Only additional research will establish if there is a direct connection between the G-G content and perceived wine aromatic quality. In the interim, research to find faster, less expensive, more convenient, on-site means of determining the G-G content (or other chemical indicators of wine flavor potential) is progressing (Gishen and Dambergs, 1998).

An objective measure of grape flavor potential would not only be of tremendous practical value to grape growers, but also would give researchers a quantitative measure of grape maturity. This could be used as an effective and pragmatic means by which the effects of modified viticultural practices could be assessed. For the winemaker, it would offer an objective criterion by which to determine grape quality, depending on the style desired. It would also give the grape grower a verifiable measure of quality, and correspondingly, the crop’s monetary value. To this end, a series of proposals have been made (Rousseau, 2001; Winter et al., 2004). A review of the efficacy of such proposals and the criteria used is provided in Mantilla et al. (2012).

Although assessment of aroma constituents is likely to receive greater attention in the future, such as with the use of electronic noses, perceived wine quality is not necessarily directly associated with grape volatile aroma content (Whiting and Noon, 1993). The prediction of wine quality based on grape chemistry is still in its infancy.

In addition to assessing properties correlated with quality, grape growers must also take into consideration factors that may lower fruit quality. These are equally difficult to predict, depending as they do so much on local climatic conditions. The detrimental effects of early frosts and protracted rainy periods on grape quality are well known, but forecasting their occurrence days in advance remains regrettably imprecise.

Beyond the difficulties of judging grape quality are those associated with predicting crop yield. These data are important in scheduling the availability of equipment and labor, and the commencement of wine production. A wide diversity of techniques is used, typically based on local experience.

Relative to the modern criteria for timing harvest criteria, it is fascinating to read Columella (De Re Rustica 11.2). He comments that during ancient Roman times, use of features such as fruit softness, transparency, or leaf fall was fallacious. Even the sweet/sour taste attributes of the fruit he considers unreliable. For Columella, ‘natural ripeness’ was most effectively indicated by seed maturity. This is still favored by some.

Sampling

Despite progress in ferreting out some chemical indicators of grape maturity, fundamental problems still exist. Part of the problem relates to difficulties in applying them under actual vineyard conditions. Potential wine quality is almost as dependent on grape uniformity as grape chemistry. Extensive variation can negate maturity indicators based on inappropriate sampling. Various studies, such as those comparing fruit size and soluble solids (Fig. 4.77) and data from yield monitors mounted on grape pickers, show that vineyard variability is often more pronounced than previously thought (Plate 4.23). Interpretation, based solely on averages, can mask marked differences in quality that cannot be corrected by blending in the vat. Such variation can arise from a host of causes, including differences in vine age and health, as well as disparities in soil structure, texture, nutrition, moisture content, and microclimate. Additional diversity may arise from protracted flowering and the location of clusters on, and within, the vine canopy.

Many methods of fruit sampling have been investigated to determine the optimal combination of adequacy and ease. Simple application is important because vineyards may be checked almost daily for weeks prior to harvest. Although different procedures are used worldwide, that proposed by Amerine and Roessler (1958) has become the standard for much of the wine industry. It entails the collection of about 100–200 berries from many grape clusters, selected at random throughout the vineyard. Berries from clusters at row ends, or from obviously aberrant vines, are avoided. Sampling usually begins 2–3 weeks before the grapes are likely to reach maturity.

Regrettably, all random sampling methods are just that. They attempt to achieve an average, but there is no guarantee, other than statistical chance, that the results are valid. With precision viticultural, it is becoming economically feasible to identify significantly different plots in a vineyard, and have them sampled and integrated relative to their proportion of the vineyard (Meyers et al., 2011).

Basic chemical analytic procedures, typically performed on the juice, are described in detail in standard texts such as Ough and Amerine (1988) and Zoecklein et al. (1995). Many of these assessments may become simpler, and determined in the field, with developments in NIRS, which has the potential to quickly measure grapes for sugar, acid, anthocyanin, and water content (Geraudie et al., 2010).

Advances in measuring vineyard variation have led to the newest buzz phrase in viticulture – precision viticulture (PV). It often involves a combination of on-site analyses (soil, disease, yield, grape composition), combined with spectrophotometric analyses via remote sensing. Its aim is to determine the sources and geographic parameters of vineyard variation. This provides the data on which nonuniformity may be reduced to a minimum. In the future, limiting fruit heterogeneity will become one of the principal tasks of the grape grower (Smith, 2004).

