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Grape Production in New York
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A short presentation which discusses a topic about which several books have been written must necessarily be brief. My goal is to remind you about factors which should be considered when choosing a training system and briefly discuss them in relation to varieties and growing conditions found in New York.
Although, by tradition, we in New York refer to training systems by name, they can also be more logically classified. Classifications include the nature of the renewal zone (that area where the buds which will produce next year's crop are formed), the extent of permanent wood (trunks and cordons), the type of bearing unit, the height, and the extent of canopy division.
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| Figure 1. Training systems used in New York state |
The renewal zone may be diffuse (Modified Keuka High Renewal) or discrete (Mid-wire cordon). It may be at the top of the canopy (Umbrella Kniffin or HRU), at the bottom (Pendlebogen), or in the vine interior (Mid-wire cordon). The location of the renewal zone affects the extent to which shading is important. Buds which develop in shaded renewal zones are reduced in fruitfulness, and because fruit is usually located at the same place, fruit is also often also shaded with the same training systems.
The amount and nature of the permanent wood (trunks and cordons) affects both cost and fruiting. Cordons are horizontal trunks (HRU). They cost more to establish, but are more permanent (except with cold tender varieties), and can make the job of pruning more simple to visualize. They also offer more space to distribute bearing units, and so can reduce canopy crowding. With cordons the vine canopy in the row becomes continuous, helping to reduce canopy gaps and increase light interception. When cordons are not used, the bearing units arise from one or more discrete heads (Umbrella Kniffin, 6-Arm Kniffin). Usually head training requires very close vine spacing or the use of long canes to ensure reasonable canopy leaf fill.
The bearing units are either spurs or canes. A spur is a short (less than 4 node) cane. Because they allow the space between vines to be filled with leaf bearing shoots, canes are usually used with head training. With most training systems cane pruning is more expensive, because the canes must be tied into place. However, with varieties with a procumbent growth habit and a high renewal zone (HRU), hanging canes which do not require tying can be used. With large vines, it is often difficult for light to penetrate to the basal nodes of the shoots which will be used for canes or spurs the next year. In many cases this results in wood which is not suitable for spur pruning. However, because the nodes farther out on the same shoots get more illumination, theywill form productive canes. Thus cane pruning has been used as a way to combat shade effects.
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| Figure 2. Effect of row spacing on hours of the day when direct sunlight is not intercepted by a leaf canopy. Note that wide rows and narrow canopies are not efficient at intercepting light during mid-day hours. Note that wide row spacing encourages vine vigor by providing a greater root volume to support vegetative growth. |
Renewal zone and trellis height are both important. Wide row spacing requires tall canopies to ensure reasonable light interception. Practical considerations restrict canopies to about 6 feet high. Theoretical considerations suggest that a 6 foot high canopies should be spaced 5-6 feet apart to ensure that light is not wasted (Figure 2), but standard equipment limits minimal row spacing to about 9 feet.
When vine growth is very vigorous, or when rows are widely spaced, canopy shading can be very important. One way to reduce canopy density and to increase light interception is to use a divided canopy (GDC, Lyre). Divided canopies mimic the canopy distribution obtained with narrow rows, but allow machine access provided by wide trunk spacing. Divided canopies are more expensive to install, but the increased yield or fruit quality (from improved light distribution) can compensate for the increased cost. Divided canopies require vigorous vines to fill the trellis, but they also provide a solution when standard training results in excessive vigor and canopy density.
Variety is the most important factor to consider when thinking about a training system. Essentially we grow three kinds of wine grapes in New York: Native American, French-American hybrids and vinifera. Each class has very important characteristics which influence training system choice. Native American varieties have procumbent growth habits which dictate a high renewal zone. Their bud development is very sensitive to shade, so there is a need for an extensive, diffuse canopy system such as obtained with HRU. With conventional pruning, special treatment such as shoot positioning may be required to obtain sufficient illumination of the renewal zone.
