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This chapter discusses the principles of grapevine dormant pruning, reviews reasons for vine training, and describes systems appropriate for use in North Carolina. Profitable grape production requires that grapevines be managed so that a large area of healthy leaves is exposed to sunlight. Such vines are likely to produce large crops of high-quality fruit each year. Grapevines must be trained and pruned annually to achieve this goal. The training system chosen generally dictates how the vines are pruned. Thus, pruning practices and training systems are discussed together in this chapter.
Grapevines require 16 essential nutrients for normal growth and development (Table 9.1). Carbon, hydrogen, and oxygen are obtained as the roots take in water and as the leaves absorb gases. The remaining nutrients are obtained primarily from the soil. Macronutrients are those used in relatively large quantities by vines; natural macronutrients are often supplemented with applied fertilizers.The micronutrients, although no less essential, are needed in very small quantities. When one or more of these elements is deficient, vines may exhibit foliar deficiency symptoms, reduced growth or crop yield, and greater susceptiblity to winter injury or death. The availability of essential nutrients is therefore critical for optimum vine performance and profitable grape production.
Like other perennial plants, mature grapevines have extensive root systems and therefore, unlike shallow-rooted annual plants, they are fairly tolerant of mild droughts. Nevertheless, a certain amount of moisture is necessary to support growth and development. Lacking sufficient moisture, vines will suffer water stress, which can reduce productivity as well as fruit quality. Supplemental moisture can be provided by permanent (solid-set) or temporary irrigation systems. Drip irrigation has become the standard water delivery system for North Carolina vineyards in recent years. Drip irrigation can represent a substantial investment (see chapter 2 for details), but the benefits can far outweigh the costs in many vineyards. In 2005, it was estimated that drip irrigation would cost $22,743 to purchase and install the equipment required for a 10-acre drip system, or $2,274 per acre. Drip irrigation can be as effective on steep slopes as on rolling and flat surfaces.
Crop prediction or estimation is the process of projecting as accurately as possible the quantity of crop that will be harvested. Why estimate the crop? The most obvious reason is to know how much crop will be present for sale or utilization. Beyond that fundamental reason, it is also important to know whether vines are undercropped or overcropped. In the absence of methodical crop estimations, the experienced grower can rely on past vineyard performance.This approach is subject to error, however, especially in grape regions subject to spring frosts or winter injury, which can greatly affect a vineyard’s productivity from year to year.
Vineyard establishment involves careful planning, thorough site preparation, vineyard design, planting, and trellis construction. Unlike dormant pruning or other annual activities, designing and establishing a vineyard must be done correctly the first time. In addition, the process must be tailored to the particular site and the grower’s intentions. This chapter discusses the basic steps in establishing a vineyard and offers suggestions for practical methods and materials.There are many alternatives. Although this chapter may be used as the sole source of information for vineyard establishment, it is advisable to obtain and compare information from additional sources before beginning. References provided here include more detailed information on particular aspects of vineyard establishment, such as trellis construction. It is also helpful to visit existing vineyards to examine their design, compare trellising materials, and discuss plant and row spacing.
High-quality wines — those that command premium prices — can be produced only from high-quality grapes. Grape quality can be defined in various ways, but ripeness and freedom from rots are two of the chief qualities. Producing ripe fruit with minimum rot and maximum varietal character is not easy in North Carolina. As described elsewhere in this publication, the combination of climate, soils, and vine vigor often leads to excessive vegetative growth. For reasons that will be discussed, luxurious vegetative growth can reduce vine fruitfulness, decrease varietal character, degrade other components of fruit quality, and hamper efforts at disease control. Canopy management practices can help alleviate these problems.