mild winter days. The fruiting bodies can form light brown cushions underneath the trunk head, displaying minute tubes, where the spores are generated.

Esca

Cross section through a trunk head. 1-healthy wood; 2- early stages of White Rot.

Bild: © WBI

Esca

Fruitingbody of Fomitoporiamediterranea.

Bild: © WBI






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