The vineyard is the realm of living creatures whose lives are as deep and mysterious as our own.
Chapter 10
This chapter looks at critical junctures and operations in the vineyard with an eye to how they can be manipulated to benefit the subsequent wines produced. It will be of the most use to those practitioners who have not yet acquired deep understanding of the vines. I have included an index of the section we are in to orient those who may be just joining in and to let everyone know what is to follow.
Section II - Winegrowing
Chapter 8 - Overall Approaches
Chapter 9 - Soil and Topography
Chapter 10 - Vineyard Management for Wine Quality
Chapter 11 - Soil Management and Nutrition
Chapter 12 - Disease and Injury Management
Chapter 13 - The Growing Year
Chapter 14 - Terroir
Chapter 10 - Vineyard management for Wine Quality
Virtually every operation carried out in the vineyard will influence the subsequent quality of the wine— this is the crux of the matter! This is even more true for red wine than for white. The vineyard is the realm of living organisms whose lives are as deep and mysterious as our own. It is a field of inquiry so vast and complex that even after a lifetime of work, new questions and conundrums will continue to arise. The major issues will first be addressed individually in some detail.
Dormant Pruning
Pruning is the most challenging of routine vineyard tasks, requiring both skill and creativity. Proper pruning gives the vine its best chance of producing quality wine. Pruned poorly, a vine will suffer both immediate and long-term losses. Each vine is in a sense a puzzle to be solved. This is especially true with cane pruning. Spur pruning also demands care, but in general requires less skill. When the weather is mild, pruning is both pleasant and gratifying. Regions without ready access to labor have developed mechanized and minimalized methods of pruning, but these are not germane to fine wine, as access to hand labor is an unnegotiable prerequisite of fine wine. When we say wines are handmade, this especially refers to the vineyard work involved. Pruning is related to—and is an extension of—training the vine. Training refers to the pruning done during the first few seasons, when the vine’s trunk is being established on its trellis. The goal of pruning is to balance the vine. Balanced pruning minimizes and, in some cases, obviates the need for further major manipulations of the vegetative growth during the rest of the season.
The art of pruning has been pursued since pre-Christian times. Both Virgil and Pliny gave advice to Roman vintners that remains applicable today. Jules Guyot, a mid-19th century contemporary of Pasteur, advocated for a form of cane pruning that now bears his name. It continues in both its single and double forms as the most common system of pruning for fine wine production to this day. Guyot’s work was translated into English and had a strong influence on the development of New World winegrowing. While spur pruning is still practiced, cane pruning is preferable.[1] As with anything, there are exceptions, and large clustered varieties may do better with spur pruning. The single or double Guyot pruning works best with in-row vine spacing of 0.8m–1.6m.
The goal of pruning a mature vine is to leave sufficient buds for a balanced crop, and enough renewal spurs properly positioned to establish the following year’s fruiting wood. A normal or balanced crop is defined as the maximum amount of fruit that will ripen without delaying maturation. With fine wine, additional caution is advisable. The goal in this instance should be a crop that the vine can ripen at the earliest possible time. A conservative approach to cropping is best, given that the conditions of the following summer and fall cannot be known at the time of pruning.
Two concepts must be clearly understood in any discussion of pruning. We must differentiate between the vine’s vigor and its capacity. Vigor is the vine’s tendency to grow vegetatively, and capacity is the vine’s ability to ripen a crop. These terms are used for the entire vine but may also be employed for individual shoots. Vigor and capacity are not synonymous or interchangeable. A young vine, for example, will often have high vigor but low capacity. A large mature vine with many buds and a massive root system may exhibit modest vigor in any given shoot and yet still have a large capacity for fruit ripening. This is mostly related to the extent of the root system. Young vines have limited root systems compared to mature vines.
Each vine must be evaluated on its own merits and then pruned to achieve balance. As the vineyard matures, irregularity between vines develops and so pruning cannot be standardized for every vine. It must be undertaken thoughtfully on a vine-by-vine basis. The prior year or two of the vine’s life should also be considered. For example, if the preceding year produced a larger than average crop, this imposed a strain on the vine which will continue into the following year or two, and thus the capacity of the vines is lowered. Factors such as disease can also lower a vine’s capacity, and longer-term weather events such as droughts can lower an entire region’s capacity. The winegrower must take the full scale of events into consideration when making pruning decisions—from the micro scale of the individual vine to the macro scale of seasonal and regional climatic variations.
