A COMPARISON OF SHORT-TERM AND LONG-TERM EFFECTS OF MIDWINTER PRUNING ON COLD-HARDINESS OF CABERNET-SAUVIGNON AND CHARDONNAY BUDS

This study examined the influence of dormant winter pruning on the cold hardiness of Cabernet Sauvignon and Chardonnay buds using low temperature exotherm (LTE) analysis. Short-term studies examined the effects of pruning 24, 48, or 72 hours prior to LTE analysis. Short-term samples taken from December to March on approximately a bi-weekly basis showed no significant difference in either LTE or bud injury. Long-term studies examined the effects of pruning one to 10 weeks or more prior to LTE analysis. These samples also indicated little difference in cold hardiness of buds. In fact, both short- and long-term studies yielded data that suggested a potential benefit of pruning on bud cold hardiness. There was no indication the pruning procedure followed in this study caused earlier budbreak and, therefore, increased susceptibility to spring frost in these two wine grape cultivars. It should be emphasized that these results represent a single season and conditions specific to the Yakima Valley of Washington.