Issue link: http://read.dmtmag.com/i/51841
VINEYARD ACTIVE PROTECTION The two primary active frost pro- tection systems used in California vineyards are overhead sprinklers and wind machines. Smudge pots as heating devices were banned from use in California vineyards in the 1980s. Continual application of sprin- kler water during low temperatures maintains temperatures of vine tissues above freezing. However, if the continual process of active freezing of water that coats the vine is interrupted, vine damage can be greater than in an unprotect- ed vineyard. Sprinkler frost protec- tion requires significant amounts of water, often 1 inch or more per night for conventional sprin- klers. Many vineyards do not have access to this amount of water, and water supplies are a major concern throughout California. Central Coast vineyards with properly working sprinkler frost protection gener- ally had little damage from the 2011 frosts. Wind devices can act to drain and remove cold air from ground level that can be replaced by warm- er air, or act to mix the higher-layer warm air with the lower colder air to raise overall temperatures. How- ever, wind machines cannot always prevent frost damage. For example, they provided no benefit for many locations during the Central Coast freeze in April 2011 because tem- peratures dropped too low, and there was no inversion of warmer air above the cool air layer to be drawn down to raise temperatures near the vines. AFTER DAMAGE OCCURS Many variables are involved in how to respond after frost dam- age occurs. Post-damage practices should be approached on a case-by- Wind devices can help protect against frost damage, but not under all condi- tions. Photo: Thinkstock 56 VINEYARD & WINERY MANAGEMENT JAN - FEB 2012 WWW.VWM-ONLINE.COM