Pruning is the vineyard management practice that has the most significant effect on vine balance. The goal is to have uniform vigor within the vineyard insofar as possible. More severe pruning can strengthen weak vines.[2] Leaving fewer buds on the vine means that each one will have more vigor. And conversely, overly vigorous vines will be subdued by leaving more buds. The goal is to have uniform vigor within the vineyard as much as possible. However, pruning alone cannot solve persistent low- or high-vigor problems. These severe imbalances are most often the result of poor decision-making during plantation and establishment of the vines, or of mismanagement of soil, moisture, or nutrition. A well-pruned vine exhibits good balance, with shoot growth adequate for its crop load. Specific guidelines have been developed in some regions using ratios of the prior year’s pruning weight to determine bud count for the current year. I have found visual assessment during the dormant period to be a better gauge, especially when summer shoot removal is a routine practice. That said, visual assessments are only accurate when all management decisions have been sound. For example, an overwatered and overfertilized vineyard may appear to need more buds left at pruning to suppress vigor, when in fact only applying less water and nutrients will correct this imbalance.
Dormant buds should routinely be dissected after leaves fall, to get a rough indication of bud fruitfulness before pruning. From this, it is possible to make an initial estimate of the potential crop. A generous count of buds should be left on the vine in relation to the desired crop load for the next year. Because adverse weather during bloom and set may greatly reduce the crop, it is best to start with a greater number of potential clusters than you desire. On the other hand, if fruit set is successful, excess crop can easily be addressed through shoot or cluster removal. Bud fruitfulness is influenced by several factors, the main determinants being warm temperature, and—to a lesser degree—greater light during the summer months.[3]
Shoots selected to be canes must satisfy several criteria.
1. They must arise from one-year-old wood;
2. They should be average or above in diameter;
3. They should be uniformly lignified throughout their length;
4. They should be from the outer part of the canopy, where they received more heat and light (therefore increasing their fruitfulness).
Overly vigorous bull canes and weaker shoots are poor choices, as both conditions lower bud fruitfulness.
The timing of pruning is determined by regional conditions. However, regardless of timing, the vines must always be fully dormant. Cold injury to dormant vines is possible in areas with severe winter weather. Vines are Mediterranean in origin and temperatures below 15F can be injurious. Where this risk exists, early pruning is not advisable. In regions with mild winters, the first few rainstorms will carry abnormally high amounts of disease spores. In this case, it is prudent to wait until several rains have fallen before beginning to prune. Extremely late pruning can delay the vine’s annual cycle, which is deleterious. Pruning wounds, especially large ones, should be avoided as they create an avenue for entry of disease into the vine. When unavoidable, large pruning wounds should be treated with appropriate protectants.
Green pruning
Removing any of the vegetative parts of the vine during the annual growth cycle is a form of pruning. Green pruning is normally described by its specific applications: shoot thinning, hedging, and leafing. Regulating crop level by the removal of flowers or clusters—while technically a type of green pruning—is called thinning and will be addressed separately. Green pruning, along with training and trellising, is an essential aspect of canopy management: addressing the microclimate within and immediately adjacent to the vine. Green pruning changes the vine’s physiology as well as modifies the microclimate. Like dormant pruning, it has a basic inhibitory effect on the vine. For example, removing some shoots will strengthen the remaining shoots, but the overall effect is to lessen the vine’s capacity.
Almost all vines require some degree of green pruning. The timing and extent of this will have marked effects on the vine. These operations, if done incorrectly, will interfere with the vine’s ability to ripen. When done thoughtfully, they improve the vine’s physiology and ultimately the quality of the wine—and therefore should be undertaken judiciously. The main categories of green pruning are addressed individually below.
Suckering
Suckering is the removal of unwanted shoots from the trunk of the vine. These adventitious shoots can arise from either the rootstock or the scion. The removal of water sprouts (shoots emerging from buds on wood older than one year) is sometimes called suckering as well. Suckering is critical in the first few years of the vine’s life. In fact, in the vineyard’s early development, it may be necessary to make several passes each season to remove the undesirable shoots. They should be removed while relatively short, so that they are easily broken off by hand or boot. Suckers arising from the rootstock are more pernicious than scion wood suckers, as they often originate below ground and are difficult to eliminate entirely. If suckers are dealt with thoroughly in the early years, it will save much labor and grief in the long term. If left unchecked, rootstock suckers can ruin a vineyard.
