Factors Influencing Critical Temperatures for Spring Freeze Damage to Developing Primary Shoots on Concord Grapevines

Abstract

A controlled freezing technique was used to determine critical temperatures for developing buds on grapevines. Critical temperatures were estimated for Concord grapevine buds at defined stages of development under both wet and dry surface conditions. Tissue surface moisture strongly influenced freeze resistance. Hardiness was similar for developing Concord buds whether forced from dormant cuttings, taken directly from the field during spring development, or allowed to develop outdoors on whole potted vines. Pre-freeze temperatures had no apparent effect on the hardiness of developing buds. Freeze resistance of grapevine buds always decreased with advancing phenological development.