Phenological Development of Different VitisCultivars

Abstract

The expansion of grape buds into shoots in the early portion of the growing season is an important series of events. Empirical observations have suggested that some cultivars begin growth earlier than others, and some grow at different rates. In most areas where grapevines are grown commercially there is an economic problem resulting from spring freeze damage. The stage of phenological development can have a direct influence on the level of low temperature stress that the developing shoot may tolerate, and still survive (3). In Concord ( Vitis labruscanaBailey), tolerance of young shoots to cold stress declined with increasing growth and elongation. This study has been undertaken to gain a better understanding of the factors leading to the early onset of growth, and loss resulting from subsequent spring freezes.