With the arrival of spring comes the opportunity to prepare your vines for a fertile season. Why is vine nutrition crucial from the start of the season? What role does nitrogen play in this delicate equation between growth and fruit quality? Let’s discover the keys to a successful wine-growing season.
Ensuring optimal nutrition from the start of the season
Pour optimiser votre saison viticole, il est essentiel de fournir dès le début un apport nutritionnel stratégique aux vignes. Un apport nutritionnel adéquat avant la floraison favorise une croissance saine et vigoureuse, assurant les bases d’une récolte de qualité. Un apport nutritif précoce, particulièrement s’il garantit l’équilibre optimal des éléments majeurs et des oligo-éléments, est stratégique car il favorise un développement racinaire sain, une floraison optimale, renforce la résistance aux stress environnementaux et contribue à produire une récolte de haute qualité. Tout déséquilibre pourrait conduire à des pertes de rendements ou un impact sur la qualité du vin.
Controlling the ideal amount of nitrogen
Nitrogen, the nutrient that most influences yield, is essential for vine growth, but finding the right balance is a challenge. Low nitrogen levels can limit fruit growth, while too high a level can lead to excessive vegetation and the risk of disease.
According to IFV, recommended nitrogen doses generally range from 30 to 60 kg N/ha for production of 6 to 10 t/ha, and 60 to 90 kg N/ha for production of 10 to 25 t/ha.
L’absorption de l’azote se déroule principalement en trois phases : la première se produit pendant et peu après la floraison. L’azote absorbé est alors principalement utilisé pour la croissance végétative. Une deuxième phase a lieu pendant la véraison, période durant laquelle l’azote absorbé enrichit principalement les baies. Enfin, une troisième phase intervient après les vendanges, si les conditions climatiques le permettent. L’azote absorbé est alors stocké dans les parties pérennes de la vigne.
Il est donc crucial de planifier la fertilisation de manière que la bonne quantité d’azote soit disponible pendant ces périodes critiques. Vous maximisez ainsi la santé de vos vignes et garantissez la qualité de votre récolte, en favorisant une croissance équilibrée et une maturation optimale.
Nitrogen, the driving force behind vine growth and quality
In addition to its crucial role in vine growth, nitrogen plays a decisive role in fermentation and wine quality. During alcoholic fermentation, nitrogen is used by yeast to metabolize sugars into alcohol and other aromatic compounds. An adequate supply of nitrogen promotes more complete fermentation, contributing to the production of higher-quality wines.
De plus, l’azote est essentiel pour la synthèse des protéines dans les baies, ce qui influence directement la composition du moût et, par conséquent, les caractéristiques organoleptiques du vin final. Un bon apport d’azote favorise la production de mouts plus riches en acides aminés, en protéines et en enzymes, éléments clés pour obtenir des vins équilibrés, aromatiques et dotés d’une texture plus complexe.
By ensuring optimal nitrogen supply throughout the vine’s growth cycle, winegrowers can significantly improve the quality of their harvest and produce exceptional wines.
Our experts anticipate nitrogen competition
Le cycle de l’azote est complexe et les facteurs de compétition azotée pour les cultures, nombreux, mais cette compétition peut être anticipée afin de maximiser la biodisponibilité de l’azote pour la vigne. Nos experts calculent avec précision le dosage d’azote nécessaire, en tenant compte du couvert végétal et du type d’engrais utilisé, pour une disponibilité optimale des nutriments dans le sol. Piloter votre fertilisation azotée et maîtriser les facteurs de compétition permet d’assurer la productivité et la santé de votre vignoble de manière durable.
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Grapevines are particularly vulnerable to diverse fungal pests and insects. High susceptibility to biotic stress of grape varieties can lead to important economic losses, reduction of wine quality and undesirable sensory characteristics.
Over time, the high disease pressure and lack of genetically resistant cultivars have encouraged the use of large amounts of pesticides in vineyards to preserve yields and quality. Every year, around 2 million tons of different pesticides are used worldwide, and this amount is predicted to rise with the increase of disease resistance.
However phytosanitary treatments should be carefully planned by selecting the optimal timing for application and determining the type and dosage of chemicals to be used. This approach aims at minimizing the environmental and human health impacts while reducing the overall phytosanitary costs forgrowers.
