Resistant Grape Varieties Research Articles

Influence of Information about Fungus-Resistant Grape Varieties on Hedonic Ratings by Consumers – a Central Location Test in Germany

This study examines the impact of information about resistant grape varieties on consumer sensory acceptance. Specifically, it investigates how consumers’ perception of fungus-resistant grape varieties is influenced by providing information about these varieties. The study utilises data from a central location test conducted with 244 consumers in Germany featuring 8 different wines. The sample was carefully selected to ensure representativeness across gender, age and frequency of consumption. The data were analysed using descriptive and multivariate statistical techniques. The results indicate that consumers rate the quality and willingness to pay for wines made from fungus-resistant grape varieties similarly to wines made from traditional grape varieties when tasted without any prior information about the wines or the influence of fungus-resistant grape varieties in viticulture. However, providing consumers with information prior to tasting results in a positive effect on their assessment of quality and willingness to pay for wines made from resistant grape varieties. By offering information about the positive effects of fungus-resistant grape varieties, it is possible to enhance consumer acceptance and increase their willingness to pay for wines from resistant grapes.

History of breeding programmes for fungus resistant grape varieties in Europe, France and the Occitanie region

History of breeding programmes for fungus resistant grape varieties in Europe, France and the Occitanie region

Adoption and Impact of Fungus-Resistant Grape Varieties within German Viticulture: A Comprehensive Mixed-Methods Study with Producers

The reduction of phytosanitary treatments in viticulture is widely demanded by policymakers and consumers. An important solution is the use of resistant grapes, which can cut plant protection applications by up to 80%. Although this is a significant improvement, viticulture is mainly carried out with traditional grapes. Therefore, the aim of this paper is to identify the factors that encourage the cultivation of fungus-resistant grape varieties (FRGV), as well as the challenges and opportunities in marketing. Our study used an exploratory sequential mixed-methods model design. In the first step, data were collected through 48 in-depth interviews and analyzed. Based on the qualitative results, a survey of 422 producers was conducted. The quantitative research results were segmented by company size and production type to provide a deeper understanding. The main drivers for cultivation are the ecological benefits resulting from the reduction of pesticide use, with organic producers particularly motivated by sustainability goals. Smaller producers are driven by the opportunity to introduce a new wine style, whereas larger producers are more cautious and focus on cost savings. The cultivation of resistant grape varieties is restricted by a large number of varieties, lack of experience, and unfavorable characteristics from initial generations of resistant grapes. A low level of grape variety prominence and customer awareness, as well as unattractive variety names, negatively affect producer acceptance. To facilitate higher market acceptance, it is important to offer attractive grape varieties, directly communicate them to consumers, and provide information about the sustainable effects.

Hybrid variety Dionis (Cabernet Franc E11 × Panonia) vs. Cabernet Franc wines: Comparative study of chemical profile, in vitro biological activity, sensory quality and potential health risk

In the 20th century, resistant grape varieties did not succeed due to the lack of wine quality analyses prior to introduction to the market. Thus, newly created resistant varieties should be tested for wine quality characteristics. This study evaluates new, resistant interspecies variety Dionis and parental Cabernet Franc wines (vintages 2017−2021): chemical characteristics (oenological parameters; polyphenolic profile by HPLC analysis), in vitro biological activity (biochemical and cell-based assays related to enzyme inhibitory, antioxidant and anti-inflammatory activity), safety aspects (ochratoxin A (OTA) occurrence), and sensory profile. According to oenological parameters, Dionis wine is very similar to Cabernet Franc wine. The most abundant phenolic acid in all samples was gallic acid (14.77−99.08 mg/L), catechin (8.12–41.09 mg/L) was the dominant flavonoid, and malvidin-3-O-glucoside (1.5–120.8 mg/L) the leading anthocyanin. Some differences in polyphenolic profile arose due to variety; annual environmental factors probably do not have great impact. All samples expressed considerable in vitro biological activity, reasonably correlated with content of some polyphenolics, such as anthocyanins. OTA was not detected in any sample. In general, sensory properties of Dionis and Cabernet Franc were similar, while, dependent on vintage, Dionis showed a more variable sensory profile.