Procedures associated with PV indicate that considerable improvements in yield and maturity prediction are possible (Proffitt and Malcolm, 2005). Developments in remote sensing are making the mapping of vineyard variability, down to individual vines, both feasible and increasingly affordable. Where considerable vineyard variability exists, it is important that random fruit selection be adjusted to reflect reality. For example, if excessive and low vigor were to, respectively, represent 25% and 10% of the vineyard area, then 25% of the fruit should be randomly selected from vigorous parcels, 10% from low vigor sites, and the rest from medium sites. Adjusted sampling would more accurately represent fruit yield and quality at harvest. It could also be the basis for selectively timing harvest for distinct sites.

Improvements in harvest timing could materialize one of the dreams of winemakers – improved fruit uniformity at the winery door. Synchronous grape ripening should yield wines with a more predictable character (Kontoudakis et al., 2011), tuned to the desires of the winemaker and consumer. Although the interrelationship between grape chemical analysis and perceived wine quality is still illusive, progress is being made (Forde et al., 2011). Thus, some of the potential inherent in greater fruit uniformity still awaits a better understanding of the chemical basis of wine quality. In addition, the geographic distribution of factors affecting chemical indicators of fruit quality, such as °Brix, pH, total acidity, anthocyanin and phenolic content, may not correlate with more easily measured features, such as yield or vine vigor (Bramley, 2005).

Harvest Mechanisms

Until the late 1960s, essentially all grapes were harvested manually. Subsequently, market forces, as well as labor shortages, combined to make mechanical harvesting progressively more cost-effective. In some regions, mechanical harvesters have been estimated to reduce harvesting costs by as much as 75% (Bath, 1993). Mechanical harvesters also permit rapid collection at the optimum time (determined by grape maturity, weather conditions, and winery preferences). Market forces, training, or cultivar attributes may permit or require the retention of manual harvesting in particular instances, but most hectarage in both the Old and New Worlds is now mechanically harvested.

Many different types of containers have been employed for collecting and transporting grapes to the winery. In Europe, traditional wicker and wooden containers reflect ancient cultural traditions and terrain limitations. In the New World, plastic or aluminum boxes have become typical. This facilitates both subsequent cleansing and stacking. From these, grapes are transferred to containers of various sizes for transport to the winery. Mechanically harvested grapes are often directly conveyed to transport containers. Any system is adequate, if bruising and premature rupture of the fruit are minimized, and where expeditious movement to the winery permits processing shortly after harvesting.

Manual Harvesting

Manually harvesting still has several advantages over mechanical procedures. This is especially true for thin-skinned cultivars that break open easily, for example, Sémillon. Hand-harvesting also facilitates the rejection of immature, raisined, or diseased fruit, as well as the selection of grapes at particular states of maturity. Some of these aspects are potentially subject to automation, using color sorting (Falconer et al., 2006). Except under special conditions, such as for carbonic maceration, sparkling, botrytized, or Amarone production (selectively using the outer arm of grape clusters), many of the advantages of manual harvesting are not realized or required.

For the advantages of manual harvesting to be fully realized, clusters must be collected and placed in containers with all due care to minimize breakage. This is particularly important if the grapes are botrytized (Seckler, 1997). In addition, the grapes must be transported quickly to the winery for rapid processing. This minimizes any potential for grape heating, or growth of undesirable microorganisms on the berries or released juice.

Although hand-harvesting is beneficial, or required under special circumstances, such as on steeply sloped vineyards, the disadvantages of manual harvesting often outweigh its advantages. In addition to labor costs and inadequate availability, manual harvesting is slower, stops during inclement weather, and seldom occurs 24 hours a day. Nevertheless, a California producer manufactures a boom containing banks of fluorescent lights that can be attached to a tractor. It can illuminate up to four rows for manual picking at night.

Relative to haze-forming proteins, there is little difference been manually and mechanically harvested grapes. However, if mechanical harvested fruit is transported long distances, enhanced protein extraction can increase clarification problems (Pocock et al., 1998). These are primarily pathogenesis-related (PR) proteins, notably thaumatin-like proteins and chitinases. Long delays between harvesting and crushing can also result in excessive oxidative browning and microbial juice contamination.

