Evaluation of Merlot and Malbec Clones

Data collected in 1998 in Merlot showed similarities to previous years. Clone 08 had the lowest yield (5.3 kg/vine) as a result of fewer berries per cluster and smaller berries. It also had the greatest pruning wt (2.4 kg/vine) as a result of heavier, not more, shoots. Clones 01, 03 and 06 were very similar in yield (about 7 kg/vine) but in growth FPMS 1 had the least at 1.98 kg. With the lower crop and greater pruning wt, clone 08 had a much lower yield:prunings ratio (2.17) versus the other clones (2.9 to 3.7). These values are dramatically different from 1997 when with higher yields and lower growth ratios were in the 5 to 8 range. Wines were made in cooperation with Duckhorn Vineyards. All wines will be initially evaluated informally at the winery. Three clones of Malbec, FPMS 04, 06 and 08, were compared on two rootstocks, 5C and 110R. Malbec had a the disastrous fruitset in 1998 similar to what it had in 1996. Yields in 1998 were 1 to 5 kg/vine. Under normal conditions, clone 08 shows a tendency to over-crop but with the poor set in 1998 it was not thinned. At these extremely low yields, pruning wts ranged from a low of 2.8 kg/vine for 08 to about 3.5 kg for clones 04 and 06. Vines on 11 OR yielded significantly more than 5C (3.4 vs 2.2 kg/vine, respectively), primarily due to more clusters per shoot and more berries per cluster. Even with the better crop load, 110R had a half degree higher Brix than 5C. Only clone 08, especially on 110R rootstock, had economically sustainable yields in 1998 with an average across rootstocks of 4.0 tons per acre versus 1.3 for 04 and 0.8 for 06.