When are vines at risk of disease?
It is crucial to precisely evaluate the current disease risk by integrating various pieces of information. This integration can be exemplified though the disease triangle, a well-established concept in plant pathology. According to this conceptual model, the actual development of a disease requires the simultaneous presence of three critical factors: a susceptible host, a virulent pathogen, and an environment conducive to disease development.
While it’s generally easy to determine the presence of a pathogen in a given region, assessing plant susceptibility and climatic propensity to disease can be more complex. Each disease reacts to specific weather conditions and attacks the plant during specific windows of vulnerability, often associated with particular phenological phases. For example, grapevines are susceptible to powdery mildew from the stage when the leaves are half-spread to the stage when the berries become resistant to penetration by the fungus, before the ripening process begins. So, to assess the real risk of disease, it is necessary to take into account not only the impact of weather conditions on powdery mildew, but also the vulnerability of vines at different phenological stages.
Predicting plant-environment-pathogen interactions and treatment efficacy
The complexity of plant-environment-pathogen interactions can pose challenges in evaluating actual disease risk and making rapid, effective phytosanitary decisions. To address these issues, precision viticulture utilizes tools that simultaneously consider all contributing factors. One effective approach is the integration of plant phenological models with disease models within a Decision Support System (DSS).
This method involves simulating the interaction between disease development and plant vulnerability. This combined modeling approach allows an accurate assessment of risk by aligning the various stages of disease progression with susceptible phenology. The resulting information facilitates more targeted and timely interventions, enhancing the effectiveness of disease management in vineyards.
Furthermore, model based DSS can predict the duration of treatment efficacy and the likelihood of wash-off if rain occurs. This means that treatment renewal is no longer a matter of speculation but based on more empirical grounds. Excess applications are avoided because growers know the protection level of their plants and can therefore save money and decrease environmental impacts while maintaining vineyard health, grape quality, and ultimately increase their profitability.
The key to a successful protection strategy: Anticipating risk
Finally, DSS offer the benefit of forecasting imminent risks using weather. Planning treatments in advance is essential to guarantee sufficient protection, especially considering that phytosanitary products for fungal diseases primarily act preventively rather than curatively. Sometimes a few days of advance can make a huge difference on final disease levels and save the yield.
The case of Italy in 2023: When experience is not enough
For example, in 2023, an unusually wet start to the growing season in southern and central Italy led to a devastating outbreak of downy mildew. The combination of frequent rain and warm temperatures in May and June created ideal conditions for fungal growth in regions where such diseases were historically rare, resulting in significant yield losses.
Many growers reacted slowly because they underestimated the risk, assuming their vineyards were historically less prone to disease. Consequently, they initiated treatments too late, unable to contain the infections in time.
In such situations, the integration of DSS, offering predictive insights into disease risk, proves invaluable for formulating effective phytosanitary strategies to protect yield. As climate-change driven disruptions become more frequent, growers will increasingly struggle to rely solely on past experiences to predict risks. Thus, the significance of predictive tools like those described will only grow more evident as time progresses.
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According to an Australian study by CSIRO, reduced precipitations during winter delay budburst and decrease subsequent yield by up to 40%. Excessively dry soil conditions can also cause growth disorders. For example, in central California, the 2021 winter drought had severe consequences on vineyards . Many growers reported delayed phenology, poor growth, and fruit abortion. Some severely impacted vineyards suffered a substantial yield loss.
The problem is known as « delayed spring growth » and can be caused by lack of soil moisture. It results in bud wilting, stunted growth and, in severe cases, fruit shatter and abortion. It is partly due to vascular impairment due to dry conditions. Dormant buds become dehydrated over winter and have relatively weak vascular connections to the rest of the vine. Spring sap flow (bleeding) helps repair any vascular embolisms that may have formed over the winter and rehydrates the buds. However, when the soil is excessively dry or the carbohydrate reserve too low, this process can be impaired and shoots with faulty connections do not receive adequate carbohydrate supplies at growth resumption, even if soil moisture is subsequently re-established.
Another consequence of soil dryness in winter and spring is the inhibition of fine root formation. Fine roots are non-woody, short-lived roots with very small diameters < 1 mm. They are important for resource acquisition and microbial interactions. Their growth is promoted by carbohydrate demand from the plant (in the spring, for example) and is strongly limited by the lack of soil moisture. For this reason, early season drought can lead to decreased nutrient absorbtion and cause nutrient deficiencies.