Consumer preferences for fungus-resistant grape varieties: an explorative segmentation study in Germany

PurposeThe significance of fungus-resistant grape varieties (FRGVs) has markedly increased across the entire value chain in recent years, becoming increasingly pertinent for the wine industry. The study contributes to the theoretical understanding of consumer behaviour in the wine industry through the identification of different clusters and the analysis of their accessibility to the FRGV on the basis of various criteria.Design/methodology/approachA quantitative survey was conducted involving 644 participants that was screened based on socio-demographic factors to ensure representation of the German population. The collected data were analysed using factor and cluster analyses, alongside various multivariate tests, to statistically elucidate similarities and differences between clusters.FindingsIn total, six clusters were examined, each displaying varying responses to and pre-existing knowledge of resistant grape varieties. In general, as one becomes more involved in the world of wine and develops a sustainable and progressive outlook towards innovations in the wine industry, a positive inclination towards resistant grape varieties can be observed.Practical implicationsPractical implications for each cluster were subsequently derived, potentially facilitating the market entry or penetration of wines produced from FRGV. Experts and Quality-averse consumer desire wines from FRGV to have a unique terroir experience, while young casual drinkers interpret them as part of pop culture. LOHAS can be addressed with sustainability-oriented approaches. Price-sensitive consumer expect good qualities in the entry price segment, and Traditionalists can be reached by preserving traditions in a changing environmental context.Originality/valueThis paper fulfils the identified need to investigate consumer preferences for resistant grape varieties.

The agroecological challenges in the wine sector: perceptions from European stakeholders

This article explores the issues surrounding the agroecological transition in the European wine industry, focusing on reducing pesticide use, developing organic certification and using genetic research in relation to resistant grape varieties. The study distinguishes between stakeholders from the wine industry, institutions and the agricultural research sector. The findings consistently identify the agroecological transition as a priority, particularly in terms of pesticide reduction. However, variations exist in the views of the surveyed stakeholders. French and Portuguese stakeholders emphasise the role of market and societal pressures as drivers of the transition, while Italian producers do not. Professionals in France and Portugal express doubts about achieving pesticide reduction through changes in practices, while others stress the importance of regulatory constraints. The research also highlights industry challenges such as decreased consumption due to health awareness and the need for social responsibility. Resistant grape varieties are seen as a viable solution, especially for the development of organic production, but market acceptability remains a significant hurdle. The study sheds light on stakeholder perspectives and challenges, thus contributing to a better understanding of priorities in the European wine industry’s pursuit of sustainable practices.

Use of the peroxidase enzyme to diagnose the resistance of grape varieties (Vitis vinifera L.) to low temperatures

Despite the global trend of the increase in average annual air temperatures observed in recent years, the recurrence of stressful negative temperatures in winter has increased in the southern region of the Russian Federation, and, therefore, the problems of grape frost resistance remain relevant. Low-temperature stresses lead to serious damage and a decrease in vine yields. In order to distinguish the most resistant grape varieties, it is necessary to carry out plant research on the physiological and biochemical level. The paper presents the results of research related to the study of resistance to low negative temperatures of grape varieties of different ecological and geographical groups according to the activity of peroxidase enzyme and its isoforms. The research objects were grape varieties (interspecific hybrids) of European-American origin – Dostoyny, Krasnostop AZOS, Vostorg; of Western European origin – Aligote; of Eastern European origin – Zarif; of Euro-Amur-American origin – Kristall. The study was aimed at exploring the activity of peroxidase and its isoforms and, based on the research results, identifying grape varieties most resistant to low temperatures under the conditions of the southern region of Russia. According to the obtained data on peroxidase activity and electrophoretic separation of peroxidases in polyacrylamide gel, most resistant and less resistant grape varieties to low negative temperatures were identified. The resistant varieties Kristall, Krasnostop AZOS, Vostorg were characterized by a weak increase in peroxidase activity during autumn-winter period (1.1-1.4 times), higher number of isoforms, and their qualitative composition. The less resistant grape varieties Dostoyny, Aligote, and Zarif were characterized by a greater increase in peroxidase activity (1.7- 2.4 times), a small number of isoforms, and their disappearance under conditions of artificial stress. Based on the results, it can be concluded that the study of peroxidase activity and changes in isoperoxidase spectrum in grapevine shoots can be used as diagnostic criteria for assessment of grape varieties for their resistance to low negative temperatures in winter period.

