The wine grape industry, like all of agriculture, is under intensifying pressure from outside. Increasingly, regulators, retailers, consumers, environmentalists, and others are weighing in on how we conduct our businesses. While most are well intended, many are ignorant about the true nature, complexity, and requirements of our work and the risks involved. At the same time, the demands of our work keep us so close to it and overwhelmed with details that we tend to lose sight of its fundamentals. Even so, if we are to effectively defend our noble grape growing endeavor, we need to understand them and be ready to state them. In this article, we will examine the most basic elements of grape growing, posing some of seemingly simple questions and then attempting to provide concise answers to them.
What are grapevines? They are perennial woody plants that go dormant during the winter, have a climbing shoot growth habit and extensive, low density root systems, and set large numbers of fruit in clusters (fig 1).
The particular vines we farm (Vitis vinifera) are not native to California and its environments, but originated in Europe. Similarly, many pests of vines in California are non-native.
What are vineyards? They are populations of grapevines aligned in a regular pattern and trained, trellised, and pruned into a specific form to facilitate sunlight interception, grape production, and vineyard operations (fig. 2). The regularity of a vineyard design gives order to grape growing enterprises. In addition, optimal vineyard designs make the most of on-site resources, are adapted to the varieties particular growth habit, and limit the need for applied inputs to grow balanced amounts of fruit and foliage, optimize fruit exposure, and achieve moderate water stress during years of average rainfall. Before moving on, it is important to note that the number and diversity of organisms other than vines is limited within commercial vineyards.
What is a vineyard setting? It is earth, atmosphere, sunlight, organisms other than grapevines, and the interactions between them that form a habitat that is more or less suitable for grapevines (fig. 3). These elements of a vineyards setting involve a multitude of processes, many of which are cyclic. They involve physical, chemical, and biological factors, and they vary in duration and effect. Some cycles are annual, resulting from the earth’s orbit around the sun and the simultaneous change in day length. The four seasons, including our typically wet winters and dry summers, are the best known annual cycle, but seasonal grapevine development (phenology) is also synchronized with it. Other cycles are multi-year, like our recent drought. The phases of the moon, which are approximately monthly, effect some cycles, including the reproductive cycles of some insects that reside in vineyards. The rotation of the earth is the driver of diurnal cycles, including the rise and fall of vineyard evapotranspiration with day and night, respectively. Other cycles are more or less on going, but accelerated when conditions are favorable. These include mineral nutrient cycles within vineyards, like the nitrogen, phosphorus, and sulfur cycles. Obviously, a vineyard setting is very complex and our ability to influence events within it is limited. Moreover, vineyard settings vary widely due to differences in climate and soil, which compounds our efforts to understand and manage vineyards.
What is vineyard management? Before answering this question, let’s consider some challenges implicit in the answers to previous three questions. First, vineyards are inherently unstable agro-ecosystems because unlike natural ecosystems, they consist of foreign plants with a low species diversity background. As a result, without consistent management inputs, vineyards rapidly degrade into chaotic, pest and disease infested patches of stressed, low vigor, and low productivity vines (fig 4).
Second, vineyards are linear, as are many of our management decisions and actions, but the nature of vineyard settings is transient and curved like circles or sine waves. Put in other terms, without a concerted effort, farming grapes can be similar to attempting to fit a square peg into a round hole. So, going back to the question posed at the beginning of this paragraph, the answer is as follows. Vineyard management is a series of actions timed to natural events and designed to enhance and stabilize vineyard agro-ecosystems and to efficiently direct vine growth and development for sustained profitable yields of high quality fruit throughout a vineyards life.
Returning now to those critical of wine grape growers. They may benefit from spending a few growing seasons in our shoes. If they did, they would grow to appreciate the resource, environment, and market risks under which we operate. They would also learn that their assumptions about grapevines and vineyards are likely too simple and too linear. For neither vines nor vineyards operate in the straightforward manner of cause and effect, but rather in one of dynamic complexity. Further, they would find that wine grape growing is not a natural enterprise even though its foundation resides in nature. Rather, it is a man-made endeavor that provides many societal and ecological benefits, and whose products have enriched the lives of generations since antiquity. Moreover, they would discover that not all farming doctrines and options are equally effective. So, rather than assessing our vineyard management practices by materials and philosophy (e.g. organic and biodynamic), we hope that they will judge us by our efforts to make the most of on-site resources, optimize the efficiency of applied resources, minimize the impacts of off-site side effects, contribute to our communities, and provide quality products to winery customers and through them, wine consumers.
This article is a reproduction of the Mid Valley Agricultural Services January 2015 Viticulture Newsletter.
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