These consequences are not homogeneous in vineyards. Only some shoots are affected by unresolved vascular embolisms and dry patches in soils are often distributed hetereogeneously depending on soil variability. This results in desynchronised budburst and phenology within the same vineyard, which makes viticultural operations more complicated.
Climate change, ants and winter drought: a terrible mix for your irrigation system
In addition to its adverse effects on plant growth, winter drought can be accounted for yet another problem in vineyards: the breaking and failure of subsurface drip irrigation systems.
In recent years many vineyards in southern France have reported damage and failure of irrigation systems at the onset of the growing season. This occurred only for subsurface drip systems and after drier and warmer than average winters such as 2019. Close investigations have revelead that water emitters along the dripperline are damaged by soil-dwelling ants that search for water at the end of winter rest. When the ants cannot find water in the soil profile, they enter the irrigation system and pierce the emitter membranes to enter in the water pipes. The phenomenon has been particularly pronounced in recent years and fueled by climate change.
In most mediterranean and temperate species, ants stop foraging for food and become inactive in winter. Because their activities are greatly reduced, they can survive with their energy reserves for a few months. This slower metabolic state is called « diapause ». The increase in temperature during the early spring months cues ants to re-emerge from their chambers, prompting workers to search for new food sources and water. In the last few years, record winter temperatures have promoted earlier ant activity, inside dry soils that had not yet been irrigated. The lack of moisture has pushed ants into irrigation systems where the damages have been done.
Many different ant species live in mediterranean soils, but only a few are small enough to enter the emitters and wander through the system. In southern France, the culprits have been identified as belonging to the genus « Solenopsis ».
How to protect your vineyard: the importance of winter irrigation
Given the adverse effects that excessive soil dryness can have in winter, it is important to ensure that soils retain their moisture during winter rest and are ready to support a healthy growth resumption at the time of budburst.
In winter months, growers should assess soil moisture, review the weather forecast, and consider whether winter irrigation may be needed. If the soil is dry and no significant precipitation is in the forecast, then irrigation is recommended. Grapevines use little water over the dormant season, and lower temperatures decrease soil evaporation, so often only one irrigation will be needed in January or February.
Irrigation experts advise to perform one « technical irrigation » to fill up the soil profile to manage any potential potential growth disorders and prevent ants from damaging subsurface drip irrigation systems. To know exactly how much and how long to irrigate, a precise knowledge of soil composition and depth and the evaluation of its water holding capacity are very useful. These information can be provided by agronomic models and irrigation DSS like Vintel.
With drought setting in southern France and no significant precipitation forecasted for the next weeks it is the right time to think about “watering ” your vineyard. A strategic irrigation now can avoid many later problems and ensure a good start of the 2022 season.
Climate is changing at a rapid pace disrupting many human activities. These changes are expected to continue and have important consequences on agriculture, due to the strong link between climate variables and crop growth.
Some agroecosystems are recognized as more vulnerable because of their their climate sensitivity and their limited resilience to change.
The climate vulnerability of viticulture
Viticultural agroecosystems are included in this category for different reasons. Among them are their occurrence in geographical areas that are already water limited and will suffer from increasingly severe droughts in the next decades, the crucial effects of climate on yield and quality, and, for some regions, a structural rigidity in the wine sector preventing swift adaptation.
Grapevines are grown in climate change hotspots
Mediterranean climates are particularly well suited to viticulture, allowing a wide range of of varieties and wine styles. The long, sunny growing season gives vines an early start and allows late harvests. It also ensures a well balanced ripening process, excellent color, soft tannins and aroma. For this reason, some of the most renowned wine regions are located around the Mediterranean, in California and South Australia.
Unfortunately the Mediterranean basin has also been pointed out as a climate change hotspot, warming 20% faster than global average and with a projected decrease in precipitation of 30% by 2080. Similarly, California has experienced some of its worst droughts in the last years as a result of climate change. 2000 to 2021 have indeed been the state’s driest 22-year period over the last 1,000 years, something which has been described a an ”emerging megadrought era” by climate experts.
These alterations are already impacting the wine sector and will likely result in a disruption of traditional viticultural agroecosystems in the next decades.