Mechanical Harvesters

Under most circumstances, mechanical harvesters are the most economic and efficient means of harvesting grapes. It has been estimated that in Europe, mechanical harvesting reduces the time involved from 160–300 h/ha to 0.6–1.2 h/ha, and the cost from 1600–2000 Euro/ha to 400–550 Euro/ha. Conveniences such as four-wheel drives, air conditioning, self-leveling, variable size options, the ability to combine harvesting grapes with stemming, crushing and refrigerated juice transport, and enhanced performance continue to extend the use of mechanical harvesters into a wider range of vineyard situations. An informative case study of mechanical harvesting in a famous Italian estate is described by Parenti et al. (2007).

All mechanical harvesters ostensibly use the same means to remove fruit. Force is applied to one or more parts of the vine, inducing rapid and abrupt swinging that detaches the fruit as individual berries or clusters. Harvesters are usually classified according to the mechanism by which the force is applied. Most harvesters fall into one of two main categories (Fig. 4.78). Those that apply force directly to the bearing shoot are variously called pivotal striker, cane shaker, striker, or impactor machines. Those that direct force to the vine trunk are termed pulsator, trunk shaker, or shaker machines. Some harvesters combine both actions, and may be referred to as pivotal pulsators. A third category, the slapper-type, directs force to the support wire bearing the shoots.

Most machines are designed to harvest vines trained as single vertical canopies. Special modifications are required to adapt them for vines trained on T-trellises, such as the Geneva Double Curtain. Major changes are required for use with Tendone or pergola (Cargnello and Piccoli, 1978) trained vines.

Once the berries or clusters have been shaken free, they are collected on a series of plates resembling enlarged fish scales. These open and close around vine trunks and trellis supports as the machine passes down the row. The plates are made of nylon or polyethylene, and arranged to slope outward. Thus, the fruit roll toward belts or buckets on either side of the vine. From here, they are conveyed for collection in one of a series of bins or gondolas. Where skin contact is not desired, the fruit may be crushed immediately. Only the juice is transported to the winery.

Pivotal Striker Harvesters

Striker (impactor) harvesters possess a double bank of upright flexible rods, arranged parallel to, and on each side of the vine (Fig. 4.78A). Formerly, the rods were solid fiberglass tubes with bent ends. Current preference is for curved, bow-shaped rods (Fig. 4.79). The bend of the bow can be adjusted to influence the rod’s surface area impacting the vine. Increasing the surface area reduces berry rupture (juicing), and minimizes contamination with MOG (material-other-than-grapes). The banks of rods oscillate back and forth, striking the vine canopy and shaking the fruit loose. For vines possessing less foliage, models with front and back banks (quad arrangement) oscillate together. Under heavy foliage, oscillating alternately tends to be more effective. With bow rods, the alternation can be adjusted so that when one set of rods reaches their maximum curvature, the other is at its straightest. Further adjustments to achieve the desired level of fruit quality and removal include the rod stroke (extent of side-to-side movement) and oscillation speed (rpm).

Striker machines are generally more suitable for cane-pruned vines, when cordons are young, or with other systems where the fruit is borne away from the permanent vine structure. Strikers are not as efficient at dislodging fruit close to the vine head. Increasing the striking velocity, to dislodge the fruit, enhances vine damage and increases fruit contamination with MOG. However, striker machines are easier on the trellis structure and accommodate themselves more readily to vine rows of imperfect alignment.

Trunk-Shaker Harvesters

The trunk-shaker typically possesses two parallel, oscillating rails that apply vibration to the cordon or upper trunk, a few centimeters below the fruit zone (Fig. 4.78C). This pulsates the vine back and forth several centimeters.

Shaker (pulsator) machines are most effective in removing fruit close to cordons or the trunk (spur pruned). Insufficient force tends to spread along flexible canes to effectively remove fruit on cane-pruned vines. However, the machines do have the advantage of dislodging fewer leaves and other vine material (MOG). The major drawback is its limitation relative to the vine training system. In addition, support stakes must be sufficiently flexible, and in perfect alignment, to withstand the force applied during shaking. Cordons must be firmly attached to support wires, and these in turn securely affixed to stakes. Magnets are typically used in the harvester to remove nails, staples, or other metal parts shaken loose from the trellis.

Striker–Shaker Combination Harvesters

Because both striker and shaker processes have limitations, machines combining both principles have been introduced. They possess a pair of oscillating rails and several short pulsating rods. They operate at lower speeds (50–75 rpm) than other machines. They tend to produce less vine and trellis damage, may be used with a wider range of training systems, and produce lower levels of MOG contamination.