French American varieties have very fruitful buds and a tendency to produce fruit from base buds (which arise at the base of a cane). Their growth habit is variable, but shoot growth is usually more erect than with the Native American varieties. The solutions to the problems with French-American hybrids tendencies are often in conflict making the training system choice for French-American hybrids difficult.
Vinifera varieties tend to have upright to very erect growth habits. As a class they are winter tender which makes it difficult to produce long lived trunks. As a result cordon training is generally not suitable except where cold injury is rare (such as Long Island).
Varieties with erect growth habits lend themselves to systems with lower renewal zones such as mid-wire cordon or pendlebogen. Varieties with procumbent habits should have a high renewal zone.
Crop control is easier with varieties with fruitful base buds when there are fewer sites for base bud retention. Cordons have many sites where base buds are retained, and these greatly increase the number of clusters produced at a given pruning level. In one study, we found that 60% of the crop of DeChaunac originated from base buds.
Another factor to consider is cluster weight. Traditional spur pruning generally retains fewer
nodes per vine than cane pruning. Thus spur pruning is useful for varieties with high crop weight production per retained node, and cane pruning is used for shy bearing varieties with small cluster weight.
Fruit and the buds in the renewal zone tend to be produced in the same place. Shaded renewal zones also tend affect the micro-climate of the fruit zone. Dense canopies restrict air flow, increase drying time and interfere with spray penetration. For varieties which are sensitive to bunch rot, such conditions can spell disaster. This is the reason that the most valuable fruit is often Pendlebogen trained. When pendlebogen trained vines are vertically shoot positioned, summer pruned and given leaf removal treatment, their fruiting zones become very well ventilated. Such procedures are costly, but can substantially reduce fruit infection. Cheaper alternatives such as Umbrella Kniffin are compromises where fruit crowding is avoided by distributing the clusters widely over the trellis, and are suitable for moderately valued fruit.
Vine and row spacing will affect the vine size and thus affect training system choice. Closer row spacing tends to decrease individual vine size by reducing root volume per vine. Very close rows may dictate vertical training. Vine canopy density tends to be decreased as in-row vine spacing increases. However, very wide in-row spacing will dictate a cordon training system in order to ensure the space between canopies is filled with leaves.
The value of the crop will dictate how many inputs the grower can afford to put into his vineyard. Economic pressures are leading more and more people to adopt machine pruning. Machine pruning systems are best adapted to cordon training which tends to enhance canopy uniformity along the row. Mid-wire cordons work well with close hedging of fruitful varieties, and top wire cordons are more useful for Native American varieties.
Ultimately the training system must be matched to the vine vigor. Training system will have little impact on the open canopy found with low vigor vines. However, these vines will also be low yielding. Most often the goal is intermediate vigor, but as vigor increases training system will have a greater and greater impact on canopy density, yield and quality. Very high vigor vines may require canopy division to prevent excessive canopy density.
The primary strategy for growing cold tender grape varieties in New York is the use of spare parts so that cold damage can be tolerated. Because both trunks and buds can be winter injured, the attempt is to provide an excess of both, and adjust the final crop only after spring growth signals winter survival. Thus training systems which are costly to establish such as high wire cordons and GDC should be avoided. It is easier to distribute and rapidly adjust the crop when many short trunks are utilized and when cane pruning is done. Thus the majority of cold tender grapes are produced on a low head, cane pruned system such as pendlebogen. This system requires intense management, and the alternative, Umbrella Kniffin is often more suitable for lower value fruit.
The winter of 1993/94 was one of the coldest on record in the Finger Lakes. Temperatures in our experimental plantings reached -16°F on more than one occasion in January, 1994. Table 1 shows winter survival of young Chardonnay vines trained to 7 different systems. Lowest bud kill was associated with highly managed systems, but maximum return yield was from Lyre training. It appears the high yield was not only due to well matured, winter hardy canes, but also to the very large number of buds available to survive the winter. The low cost mid-wire cordon system produced quite substantial yields, but we will have to replace all of these cordons over the next few growing seasons.
© Copyright 2000 Robert Pool
