Working the Land (Viticulture)
Viticulture can best be defined as growing grapes for the purpose of making wine. There are other factors in the equation of producing quality wine, including the winemaker’s skill. However, just as a top chef relies on the best ingredients to make a great meal, so too the quality of any wine is largely determined by the quality of the grapes that go into it.
In California many of the most important recent advances in viticulture have taken place during the last three decades in the aftermath of phylloxera in the 1980s and early 1990s. In fact, a new term called “winegrowing” has been coined to reflect the symbiosis between the vineyard and the winery.
The Annual Life Cycle of the Vine in California
The annual cycle of the vine begins with bud break in the spring. Once the ambient temperature reaches 50°F/10°C in late February or early March, the vines emerge from dormancy and start to weep watery sap from the canes which have been pruned over the winter. The root systems of the vines start to uptake minerals.
Budbreak occurs within weeks, in late March or early April when the first leaves start to break through buds left from pruning. Pruning for spring growth continues and the vines are vulnerable to frost. If frost develops overnight, it can be tackled using sprinklers or fans, circulating warmer air through the vineyard.
After budbreak the vines quickly start to develop shoots and leaves that will be the new season’s growth. Tiny embryo clusters form which will in time become grape clusters. Sulphur, an approved organic material, might be applied at this time, along with the use of Integrated Pest Management techniques for natural pest control. Fertilizers, such as compost, may also be used.
Depending on location and climate, the tiny embryo bunches bloom six to thirteen weeks after budbreak. During flowering the vines begin to self-pollinate, a process that will result in grape clusters, or fruit set. At this time the vines are also susceptible to damage from cold, wet, and windy conditions. Frost is still the greatest hazard.
Grape clusters develop out of embryo bunches that have been pollinated. The individual green berries grow larger with high levels of acidity and low grape sugar. Some berries fail to pollinate and never ripen. Spraying, summer pruning, and weeding continue in the vineyard.
In August veraison begins with the grapes starting to soften and change color from green to yellow or red. The sugar content increases as the grapes ripen while overall acidity level decreases. However, with some varieties like Zinfandel, the clusters of grapes do not ripen evenly. Along with veraison, the canes and stems start to accumulate carbohydrates for the winter months. During this time spraying and weeding in the vineyard continues, as well as leaf-pulling and canopy management.
Harvest begins after the grapes have reached a desired balance of sugar and acid. The timing of harvest ranges from early August for sparkling winegrapes to October (even November) for late-harvest wines. With the exception of dessert wine production, white grapes are harvested first with red grapes later in the season. Harvest is either done by hand or machine. Hand-harvesting is labor-intensive and costly. Machine harvesting is commonly used unless the topography of the vineyard prohibits it.
After harvest the vines lose their leaves as cold weather sets in during the late fall. Eventually, the cold will cause the sap in the vines to retreat back into the roots. The canes then harden which is called passerillage. Grapes used for ice wine are harvested by hand with the first hard freeze. Winter pruning begins and will continue into the new year and the new season.
The Basics of Viticulture: Vine Needs
These factors remain fairly similar year to year. Daily variations account for weather patterns, which can create vintage variation over the course of an entire growing season. The terms macroclimate, mesoclimate, and microclimate are further used to specify climate and viticulture.
The overall climate of a region which is usually a large geographic area. For example, the microclimate of much of coastal California is Mediterranean.
Refers to the climate of a particular place such as a specific vineyard site.
Refers to the specific conditions in a smaller section of a vineyard, even rows of vines.
Is a necessary part of the equation for viticulture. Sunlight is needed for photosynthesis and to help ripen grapes. Grape vines need an average of 1,300 hours of sunshine during the growing season.
Grape vines need an ambient soil temperature of 50°F/10°C to be able to transport minerals and water from the soil to all parts of the vine. Vines also require air temperatures between 50°F/10°C and 68°F/28°C to grow. Red grapes require warmer temperatures to ripen, generally in the 70°F/21°C range. These temperature requirements place vitis vinifera vineyards between 30° and 50° latitude in both northern and southern hemispheres. Even in California’s cooler coastal climates, these temperature requirements are met.
