By
Adam Jacobs, Director Vitiwise Pty Ltd
INTRODUCTION
In the Australian Wine Industry, trellis systems have evolved from using single bush vine arrangements to very sophisticated and sometimes complex systems.
A trellised vine is one with an elongated trunk of varying length, with either cordons or canes trained onto a support system (Coombe & Dry, 1992).
Throughout Australia, the mechanisation of vineyards has meant that grapevines are trellised in a fashion that suits operators and management, whilst providing for the necessary canopy to ripen a quality product.
This article aims to indicate 3 relative systems being adopted throughout the Australian Wine Industry and outline some advantages and disadvantages in the adoption of such systems.
While considering these systems, one must take into consideration the following in the decision process of what trellis system to adopt:
1. Vigour which causes shade, resulting in less fruitfulness,
2. Balanced vine growth to potential fruit production and quality,
3. Environmental factors such as temperature, rainfall and soil type which will have a bearing on trellis selection, and
4.
Economic considerations in relation to the total investment and
subsequent management in years to come with the use of labour.
VINE TRELLIS
SYSTEM DISCUSSION
Single wire VSP
This vertical shoot position VSP system is widely adopted throughout Australia. It forms a continuous row of foliage and is relatively inexpensive to develop, compared with divided canopy systems. Vines can be cordon trained and either spur or cane pruning can be adopted, depending on vigour and vine balance.
Foliage wires can be installed (up to 6) to ensure total closure of foliage, however crowding of leaves, canes and fruit can lead to disease issues.
It is extremely well suited to all types of mechanisation, and additionally this system can be adapted to two cordon wires.
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Advantages |
Disadvantages |
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1. Consistent training and management within regions in regard to staff knowledge and adoption practices. 2. Relatively easy to set up. 3. Suited to mechanisation 4. Allows for exposure of fruit. (Although a disadvantage in hot climates due to sunburn) 5. Suited to low vineyard potential sites. |
1. Can cause crowding of fruit. 2. Not suited to over vigorous sites due to disease incidence. (high vineyard potential) 3. Possible poor set due to upward growing shoots. 4.
Rolling of cordons if foliage wires are not applied. |
Scott Henry
System
This system was developed in Oregon, USA by Scott Henry and has been widely adopted in New Zealand, California and lately in some situations in Australia. This system can be spur or cane pruned to suit, while offering an excellent opportunity for canopy spray management due to its upward/downward shape.
It suits mechanisation and allows for a decrease in canopy density. Sugar, acidity and pH (during veraison) can come into balance very quickly with this system and improved yields are evident.
It is particularly advantageous in cooler climates however overcropping can result in lower baumes. Most common varieties are well suited especially cabernet sauvignon and point noir.
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Advantages |
Disadvantages |
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1. Less disease incidence due to open canopy. 2. Higher yields 3. Suited to mechanisation 4. Downward growth is devigourised, assisting the balance equation. 5. More sunlight in canopy. 6. Suited medium vineyard potential sites. |
1. Economically more expensive due to wire construction and vine training than VSP. 2. Labour intensive in relation to folding canes down and lifting up. 3. Can crop too high on vigorous sites, causing late ripening. |
U or Lyre Trellis
The U or Lyre trellis was developed by Carbonneau in France during the 1970s. Its divided nature with cordons spaced at a minimum of 900mm apart allow for sunlight and increased aeration. It has proved to increase yield due to a larger canopy surface area/ha and examples throughout Australia suggest wine quality is also improved.
The inclined walls of foliage are shoot positioned upward and with 2-3 sets of foliage wires on either side, can provide a 1.2m division at the top of the canopy.
This system is ideal for achieving a distinct canopy division and does suit most common wine varieties.
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Advantages |
Disadvantages |
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1. Excellent canopy division. 2. Higher yields and good exposure inside the division. 3. Higher aeration in the division. 4. Easy to hand harvest. 5. Suited to medium vineyard potential sites. |
1. No machine in Australia is available to harvest such a system. Due to lack of personnel to perform hand harvesting in Aust. today this system is disadvantaged. 2. More expensive to develop and train than other systems. 3. More training is required to introduce the system into industry. 4. Not suited to many mechanised tasks. |
Other Systems
Many examples of other systems are featured throughout grapegrowing districts of Australia. For example TK2T ( Kauwhata Two Tier), which was developed in New Zealand by Smart in 1985 to overcome dense canopy problems, experienced with the VSP system. By training vines to 0.4m and 1.2m alternatively, foliage is trained upwards, utilising foliage wires. This system is suited to mechanisation, but one must suggest that there may be grape maturity and yield differences from vines trained at 0.4m and vines at 1.2m due to shading. It is extremely suited to high fertile sites.
The Slyvoz or hanging cane method provides for a varied wine/grape product but has the tendency to increase node numbers, which invariably will alter the vine balance of growth vs fruit production.
The cordon wire height must be sufficiently high at the 1.5m mark to achieve the desired result if allowing canes to hang. This system is suited to warm to hot regions and only requires minimal pruning. Advantages are the increased canopy surface area and increased fruit exposure resulting in increased wine quality.
Bush vine (free standing) is the certainly the oldest and least expensive to set up and manage. They are designed to be kept low to maximise ground heat, which is beneficial in cool climates, and must be spur pruned. The cost of development is offset by the low yield they produce and production does take some 3-4 years to maximise. Systems such as this must be developed on fertile soils as soil moisture is drained quicker due to increased airflow over the exposed canopy. Fruit quality is generally excellent due to the low yields this system produces.
RT2T was developed by Smart and Smith in 1988 in New Zealand and is very suited to high fertile sites (high potential). Vines are trained to high node numbers to assist devigoration and spur pruning is well suited. Consideration should also be given to fruit composition and yield differences between the tiers.
SUMMARY
In deciding on a suitable trellis system one must consider the following factors of vine capacity along with vigour. The vine capacity I refer to is related to root contribution/development of the entire vine and vine growth (vigour) is related to the production rate of its shoots. The simple rule to apply is “A simple trellis system is suited to a vineyard that is deemed to have low capacity or potential and a more complex trellis system for the site that has high capacity or potential”.
The balance of fruit production vs vine growth can be obtained by pruning weights and by referring to the rule that vines producing less than 1kg of pruning weight are more likely to be suited to a simple trellis system (ie single wire). On the contrary, vines that produce excessive vigour (over 1 kg pruning weights), a more extensive trellis system (ie RT2T) is needed to allow for the retention of additional nodes to cause devigoration. The trellis’s ability to accommodate the vine capacity and balance of production vs growth determines the canopy microclimate and associated fruitful characters.
The choice of trellis system comes down to the selection of a suitable system considering the advantages and disadvantages featured and using the above rules relating to site potential, vine capacity and vigour. The ability to mechanise and finally the economic factors relating to budget and labour availability also play an important component in the final deliberation.
Additionally, one cannot underestimate the “cold face” experiences many managers and consultants have had with the various systems featured so consultation would be necessary and advantageous before deciding and investing into a suitable trellis system.