Horizontal Impactor

The horizontal impactor (Fig. 4.78B) is designed for use with training systems employing wide-topped (T-) trellises, such as the Geneva Double Curtain. For use, canopy wires must be attached to movable crossarm supports, or the canopy wire must be held loosely in a slot on rigid crossarms. This is necessary as the jarring action required to dislodge the fruit comes from a vertically rotating wheel whose spokes strike and raise the canopy or cordon wire from below (Fig. 4.80). Because of the extra stress placed on the trellis system, stronger canopy wire than usual is required.

Robotic Harvesters

Although not currently used in commercial production, robot harvesters have been investigated (Kondo, 1995). The prototype uses a video camera to measure light frequency, and from that determine fruit position. Secateurs then selectively remove fruit clusters.

Factors Affecting Harvester Efficiency

In addition to the training system used, the growth and fruiting habits of the cultivar can significantly affect harvester efficiency and suitability. The two major fruiting characteristics that influence varietal suitability for machine harvesting are the ease with which the grapes separate from the vine and berry fragility. Features such as ready separation as whole bunches, easy fragmentation at rachis divisions, or dehiscence with facility at the pedicel are ideal attributes for mechanical harvesting. Ease of detachment reduces the force required and, thus, minimizes fruit and vine damage. Because wine grapes are predominantly juicy, firm attachment, fibrous rachis, and cluster structure may predispose the fruit to rupture and juice loss, as for example with Emerald Riesling and Zinfandel. This problem may be reduced by the application of methyl jasmonate. It is a natural growth regulator that promotes formation of an abscission layer at the pedicel, facilitating separation. For example, application of 4500 ppm methyl jasmonate reduced the force required for separation by 66 and 75% with Cabernet Sauvignon and Merlot grapes, respectively (Fidelibus et al., 2007). Soft-skinned varieties, such as Sémillon and Muscat Canelli, also lose much of their juice if mechanically harvested (Table 4.15). This problem may be relatively insignificant if prolonged skin contact is not desired and crushing occurs simultaneously with fruit harvesting.

The vegetative characteristics of the vine most affecting harvester function are cane flexibility, plus foliage density and size. Dense canopies interfere with force transmission and fruit dislodgement, as well as plug and disrupt conveyor-belt operation. The detrimental effects of excessive MOG contamination can be largely eliminated with fans blowing over the collector belts (Messenger, 2007) or other devices, such as optical sorters or special screens. However, small leaf fragments tend to become wet with juice and stick to the fruit, or are propelled into it. Brittle wood can produce spur breakage and conveyor plugging. Preharvest thinning of the vines often diminishes the severity of undesirable growth characteristics on harvester function. Additional problems can develop when harvesting old vineyards and trellises. Bits of wood from posts, trellis wire, staples, bolts, and other metal can be dislodged. These can result in significant repair costs and downtime caused by damaging crushers.

MOG contamination is normally considered undesirable, increasing the amount of undesirable leaf aldehydes in wines. It can also augment the amounts of cineole in wines, derived from vines planted close to eucalyptus trees (Capone et al., 2012b). Nonetheless, leaves can also enhance the content of rotundone in Shiraz wines (Capone et al., 2012b). The latter is important to the peppery aroma characteristic of Shiraz grapes.

Other factors influencing harvester efficiency are timing, vineyard slope, and soil condition. As grapes and other vine parts are typically more turgid at night, berry and cluster separation usually requires less force. Night harvesting also has the advantage of removing fruit at a cool temperature in warm climates. However, poor visibility, even using headlights, can make adequate observation of harvesting performance difficult. Slopes of more than about 7% require harvesters that can adjust their wheels independently to level the catching frame of the harvester. Soil grading may also be required to facilitate steering and remove ridges that can interfere with keeping the catching frame close to the ground.

Relative Merits of Mechanical Harvesting

With improved harvester design, and increasing awareness of the importance of vine training and uniform trellising, fruit of equivalent quality often can be obtained by either manual or mechanical means (Table 4.16). Wines produced from grapes harvested by different means can occasionally be distinguished, but no clear consensus on sensory preference has arisen, either in North America or in Europe (see Clary et al., 1990). Expected increases in phenolic contents, due to fruit rupture, often do not materialize. This absence may be due to rapid oxidation and the early precipitation of phenolics during fermentation. An exception to a lack of difference between manual and mechanical harvesting applies to Sauvignon blanc grapes. In this instance, mechanical harvesting was associated with a marked increase in the varietal (thiol) character in the wines (Allen et al., 2011; Capone and Jeffery, 2011). Nevertheless, mechanical harvesting has been correlated with increased problems with protein instability in wine, when associated with delays or extended transport times to the winery (Pocock et al., 1998).

