Systems (GIS) to help organize the data into a useful form and plan out blocks, is increasingly common (Smith, 2002).
Being thorough and methodical in investigating a site is vitally important, but predicting its potential to produce quality grapes, even with the increased level of knowledge and experience available today, is still quite difficult.
However, it is worth this effort to try to get it right since, once the vineyard is planted, alterations to many aspects of production become almost impossible.
It is helpful to remember that management inputs can overcome many deficiencies a vineyard may have, but this may result in decreased fruit quality or increased site costs through the life of the vineyard.
At the end of all this, there are two questions to answer: (i) are there one or more factors associated with the site that will prevent it from growing the grapes the market needs? (ii) if so, then what grapes could be grown, how best should they be managed and will it be economic?
The alternative is to investigate another site. However, if the site is appropriate, then it is time to move to the next stage of development, determining how the site will be planted out.
However, east⫺west-running rows can be beneficial in raisin production, for example, for if the grapes are to be dried in between the rows, they obtain sun exposure for most of the day. In some cases, rows will run along the contour of a hill, to minimize erosion or facilitate use of machinery (see Fig. 5.3). Row orientation can also be changed to account for site-specific factors, such as in areas with more rainfall, running the rows in a direction that enhances morning sun exposure in the canopy to help dry out the fruit. Likewise, maximizing canopy exposure in the mornings rather than in the afternoons can be beneficial, as the latter tend to be hotter. This can be an advantage in a climate that is a bit too hot for the variety being produced, as it lowers fruit temperature and modifies the development of flavour and aroma compounds.
Preparing the site
Prior to planting, you may need to clear the land. If possible, do this in the season before you intend to plant and establish a cover crop in the meantime (see Fig. 5.4). This may help to reduce pest (e.g. nematode) and disease (e.g.
root rot) populations and, in particular, will allow the control of problem weeds before the vines are established (e.g. cultivation and herbicide use in the season before planting will reduce weed seed populations (Brenchley and Warington, 1933; Schreiber, 1992)). If the land has been used for other crops, it is worth checking to see whether there could be carry-over effects from those to
Fig. 5.3. An example of a vineyard where the rows are contoured along the hillside instead of running straight.
grapevines. In some cases, microorganisms or their products build up in the soil and can hinder the establishment of the vines (Westphal et al., 2002). This is also the stage to make any soil changes, such as ripping, terracing, adjusting nutrients or pH, etc. or to improve drainage through the laying of tiles.
If a source of water is needed at the site, then a well should be dug to ensure water supply before plans are finalized. If the yield of the well is below expectations, then a redesign of the vineyard may be necessary to accommodate it (e.g. incorporation of a storage pond, change to rootstock choice or a reduction in the number of vines grown). If water is necessary for grape production in an area under consideration, then purchase of the land should be conditional on the availability of water.
Shelter from wind
If the area where the vineyard is to be established has high winds, it is worth considering establishment of windbreaks (see Fig. 5.5). Compared with vines growing without protection from the wind, those sheltered by windbreaks exhibit (i) better budburst; (ii) larger leaves with more stomata; (iii) more clusters per shoot; (iv) longer internodes and longer shoots; (v) higher pruning weights; (vi) increased capacity to carry and ripen a crop; (vii) increasing Fig. 5.4. Mixed plants on a future vineyard site. Planting a cover crop prior to vineyard establishment can decrease weed problems in subsequent years, modify soil nutrients and structure and, in some cases, provide an interim cash crop.
phenolic content in the fruit (Lomkatsi et al., 1983; Dry et al., 1989; Bettiga et al., 1996; Smart, 1999; Neel, 2000).
Sheltered vines are also less susceptible to damage caused by whipping of the shoots and breakage (usually snapped off at the base early in the season).
Sometimes loss of shoots can result in a potential 10⫺15% loss of productivity (P. Evans, New Zealand, 2000, personal communication). Studies that have compared the productivity of sheltered versus non-sheltered vines tend to show around a 15% increase in yields (Lomkatsi et al., 1983; Bettiga et al., 1996). One South Australian study (Dry et al., 1989) suggested that yield gains are from increases in flower cluster number rather than from percentage fruit set or berry size, although gains in percentage fruit set could be envisaged in other situations.
Ideally, a windbreak is permeable to the wind so that the air moves both through and over the top of the obstacle (Cleugh, 1998). This slows the speed of the air in the vineyard and also provides protection from the fastest air, which is shunted over the shelter. The latter is provided for a distance of up to 20 times the height of the windbreak (Marshall, 1967), so windbreaks need to be high enough to justify the area of land that they take up. However, with their use comes competition with grapevines for water, nutrients (Cleugh, 1998) and even sunlight due to shading, especially at latitudes closer to the poles (Abelet al., 1997).