Shoot thinning
The removal of unwanted shoots is the key task of green pruning. The primary purpose of shoot thinning is to alleviate crowding in the canopy, in order to ensure a balanced spacing of clusters in the fruit zone. Most vines will initiate far more shoots than are consistent with a healthy ripening environment. If unregulated, this overcrowding creates two negative conditions: shade and humidity. The high number of leaf layers shades both the fruit and the shoots. Densely shaded clusters make for wines with poor color and high potassium. Shaded shoots will not produce sufficient fruitful buds for the subsequent season. This dense environment is also more humid than desirable. Powdery mildew and other fungal disease pressure increase, while at the same time, the dense canopy blocks preventative sprays from reaching the fruit. A denser canopy is also slower to dry out after rain events, increasing the likelihood that fungal diseases will infect and spread.
As with so many things, the timing of shoot removal is important—in general, the earlier the better. Thinning should commence once shoots have reached an average length of 25–35 cm.[4] By this growth stage, it is obvious which shoots are strong or weak. Typically, shoots that are less than half the average length will be removed. A shoot’s diameter will also influence the selection. with the spindlier shoots preferentially removed. Double shoots should be reduced to singles. Areas of the vine which tend to be crowded such as the head need extra attention. Many of the shoots that arise in the head area are sterile water sprouts and these are preferentially removed, versus fruit-bearing shoots. This thinning pass establishes the spacing between shoots and gives the vines energy to produce the optimum number of full-strength shoots. Effective shoot removal often obviates the need for subsequent cluster thinning, as only shoots with the capacity to ripen their crop will remain.
Leafing
Removing leaves from the base of the shoots improves light penetration and lowers humidity within the fruit zone. Typically, a few leaves around the cluster are removed just after fruit has been set. Normally, it is the side of the vine facing the morning sun that should be leafed. If there has been growth of laterals in the fruit zone, these should also be removed during this pass. Hand leafing is gentler and more precise, but good mechanical leafers are available, and large enterprises or regions with low labor resources rely on these. Mechanical leafing, when followed up by a quick hand pass, is almost as effective as hand leafing. The degree or severity of leaf removal is specific to vineyard conditions and the needs of the variety.
Vines for white wines have varying needs for leafing. For example, Sauvignon Blanc in cooler climates requires removal of all leaves in the fruit zone. In this scenario, a so-called “naked” fruit zone minimizes the mostly undesirable pyrazines that would be produced by a shaded zone. On the other hand, minimal leafing may be effective for varieties such as Chardonnay and Riesling, which are not improved by direct sunlight on the clusters. In their case, only enough leaves to facilitate air movement need be removed.
With red varieties, increased light leads to greater formation of anthocyanins, which is almost universally desirable. The risk in red varieties of too much leaf removal is the possibility of sunburn, raisining, and heat damage. The dark color of red fruit results in greater heat absorption from direct sunlight. Clusters exposed to direct sunlight can be 10–15 C above ambient. On a hot day, this can lead to temperatures high enough to severely damage berries. An overly sparse or thin canopy would not be leaf thinned. It is impossible to give general advice on the degree of leafing needed, as every block of a vineyard will have different leafing requirements.
Densely shaded fruit will invariably affect quality negatively. Fruit shaded by more than one leaf layer is associated with increased berry size, lower sugars, higher potassium, higher pH, higher malate, higher pyrazines, and lower tannin and anthocyanin production. Disease pressure within dense canopies is also increased for both powdery mildew and Botrytis, the two most destructive fungal diseases. All of this supports the idea that some leafing is needed in most situations to produce the best wine. In areas with low humidity and high heat, leafing should be done so that the clusters retain some shade during mid-day and early afternoon peak heat. This is especially true of red wine grapes, which can easily sustain damage from intense direct sunlight. Spending time in the vineyard throughout the day during the fall ripening period to observe angle and intensity of light will educate the winemaker about appropriate leafing. Small handheld digital thermometers help quantify these observations by easily measuring surface temperatures.
