Vine Stocks Research Articles

A test-tube vinification method for high-throughput characterisation of the oenological and aromatic potential of white wines

The quality of wine largely depends on aroma perception, but the genetic basis explaining the variations of aroma compound concentrations in wines is still fragmentary. To unravel links between genetic variations and aroma compound variations in hundreds of genotypes, we developed a small-scale, high-throughput test-tube vinification (TTV) method capable of producing white wines that reveal the genetic potential at the scale of a single vine stock. We evaluated this method on commercial grapevine varieties (Riesling, Gewurztraminer, Chardonnay, Chasselas, Floreal, Muscat à petits grains blancs) and genotypes resulting from a bi-parental cross, covering a wide aromatic palette. The wines produced were described by usual oenological parameters and GC-MS profiling of volatile compounds. We compared the wines obtained with the TTV method to commercial wines and to wines obtained from larger fermentation volumes (5–10 L). Our results show that the TTV method is suitable to produce white wines on a very small scale, i.e., less than 100 mL and that these small-scale wines faithfully reflect the aromatic potential of the different varieties, as would larger volume methods. The proposed method is a high-throughput approach to assess the oenological potential of hundreds of grapevine genotypes from grape material harvested on a single vine. This wine-focused direct phenotyping method will pave the way for a better understanding of the genetic determinism of wine aromas, especially for molecules that are not directly present in grapes, such as volatile thiols and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).

Recovery after curettage of grapevines with esca leaf symptoms

Grapevine curettage was re-introduced in France in the early 2000s, and is important for facilitating recovery of plants from esca disease. This surgical practice involves removal of deadwood of vines with leaf symptoms, focusing on white rot generally observed at the centres of grapevine trunks. Assessment of the efficacy of this practice was initiated in the Bordeaux region in 2014. One ‘Sauvignon Blanc’ vineyard severely affected by esca was initially surveyed in the summer of 2014, to identify and treat vines with esca foliar symptoms. Annually thereafter, from 2014 to 2018, selected vine stocks were curetted. Two other ‘Sauvignon Blanc’ vineyards also displaying high levels of esca damage were added to the study in 2015 and 2016. Curettage treatments ceased in 2018, resulting in 11 trials (vineyard × year combinations). In total, 856 vines (422 curetted and 434 control vines) were then surveyed annually up to 2021, for assessments and comparisons of esca development. At each site, plants with esca symptoms recovered well after curettage: on average 85% of all curetted vines became asymptomatic the year immediately after the treatment. Six years after treatment, for curettage campaigns carried out in 2014 and 2015, more than half of the curetted vines were symptom-free, whereas <12% of the control vines were asymptomatic, and gradual loss of efficacy was observed at each site. The mean annual proportion of efficacy erosion was approx. 8% per year. This study highlights the possible short- and mid-term benefits of trunk surgery to enable recovery of esca-affected vines, and for them to recover and remain leaf-asymptomatic for several years.

Returns to public investments in clean plant centers: A case study of leafroll virus-tested grapevines in support of cost-effective grape production systems

AbstractViruses and related graft-transmissible pathogens cause diseases that cost the grape industry billions of dollars annually if left uncontrolled. The National Clean Plant Network (NCPN), a USDA Farm Bill program, is an organization of clean plant centers that produce and maintain virus-tested foundation vine stocks and distribute propagation material derived thereof to nurseries and growers to minimize the introduction of viruses and virus-like diseases into the vineyard. Foundation Plant Services (FPS) is the major NCPN-grapes center. We examined the economic impacts of public investments in FPS from 2006 to 2019. By focusing on grapevine leafroll disease, our analyses revealed a benefit-cost ratio ranging from 22:1 to 96:1, with a 5% and a 20% disease infection rates in commercial vineyards, respectively. A welfare analysis was consistent with grape growers and nurseries capturing most (64–98%) of the benefits from adopting clean planting material compared with winemakers and other actors in the downstream wine supply chain system. This study provided new insights into the returns to public investments in a clean plant center and documented strong financial incentives for higher adoption of clean vines derived from virus-tested stocks, while justifying continued support of NCPN centers from public and private sectors.