Grape production depends on temperature and water availability
Viticultural systems, even more than other crop systems, are characterized by particularly strong ties between climate and production in terms of quality and quantity. Indeed, climate has a greater impact on vine development and fruit composition than soil and grapevine variety . Many individual atmospheric factors (e.g., solar radiation, wind, humidity, etc.) influence the growth and productivity of grapevines, but temperature and water availability are probably the most important. These climate variables are also those expected to change the most in the next decades, as projected by climate change scenarios.
In addition to affecting grape physiology, temperature and humidity affect also disease occurrence which is an indirect driver of yield and quality. Pests and diseases are strongly promoted/inhibited by weather variables, and climate change will probably alter the distribution of disease hotspots. For example a warmer and drier weather might result in a decrease in cool climate diseases such as downy mildew and an increase warmer climate diseases or insect pests in some regions. These changes imply that phytosanitary practices might need to be adapted to offer adequate protection to vines in the future.
Traditional wine regions are not adapting fast enough
In regions traditionally producing high-value wine such as Bordeaux in France or the Barolo region in Italy, regulations are put in place as a guarantee for the consumer. Producers may use only grapes that are permitted by the appellation authorities and the grapes may come only from certain areas. This system, thought to protect producers and consumers may reveal its fragility in times of rapid climate change. Indeed, the optimal climate for varieties and wine types is shifting quickly, meaning that new varieties and methods cannot be introduced easily without losing their prestigious labelling. Such restrictions do not exist in new world wine regions, where it is largely up to individual producers to decide what they grow and how they make their wines, making it easy to take adaptation measures.
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Climate change adaptations : towards a climate resilient viticulture
With so much at stake, it is no wonder that vine growers, wine makers and researchers have been experimenting to find adaptation measures to climate change. Some are :
Growers are considering a change in traditional varieties
Some grapevine varieties are better suited to warm climates than others. They generally have a later phenology, they are more tolerant to drought and high temperatures and they are more resistant to disease and produce less sugar with higher acidity. New varieties can also be created by specifically selecting climate-resilient traits, helped by genetics and ecophysiology. These varieties can be planted in areas that have cool climate varieties and are suffering because of climate change. This is already happening in Bordeaux and Napa Valley, two prestigious regions closely associated with cabernet sauvignon. In Bordeaux, where producers may use only grapes that are permitted by the appellation authorities and they can substitute traditional varieties only up to a small percentage. In new world countries such as California, grape growers are more free to adapt their production to the changing climate.
Practices are adapting to buffer climatic changes
Viticultural practices can be adapted to maximize available moisture and minimize heat in the vineyard. For example, decreasing the density of plots reduces hydric stress and choosing trellis systems resulting in more horizontal canopies can shield grapes from sun and excessive heat. Soil practices also matter, in particular those increasing organic matter that maximize water retention near the roots.
Finally, irrigation is key to protect yield and quality. However, as water is becoming a precious resource in dry areas, the focus is on more and more precise irrigation strategies, providing vines with the right amount of water in the moment when it is most needed.
Vineyards are moving to cooler areas and regions
As a result of warming, areas that were previously considered too cold are now becoming suitable for commercial viticulture. Vineyards are now planted at higher altitudes, or in cool regions that are not classically considered suitable for wine making, but are becoming so as a result of warming. For example, many viticultural domains have been planted in recent years in the south of the UK , where the surface of grape-growing land is increasing by 1000 ha each year. Another adaptation has been the planting of vineyards on north facing slopes in warm regions. Northern exposure decreases solar radiation and temperature counteracting the negative effects of warming on vines.
A smarter viticulture
It is now clear that the key to ensuring viticultural sustainability in the face of climate change will reside in the flexibility and willingness to change traditional habits to embrace new, climate-smart habits and technologies. To increase viticultural resilience and preserve yield and quality, it is crucial to optimize viticultural practices to match the changing climate and increase their precision.
Smart technology come to the aid of growers to anticipate the effects of these changes and put in place resilient practices ans tools to protect production.
One of them is Vintel : an all-in-one solution to manage vineyards. Vintel is an application for computer and smartphone, based on agronomic models that simulate, day by day, the water, nutrient and disease status of your vineyard and help you take the best decisions in the face of climate change.
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