Nature and geography’s many blessings, along with the hard work of Napa Valley’s grape growers and farmworkers, have made Napa’s grapes the most valuable in California. The value of Napa’s wine grape crop exceeded $650 million in 2012, and an average ton of Napa Valley cabernet sauvignon grapes sold for approximately $5,000 — more than twice as much as any other California county or region. Cabernet from top growers and vineyard sites fetches significantly more than that.
Understanding the value of their grapes and the need to preserve their vineyards, Napa’s grapegrowers are on the cutting edge of viticulture, combining new technologies with traditional practices to develop sustainable farming programs. Sustainable farming means different things to different farmers, and that is reasonable given that each farm has its own challenges. The basic tenets include protecting our natural resources, social responsibility and profitability.
To create an environmentally friendly farming program, grapegrowers need to evaluate the challenges specific to their vineyard. Most vineyards are susceptible to pests and diseases, although the risk varies based on factors such as varietal, microclimate and neighboring land uses. In a sustainable farming plan, the grower needs to asess risks in the context of the season and plan to mitigate or eliminate the risk.
For example, if growers did not implement a mildew prevention program, nearly every vineyard in Napa Valley would get infected with powdery mildew, a disease that can create off flavors in wine with as little as one to two percent infection in the vineyard. Carneros chardonnay is at a higher risk of developing a more severe infection than hillside cabernet because of the climatic differences as well as chardonnay’s susceptibility to the disease.
Growers have many tools to assess and combat a possible infection. Proper air flow and sunlight around grape clusters can greatly reduce powdery mildew; so can diligent canopy management practices, such as removing leaves and lateral growthors.Weather stations are often used to monitor climatic factors, and models have been developed to assess the index of risk for developing mildew. Based on this index, growers can extend any treatment intervals in lower-risk periods. If treatment is necessary, a grower can choose among many chemicals, including several organic options.
Sustainable farming is about balance. Techniques used to prevent mildew can carry their own risks, such as exposing the fruit to too much sunlight, or treating with the organic fungicides sulfur or oil in the heat can cause fruit to burn.
Mildew is just one of the challenges to grapegrowing. Insect pests can cause economically significant damage; however, treating insects with insecticides is only a last resort in a sustainable farming program, especially since insecticides can further disrupt the balance between pests and their natural predators.
In a sustainable farming plan, low levels of pest presence are often tolerable, and thresholds may vary depending on the presence of natural enemies. Sustainable farm plans also include supporting a population of natural enemies by providing habitat through insectaries and cover crops or releasing them into the vineyard. Treatment is only applied if it is necessary, and there are many organic and non-organic options, each with their own benefits and risks.
But farming is not always about problems. In fact, healthy vineyards have minimal problems when they are in balance. Maintaining a healthy vineyard begins with healthy soils. Many of Napa’s vineyards are planted on hillsides, and preventing soil erosion is a paramount concern. Installating subsurface drainage and surface water diversions and using straw and planting cover crops can help fix the soil in place and improve water infiltration. Cover crops are also useful for soil nutrition in vineyards of all types.
Cover crops build soil organic matter, providing nutrients for plants and microbes to maintain a healthy nutrient cycle. Using compost, preferably from recycled grape and vineyard waste, and naturally derived fertilizers is also important in sustainable farming plans.
Water conservation is critical. Sustainable farmers use weather stations and other technology to measure vine water use, and apply only conservative amounts of water through well-maintained drip irrigation systems. Fortunately, wine quality can benefit low levels of stress to vines, so vineyards use less water compared to many other crops. New technology has helped growers reduce overall water use by applying water based on vine and soil demand.
The social responsibility of a sustainable farming plan begins with the employees on the farm. Although we harvest grapes only once a year, grapegrowing requires year- round work, and the majority of Napa’s farmworkers are employed throughout the year. The 2011 Napa Valley Grapegrowers Wages & Benefits Survey showed that 91 percent of supervisors and 69 percent of vineyard workers are offered medical insurance plans, compared to 52 percent nationwide in the private sector, and 55 percent of farm workers are offered retirement plans. Napa is the only county in California to have a farm worker housing assessment levied on all growers; this has built three farmworker centers that provide lodging, meals, laundry and recreational amenities.
The sustainability of the Napa wine industry begins with the efforts of grapegrowers, but also important is the hard work of Napa’s policy makers and leaders and organizations such as the Land Trust of Napa County, the Napa Resource Conservation Services and the Resource Conservation District.
It’s no accident that we find ourselves living in one of the most beautiful valleys on earth. It is because this is a community and an industry that works together, and our shared goal is the sustainability of this place we call home. Here’s to a great 2013 harvest.