The effect of harvest time and vintage year on the phenolic composition of Nero and Bianca wines

Abstract Fungal disease resistant (PIWI) interspecific grape varieties are playing an important role as an alternative for organic wine production. Organic (bio) wines are demanded by numerous conscious consumers around the globe. They choose this kind of wines predominantly because of the absence of synthetic pesticides, fertilisers and sustainable agriculture. Resistant grape growing moreover results in additional environmental and health benefits. Nero and Bianca are among Hungary's most promising interspecific grape cultivars gaining international interest recently, there are, however, limited vitivinicultural knowledge on them. Our aim was to examine the flavonoid and anthocyanin composition for both interspecific varieties during different harvest times in two consecutive vintages. The date of harvest and vintage played a significant effect on grape and wine quality.

РЕЗУЛЬТАТЫ ИЗУЧЕНИЯ ЭЛЕМЕНТНОГО СОСТАВА И КАЧЕСТВА ВИНОМАТЕРИАЛОВ ИЗ УСТОЙЧИВЫХ СОРТОВ ВИНОГРАДА НОВОГО ПОКОЛЕНИЯ

In recent years, much attention has been paid to the restoration and development of viticulture and winemaking in our country. The state promotes the planting of new vineyards by providing subsidies for for the establishment of vineyards and the care of young plantings. Favorable conditions are created for the competitiveness of domestic winegrowing products. Another vector of agricultural development is the growing popularity of organic farming products farming in the world. The Federal Law No 280-FZ “On Organic Products and on Amendments to Certain Legislative Acts of the Russian Federation” was adopted and entered into force on January 01, 2020. The principles of organic production are increasingly spread in viticulture production. Consequently the cultivation of resistant grape varieties is of great importance, because classic European varieties require repeated pesticide treatments to protect crops and plants from diseases. The purpose of the research is to assess qualitative composition of wine materials of a group of new resistant grape varieties for the production of red wines. The research involved the following resistant wine grape varieties by VCR breeding with red berry color: Merlot Early, Merlot Khorus, Cabernet Volos, Cabernet Eidos. Merlot variety served as the control. The origin of varieties is complex interspecific. The evaluation of the varieties of a new generation was carried out according to the methods generally accepted in viticulture and winemaking. When assessing the elemental composition of wine materials, quantitative parameters of the presence of 27 mineral elements in leaves and wine materials were established. It was found that potassium (1329.0–1877.0 mg/l) is in the first place in terms of content in wine materials, followed by sulfur, calcium, magnesium, silicon, phosphorus, sodium, boron, iron, copper, manganese, zinc. A significant excess of the content in the leaves and wine materials of the control variety compared with the experimental varieties was established by the content of iron, sodium, sulfur, phosphorus. The silicon content was higher in the experimental wine materials.

Multidimensional assessment demonstrates sustainability of new low-input viticulture systems in north-eastern France

Current demand for more environmentally, socially, and economically sustainable farming practices requires multicriteria assessment of innovative agricultural systems to help enhance cropping systems. We assessed the sustainability of 11 systems intended to substantially reduce inputs, especially pesticides, to viticulture systems. Pesticide use was reduced using three methods: (i) technical (e.g., essential oils instead of some copper use, 100 % soil covering applied); (ii) organizational (e.g., new spraying decision rules, decision aid tools); and (iii) redesign of the entire system (e.g., resistant grape varieties planted). Sustainable performance of the new low-input vine systems (NLIVS) was assessed over 6 years (2013–2018) based on 25 indicators. They covered all aspects of system sustainability: environmental, agronomic, economic, and social. This included the evaluation of human capital and the quality of the wines produced. The results showed that it is possible to combine good environmental performance, such as reducing treatment frequency by up to 89 %, with good agronomic and wine quality performances. The socio-economic performance of these NLIVS was more moderate. Nonetheless, the results demonstrated that the NLIVS are sustainable according to many diversified indicators. NLIVS are also resilient, as shown by the consistent sustainability results over six consecutive years. They are a realistic tool enabling winegrowers to consider reducing viticulture inputs.

Downy mildew is able to carry out its sexual cycle on resistant grape varieties

Previous studies have shown that new resistant grape cultivars limit epidemics caused by asexual reproduction of downy mildew. However, until now, there was a lack of knowledge on the sexual phase of the pathogen. This study demonstrates that host resistance has little effect on the sexual cycle of downy mildew. Thus, the pathogen can complete its life cycle (asexual and sexual phases) on partially resistant grapevine varieties. The persistence of pathogen populations on partially resistant varieties from one year to the next represents a major challenge for the sustainability of genetic resistance of grapevines.

