There has been considerable debate in viticultural circles about the best way to get the vines established and on to the trellising system. One of the basic decisions to be made is whether or not to train up the vines in the first year. The sprawling method (see Fig. 5.11) allows the vines to grow wherever they like on the ground, and little is done to them in the first season, aside from sprays to control disease. The advantages of this may be increased photosynthetic productivity of the vines compared with those trained up and with a single shoot, as the leaf area is greater in the former case. This is beneficial as the vine has more carbohydrates available, which means more shoot and root growth.
Also, the trellising system does not have to be installed before planting, which creates less work in pre-planting preparations and increased flexibility in moving about the vineyard (e.g. for cross-cultivation). The downsides are that it is nearly impossible to control weeds when they are intermingled with the Fig. 5.10. An augered hole for planting a vine. Note the friable sides of the hole, which will allow vine roots to grow unhindered.
grapes, disease control can be problematic and the quality of canes produced may not be as great (e.g. possibly not as straight or as long as vines trained upward). To counter the weed problem some have used polythene, which controls the weeds and has the additional benefit of conserving moisture for use by the vine (see Plate 25). However, disposal of the plastic in later years can also be a problem.
The alternative to allowing the vines to sprawl is to train them up. This can be achieved through the use of individual stakes for each vine, or installation of end assemblies (or at least end posts), the fruiting wire and a fraction of the total number of intermediate posts, providing something to tie or secure other vine support to. Training the vines up is thought to be beneficial because the vine grows more quickly upward than downward (Kliewer et al., 1989;
Schubert et al., 1999) and it allows the vine to be trained to the fruiting wire in the first season (if growth is sufficient). The downsides are that the vine may not have the same carbohydrate production as vines that are allowed to sprawl and, since they are up to the wire in the first year, there could be the temptation to leave a crop on the vines in the second year, which may have consequences to the health of the vine (see Chapter 3).
In addition, there are numerous ways to help the vines grow up to the wire and reduce some management requirements. Vines can be individually staked Fig. 5.11. A recently established vineyard showing the vines without any supports, leading to a sprawling growth habit.
or string can be tied from the vine (some part of the vine that will not have any growth distal to it, to prevent girdling of the cane/shoot) to the fruiting wire. In either case, it will be necessary to fasten the vines to the stake or string to ensure the shoots grow upwards, which is a materials and labour requirement.
Vine shelters
The use of vine shelters has increased manyfold in recent years. These range from short plastic or cardboard sleeves (in the latter instance, empty milk cartons have been used), to narrow tubes of some kind, usually made of plastic, that are slipped over or wrapped around the vines (see Plate 26).
Simple plastic or waxed cardboard sleeves (e.g. milk cartons), perhaps 30 cm tall, are commonly used and are effective at protecting the vine from herbicide and perhaps some rodent damage. They are inexpensive, but do not provide all the advantages of using taller structures.
Taller plastic sleeves, ideally rigid, encourage shoots to grow up and straight to the wire, provide protection against herbicides and herbivory of the young plants, but also increase the rate of growth of vines so that they reach the trellis wire more quickly. The environment inside the structure is warmer and more humid, and also protected against the effects of wind (Wample et al., 2000). Warmer temperatures increase the growth rate in the spring, when average air temperatures tend to be cooler. The greater humidity and reduced air movement places less water stress on the vines, allowing them to grow unhindered. The rigid shelters also guide shoot growth upward, meaning there is no training needed and reduced water use by the vines.
Disadvantages of shelters in general include their cost to purchase and apply, difficulty in controlling disease inside them and in accessing the vine (e.g. for shoot-thinning and watershoot removal), and possibly increased damage during frost events (although some have observed that the vines are protected against a frost). As well, the shoots that develop within the tube are often noted to be thinner, which some perceive as a weakness in the vine.
Disadvantages of using tall, rigid shelters include (i) their cost (although they can be used on more than one set of vines); (ii) the extra labour required to open and close them again when working on the trunks; (iii) the possibility of temperatures exceeding damage thresholds on hot and sunny days; (iv) the requirement of the presence of a fruiting wire or stake to steady the sleeve; and (v) perhaps more spindly growth inside the shelter (Due, 1990; Wample et al., 2000; Olmstead and Tarara, 2001).
Regardless of the method of training used, it is important to train the vines to have a straight trunk. This improves the load-bearing capacity of the vine (thus reducing the load on the trellising system) and ensures that mechanization is more readily brought into the vineyard.
Young vine care
The goal for establishing young vines is to maximize vegetative growth, which includes the growth of the root system. To enhance this, the irrigation and weed management programmes should maximize water availability and minimize weed competition. Many newly planted vineyards will have bare ground to avoid competition from weeds, and soil moisture monitoring should be practised to keep water readily available to the vines in the volume of soil where their roots are positioned (i.e. shallow in the soil profile). Diseases should be monitored and controlled as needed.
Young vine trunks need protection from herbicide sprays because, not only will green tissue take them up, but the thin bark on the canes will also be able to absorb the chemicals. Hence the use of vine guards of some sort is desirable.