Hedging or topping
Hedging is mandatory in areas with regular summer or heavy spring rainfall. Tight spacing and high soil fertility can also increase the need for hedging, As many as five or six hedgings may be required under some conditions. The timing and severity of the hedging should of course be considered in relation to the metabolic needs of the plant. (See footnote #4 on shoot removal.) In almost all cases, one should avoid hedging that is proximal to the ripening period.
Water management and irrigation
Along with temperature and light, the relative availability of water is a primary driver of vine growth and, ultimately, of wine quality. Grapevines possess an unusual combination of drought tolerance and sensitivity to moisture inputs. This is attributable to their sparse and largely vertical root system as well as to the stomatal sensitivity of the leaves, which protects the plant from aridity. As a result, vines can adapt to high moisture stress and still be managed or manipulated by minimal rainfall or small irrigation inputs. As discussed in the section on climatic influences (Chapter 8), the ideal scenario for moisture supply is one where there is regularly occurring and moderate summer rainfall, and largely dry, sunny autumns. An equally valid countervailing opinion holds that the dry summer Mediterranean climate augmented by the availability of adequate irrigation water makes for the most reliable wine quality.
There are both sites and individual seasons where moisture will be overabundant at some stage and lacking during another. Even in areas that receive summer rainfall, the availability of irrigation will be useful to offset atypically dry or hot growing seasons. An irrigation system offers some insurance, especially as ongoing climate change will undoubtably effect rainfall patterns. That said, irrigation systems are costly in and of themselves, and developing a source of irrigation water is a widely variable expense as well. In areas with high summer rainfall, techniques must be employed to offset the effects of overabundant moisture.
When dormant, the vine is largely resistant to waterlogging. However, vines in their first year or two are susceptible to rot if exposed to saturated soil conditions for extended periods. Extreme drought during the dormant season is also harmful. Areas with light soil and sparse rainfall will require irrigation to maintain soil moisture even during winter dormancy. The annual cycle of moisture requirements for the vine’s growth has four distinct periods.
The first period encompasses budbreak until flowering, the main period for vegetative growth of the vine—when it is vulnerable to both drought and waterlogging. The former can be offset by applying irrigation during this period. The latter is a function of soil drainage and cover cropping, and when excess water is a problem, prevention is the best plan. In areas where heavy rainfall is common in the spring, it becomes imperative to locate your vines on sites with coarsely structured, well drained soils. If native drainage is insufficient, subsurface drains installed at plantation will augment natural drainage. Perennial cover crops are more effective than annuals for absorbing excess moisture. Management decisions regarding cover crops—such as percentage of coverage and mowing height—are more important than the choice of exactly which plants to use.
The second period, from flowering to veraison, has complex and variable moisture needs. A large flush of root growth occurs in this period, and both drought and waterlogging will inhibit proper growth. Adequate water is needed early on, when flowering and fruit set occur. However, overly abundant rainfall during this period is more damaging than a shortfall. Heavy rain negatively affects fruit set and can promote vigorous growth, which in and of itself interferes with flowering and set. Rain during flowering also provides an opening for Botrytis to establish itself in the nascent berry, leading to fruit rot problems later in the season. Mid-period, from set to lag phase is when berry size is determined. Abundant water tends to maximize potential berry size, while mild moisture stress[5] during this period will minimize berry size[6]. The latter part of the summer, from lag phase to veraison, is a time of reduced water needs. Shoot growth should have largely ceased, and only water sufficient to maintain leaf function is needed. A mild[7] moisture stress during this period just before veraison is beneficial, to accelerate the onset of veraison and the subsequent ripening. As has been mentioned previously, actions which shorten the cycle of vine growth and ripening almost always benefit wine quality.
The third period, from veraison to harvest, encompasses ripening—the most critical part of the season. Undue moisture stress during ripening will lower quality. Some winegrowers believe that slight moisture stress accelerates the ripening process, but this conviction is not universal. Varieties including Pinot Noir are extremely sensitive to moisture stress from mid-ripening onwards, whereas others, including Chardonnay, are much less so. For all vines, sudden increases in moisture from heavy rainfall inevitably cause damage when close to harvest. In dry areas, rain if it arrives will cause berry splitting due to a sudden uptake of water. Rainfall or persistent fog makes control of Botrytis and other rots difficult, and regions with high autumnal rainfall are not congenial to fine wine production. Splendid fall weather is a hallmark of great wine areas for a reason.
