Issue link: http://read.dmtmag.com/i/51841
VINEYARD comparison evaluation of treat- ments of frost-damaged vines in a 12-year-old cabernet sauvignon vineyard in Lodi – although without time and funding for an in-depth look with full replications of all treatments. The treatments includ- ed a "clean up" of the cordon and spurs on frosted vines by removing dead and unwanted shoots, shoot- thinning on unfrosted vines, and no shoot thinning or treatment on frosted vines. The observed results were similar to past research results and recommendations. Although Verdegaal acknowl- edged that "many factors can com- plicate the best course of action following a spring frost," he sum- marized some general guidelines based on past experience and research: Don't thin clusters. Don't remove all shoots and start again. Don't shoot-thin if only shoot tips are damaged. If half or more of the shoots are killed to the clusters and beyond, shoot - thinning of damaged shoots may be helpful in some cases, depending on variety, severity of damage and cost fac- tors. However, it's best in most cases to do nothing, other than necessary irrigation and pest management. Don't add extra nitrogen, and probably use less due to a small- er crop. The cost-benefit ratio of manag- ing a lower-yielding crop is another factor to consider. As Verdegaal observed, "Already suffering from a loss of crop and starting the sea- son all over, it is difficult to spend more than what was intended for the yearly budget, unless it will pay to do so." Some management oper- ations and vineyard passes, par- ticularly for canopy management, may be unneeded and not cost- effective. The anticipated price per ton for the crop can also factor into 58 VINEYARD & WINERY MANAGEMENT JAN - FEB 2012 management actions, as lower- priced varieties used for blending may warrant less attention than an old-vine zinfandel normally used for a vineyard-designated wine. If secondary buds are also dam- aged by frost (a less likely situation in California vineyards), managing the vines for a harvestable crop may not be cost-effective. In such cases, vines must still be minimally managed and irrigated to maintain vine health for the following sea- son. Pest and disease management will also be required as needed to maintain vine health, and to prevent spread to other vines. TEMPERATURE INVERSION RESEARCH PROJECT UC Cooperat ive Extension received a $60,000 grant from the USDA Specialty Crop Block Pro- gram in 2011 to gather data on spring temperature inversion con- ditions in vineyards in Sonoma, San Luis Obispo and Santa Barbara counties to assess the potential effectiveness of wind machines for frost protection in these areas. A major reason is to determine if wind is a viable alternative to sprinkler water frost protection in targeted locations. Water for frost protection is a major issue in the Russian River Watershed in Sonoma County, with growers facing regulatory pressure to reduce water use. Battany is the lead researcher for the project. He has done some temperature inversion monitor- ing trials in the past by launch- ing weather balloons in the early morning on spring days during frost episodes. The balloons can collect several hours of data. The plan for the new research proj- ect, which begins this spring, will involve placement of 35-foot-high fixed towers in frost-prone vineyard locations, each topped with a Hobo temperature data logger that will record temperatures throughout the full frost season. In the Central Coast, this gen- erally runs from March 1 through May. "We don't have too many areas in the Central Coast that are not at risk for frost damage," Bat- tany said, "and this is also true for much of Sonoma County. There is a lot of contention about water use with sprinkler frost protection, so finding alternatives to water use is important for California vineyards. This is a three-year project, and we should have good information in 2014 to bring the results to the industry." For more frost protection recom- mendations, see ht tp: / /cesanluisobispo.ucda- vis.edu/Viticulture/Frost_Protec- tion/ and www.extension.org/ pages/31768/ f rost - injury- f rost - avoidance-and-frost-protection. Ted Rieger, CSW, is a writer and photographer based in Sacramento, Calif., and has been a contributing editor for V&WM since 1990. Comments? Please e-mail us at feedback@vwm-online.com. Quality Stainless Tanks 30 years of fabrication experience Custom tank designs & features Tank modifications & repairs Dependable quality & completion Quick & competitive price quotes Tanks from 250 to 50,000 gallons "QST's previous clients are our best source of advertising" Quality Stainless Tanks 510 Caletti Ave. Windsor, Ca. 95492 707-837-2721 or 877-598-0672 Fax 707-837-2733 www.qualitystainless.com winetanks@aol.com WWW.VWM-ONLINE.COM