Evaluation of Winegrape Clones

Thirteen clones or selections of Pinot noir were harvested for sparkling wine. Large differences were seen in maturity. Plots picked at 19 Brix were harvested over a 3-week period from August 21 through September 10. Yield was correlated more with cluster wt and cluster number than with berries/cluster. Among the clones, large differences were seen in virtually all measured parameters, including pruning wt, the several yield components, and in juice yield/ton of fruit. Duplicate wine lots were made from each clone or selection. Three clonal wines were rejected (both lots): one clone was defective in its aroma and two clones were lost because they underwent malo-lactic fermentation. The remaining 10 clones or selections are undergoing duo-trio analysis and further evaluation by cooperating winemakers. Further analysis of previous years’ data from two Chardonnay plots and one Cabernet Sauvignon plot reveals a close correlation of yield with cluster wt, more so than cluster number. For both varieties, there was a slight negative trend of pruning wt with yield, indicating that some yield increases were obtained at the expense of growth or that the yield:prunings ratio could have been altered by formula pruning, i.e. adjusting the buds retained at pruning based on the pruning wt. The Zinfandel clonal trial suffered heat damage and fruit shriveling prior to harvest skewing the data and resulting few reliable differences. Other trials with Merlot, Cabernet Sauvignon and Chardonnay are maturing and will be available in the near future.