The fourth period, from harvest to dormancy, has limited water needs, and normal autumnal rains are almost always sufficient. Cases of extreme drought post-harvest should be offset by irrigation to maintain functioning leaves until the first frost. As long as the leaves are active, they continue to produce carbohydrates that will be stored in the trunk and roots for the next year’s growth. The second major flush of root growth also occurs now, and overly dry or waterlogged soil will interfere with it. An excess of moisture and mild temperatures during this period can cause the vine to recommence vegetative growth. This consumes carbohydrates that would be better stored, and also creates green tender tissue that is susceptible to freezing injury.
Irrigation principles and strategies
Drip irrigation has become the default method for vineyards. It is the most efficient in terms of water usage and can be used effectively in variable terrain[8]. Of course there are exceptions. Below-canopy sprinklers or micro-jets can be superior in shallow or lightly structured soils. In looser soils, irrigation tapes laid underground between the vine rows also work well. Flood or furrow irrigation, which not so long ago was common, is increasingly rare. Overhead sprinklers, while still used for frost protection, are much less commonly used for routine irrigation purposes. Overheads can also be used for cooling vineyards during extreme heat spikes. As with furrow irrigation, overhead sprinklers demand a larger-capacity system both in terms of storage volumes and delivery infrastructure.
The design of irrigation systems, when needed, should take into account patterns of rainfall, soil texture, and soil depth. Soils of sufficient depth and water-holding capacity can store enough water to supply the vine throughout the season, if rainfall is sufficient. The structure of the soil determines the extent of the active root zone. In densely structured clay soils, the roots will be limited to 2–3 feet deep. In comparison, he coarsest gravelly soils have root zones that can plunge to 20 feet or more. In all cases, most of the active roots are in the soil’s top profile. Soils vary greatly in the rate at which water infiltrates and evaporates from them.
Given the cost and complexity of factors involved in developing irrigation systems, I strongly recommend relying on outside experts. An overview of factors warranting consideration follows here. Both quantity and quality of water supply must be addressed. A mature vine under irrigation will need 4 gallons or so of water per week throughout the period of irrigation[9], but water supply capacity should be at least twice this to offset heat and low humidity events. Note that not all water is of equally good quality. Water supply can have a wide range of salt or mineral content—from too low to toxically high. Most irrigation water will contain some degree of naturally occurring salt, which accumulates in the soil until it is leached out by rainfall. The better the soil drainage and the greater the average annual rainfall, the lower the danger of irrigation salt buildup. In most circumstances, seasonal rainfall will flush the salts out of the root zone, but there will be situations and seasons when the irrigation system itself must be used to leach out salts. Irrigation always leaches nutrients from the soil to some extent. Fertigation is used to offset this and keep the nutritional balance of the soil healthy. This is discussed in greater detail in the chapter on nutrition (Chapter 11). Irrigation can be a boon in establishing young vineyards even in areas with sufficient rainfall to sustain the vine without irrigation. A temporary portable system should be considered for the first two vine years, even if a permanent system will not be necessary.
Irrigation scheduling
Three common methodologies exist for determining when to commence irrigating, and then to subsequently schedule ongoing irrigation, both with regard to frequency and quantity. Some growers use only one method, others use two, and yet others use all three in combination. In years with generous winter and spring rainfall, midsummer may arrive before the vines need any supplemental water. Rains in April and May are particularly useful, and in soils with adequate water-holding capacity irrigating may not need to commence until late summer or even early fall.
Plant-based methods are first and foremost. Traditionally, growers use visual observation of the growth habit of the vine itself. The growing tips of active shoots with adequate water supply are pale yellowish green and tender. Tendrils that extend beyond the shoot tip when vines are actively growing are another indicator of sufficient moisture. As the water supply diminishes, growth at the tip slows, and then the tips and tendrils dry and finally die off. Moisture stress causes leaves to curl, and the angle of the leaf to the petiole increases. As water stress continues, older basal leaves senesce and fall. Clusters become much more susceptible to sunburn under conditions of water stress. Feeling the temperature of active leaves in the shade can indicate whether they are actively transpiring water. When you gently cup a leaf in your hand active leaves feel cool in the hand compared to the ambient temperature. There is no cooling sensation in the hand from inactive leaves which are not transpiring water vapor. Pressure bombs that measure the water stress of leaves are an effective way to measure water stress of vines. The equipment is portable and moderately priced, and techniques for assuring accuracy and interpreting the data are well established. This pressure bomb is my preferred tool for determining when to begin irrigations. Xylem sap measurements and changes in trunk diameter can also be correlated with water stress but are less commonly used.