TOWARD A LOW-COST, MULTISPECTRAL, HIGH ACCURACY MAPPING SYSTEM FOR VINEYARD INSPECTION

Abstract. Confronted with the climate change challenge and the territorial constraints, agriculture has to modernize itself. The use of georeferenced data and remote-sensing imagery is a major step in this direction. This precision mapping of crops requires powerful and accurate acquisition systems, while remaining financially attractive. The development of multispectral sensors and low-cost GNSS makes it possible to consider systems that will be able to map at the plant scale. However, these positioning systems do not yet guarantee a precise overlap of data acquired at different times. Thus, we propose in this paper a method to register terrestrial image data, acquired on vineyard plots. Our method seeks to avoid image registration problems, such as illumination changes, by detecting the vine stocks, reconstructing them in 3D, and registering them individually. The 3D detection method is based on an image-based object detection method (Faster R-CNN) and a structure-from-motion reconstruction of object-masked images. The results that we obtained on a vineyard plot, allowed us to validate the method, with a precision of less than 10 cm, making it possible to map the vine by stock.

Transmission of Grapevine Red Blotch Virus by Spissistilus festinus [Say, 1830] (Hemiptera: Membracidae) between Free-Living Vines and Vitis vinifera 'Cabernet Franc'.

Grapevine red blotch disease emerged within the past decade, disrupting North American vine stock production and vineyard profitability. Our understanding of how grapevine red blotch virus (GRBV), the causal agent of the disease, interacts with its Vitis hosts and insect vector, Spissistilus festinus, is limited. Here, we studied the capabilities of S. festinus to transmit GRBV from and to free-living vines, identified as first-generation hybrids of V. californica and V. vinifera ‘Sauvignon blanc’ (Vcal hybrids), and to and from V. vinifera ‘Cabernet franc’ (Vvin Cf) vines. The transmission rate of GRBV was high from infected Vcal hybrid vines to healthy Vcal hybrid vines (77%, 10 of 13) and from infected Vvin Cf vines to healthy Vcal hybrid vines (100%, 3 of 3). In contrast, the transmission rate of GRBV was low from infected Vcal hybrid vines to healthy Vvin Cf vines (15%, 2 of 13), and from infected Vvin Cf vines to healthy Vvin Cf vines (19%, 5 of 27). No association was found between transmission rates and GRBV titer in donor vines used in transmission assays, but the virus titer was higher in the recipient leaves of Vcal hybrid vines compared with recipient leaves of Vvin Cf vines. The transmission of GRBV from infected Vcal hybrid vines was also determined to be trans-stadial. Altogether, our findings revealed that free-living vines can be a source for the GRBV inoculum that is transmissible by S. festinus to other free-living vines and a wine grape cultivar, illustrating the interconnected roles of the two virus hosts in riparian areas and commercial vineyards, respectively, for virus spread. These new insights into red blotch disease epidemiology will inform the implementation of disease management strategies.

Determination of chlorpyrifos-methyl, lambda-cyhalothrin and tebuconazole residues in Sultana seedless grapes sprayed with pesticides under farmer’s conditions

The aim of this study was to investigate pesticide residues on Sultana Seedless Grapes harvested at different times and consequently evaluate the risk. Analyses were performed with the Quick-Easy-Cheap-Efficient-Rugged-Safe (QuEChERS)-liquid chromatography/tandem mass spectrometry (LC-MS/MS) procedure. Pesticide-free grapes were spiked at 3 levels. Chlorpyrifos-methyl, lambda-cyhalothrin and tebuconazole detection limits were 20, 10 and 1 µg kg−1, respectively. These values were below maximum residue levels (MRL) of 1000, 80 and 500 µg kg−1, respectively. The overall recovery of the method was 108.60%. Present values were within acceptable recovery (60–140%) and repeatability (≤20%) ranges set by the Directorate-General for Health and Food Safety (SANTE). The vineyards were sprayed 4 times. Grapes were harvested in the 1st, 3rd, 5th, 7th and 14th days from the last spray. The residues in the samples taken from 5 vine stock groups were determined. MRL-exceeding chlorpyrifos-methyl residue of 1140.09 µg kg−1 was detected in the 1st day. The MRL-exceeding lambda-cyhalothrin (381.15 and 307.39 µg kg−1) and tebuconazole residues (650.58 and 570.85 µg kg−1) were detected in the 1st and 3rd days, respectively. The residues of 7th and 14th day samples were significantly different from the others. Excessive pesticide concentrations did not pose any health risks on consumers.