Table 4.16

Effect of Harvesting Method on Crop and Juice Characteristicsa

 Treatment
Property Striker harvester Shaker harvester Manual harvester
Yield (kg/ha) 12,509 12,475 12,800
Stem content (kg/ha) 155 288 524
Ground loss (kg/ha) 317 249 338
Juice loss (%) 5.7 8.0 0
MOGb (%) 1.3 0.7 0.5
oBrix 22.2 22.2 22.6
Total acidity (g/100 mL) 0.75 0.76 0.74
pH 3.26 3.28 3.27
Malic acid (g/liter) 4.552 4.409 4.137

Image

aThe slightly higher oBrix and lower total and malic acidity of the hand-harvested grapes is likely explained by the absence of second crop fruit.

bMOG, material other than grapes.

Source: Data from Clary et al., 1990.

With cultivars suitable for mechanical harvesting, the choice of method often depends on factors other than fruit quality. Features such as the potential for night and rapid harvesting, cost savings, shortage of manual labor, juice loss, and vineyard size become deciding factors. For example, where grapes grown in hot climates must be transported long distances to the winery, harvesting during the cool of the night can result in grapes arriving in a much healthier condition. Field crushing and storage under cool anaerobic conditions, immediately following harvest, is another solution that preserves juice quality of fruit picked at a considerable distance from the winery. For high-priced, low-yielding cultivars, juice losses between 5 and 10% may negate the economic benefits of mechanical harvesting. Also, for French-American hybrids that may produce an extensive second crop, the detrimental effects of harvesting immature grapes on wine quality may outweigh the cost benefits of mechanical harvesting. Whether features usually associated with mechanical harvesting, such as lower stem content, marginally higher MOG contents (Clary et al., 1990), increased potential for juice oxidation, and increased fungal growth on juice-soaked canes of the vine (Bugaret, 1988) materialize or are of practical significance cannot be generalized. If they are of practical significance, this probably varies considerably depending on the cultivar, harvesting conditions, and wine style desired. Nevertheless, leaf defoliation, if pronounced, can have a negative influence by reducing the vine’s ability to produce and store carbohydrate reserves in the autumn. This could decrease productivity in the succeeding year, especially if the current year’s crop were high. Because of the perennial nature of the vine, such influences can be cumulative (Holzapfel et al., 2006).

Measurement of Vineyard Variability

The major theme in this chapter has been the means by which grape growers can achieve maximum yield relative to optimum fruit quality and long-term vine health. The measure of success has usually been in terms of average yield or wine production per hectare. However, this can mask important variations in yield and quality within the vineyard, and their causes (Figs. 4.77 and 4.81).

One of the most significant viticultural developments during the past few years has been the introduction of PV. Its philosophy can be summed up in the old adage:

‘You can’t manage what you can’t measure.’

Central to PV is global positioning (GPS). High-accuracy receivers permit measurements not only of longitude and latitude, but also altitude. From this, slope, aspect, and other pertinent topographic parameters can be derived. These data can be fed directly to mechanical harvesters or other field equipment. The data may also be combined with: information provided from airborne remote sensing equipment (using multispectral imaging) (Hall et al., 2002); improved and automated soil sensing devices (Adamchuk et al., 2004); and/or telemetric vineyard monitoring apparati. These can be simultaneously integrated due to the increasing availability of computing power and appropriate algorithms. These changes are bringing detailed vineyard assessment within the financial reach of an increasing number of grape growers. Resolution with remote sensing devices on low flying aircraft (150 m to 3 km) is currently adequate to assess individual vines, and distinguish between vines and other vineyard features. Multispectral sensors can simultaneously record data from at least four distinct wavelengths (infra-red, red, green, and blue). Sensors that detect up to 18 wavelengths are available. With these devices, the precise vineyard distribution of iron deficiency chlorosis has been assessed (Martín et al., 2007). On-the-go grape assessment systems are also under development that could make spatial fruit assessment during harvesting as easily precise.