Negative regulation by transcription factor VvWRKY13 in drought stress of Vitis vinifera L

Drought is a major environmental factor limiting crop growth and development worldwide. WRKY transcription factor, a unique transcription factor in plants, has been shown to play important roles in plant response to abiotic stress. Previously, we have cloned the VvWRKY13 gene from resistant grape varieties and found that its expression was obviously induced by drought. Here we further explored the mechanism of VvWRKY13 in response to drought stress. After drought treatment, the expression of VvWRKY13 in the sensitive grape varieties was significantly higher than resistant grape varieties. Moreover, phenotypic changes of VvWRKY13 transgenic Arabidopsis were observed and drought-related indexes were detected under drought treatment. The results showed that VvWRKY13 transgenic Arabidopsis exhibited more sensitive phenotype to drought stress compared with wild type. The water loss rate of leaves in the transgenic Arabidopsis was significantly higher than wild type. The content of proline, soluble sugar and the expression of related genes decreased in transgenic Arabidopsis leaves under drought stress. The level of endogenous hydrogen peroxide and oxygen free radicals was increased, while the activity of catalase (CAT) and superoxide dismutase enzyme (SOD) were decreased. In addition, the expression of stress response gene was significantly decreased in transgenic Arabidopsis. Taken together, our results suggest that VvWRKY13 negatively modulates plant drought tolerance through regulating the metabolism of intracellular osmotic substances (proline, soluble sugar), the level of ROS, and the expression of stress-related genes.

Does minimal pruning and reduced fungicide use impact spiders in the grapevine canopy?

Agricultural management should aim at high densities of beneficial organisms such as spiders. Here, we asked whether spiders in vineyards can be promoted either by using novel disease resistant grape varieties that allow for a reduced number of fungicide applications, or by minimal pruning which enhances the structural complexity of the grapevine canopy. We compared spider communities in vineyards planted with fungus-resistant varieties (PIWIs) to vineyards with traditional grapevine varieties, and minimally pruned vineyards to vertical shoot positioned vineyards. Densities of Theridiidae were more than doubled in fungus-resistant grape varieties, but the remaining families were not significantly affected. Minimal pruning enhanced Philodromidae and Dictynidae but reduced Salticidae. However, neither pruning method, nor the reduced fungicide use in PIWI vineyards, had significant effects on overall spider abundance or species richness. Hence, effects of vineyard management were family-specific and possible consequences for pest regulation will thus depend on the pest control potential of the involved families.

THE ECONOMIC EFFECTS OF APPLYING BENEFICIAL MICROORGANISMS IN VITICULTURAL PRODUCTION UNDER CLIMATE CHANGE CONDITIONS

The paper aimed to present the economic effects of applying beneficial microorganisms in viticultural production under climate change conditions. It was found that increasing climate change effects calls for a broad range of adaptation and mitigation strategies in agriculture, especially in viticultural production. One of them might be the innovative use of microorganisms that have the ability to interact with plants, and thus contribute to the prevention of stresses as well as respond to them, both abiotic – like drought and biotic – like pests. Based on the direct survey carried out in 2018 among experienced winegrowers from Germany, Italy and Poland, it was observed that there was a direct economic effect of the inoculation of beneficial microorganisms to the cultivation of resistant grape varieties. The majority of farmers think that such innovation in vineyards could reduce both the costs of protection and cultivation as well as increase direct benefits. Empirical evidence from the case study performed in 2018 in the Italian sustainable farm showed that such innovation, despite increasing the costs of irrigation and organic fertilization, also led to a significant reduction of artificial fertilizer and pesticide use, the costs of which predominated.

The Pecuniary and Nonpecuniary Costs of Powdery Mildew and the Potential Value of Resistant Grape Varieties in California

Powdery mildew (PM) is the most expensive grape disease to control and causes the greatest losses in quality and yield worldwide. Grape varieties resistant to PM are being developed, but the value of such varieties to growers in different industry segments is not yet determined. Barriers to adoption of new varieties vary by industry segment and are likely to affect the total potential benefit realized by growers. The first step in estimating the potential value of PM-resistant varieties is to establish the costs of PM management that these varieties will mitigate for each major segment of the grapegrowing industry. We used Pesticide Use Reports from the California Department of Pesticide Regulation, data on pesticide application costs, and measures of environmental impact to evaluate the pecuniary and nonpecuniary costs of managing PM in California grape production. We estimate the statewide cost of PM management in 2015 at ~$239 million, of which $176 million was borne by growers of winegrapes. In addition, PM management accounted for 89% of restricted material (pesticide) applications by grapegrowers, so eliminating PM would reduce the environmental burden from disease management in grapes significantly. Using choice experiments, we evaluated the preferences of individual growers for specific varietal traits and found that winegrape growers place a high value on both the varietal name and the savings in costs from reduced application of fungicides. We conclude by discussing possible adoption scenarios for resistant varieties and the resulting benefits to the industry.