The micro-economic impacts of a ban on glyphosate and its replacement with mechanical weeding in French vineyards

In France, viticulture is the production sector that uses the highest amount of glyphosate per hectare. The prospect of banning this pesticide in France, and in Europe as a whole, has led us to study the existence of alternatives to this herbicide, following article 50.2 of the European regulation 1107/2009, and to estimate the additional costs involved. Based on a national public database, we synthesized the different weed control practices in viticulture and calculated their costs. Our results showed that alternative methods to the use of glyphosate are more or less widespread depending on the wine-producing area in France.Inter-row non-chemical weed control is widespread and involves mechanical operations, with or without the use of cover crops. The most difficult aspect concerns weed control between vine stocks within the rows (intra-row), without applying herbicide. The size of the farms, the structure of the vineyards and especially the distance between rows largely account for the differences in the adoption rates of glyphosate-free practices in wine-producing areas. In total, the additional cost of mechanical weeding compared to glyphosate chemical weeding is €250/ha on average, and varies from €12 to €553/ha depending on the wine-producing area. The generalization of alternatives to glyphosate-use under the European ban on glyphosate could have economic consequences on the income of farmers, the magnitude of which depends on several factors, including the type of vineyard, availability of labour and equipment on each farm, as well as marketing channels.

Physiological indicators to assess water status in potted grapevine (Vitis vinifera L.)

Many physiological parameters were compared to identify the most sensitive and reliable indicator of grapevine water status. One-year-old potted grapevines (Vitis vinifera L., cvs. ‘Sangiovese’ and ‘Cabernet Sauvignon’) were studied under two irrigation treatments: 100% and 0% of daily water consumption. Measurements of pre-dawn (PD) and midday (MD) leaf water potential (Ψw), MD stem water potential (ΨS), leaf temperature (T°L) and stomatal conductance (gS) were taken throughout twenty days and analyzed in conjunction with climatic data, relative cumulative sap flow (RCSF) and the maximum daily shrinkage (MDS) of the vine stock. Physiological indicators showed substantial differences in sensitivity. The first indication of changes in vine water status was the increase of MDS and the decrease of gS. MDS and RCSF revealed significant differences between the two irrigation treatments even when PDΨw, up to now widely accepted as the benchmark of water status indicators, did not show any significant variation. Measurements of water potential showed ΨS to be a better indicator of vine water status than Ψw and T°L. In conclusion, we classified the tested indicators according to a descending order of their early detection capability: gS = MDS > RCSF > PDΨw = MDΨS > T°L > MDΨw.

A tool for technical and economic evaluation of dieback in wine-growing holdings

Dieback in the vineyards is causing a long-term decline in the productivity of the vine stock and/or its sudden or gradual premature death, related to a number of different factors. It is a problem in all wine regions around the world. Its economic importance was estimated to represent €2 billion turnover in 2020 if the trend in yield loss continues at the same pace. How do we diagnose dieback in the wine-growing holdings to provide a better understanding of the risks and to respond? The aim of the work is to identify the factors to be taken into consideration in the development of a dieback self-diagnosis tool for wine growers. The first study takes into account all aspects of the wine-growing system in very mixed French conditions of production. The survey was fielded in 124 wine-growing and contains over a hundred questions. The analysis and classification of the holdings are based on yield and longevity which are constructed from socio-technical and economic data, complementing the agronomic aspects. These parameters have been combined to create a classification of wine-growing holdings affected by dieback. The finished tool is based on the answers to 30 questions identified by the survey. We can calculate a score that places the winery in relation to other wineries in the same situation.

Viticulture of Hungary

For several thousand years, vine has been grown in the Carpathian basin, where the climatic and soil conditions are favourable for viticulture. During this long period, vine growing has been developing until it reached its current niveau. We grow propagation material, table grape and wine grape. The produced wine grape varieties are grown on the largest area, of which 72% is white wine and 25% is red wine. Only 3% remains for table grapes. The surface of vineyards is about 63 000 ha, which can be found in 22 wine regions. The biodiversity of vine is very rich in our country. There are a lot of native and valuable bred varieties and clones in cultivation. The resistant and winter frost resistant vine varieties have an important role in our continental climate. The in 75% of the vineyards is on hills and mountains, 25% of them is on the Great Hungarian Plain. High cordon with cane pruning dominates the training and pruning system.
 Unfortunately, vine stocks suffer from a lot of diseases and by using pesticides we pollute the nature. Viticulturists in Hungary produce excellent raw material and provide oenologists with them who make wine of excellent quality.

How can remote sensing techniques help monitoring the vine and maximize the terroir potential?