The Winkler Scale
Is a system of using temperature to classify wine regions in California. It was developed at the University of California, Davis by A.J. Winkler and Maynard Amerine. The system attempts to help vineyard owners and wineries match certain grape varieties to their optimum growing regions in regards to climate. The scale uses the California Heat Summation Index to divide California’s wine regions into five regions, ranging from coolest on average to the warmest. In the system, the days in each month during the growing season—April 1 through October 31—are multiplied by the mean number of degrees over 50°F/10°C in that particular month. Every degree over 50°F/10°C is called a degree day. The regions range from a minimum of 1,500-degree days in the coolest Region I to 4,900-degree days for the warmest Region V.
Grape vines need between 10 and 30 inches (25-76 cm) of rainfall a year to grow and successfully ripen. Most of the major wine regions in California are classified as having a Mediterranean climate, meaning a majority of rainfall takes place during the winter months. Thus, irrigation and sources of water are a viticultural necessity in many areas of the state.
Is a climate factor not usually accounted for. If wind is persistent it can slow down and even impede photosynthesis in the vines. High winds can also damage vine foliage. However, it should also be noted that wind can decrease humidity and lessen the incidence of mold and fungal infections.
Can be found in places in Northern California where volcanic eruptions took place over 30-million years ago. In particular, volcanic soils can be found in the Red Hills AVA of Mendocino County, as well as the Vaca Range and Mayacamas Mountains that frame Napa Valley. Here, red grapes such as Cabernet Sauvignon and Merlot do well and the wines are deep, concentrated, and powerful.
Are commonly found in and around rivers and watershed areas. Over the millennia many of these rivers have carved out valleys, and loose weathered rock, gravel, and soil have washed downhill, forming colluvial deposits. Napa Valley and Sonoma’s Russian River Valley are known for alluvial soils. Bordeaux varieties as Cabernet Sauvignon and Merlot grow well in alluvial soils.
Are formed at the base of hillsides by running water, the slow downhill settling of rocks and soil over time, or a combination of both. Colluvial soils are made up of a range of different sediments and rock types. Bordeaux varieties, Sauvignon blanc, and Chardonnay, thrive in these soils.
Chalky or calcareous soils are based on decomposed limestone from the fossilized remains of ancient sea creatures. Calcareous soils are well suited to viticulture because of their water retention and drainage properties. In California, calcareous soils can be found in much of the Paso Robles AVA. Here Rhône varieties such as Grenache, Syrah and Mourvèdre thrive. I
Sandy soils retain heat and are well-drained. They are also resistant to vine pests such as phylloxera. Sandy soils are found throughout California in places such as Dry Creek Valley AVA in Sonoma County, the Lodi region, and parts of Monterey County. Sand also mixes with other soil types such as loam and calcareous. A number of grapes, including Chardonnay, Pinot noir, and Zinfandel, all thrive in sand-based soils and variations.
Loam soils are a blend of silt, clay sand, and humus. Loamy soils are overly fertile and often create vigor and overcropping problems in the vineyard, necessitating frequent pruning. Sandy loam soils are found in places such as Sonoma Valley, Napa Valley, and Monterey County. Grapes such as Chardonnay, Sauvignon blanc, Pinot noir, and Merlot do well in sandy loam soils.
Further, the vines are easier to prune, maintain appropriate canopy management, and harvest. Yields from vineyards planted on flat expanses tend to be higher, as the soils are richer in nutrients leading to more vigor. Vineyards planted on hillsides typically must be worked by hand, increasing labor and costs. Further, yields are usually diminished because hillside soils are often meager and nutrient-poor. However, wines made from hillside vineyards are known for their concentration and unique qualities.
The aspect of the vineyard is also important. The optimum aspect of vineyard rows is north or south to maximize sun exposure on both sides of the vine canopy. Other vine row arrangements also work well. However, managing the canopy requires far more attention, detail, and work. For example, vineyards facing east experience morning sunshine but are in the shade during the long hours of sunlight in the afternoon and evening. Here the east-facing canopy must be open, with the vines protected by foliage to the west. The opposite is true for vineyards facing west that get little if any morning sun while being fully exposed to extended sunshine in the afternoon.
Traditionally, vineyards in California were set up to have vine spacing at 8 feet by 12 feet (2.5-3.6 m), with approximately 450 vines per acre (0.4 ha). This spacing allowed easy access for tractors and other equipment needed to work the vineyards. However, from the 1980s onward, row spacing became narrower as newer, smaller farm equipment was developed. Over time vine density also increased dramatically, ranging up to several thousand vines per acre (0.4 ha). Depending on the specific grape variety, high-density vine spacing can be as compact as 4 feet by 4 feet by 2.5 feet. Greater vine density allows vineyardists to decrease yields by up to half, maintain the same overall crop load, and increase quality of the fruit while maintaining healthy vines.