The second large group of methods are soil-based measurements. Tensiometers, moisture blocks, and neutron probes are all in wide use, and all can be effective. The more expensive neutron probe is generally considered the most accurate. Measuring soil moisture continuously aids in scheduling the intervals between irrigations. These soil-based measurements are the only way to monitor the longer-term availability of water in the soil at various depths.
Weather-based methods are useful for scheduling ongoing watering once another method has been used to determine the initial application of irrigation. The amount of soil moisture that must be replaced by irrigation is calculated from the weather, based on the measured evapotranspiration loss of a test crop—usually grass. Governments measure and publish these loss indices. Various specific crop coefficients have been established for many locations and can be calculated for areas where they have not been published.[10]
[1] Many treatises on winegrowing describe systems and methods of pruning. Practical manuals such as the Oregon Winegrape Grower’s Guide are an excellent resource. No book, however, can compare with hands-on practice. Working under the guidance of an experienced pruner is the best way to learn, ideally for several seasons in various vineyards.
[2] Crop must subsequently be thinned off weak vines to best bring them back to full vigor. Pruning can help, but it must be combined with crop removal to successfully revive a weak vine.
[3] More complete leaf removal in the head area of the vine where the next year’s canes are growing can help promote bud fruitfulness. The entire fruit zone need not be leafed identically.
[4] Shoot removal, like all vegetative interventions to the vine, causes its physiology to be retarded for some period. The vine perceives the removal of green tissue as insult or injury and responds by temporarily ceasing or slowing metabolism. Therefore, the timing of green pruning in relation to the major events in the vine’s cycle must be considered. It is best to allow at least two weeks between a green pruning operation and events in the vine’s cycle that take significant energy. For example, neither hedging, shoot thinning nor leafing should take place just before or during flowering and set. Even more critically, all green pruning and thinning should be completed at least two weeks before veraison. As with all advice, there are exceptions that prove the rule. In conditions of very vigorous growth during bloom, pinching back the growing tips of the shoots may help with fruit set.
[5] Some vintners believe that vine stress is beneficial for wine quality. The theory is that if the vines struggle and suffer, the wine is better for it. Of course, this is not universally true. There are times when mild stress can be beneficial, but in general a balanced healthy vine with an intact functional canopy makes the best quality wine.
[6] Potential berry size is regulated primarily by seed count, which is a function of how successful bloom and set were. Actualizing that potential berry size is a function of moisture availability. Therefore, a season with relatively low seed count would benefit from relatively more moisture availability in the set-to-lag phase, while a season with high seed count could be offset by some mild moisture stress during this period.
[7] If greater than mild stress occurs, the vine may begin shutting down and defoliating with dire consequences for the ripening period to follow.
[8] Prior to the development of drip irrigation, sprinklers were the only option for hilly sites, as flood irrigation can only be used on the flats.
[9] Obviously, water needs per plant are highly variable. It is worth keeping in mind that under any condition of moisture stress, the needs of the vine are driven by leaf area. Widely spaced larger vines with a greater leaf area need more water per vine than smaller more tightly spaced vines. Fruit load does not seem to directly influence the amount of water needed, but a large fruit load does require a greater quantity of active leaves to ripen, so fruit load can be considered an indirect effect.
[10] Using these models, one can determine what percentage of evaporative loss will be replaced by irrigation for a given time of year. The most critical time of year for the winemaker to focus on irrigation is the period from veraison to harvest. The texture of the soil and how quickly it responds to irrigation inputs must be considered in making these decisions especially in areas where the combination of high heat and low humidity can occur during the fall. For example, a lighter sandier soil will take up and deliver water quickly and so can be held safely at lower water content because when heat is predicted irrigations can be applied and taken up by the vine in a short time period. With heavier clay soils, this is not the case. It will take a few days with these soils for water to infiltrate the root zone and the heat will have done its damage before the vines have access to the added water. With heavier soils it is best to keep the water well supplied through the ripening period and not let deficits accumulate. How long it takes to irrigate the entire vineyard is also a concern under periods of high heat stress during ripening. In the ideal scenario, it would be possible to irrigate all blocks in one to two days.