The 2011 ASHS Annual Conference

Our previous research has demonstrated the potential of crop forcing to shift fruit ripening of grapevines to the cooler portion of the growing season in warm regions. An experiment was conducted in a mature Cabernet Sauvignon vineyard in Fresno, CA in 2010 to determine the inhibiting effect of primary clusters, leaves, and laterals on current season compound bud break, vine regrowth and yield components under crop forcing.  At pea-sized berry stage vines hedged to 6 nodes were subjected to removal of all possible combinations of primary clusters, leaves and/or laterals.  Retaining primary clusters on the vine resulted in a similar number of forced shoots and clusters compared to that of complete removal, but lower vine vigor, smaller clusters, and lower yield of forced crop. Retaining leaves or laterals in combination with or without primary clusters had similar inhibiting effect, producing fewer forced shoots and clusters, approximately 50% that of complete removal or when only primary clusters were retained. Retaining both leaves and laterals or retaining all produced the least forced shoots and clusters, suggesting that the inhibiting effects of leaves and laterals are cumulative. Highest yield of forced crop and pruning weight of forced shoots were observed when all primary clusters, leaves, and laterals were removed. The research demonstrated the need for complete removal of shoot tips, clusters, laterals, and leaves to achieve maximum vine vigor and yield when crop forcing is used to force vine regrowth in order to produce better quality fruit of Cabernet Sauvignon in warm regions for winegrape production.