Improving Yield and Quality of Sauvignon Blanc

Clonal Trial: During the 2010 growing season, a trial containing 12 clones of Sauvignon blanc were grown and harvested. The vineyard is farmed organically, drip irrigated and planted in a Russian River loam soil in Hopland, Mendocino County, California. Clones include: UC FPS# 1, 6, 7, 14, 18, 20, 22, 23, 25, 26, and 27. The experimental design is a ANOVA Randomized Complete Block with 8 replications of 5 vine vines planted in 4 long east ?west rows. Replications are clearly marked with plastic cattle ear tags at the beginning and end of the plot containing the replication number and clone for easy identification. This is the fifth bearing year of the vineyard, and the vines were trained with two canes containing an average of 12 buds per cane on a vertical shoot positioned trellis (VSP). Vines were managed during the growing season to the cooperating grower?s commercial standards including trunk and cordon suckering and removal of sterile shoots, positioning shoots upright inside of fruiting wires, and a standard powdery mildew program utilizing stylet oil and wettable sulfur pre-bloom, and sulfur dust post bloom. No insecticides or miticides were applied. Nearly all vines are bearing at commercial levels, and we were able to sufficiently harvest enough fruit to make valid mean comparisons. This growing season was relatively cool and overcast. Consequently, the growing season was delayed by almost two weeks. Bud break occurred between April 1st and April 7th. Flowering occurred between June 15th to June 18th. Veraison was also late, between August 4th to August 12th. Harvest occurred on October 8th, and was scheduled to coincide with other Sauvignon blanc being crushed by the cooperator. In general, phenology was not significantly different between all of the clones. The exception is that veraison and ripeness were accelerated for UC FPS # 14 which generally has lighter crop loads ( Target fruit maturity was 22.5 to 23.5 %brix.) Based on our data, these observations were concluded: ? The vines are becoming mature and are probably yielding within their commercial potential. Vine yield have a statistically significantly different range, from 3.7 kg to 9.9 kg, which would correspond from 3.2 to 8.5 tons per acre. Cluster counts are also significantly variable, from 31 to 65 clusters per vine. ? There are differences in cluster weights ranging from approximately 81g to 133 g. There is considerable variability in the clones in cluster size, looseness and yield potential. This allows growers some choice if they are in need of lighter crop loads to insure that fruit will ripen under cooler conditions. ? Fruit ripeness varied from around 21 %brix to 24 %brix. It appears that ripeness was affected by crop load. Clones that were carrying heavier crops were less ripe at harvest. ? The pH was higher than is typical for the cultivar in our region (ranging from around 3.5 to 3.7) and titratable acidity was moderate (ranging from .5 to .7 grams per 100 ml). Often fruit from our area has more acidity, but because of the large crop and the long hang time, acidity was lower than harvests that mature early and are lighter in size. ? UC FPS #1 is still an excellent clone, and yields consistently well from one season to the next. Trellis Trial: The trellis trial is in adjacent row to the variety trial. The experimental design is a randomized complete block, with 4 reps of 10 vines for each treatment. The trellis types were selected with the ability to be mechanically harvested. The following trellis types are being used: 1. Vertical Shoot Positioned Trellis (VSP), bilateral cordon, highway post, fruiting wire at 36 inches. 2. VSP, 4 canes, with 2 pairs stacked on fruiting wires at 36 inches and 44 inches. 3. VSP, bilateral cordon, fruiting wire at 36 inches, 12 inch cross arm at 48 inches, and 16 inch cross arm at 60 inches to create more pendant growth to help divigorate the vines (a modified California sprawl system). 4. VSP, modified cane pruning (continuous fruit curtain), cordon wire at 36 inches, 4 short canes are tied to fruit wire at 44 inches. 5. VSP, 4 canes tied to two parallel fruiting wires at 36 inches, two cross arms, one at 48 inches, and one at 66 inches. In 2009, we balance pruned the vines, meaning that we left 3 bud spurs, and tried to have an average of 40 buds per vine. Regardless, it is clear that the cane pruning systems are able to set larger crops than spur pruning systems.