Sustaining Bud Fruitfulness, Yield and Wine Composition of Pinot Grigio and Shiraz in Southern San Joaquin Valley

Canopy microclimate of Syrah06/SO4 was altered through application of three dormant pruning, and two leaf thinning treatments arranged factorially in four randomized complete blocks to investigate how to rejuvenate vineyards with declining productivity. Vines were either pruned by hand to 22 nodes, or mechanically box-pruned to a 10 cm hedge, or cane- pruned by hand to six, 8 node canes arranged in opposing directions of the row with horizontal canopy separation, and leaves were removed on the east side of the canopy in the fruit zone, or not. Percent photosynthetic photon flux density (%PPFD) transmittance of mechanically box-pruned vines was 34%and 38%greater than spur or cane-pruned vines, respectively. Leaf removal increased %PPFD by 47% compared to control. Canopy separation decreased cluster and berry weight, while increasing cluster number and yield per vine. Canopy separation delayed harvest by one week, while retaining lower juice pH and higher total acidity. Berry weight of spur-pruned vines was 15% greater than other pruning methods. Cluster number was 37% higher on cane-pruned vines with canopy separation compared to mechanically box-pruned vines, which were 22% higher than spur-pruned vines. Berry skin total phenolics at harvest of cane-pruned vines was 11%greater than spur-pruned vines, which was 8% greater than mechanically box-pruned vines. Pruning method and leaf removal interacted to affect the total iron reactive phenolics and tannin concentration in resultant wine. Crop load of cane-pruned vines was 43% and 32% greater than spur-pruned and mechanically box-pruned vines, respectively. The results from this study provide information for largescale growers on how to rejuvenate vines that have declined in productivity. Canopy microclimate of Syrah06/SO4 was altered through application of two dormant pruning, three shoot thinning, and two leaf thinning treatments arranged factorially in four randomized complete blocks to mitigate crop load. Vines were spur-pruned to 22 nodes or mechanically box-pruned to a 10 cm hedge, shoot thinned to 23 shoots/m of row (low), 32 shoots/m of row (medium), or 49 shoots/m of row (high), and leaves were removed on the east side of the canopy within a 45 cm zone of the fruit zone, or not. The cluster number (p<0.0001), leaf area to fruit ratio (m2/kg) (p<0.0115), shoots exposed per acre (p<0.0111), and yield (p<0.0001) increased linearly with the increase in crop load, while the pruning weight per vine (p<0.0001), berry weight at harvest (g) (p<0.0222), cluster weight (g) (p<0.0011), increased with the decrease in crop load. Leaf layer number of the Syrah canopies were better predictors of berry skin anthocyanins (p<0.0285), and tannins (p<0.0166) when compared to crop load (p<0.1435 and p<0.3721, respectively). The most preferable fruit at the farm gate was achieved with 65,000 shoots exposed per hectare, that were 5.0 cm apart along the cordon, with 3.2 leaf layers resulting in 20.5 tons per hectare yield when harvested at 24% total soluble solids. This study provides information for growers who aim to balance vine growth with fruit and quality through on-site measurements for mechanically managed vineyards in the southern San Joaquin Valley of California. To better understand the optimal canopy management techniques necessary to meet the demands of both vineyard and cellar, a study was conducted analyzing the interactions amongst canopy management steps for Pinot Grigio in the southern San Joaquin Valley. The treatments were arranged factorially where two pruning methods (spur vs. mechanical box-pruning), three shoot density levels (low (23 shoots/m), medium (33 shoots/m), high (49 shoots/m)), and two leaf removal methods (east-side leaf removal, or none) were applied to alter the canopy microclimate in four randomized complete blocks. Pruning method and shoot density interacted to affect the count shoots and total shoots retained per meter of row. Canopy microclimate was affected by pruning method, shoot density, and leaf removal treatments. Light interception into the fruiting zone was 49% higher for spur pruned vines compared to mechanically boxpruned, and was 44% higher for low shoot density compared to high shoot density treatments. A 17% decrease in leaf layer number was observed for vines with leaf removal. Yield was impacted by both dormant pruning and shoot thinning methods where an increase of 42% in mechanically box-pruned vines was seen compared to spur pruned, and increase of 27% from low to high shoot density. Crop load and vine vigor was impacted by the interaction of shoot density and leaf removal. Leaf area to fruit weight ratio reached the desired range (0.8-1.2 m2/kg) for medium shoot density treated vines that were mechanically box-pruned. Wine phenolics analysis indicated a three way interaction amongst pruning method, shoot density, and leaf removal indicating quantitative wine parameters were multi dependent on canopy management methods.