Abstract
Winegrape production in the Pacific Northwest has expanded into areas where low winter temperatures periodically cause cane damage or death. In the Walla Walla Valley, for example, minimum temperatures plummeted to below -20 F for several days in 1996 and 2004, killing most exposed canes. Cane temperatures most certainly remained below 0 F during this time. If vines are grown on their own roots (i.e., not grafted), regrowth and training of new canes from below-ground plant parts is possible. Fruit and wine production is reduced, however, during the time required to retrain the canes. Regrowth of Merlot canes is especially problematic, as new canes tend to be stunted and nonvigorous. Canes can be protected from freeze damage by burying them or covering them with mulch. This publication describes three systems that may help prevent injury from winter freezes.