These techniques can quantify the spatial distribution of intra-vineyard variation to a degree heretofore thought impossible (Plate 4.23). Although measures of grape quality often differ more among sites and individual vines than between vintages, these variations are often considerably less than differences in yield (Bramley and Lamb, 2003). Yield among individual vines in a vineyard can differ by a factor of 8–10 (Bramley and Hamilton, 2004). Objective assessment of such nonuniformity has spurred a desire to reduce its occurrence, either by selective management of specific sites, or by selective harvesting. Although some attributes may average out on blending, features such as flavor do not. Rarely do under- or over-mature grapes blend to show ‘ideal’ flavor attributes. PV techniques should also provide grape growers with more precise tools for estimating yield and quality.

It has usually been viewed that selective harvesting is only feasible with small lots, and not scalable up to large commercial operations. Bramley et al. (2011b) have demonstrated that with PV, and where market conditions are appropriate, selectively harvesting a vineyard could be to the financial advantage of even large-scale wineries.

Bramley (2005) gives an example of PV, what he terms zonal vineyard management. It employs remote sensing to map variation in vine growth throughout the vineyard. Spatial variation maps are correlated with on-site assessments of grape quality and health, soil, and topographic conditions. The data so derived can be used to direct customized fertilization, irrigation, pruning, salinity adjustment, and pest management. Subsequent assessments can be used to assess the degree to which management adjustments have succeeded in enhancing vineyard uniformity. By reducing the sources of intra-vineyard heterogeneity, average grape quality and synchronous fruit ripening can be enhanced. In addition, savings on improved efficiency of fertilizer, water, pesticide, or other applications are possible. Proffitt and Malcolm (2005) found that improved fruit uniformity was achieved by decreasing irrigation in vigorous regions, and augmenting it in areas with impoverished growth. Not only can this enhance synchronization of berry development, but also reduce costly procedures such as basal-leaf removal. Alternatively, grapes from distinct parcels of a vineyard may be harvested at different times, or separated at harvest. Overall wine quality is partially dependent on grape uniformity. For example, in red grapes the incorporation of immature grapes in the crush is generally viewed as increasing the release of higher amounts of proanthocyanidins from the seeds (Canals et al., 2005). Being highly galloyated (Romeyer et al., 1986), these generate greater bitterness and astringency (Vidal et al., 2003).

Several features are prerequisites for converting zonal vineyard management from an option to standard practice. Under most circumstances, spatial variation in yield and vigor is relatively constant from year to year. Although readily observable features, such as yield and vine vigor, tend to correlate well with important quality features, such as °Brix and phenolic content, other chemical attributes may not. Although critical vineyard factors, such as nutrition, irrigation, and pest management, can be selectively adjusted in an existing vineyard, other attributes such as slope, soil depth, or drainage can be most effectively modified only at inception or replanting. In addition, although underlying factors such a drainage and soil depth remain constant, the influence of these factors can vary, depending on yearly variations in temperature, frost prevalence, or rainfall (Lamb, 2000). Finally, the economic feasibility of zonal vineyard management will depend on several independent factors, including the extent and severity of vineyard variation, the costs of implementing remedial action, the commercial value of the crop, and the demonstration that improved and more uniform grape quality lead to superior wine.

Finally, PV provides spatial knowledge on what features most influence vine growth and fruit quality. Without this knowledge, researchers are forced to use randomized plot designs to statistically predict distribution. Although better than nothing, such procedures can lead to statistically significant but invalid conclusions, if the plots do not accurately represent the actual variability. Despite the value of PV, when looking at vine properties multi-year data should be collected to avoid falsely assuming consistency over time. Data on features such as yearly yield and flavor potential may vary markedly across a vineyard from vintage to vintage (Reynolds et al., 2007).

PV offers grape growers and researchers alike new opportunities to accurately assess the significance of vineyard variables on grape growth and wine quality (Trought and Bramley, 2011). In some instances, it may indicate that viticultural practices, such as the pruning and bud selection, possible with manual pruning, may already be achieving some of the goals of PV (Bramley et al., 2011c).

Despite all the advantages associated with precision viticulture, there are potential risks to uniformity. As monoculture increases the potential for pathogen damage, vineyard uniformity could lead to more severe physiological disruption under unfavorable growth conditions – there would be no part of the vineyard unequally damaged. In addition, grape uniformity also runs the risk of a less complex, less interesting wine-flavor profile. For example, blended wines are often perceived to be of better quality than the individual component wines. As so often is the case, there are both potential advantages and disadvantages to every vineyard and winery option. It is a conundrum that faces every grape grower and winemaker daily, and why winemaking is as much an art as a science.