In each winegrowing region, the winegrower tries to value its terroir and the oenologists do their best to produce the best wine. Thanks to new remote sensing techniques, it is possible to implement a segmentation of the vineyard according to the qualitative potential of the vine stocks and make the most of each terroir to improve wine quality. High resolution satellite images are processed in several spectral bands and algorithms set-up specifically for the Oenoview service allow to estimate vine vigour and a heterogeneity index that, used together, directly reflect the vineyard oenological potential. This service is used in different terroirs in France (Burgundy, Languedoc, Bordeaux, Anjou) and in other countries (Chile, Spain, Hungary and China). From this experience, we will show how remote sensing can help managing vine and wine production in all covered terroirs. Depending on the winegrowing region and its specificities, its use and results present some differences and similarities that we will highlight. We will give an overview of the method used, the advantage of implementing field intra-or inter-selection and how to optimize the use of amendment and sampling strategy as well as how to anticipate the whole vineyard management.

Clonal selection of rootstocks by means of determination of hard bast layers

Determination of the number of closed circles of hard bast plates on matured shoot cuttings, which is used for wood maturity control, was applied as selection method to four rootstocks: Vitis berlandieri x V. riparia Kober 5 BB, Teleki 5 C, Craciunel 2 and V. riparia x V. rupestris Schwarzmann. For each selected vine stock the linear regression of wood maturity was calculated, considering the distance from the base of the cane. From the linear regression equation the average length of the matured wood part was calculated for each stock The results of 3-year investigations show that the degree of rootstock wood maturity is not only dependent on the meteorological conditions of the years but is also genetically conditioned.

Characterization of some Vitis vinifera L. Indigenous Varieties by Analysis of Leaf Photosynthetic Pigments

Chlorophyll content in leaves of 11 Vitis vinifera L. indigenous varieties (Iasi vineyard, Romania) was determined by two independent methods: spectrophotometry (extraction) and with an Opti-Sciences CCM-200 plus chlorophyll content meter (non-destructive method) with the aim of comparing the results. Also, this study was conducted to establish the values of chlorophyll a /chlorophyll b and chlorophyll/carotenoid ratio in middle leaves of vine stocks, in the phenophase of progressive growing of shoots. Area and perimeter of leaves in this phenophase were determined. Total chlorophyll concentration in leaf extract varied from 0.67±0.01 mg/g f.w. to 1.00±0.03 mg/g f.w., being highly correlated with the chlorophyll content index values (CCI) recorded by CCM-200 (R 2 =0.9839; p<0.001). Similar situation was identified in the case of the chlorophyll b and CCI correlation (R 2 =0.9638; p<0.001). Chlorophyll a / b ratio in leaf extract varied significantly depending on variety, ranging from 1.06±0.01 to 2.43±0.01, with a chlorophyll/carotenoid ratio reaching up to 3.19±0.08. Compared to spectrophotometry, CCM-200 plus affords fast, reliable, economical, non-destructive chlorophyll content measurement, however, providing no details regarding chlorophyll components and ratios.

How sweet potato varieties are distributed in Uganda: actors, constraints and opportunities

Sweet potato varieties are distributed in Uganda by three systems: formal, project-based and informal. In a partial formal system, the National Sweetpotato Program (NSP) breeds and tests both orange (O)- and white (W)-fleshed sweet potato (FSP) varieties. The NSP and other national institutions provide vine stocks of mostly OFSP varieties to project-based seed systems involving large private sector multipliers, which are found predominantly in east and central Uganda. These are mainly either cooperatives derived from smallholder groups organized by projects or are individual farmers with large holdings who had hosted NSP variety trials. The private sector multipliers sell planting materials of released varieties to projects, which distribute them free to selected households. Projects buy hundreds and occasionally thousands of sacks of vines but they distribute them to only a limited number of needy households and for only one or a few seasons. The informal system functions predominantly in areas with a long dry season, in which vines cannot survive. Its vine multipliers use the wetter lowlands to maintain mostly landraces, which they sell as small bundles of vines to many smallholders at the onset of the rains. Very few multiply released varieties. Thus, with a ready market, the system is sustainable but quantities sold are price limited. All vine multipliers supplied healthy planting material. It is proposed that the NSP should aim their trials of new varieties at informal vine multipliers and projects should supply vines to these multipliers in order to improve their access to them. This would promote the sustainable distribution of vines, including new varieties, over a greater area and to a larger number of farmers.