Or root systems anchor the vine. They also affect vigor and transport water and nutrients to all parts of the vine.
Is a former shoot that has become permanent and supports all the leaves, stems, flowers, and fruit. Root systems uptake water and minerals to the vine helping it grow and produce grapes.
Are the primary growth of the vine and made up of the stems, leaves, tendrils, and eventually the fruit. Pruning and other vineyard work is concerned with controlling the shoots. Canopy is the term used to describe the arrangement of the vine’s vegetative output.
Are points of growth on a vine that develops at the axils, or the place where a branch is connected to a stem. At bud break, these growths begin to grow becoming flowers and eventually embryo clusters of grapes.
From veraison onward, through harvest and after, shoots begin to harden (“lignify”). After the leaves have fallen from the vine, these shoots are called canes. During the winter when the vine is dormant, the canes are pruned in a number of different ways for the next season’s growth. When canes have one to four buds, they are called spurs or fruiting spurs.
In choosing a grape, the vineyardist has two choices, to use either a clonal selection or mass selection which is often called “selection massale.” Clones are genetic copies of a single vine, selected for its disease resistance, potential yield, or aroma and flavor profile. Specific clones can be purchased from a nursery where the plant material has been quarantined and treated for viruses. However, so-called “suitcase clones” are also sometimes brought into the country illegally. Otherwise, mass selection is defined by taking budwood from a number of existing vines in a vineyard vs. using a single clone. Using a broader diversity of budwood results in the best traits being retained and negative ones avoided.
After budwood is chosen, the rootstock must be selected. Because of phylloxera (see below), few California vineyards are planted on their own rootstock. Instead, the budwood is usually grafted onto a different, non-vitis vinifera rootstock. Vitis riparia rootstock is often used because of its resistance to phylloxera. Other factors that are considered when choosing a rootstock include resistance to other diseases, vigor, and matching to a particular soil type.
The cambium is the single layer of cells just below the bark. The more cambium contact between the scion (cutting of budwood) and rootstock the better the chances for success in the graft. Grafting is also a time-consuming, labor-intensive process that must be done by hand. The scions used for grating must be healthy and disease-free.
Once grafted, vines take at least three years to bear a crop of fruit that can be used for winemaking. At six years vines are considered mature enough to bear fruit and withstand various environmental stresses. After 20 years the vines of many classic grape varieties will start to decline and need to be replaced. There are notable exceptions such as Syrah and Zinfandel which can age far longer.
In the last 20 years advancements in designing vineyards, trellising systems, and canopy management have led to considerable improvements in the overall quality of grapes and wine in California. Before then a standard trellising system was used throughout the state without much consideration of the specific climate, soil type, variety, and rootstock. Here are the most common trellising systems used in California.
Bush or Goblet
*Insert image of bush trained vines.
Many of the early vineyards planted in California used a “bush” or Goblet system of trellising, where the vine is free-standing and secured to a stake. The French term “Gobelet” translates as goblet, and refers to the shape of the vine—a trunk with eight or more spurs. The Goblet system was and remains especially effective in warmer, drier areas where sunburn could be a potential issue for the fruit during the growing season and dry conditions result in less incidence of fungus and rot. Vineyards planted to Syrah and other Rhône varieties and Zinfandel were traditionally planted using the bush or Goblet system. Some vineyards planted using bush or Goblet are over a century old.
Vertical Shoot Positioning (VSP)
*Insert image of VSP vineyard
Vertical Shoot Positioning is one of the most widely used trellising systems for quality vineyards in coastal regions with low to medium vigor. In VSP the vine shoots are trained upwards on several wires, with the fruit zone just below, about three feet (1 m) off the ground. Though more expensive to install and maintain, the VSP system helps with canopy management techniques such as leaf removal, shoot removal, and green harvesting, while also making it easier to achieve even fruit ripeness. VSP is also optimal for vineyards that are mechanically harvested.
*Insert image of California Sprawl vineyard
California Sprawl is a simple single curtain trellising system consisting of a single cordon wire and just one foliage wire above it. The system promotes vigorous—sprawling—vine growth; hence the name. While it is relatively inexpensive to install and maintain, the system is not conducive to even ripening because of the shaded canopy. It is also more prone to mold/mildew during a wet growing season. California sprawl is widely used in high-yielding vineyard areas.