Success of organic and biodynamic system experiment to produce high quality wines

Reducing input use and in particular pesticide use is very important in OIV 2018 new resolutions. Also Europe and France promote research and co-design with winegrowers in more sustainable viticulture according to a combination of climate change. It is also very important to take into account soil diversity and Protected Designation Areas constraints to make sure that new wines will ensure the sustainability of the wineries. This study explores design, experiment and assess of new realistic viticulture production systems located in Protected Designation of Origin (PDO) areas and with already organic or biodynamic certification for six consecutive years, in winery production conditions. It also discusses the chosen assessment indicators and the adoption of such new production systems by winegrowers. Eleven cases were studied in a system experiment network in Alsace (France) and in six consecutive production years. Contrasted production years, PDO areas combined to organic or biodynamic certification allow testing the resilience of experimented systems over time. Combination of new practices are tested to drastically reduce input and in particular pesticide. Assessed performances of the systems deal with 14 main indicators: social acceptability (1) and economic viability (1), agronomy (yield (1), harvested berries quality (2), fungi damage (3), soil quality (1), and wine sensorial analysis (1) and environment (Frequency Treatment Index (1), Cupper rate (1), INDIGO® method (2)). Several innovations were selected by co-design with winegrowers: adding essential oil and Propolis to copper spraying; total grass cover of the vine site; new decision rules for rate and time pesticide spraying; decision aid tool; resistant grape varieties planted. The assessment results support that the performance of the 14 indicators is very good for most of the eleven systems during the six assessed years. Combinations of tested innovations are neither dangerous nor difficult to enforce in the field by the vineworkers. Innovations do not increase the cost of grape production. The yield ratios were satisfactory the 6-yeared of observation because calculated yield match with targeted yield. Harvested berries quality support that the 7 vine sites succeed in targeted total acidity and sugar rate according to the different PDO conditions every years. Wines were Alsace or Grand Cru PDO labelled and successful marketed. At least, the Treatment Frequency Index is reduced by an average of 40% for all vine sites and assessed years. TFI can be reduced at a maximum of 89% and TFI median is 38%. Cupper rate can be reduced at a maximum of 97% and Cupper rate median is 54%. I-pest from INDIGO® method indicate a minimal risk taking for groundwater, surface water, air and beneficial organisms contamination. And finally, flora richness indicator is stable or steadily increases during the 6 study years. In this study, we demonstrated that drastically monitoring reduction of pesticide and other inputs is possible. Chosen indicators allow a exhaustive assessment, but could also been aggregated all together to give a synthetic information to winegrowers and make them easier to adopt the innovative systems. Introduction of innovation combinations in highly sustainable organic and biodymanic systems are validated to produce high quality wines. Now, it is possible to serenely promote and disseminate these highly sustainable innovative systems, taking into account of course vineyard diversity.

Resistant grape varieties and market acceptance: an evaluation based on experimental economics

We analyze consumers’ evaluations of white wines from resistant varieties, produced in the Languedoc winegrowing region of France (2016 vintage). We use the results from a laboratory experiment performed in Paris in June 2017, where a panel of more than one hundred and sixty consumers, regular buyers of this type of wine, were asked to evaluate a wine of the Bouquet 3159 grape variety (monogenic variety resistant to mildew and powdery mildew and optimized for quality) and compare it with two conventional wines of different quality levels, and with a certified organic wine of similar type and price. The environmental and health performances and the production methods of the different wines were quantified according to several indicators: treatment frequency indicator (TFI) and pesticide residue analysis.
 The consumers first evaluated the wines after tasting, having been given only a minimum amount of information about the region of origin and the vintage, then again after receiving information on production methods and the levels of our indicators. The method used to lend credibility to individual valuations used experimental economics, via a mechanism based on direct disclosure of their willingness to pay (maximum purchase price for a bottle of wine according to available information). The results showed that, on a purely sensory level, consumers had difficulty in accepting wine from a resistant variety. We were then able to see that communication focusing on environmental and health performances very much improved the position of the resistant variety of wine, putting it ultimately at the top of the average qualitative evaluations. In economic terms, we show that this promotion results in high market share, gained from conventional wines. Market share losses were lower, however, for the premium conventional wine, suggesting that the higher quality wines would be less directly challenged by wines produced from resistant varieties.