Research Regarding the Ecotechnological Factors that Influence the Biological Decline of the Vine, in the Wine Center Blaj

SUMMARY The biological decline of the vine is the result of multiple factors that may act simultaneously or successively, synergically or otherwise (Tomoiaga, 2006). The objective of this paper is to identify, monitor and characterize the ecotechnological risk factors that play a major role in the biological decline of the vine in the wine center Blaj. The study regarding the premature drying of the vine stocks was conducted during 2009-2010, on plots cultivated with the varieties Feteasca regala, Muscat Ottonel, Riesling Italian and Sauvignon blanc. During the study a number of 1000 stocks from each variety were analyzed. Observations were made both during growth time, as well as during the dormant stage of the vine. Among the ecotechnological risk factors, an important role is reserved to abiotic factors such as: temperature (sudden variations, late spring frosts, low temperatures during winter time), climatic accidents (heavy rainfalls, prolonged drought, hail), incorrect application of the cultivation technology (vine left unprotected during winter). The researchs undertaken in the field and laboratory have identified numerous pathogens responsible for the degradation of the bark and wood of the vine, the most important being: Agrobacterium tumefaciens, Eutypa lata, Phomopsis viticola, Stereum hirsutum (Tomoiaga, 2007). In 2010 the number of stocks affected by premature decline was significantly higher compared with 2009. The main contributing factors were both the unfavourable climatic conditions (the low temperatures in the winter of 2010, below the freezing limit of the vine; heavy rainfalls and the cool weather in the first part of the vegetation period) as well as the development of pathogens.

Switching from a mechanistic model to a continuous model to study at different scales the effect of vine growth on the dynamic of a powdery mildew epidemic.

Epidemiological simulation models coupling plant growth with the dispersal and disease dynamics of an airborne plant pathogen were devised for a better understanding of host-pathogen dynamic interactions and of the capacity of grapevine development to modify the progress of powdery mildew epidemics. The first model is a complex discrete mechanistic model (M-model) that explicitly incorporates the dynamics of host growth and the development and dispersion of the pathogen at the vine stock scale. The second model is a simpler ordinary differential equations (ODEs) compartmental SEIRT model (C-model) handling host growth (foliar surface) and the ontogenic resistance of the leaves. With the M-model various levels of vine development are simulated under three contrasting climatic scenarios and the relationship between host and disease variables are examined at key periods in the epidemic process. The ability of the C-model to retrieve the main dynamics of the disease for a range of vine growth given by the M-model is investigated. The M-model strengthens experimental results observed regarding the effect of the rate of leaf emergence and of the number of leaves at flowering on the severity of the disease. However, it also underlines strong variations of the dynamics of disease depending on the vigour and indirectly on the climatic scenarios. The C-model could be calibrated by using the M-model provided that different parameters before and after shoot topping and for various vigour levels and inoculation time are used. Biologically relevant estimations of the parameters that could be used for its extension to the vineyard scale are obtained. The M-model is able to generate a wide range of growth scenarios with a strong impact on disease evolution. The C-model is a promising tool to be used at a larger scale.

Energy forests or vineyards?

This paper primarily aims at giving an introduction to an alternative opportunity for vineyards owners many of whom have come to adecision about elimination of their vineyards. The paper is focusing on the Mátra wine-region as a study area, which is the largest mountainwine region in Hungary where more than one third of supported clearing of vineyards have been implemented in the last few years. Theabandoning of vineyards is explicable in more than one way such as very small average size of land or the increasing mean age of ownersetc. The fundamental reason is the chronic doubtfulness of the grape and wine market and the low level of overall profitability of production.Grape production has a long tradition in this region, thus the disappearance of vineyards caused serious problems in land use through theabsolute lack of plans for the future. The popularity of biomass production in the press and the biofuel resultant from vine stocks raiseinterest for short rotation forestry within a group of farmers. Short rotation forestry offers a new chance for some farmers to cut oneself adriftfrom the harmful effects of the market of agricultural products.

Esca et Black Dead Arm : deux acteurs majeurs des maladies du bois chez la Vigne

Grapevine trunk diseases are very harmful to wine-growing heritage durability because the fungi responsible, by attacking perennial organs, cause at a more or less long-term the death of the vine stock. Esca and BDA are the two main pathogens inducing such decaying diseases. The infection can be diagnosed by the presence in the wood forming tissues of sectorial and/or central necrosis, which revealed itself by brown stripes or canker, and at the foliar level by discoloration and withering. This review presents an overview of both Esca and BDA, their symptomatology, the characteristics of the associated fungi and host-pathogen interactions. To conclude, a progress report on the control of both diseases is discussed. To cite this article: P. Larignon et al., C. R. Biologies 332 (2009).

