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Cover Story

May / June 2000

Windbreaks mitigate climate Don Neel

Nearly every afternoon in Soledad (Monterey County) on California's Central Coast, the wind rises and blows steadily and strong from the northwest for several hours. In 1987, when Franciscan purchased the 800-acre ranch east of Soledad that is now Estancia Estates, this wind was a factor that Howard Tugel, general manager (vineyard manager until 1998), knew had to be dealt with if the vineyard was to produce high-quality grapes. In 1988, during redevelopment of the 660 acres originally planted by Paul Masson in 1961-62, Estancia planted windbreaks of Casurina trees to protect the grapevines. Spaced one meter apart and almost 50 feet tall after nearly 12 years, the trees reduce the wind impact significantly. When winds measure 20 to 25 mph outside the windbreaks, they are only 12 mph inside. Winds of 7 to 10 mph are reduced to 3 to 5 mph inside the windbreaks. As a result, Estancia has achieved a consistent set every year. Windbreaks offer many benefits. They reduce leaf tatter, sandblast desiccation, and wind damage to growing tips. Protected grapevines produce greater leaf area with larger leaves, longer shoots, higher pruning weights, increased vine capacity, longer internode length, improved pollination and fertilization, improved berry set, and improved stomatal conductance and photosynthesis. Evapotranspiration is improved and water stress is reduced. Estancia reports increased bunch weight with more berries per bunch and increased bunch number per vine. In addition, time to grape maturity is reduced by as much as two weeks compared to unprotected neighboring vineyards. Windbreaks improve irrigation efficiency, and they improve spraying conditions by allowing a 10-hour spray day despite surrounding winds. Spraying of two or three vine rows can be done with an over-the-row air-blast fan system mounted on a Braud harvester chassis. Windbreak establishment In the first tree-protected vineyard section of 104 acres planted in 1988, a row of Casurina seedlings six to eight inches tall was planted every 500 feet. The tree rows are parallel to the vine rows of Clone-4 Chardonnay on 5C rootstock, which are east-west oriented and spaced 10x6. In addition, cross rows of Australian willow trees were planted in three main avenues and along the outside perimeter of the ranch to protect the vines from the potential wind channeling effect. Two rows of the willow trees were planted five feet apart in a staggered pattern with 10 feet between trees. They are 35 feet from grapevines and have grown to be 40 to 50 feet tall. "Our goal was to achieve a 'boxed in' vineyard as seen commonly in New Zealand," explains Tugel. "We planted Casurina trees within the vineyard because leaf-out occurs early enough in the growing season to provide protection when grapevine budbreak occurs. We did not want willows in the vineyard itself because they have a shallow, spreading root system. Also, willows are deciduous, and we did not want to end up spraying fallen willow leaves when trying to control weeds." Within the vineyard in 1991, a 45-acre block of Chardonnay was planted with north-south oriented vine rows spaced 8x4. Rows of Casurina trees were planted 250 feet apart. Tugel says new vines are spaced 6 feet 3 inches by 5 feet, and tree rows are being planted every 250 feet because their experience has taught them that this spacing gives the most effective windbreak protection. Resulting vineyard sections are 250 feet wide, 1,200 or 1,600 feet long, with trees surrounding six to nine acres of vines. In general, the area protected by the trees extends 10 to 12 times the height of the windbreak on the leeward side and three to five times the height of the windbreak on the windward side. Vine rows are planted no closer than 15 feet on each side of the row of Casurina trees. The trees are laterally pruned in February or March up to 12 feet high to improve tractor access to the vines. Casurina trees grow four to eight feet in height per year and have a maximum circumference of about three feet. Casurina trees Casurina is a tall, evergreen Australian tree, commonly called the river she-oak. It has a tap root rather than a filamentous root system and has dark green branchlets, which are jointed and look like pine needles, allowing some blow through. The tree has separate male and female flowers, and when the female flowers mature, they resemble small pine cones. Seeds are small, winged nutlets. The Casurina tree tolerates alkali and saline soils, is drought resistant, and will withstand strong prevailing winds. It tolerates temperature to 15ºF, or colder if it is well watered. Periodic cultivation is recommended to reduce competing vegetation and improve planting survival and growth. At least two discing passes in the tree row are needed each year for weed control. The trees receive the same fertilization as grapevines through the drip irrigation system. Every winter for the first five to seven years after planting, Estancia prunes the tree roots at about four to six feet on either side of the tree row, using a four-foot deep single shank pulled by a D68U Caterpillar tractor at 3 to 3.5 mph. Older trees are root-pruned on one side of the tree row only (alternated each winter). Yield benefits The most important benefit of planting windbreaks at Estancia is told in the resulting grape yields. An 85-acre Estancia vineyard block grafted to Chardonnay in 1988 that has not been protected with windbreaks has internode lengths of less than 3/4-inch and yields only 2.5 to 3 to tons per acre. But in the tree-protected vineyard sections, reports vineyard manager Peter Figge, "The yield from Pinot Noir is 5.5 to 6 tons per acre, from the Clone-4 Chardonnay is 6 to 7 tons per acre (11 to 15 pounds per vine), and from Pinot Gris is 5 to 6 tons per acre." Tugel and Figge agree that this boost in yields validates the use of windbreaks in their vineyard.