Issue link: http://read.dmtmag.com/i/51841
VINEYARD Before and After the Frost Preventing and managing spring frost damage By Ted Rieger, senior feature editor ine damage and crop loss from spring frosts are poten- tial dangers in most winegrow- ing regions. California growers in recent years have seen frost events characterized by unusual or unanticipated severity. Central Coast vineyards in parts of Monterey, San Luis Obispo and Santa Barbara counties experi- enced significant frost damage over three days in April 2011 when morning temperatures dipped below 28°F. This frost event was much more severe than most regional weather forecasts had pre- 54 VINEYARD & WINERY MANAGEMENT JAN - FEB 2012 dicted. Vineyards nearer the coast, or with a coastal marine weather influence, generally were less affected than the inland areas of northern San Luis Obispo County and southern Monterey County, where temperatures were coldest. Some initial reports from Cen- tral Coast growers after the 2011 harvest estimated that frost dam- age, coupled with lower yields due to a cool and late growing season, resulted in overall 2011 yields that were 40% lower than average. Spring frost is a danger any time after bud break, with poten- tial damage to opening buds and young shoots. Frost damage among vines at different stages of growth often varies within a vine- yard and sometimes within a single vine. It commonly kills the primary buds and shoots that produce the most fruitful crop. Death of the pri- mary buds usually results in sub- sequent development of a shoot from the secondary bud within the same compound bud. Most culti- vars produce significantly less fruit from the secondary buds, although some can produce up to 50% of the normal crop. WWW.VWM-ONLINE.COM