Évolution des teneurs en polyamines libres et conjuguées dans les feuilles de vigne (Vitis vinifera 'Cabernet Sauvignon') saine et atteinte d'eutypiose

Effects of Eutypa lata, the fungal agent of eutypiosis, on polyamine (putrescine (Put), spermidine (Spd), spermine (Spm), diaminopropane (Dap)) and tyramine (Tyr) contents in grapevine leaves were studied to determine the relationship between these components and disease development. The external symptoms of eutypiosis are small and necrotic leaves, which could be observed on only one arm or on two arms of the vine stock. This study was carried out on healthy leaves (S, borne by healthy vine stock), apparently healthy leaves (Aps, borne by one arm without symptoms, whereas the other arm was diseased), and moderately (M. mal.) and strongly (F. mal.) diseased leaves. We analysed free polyamines (free PAs, chlorhydric acid soluble fraction), conjugated polyamines (PAs-fpm, PAs covalently linked to molecules with low molecular mass like hydroxycinnamic acids), and bound polyamines (PAs-mm, covalently linked to macromolecules) in Vitis vinifera L. 'Cabernet sauvignon', a variety sensitive to eutypiosis. In diseased leaves, we noted a decrease of free PAs, PAs-fpm, free Tyr, and Tyr-fpm levels. By contrast, the Dap-fpm level was increased by the disease. Eutypiosis also induced an increase of Spm-mm and Dap-mm levels, whereas the Put-mm and Spd-mm levels were decreased. Free Put, free Spd, PAs-fpm, free Tyr, and Tyr-fpm levels were higher in apparently healthy leaves than in healthy leaves. The PAs-mm levels were slightly affected by eutypiosis in apparently healthy leaves. The specific role of each type of polyamines and tyramine is discussed with regard to the host-parasite relationship.Key words: polyamines, leaf, Eutypa lata, Vitis vinifera.

Evaluation of the productivity of the hybrid vine Seyval blanc in function of several types of protection against frost in Quebec

&lt;p style="text-align: justify;"&gt;In Quebec, winter frost is one of the determining factors influencing vine survival and yield. To evaluate the quality of the different types of winter protection, ground temperature data under different covers (ground knolls, leaf mounds, carried over snow and natural snow) and ambient air temperatures were recorded. Results show that the Seyval blanc, if not protected against winter frost, can sustain quite serious damages when the air temperature reaches -30 °C. Ridging, leaf covering and the natural snow cover as well as carried over snow have a positive effect on ground temperatures, since over the site without protection, frost penetrated down to a depth of 50 cm. However, it seems that the root System did not sustain significant damages from the ground frost since regrowth occurred in the Spring. Because of its direct exposure to radiation and surface climatic conditions, bare soil warms up more quickly in the Spring compared to the other sites benefiting from protection. Results also indicate that the mortality rate of the vine stock fruit buds without protection is nearly 100 % compared to the protected vine stocks with a fruit bud mortality rate varying from 22.5 to 35.8 %. The protected vine stocks, regardless of the type of protection used, had satislactory yields from 7.2 t/ha to 24.4 t/ha. On the other hand, the raisin yield of the vine stocks without any winter protection is null. The best raisin yields were obtained over sites where vine stocks were protected by ridging (40 cm of earth), while the vine stocks protected by leaf covering showed an average yield. We also observed that when vine stock leaf covering is coupled with lodged vine shoots, raisin yields are higher than when the vine shoots are erect. However, in both cases, potential yield per hectare is satisfactory. Hence, the lodging of vine shoots becomes a useless operation. The vine stocks protected by natural snow as well as by leaf covering (30 cm + carried over snow and lodged vine shoots) gave the fruit with the highest sugar content. Snow is also an excellent insulator because a 37 cm high snow cover permitted the survival of the vine stocks protected by snow even when the temperature reached -30 °C. The only problem still posing a threat is snow cover variability during the winter season. A reduced snow cover, coupled with temperature conditions under the threshold of tolerance of the vine to cold, could not insure satisfactory protection ol the fruit buds.&lt;/p&gt;