DNA-marker based identification of the RPV3 gene determining downy mildew resistance in grapevines

Downy mildew is one of the most common fungal diseases of the vine, caused by Plasmopara viticola. An effective way to control the spread of the pathogen is to cultivate resistant varieties. Cultivars of Vitis vinifera, being the basis of high-quality viticulture, practically do not possess genetic resistance to P. viticola, so screening for resistance donors is an important stage in breeding. One of the major resistance loci to downy mildew, the Rpv3 gene, was identified in the genotype of a complex interspecific hybrid of grapes Bianca. Later, it was found that this gene had seven haplotypes of resistance inherited from North American grape species, and that it was possible to identify the allelic status of the gene using DNA-markers UDV305, UDV737. However, only two haplotypes can be combined in one diploid form. To determine the Rpv3 gene in the grape gene pool we, using these markers, studied 35 different genotypes of grapevines, most of which are interspecies cultivars. Three varieties with known allelic status of the Rpv3 gene (Dunavski lazur, Noah, Seyve Villard 12-375) were included in the study as reference genotypes. The genotypes were studied through polymerase chain reaction with separation of amplification products by capillary electrophoresis in automatic genetic analyzer ABI Prism 3130. In the studied grape cultivars DNA marker analysis indentified the Rpv3 gene in sixteen genotypes of interspecific origin, including haplotype Rpv3299-279 found in twelve varieties, Rpv3321-312 – in three, and haplotype Rpv3null-271 – in one variety. Seyve Villard 12-375 turned out to be the donor of resistance gene in the most of the genotypes carrying Rpv3 in this study. The obtained data can be useful in selection of mildew resistant grape varieties and screening for hybridization pairs.

Disease resistant grapevine varieties and quality: the case of Bouquet varieties

The disease resistant grapevine varieties (ref A. Bouquet) were obtained by INRA from 4 or 5 generations of backcrossing between Muscadinia rotundifolia and Vitis vinifera and exhibit a high level of resistance against downy and powdery mildew. These varieties carry the resistance genes RUN 1 and RPV1, with several other secondary genes at one chromosomal locus. Agronomic criteria were studied for all these selections. Among the selected grapevine species, some have high levels of polyphenols. Some (white and red) have a high aromatic potential, while others have low sugar contents (135 g/L to 150 g/L) and adapted sugar/acidity ratio. All these characteristics were combined to design a new set of vine cultivars dedicated to the production of either low-alcohol wines, grape juices, or classical wines. Since 2012, within a France Agrimer/CIVL/INRA financial framework, 10 plots (0.5 ha each) were planted at INRA Pech Rouge with 8 resistant grape varieties (ref A. Bouquet) in order to examine long-term resistance to diseases and to define quality criteria for the classification of the wines obtained from these new grape varieties.

The Ecology of Agrobacterium vitis and Management of Crown Gall Disease in Vineyards.

Agrobacterium vitis is the primary causal agent of grapevine crown gall worldwide. Symptoms of grapevine crown gall disease include tumor formation on the aerial plant parts, whereas both tumorigenic and nontumorigenic strains of A. vitis cause root necrosis. Genetic and genomic analyses indicated that A. vitis is distinguishable from the members of the Agrobacterium genus and its transfer to the genus Allorhizobium was suggested. A. vitis is genetically diverse, with respect to both chromosomal and plasmid DNA. Its pathogenicity is mainly determined by a large conjugal tumor-inducing (Ti) plasmid characterized by a mosaic structure with conserved and variable regions. Traditionally, A. vitis Ti plasmids and host strains were differentiated into octopine/cucumopine, nopaline, and vitopine groups, based on opine markers. However, tumorigenic and nontumorigenic strains of A. vitis may carry other ecologically important plasmids, such as tartrate- and opine-catabolic plasmids. A. vitis colonizes vines endophytically. It is also able to survive epiphytically on grapevine plants and is detected in soil exclusively in association with grapevine plants. Because A. vitis persists systemically in symptomless grapevine plants, it can be efficiently disseminated to distant geographical areas via international trade of propagation material. The use of healthy planting material in areas with no history of the crown gall represents the crucial measure of disease management. Moreover, biological control and production of resistant grape varieties are encouraging as future control measures.