![]() Machines, such as sprayers, leafers and cane-cutters, work in a linear fashion, and the head-trained vine is not trained in a line. The major disadvantage of this system is that it is not easily managed using machinery, which makes it uneconomical for most operations. It is, however, likely that Zinfandel grown on a different trellis system can match the quality of a head-trained vineyard. Some people swear that this system is the only way to grow Zinfandel and, because of that feeling, a few new Zinfandel vineyards are still being planted in this manner. Such vineyards are frequently non-irrigated. Many older vineyards were planted in this fashion, which allows for planting on a square grid, and cultivation or other cultural practices may be performed in two directions (i.e., cross-wise). Most often, the shoots are allowed to grow without any manipulation, where they droop over and trail on or near the ground. Head-trained vines are trained to a vertical trunk, often without a strong support structure and are usually pruned to spurs that emanate from all directions out of the center. In actuality, a cane-pruned vine that is on a trellis is also head-trained, but the common colloquialism for non-trellised vines is “head-trained.” Australians refer to them as “bush vines,” which is probably a more meaningful descriptor. ![]() In a head-trained vineyard, vines are not trained onto a trellis but are left to be on their own (not connected to other vines by a trellis system). Though pretty, head training makes mechanizing vineyard tasks difficult I like to think of three basic categories with regard to their canopy structure: head-trained, non-divided and divided vine canopies. I will instead discuss the systems in general terms. I have found that the topic is well covered in Freeman et al., 1988 1. There is no need to cover all of the trellis types and training systems out there. ![]() But those systems do not always perform well in warmer growing regions where they may be completely inappropriate. The goal of much trellis development has been to maximize the leaf area to capture more sun energy and increase productivity in regions that experience short seasons (due to late spring and early fall frosts). Many of the trellis systems developed in the last few decades have come from universities and growers in cool-climate grape growing regions (e.g., New Zealand, New York, Oregon and some regions of France). Coupled with numerous training and pruning styles (most generally divided into either cane or spur-pruning, or hybrids of both), the number of permutations of trellis, training and pruning systems is mind-boggling. Over the years, there have been countless variations on trellis system designs. Trellis systems were developed to channel the grapevine’s natural tendency to grow upon other structures into a form that serves our purposes for improving both vineyard productivity and wine quality. If a grapevine had its way, it would: (a) not be grafted onto some strange rootstock of a different species mix, (b) not be grown on some shattered rock hillside nor in the middle of the desert, (c) have its fruit eaten by birds or deer rather than being shipped across the county or state to some processing plant, and (d) rather grow up the side of a tree than up a steel stake and thin wire.
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