Scott Henry System
*Insert photo of the Scott Henry System
The Scott Henry system is used in coastal vineyards where the expected vigor is too high to use VSP and narrow row spacing is required. In the Scott Henry system two fruit zones are created by training spurs on sets of two upper and two lower training wires. The system is relatively inexpensive to install and maintain.
Richard Smart System
*Insert photo of the Richard Smart System
Australian Richard Smart is widely considered one of the most influential viticulturists in the last two-plus decades. His work on canopy management techniques has revolutionized grape growing internationally. Smart’s trellising system is a variation of the Scott Henry system, except that spurs on cordons are alternatively trained up and down, creating two canopies and two fruit zones.
Includes organic or biodynamic farming practices. Examples of sustainable practices include using sheep and certain species of birds to control weeds and pests, planting cover crops to control erosion and insect pests, and installing drip irrigation systems and collection ponds to conserve water. Other practices include composting and recycling to minimize waste.
Vineyards that are farmed organically must follow guidelines set up by the National Organic Program (NOP). These include the mandated use of NOP-approved materials including natural fertilizers and pest controls. The country’s largest organic certification organization is the CCOF, or California Certified Organic Farmer.
Is an elevated form of sustainable farming based on principles set out by Rudolf Steiner in 1924. Biodynamics takes lunar forces and tides into consideration in farming. For example, planting and pruning are done according to the phases of the moon. Further, the farm is seen as a single, closed entity. In biodynamic farming no artificial pesticides or fungicides are used. There are eight biodynamic treatments used in the vineyard, made of organic materials from the estate. These treatments are used to improve and maintain the health of the microbiome in the soil. In California, wineries and vineyards are certified by the international organization called the Demeter Biodynamic Trade Association. It should also be noted that the practice of biodynamics is still considered controversial by some in the industry.
Powdery Mildew (Oidium)
Though native to North America, powdery mildew spread on a global scale. It thrives in humid and wet conditions. Powdery mildew infects all green parts of the plant with a dusty white powdery substance. If a vine is infected before flowering the yields will be reduced. Vine infection after fruit set will result in smaller berries that never reach full size. The fungus is controlled by applications of sulfur and other fungicides.
Downy Mildew (Peronospora)
In the 1880s downy mildew was transported to Europe on native American vines and quickly spread through France and the rest of the continent. The fungus infects all green portions of the vine, inhibiting photosynthesis. Over time a white fuzzy growth forms on the underside of the leaves. Bordeaux Mixture, a solution of copper sulfate, water and lime, was developed to prevent outbreaks of downy mildew.
Pierce’s Disease (Xylella Fastidiosa)
Is a disease spread by the blue-green sharpshooter. As the insects feed on the vines, they inject the disease into the vine which quickly spreads throughout the plant. There is no cure for Pierce’s Disease as of now. Current control is through the use of parasitic wasps that prey on the eggs of the sharpshooters.
Phylloxera (Daktulosphaira Vitifoliae)
Phylloxera is a tiny louse that feeds on roots and leaves, creating fungal infections which block the flow of water and nutrients to the vine. At present there is no cure for phylloxera. However, grafting vinifera budwood on to non-vinifera rootstock has historically proven to be the most successful remedy
Is a form of botrytis that can infect leaves and/or berries at any time of the year when wet conditions occur and temperatures range between 60 and 75°F (15.5-24°C). Initially spots appear on the leaves, which soon turn brown and start to rot. With grapes, infection covers the berries with mold and decay.
Black Rot (Guignardia Bidwellii)
Is another fungal disease native to North America. Black Rot was transported to Europe in the 1880s with the importation of native rootstock to combat phylloxera. It appears as black spots on shoots, leaves, and berries. If untreated yields can be considerably reduced. However, vines can be treated with fungicides.
Esca (Black Measles)
Is a fungal vine trunk disease. Infected vines initially show discoloration with the leaves eventually shriveling in the middle of the season and dropping off. Infected grapes do likewise, with the vine suddenly dying within days of infection. Esca is a problem worldwide, especially in warmer climates. There is no known cure or treatment.
Or Eutypa lata, is one of the most destructive fungal diseases. It initially appears on a single spur before spreading to the rest of the vine. Eutypa stunts the growth in shoots and leaves and shrivels the grapes. There is no known cure or treatment.