Any vines that do not survive should be identified quickly and replaced after a likely cause for their death has been determined. For example, if the irrigation emitter was faulty, it should be replaced before the new vine is planted. To attain maximum vineyard uniformity, it is best to replant failed vines as soon as possible in the same year, as long as the vines will be able to grow enough to survive the dormant season. Extra vines can be planted in between others at the ends of rows and used for replanting. This ensures the replants are as strong as the neighbouring vines when repositioned.
The strongest-looking shoot should be retained, eventually to form the trunk of the vine. This is done to focus the energy of the plant into a single shoot, ensuring that it grows as much as possible in both length and girth.
When the vines reach the fruiting wire there are the options of training the growing tip along the fruiting wire in one direction or cutting off the shoot tip above the wire, allowing lateral shoots to be trained along the wire in both directions. This sets the vine up for development of the head later on, during pruning.
During the first dormant season, vines should be pruned back to a point that is relative to their growth in the previous season. If the vines have grown a lot, several to many nodes may be left on the vine but, if it has only just grown past the fruiting wire, it may be pruned to just above the wire with the cane tied straight against the wire. It is important when tying vines to remember not to bind them in such a way that later growth will be girdled (see Fig. 5.12).
If vines have not grown much at all, it may be best to prune them back to the most distal and viable bud and tie them with string up to the fruiting wire or against a stake (see Fig. 5.13) or, if in a tall vine shelter, left on its own. This ensures that the next season’s growth will start from as close to the wire as possible.
Vines that have been left to sprawl in the first season should have their strongest healthy shoot retained and tied up to the wire as already described.
If vines have grown well and already have been wrapped on the fruiting wire, it may be a good time to disbud the trunks. If this procedure is done well, it will
Fig. 5.12. It is important to tie canes distal to the last node, to prevent girdling in the subsequent growing season. Note that the end node has been cut through diagonally so that the bud has been removed, but there is still part of the node (and tendril in this case) there to prevent the tie from slipping off. The topmost bud that will grow in the following season is just below the fruiting wire.
only need to be done once ⫺for the life of the vineyard. Figure 5.14 shows how this is done ⫺all of the bud must be removed from the cane/trunk to prevent leaving any latent buds in the wood. Please note, however, that once a bud has been removed in this fashion, it will never form another shoot from there: the viticulturist must be certain that it will never be needed in the future. A general rule of thumb is to leave three to four buds below the fruiting wire so that, if the vine head needs to be re-established, there will be a source of shoots to do it. In climates with very cold winter temperatures, buds should be left at the base of the vine to be able to train new trunks, should there be frost damage.
Second season
In most cases, the management goal for the second season is the same as the first: to maximize vegetative growth, including growth of the root system. To
ensure this, any fruit that the vine may set should be removed as soon as possible. The easiest time to do this is early in shoot development, when the flower clusters are easily seen and flicked off quickly by hand. In the case of tall trellising systems, a second year of growth may be needed to establish the vines on the trellis (see Fig. 5.15).
In certain environments, it may be possible for the vines to carry a small crop in their second year of growth. Usually, this would be in warm climates where the vines had made a lot of growth in the previous season and there was ample development of both shoots and roots. In areas where this is not possible, carrying a crop will be a drain on the vine, resulting in poor vine performance in future seasons.
In addition, it is important to replant any vines that haven’t survived as soon as possible, again, to ensure that there is as little developmental difference between them and the more established vines.
Fig. 5.13. Upward growth that young vines make during the season should be preserved by leaving the topmost viable bud so that the shoot will reach the fruiting wire as soon as possible. Here, the vine is tied to a stake, which is tied to the fruiting wire at the top.
Fig. 5.14. Disbudding young vine trunks. Secateurs are used to cut the entire bud out of the nodes along the lower part of the trunk. This prevents future, and unwanted, shoot development.
Fig. 5.15. Second-year ‘Pinot gris’ vines growing up to be established on a divided- canopy trellising system.
What looks like the beginnings of a proper canopy may appear in the second season, which ensures that the plants are investing lots of carbohydrate energy into the vegetative parts of the vine.
Irrigation and disease and weed control are still important in this year.
Powdery mildew can easily appear on young vines as they grow rapidly, and maintaining adequate fungicide coverage can be difficult. Any disease on the vines will reduce the amount of energy they can invest in other parts of the vine structure and will have an impact on future vine performance, so therefore should be controlled.
By the time the second dormant season comes around, vine pruning will take a lot more time than in the first. Strong canes should be trained along the wire. The number of nodes left on the vines should depend on, and be proportional to, the amount of growth the vines have put on in the past season:
larger vines should have more nodes left on them than smaller ones.
Disbudding of the trunks should also proceed on vines as they grow large enough for removal of buds to be performed safely.
In instances of less vigorous growth, canes can be cut back to just above the wire and tied for a straight trunk and weaker vines similarly treated as for the first year. Spot fertilization or investigating why these vines have done poorly is worthwhile to ensure they catch up with their neighbours.
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© G.L. Creasy and L.L. Creasy 2009. Grapes(Creasy and Creasy) 105