Fig. 5.5. A living windbreak in Canterbury, New Zealand. In this case, the trees in use are poplars. Another effect of windbreaks is evident here, too: the vines closest to the trees are noticeably smaller than the ones further in due to the trees
competing for light, water and nutrients.
Windbreaks can be made of artifical woven nets, but more often they are grown. Judicious use of windbreaks can help in areas that are frost prone by preventing cold air from moving into a vineyard area from above (deflecting it away), though this precludes the use of deciduous plants in their make-up.
However, deciduous tree shelters better allow cold air movement through them in the dormant season, which can be helpful in frost-prone areas as well.
Windbreaks do require extra effort and cost to establish and maintain, take up land area that could be used to grow grapes and also can be a nesting site for pest bird species; however, in certain areas these drawbacks are countered by increased production and greater vine productivity.
Vine planting density
One of the early decisions that will need to be made in planting a vineyard is: at what density will the vines be planted? Across the world there is the whole gamut of spacings, from very high density, e.g. 1 m between vines and 1.1 m between rows (for example, Château Lafon-Rochet, Saint Estèphe, France has a planting density of 9000 vines/ha, which works out to this spacing) to low density 3 ⫻3 m systems (1100 vines/ha) or even greater spacings for some dry-land vineyards. How is the vine spacing determined?
In earlier times, vine spacing was determined by who, or what, was going to be working the soil and the vines. In days when people did all the work, it is said that vines were planted at densities that equated to tens of thousands of vines per hectare. Later, when animals began to be used for tilling the soil, between-row spacings were determined by how wide the animals were. More recently, especially in the New World areas, vine spacing has been determined by the width of machinery that was available to work the soil and plants (see Fig. 5.6), which were generally large-scale agronomic crops.
Another factor involved is the availability and value of the land. In Europe, land was in short supply given the number of people it needed to support, hence it was used intensively (a higher plant density means greater productivity per unit area). When people moved to the New World land was in abundant supply, so wider row spacings were seen as being convenient.
From the point of view of the vine, however, things are a bit different. In establishing the vineyard, row spacing should be determined by the predicted vigour of the site. In an area where there are no existing vines, this can be nothing more than an educated guess, which can sometimes lead to those guesses being wrong. The notion went that as the predicted vigour went up, so did the planting densities. The thought behind this was that, as the number of vines per unit area increase, the resources available to each vine (e.g. water, nutrients) decrease, thus leading to less vigorous vines.
This appeared to work in the Old World areas, such as practised in many Grand Cru vineyards, and so was emulated in many other, newer, grape-
growing areas. However, the result in these new areas was sometimes very different, in that the vines remained very vigorous, and eventually declined into vinous messes producing poor-quality fruit. It is thought that this was caused by the different soils that are typical in many of the newer areas, in that they tend to be more nutrient rich than the farmed-for-centuries soils in the Old World and, in many cases, the soils are much deeper, leading to luxury levels of water and nutrients being available to the vines.
So the high vine density to combat vine vigour hypothesis proves not to be a rule, and brings us back to the question of how to determine planting density.
One of the current theories is that between-row spacing should be determined by the availability of equipment used to work the vineyard, and within-row vine spacing is the tool to really influence vine vigor. Closer vine rows result in more efficient use of the land area (meaning that if vines are cropped to the same level per unit of vine row, the total tonnage of fruit per unit of land for a narrow row-spacing vineyard is greater than that from a wide row-spacing vineyard), so the goal should be to have the closest row spacing that is still compatible with the equipment.
Fig. 5.6. An example of a vineyard with wide row spacing, necessitated by the desire to use large machinery. Here, weeds are being controlled with an in-row mechanical hoe.
Within-row vine spacing will vary depending on the predicted vigour of the site (and rootstock/ cultivar combination) and how it’s managed. Again, there are many different vine spacings used in practice, and there will be no one spacing that is ideal for any given situation.
For most vineyards using discreet rows of canopies, row spacing will approximate a 1:1 ratio with canopy height, which ensures that between-row shading is minimized. Figure 5.7 demonstrates one of the problems with close, but tall, rows. Therefore, if the vineyard has very close row spacing, the canopy height must be low to prevent between-row shading, and so the height of the fruiting wire must be low, too. Working with low fruiting wires has challenges in terms of equipment and labour, as the vines are so close to the ground working with them is very difficult. Row spacing is also influenced by trellis type used, with divided canopy systems requiring wider rows.
Fig. 5.7. Vineyard with close row spacing, but high fruiting wires and therefore tall canopies. Self-shading here is limiting the productivity of the vines as well as having a negative effect on fruit composition.