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With natural rainfall and surface water availability becoming scarce, prolonged droughts are expected to become more frequent, thereby creating issues for agriculture. In viticulture, a lack of rainfall is often supplemented with irrigation during the growing season and/or dormancy. However, with surface and groundwater resources declining in addition to current changes in rainfall patterns, it is unlikely that supplemental irrigation will continue to be an available tool for most growers. As such, this study aims to evaluate the effect of dry farming and supplemental irrigation during the growing season on vine performance and fruit composition as a function of vine age in Zinfandel grapevines. A historically dry-farmed vineyard block with interplanted vines of varying ages was evaluated during the 2021 growing season. Treatments included young vines (5–12 years old), control vines (2:1 ratio of old to young vines representative of the block), and old vines (40–60 years old); each age designation included irrigated and dry-farmed vines. Based on age-specific ETc and to replenish 95% of crop evapotranspiration (ETc), irrigation was manually applied to the irrigated treatment vines at véraison and véraison + 4 weeks. Results indicated no significant changes in phenological progression, leaf senescence, or physical berry analysis when irrigation was added to dry-farmed vines, as most differences were driven by vine age in most parameters measured. Irrigated vines were slightly more advanced in phenological growth and senescence progression compared to dry-farmed vines. Results suggest that the practice of applying supplemental irrigation during the growing season, provided winter rainfall or additional winter irrigation is sufficient, does not have significant impacts on vine performance. Thus, dry farming during the growing season is a reasonable alternative practice in Zinfandel, even in periods of drought. [ABSTRACT FROM AUTHOR]

Demand for vine plant material has increased drastically due to the ongoing expansion of viticulture, and recent widespread replanting efforts. Nurseries and growers are turning to green-grafted vines to meet demand. Unfortunately, most vineyard establishment studies have centered around dormant benchgrafted vines. Thus, little is known regarding the specific establishment trends of green-growing benchgrafts. This study aimed to explore the role rootstock selection has in green-growing benchgraft establishment and development over the first four years post-planting. Vitis vinifera L. cv. Sauvignon blanc was grafted onto multiple rootstocks of varying parentage, including '101-14MGT' (V. riparia × V. rupestris), '1103P' (V. berlandieri × V. rupestris), '110R' (V. berlandieri × V. rupestris), '420A MGT' (V. berlandieri × V. riparia), and 'Teleki 5C' (V. berlandieri × V. riparia). The experimental site was organized using a completely randomized design (n = 12) with all vines managed to industry-standard cultural practices. Vines grafted onto 1103P had the largest average trunk diameter (p = 0.0012) and circumference (p < 0.0001) at 22.2 mm and 7.57 cm, respectively. Vines grafted onto 110R had the second-largest trunk circumference at 6.65 cm. Vines grafted onto 110R had the largest concentration of total non-structural carbohydrates at planting at 1.47 g/L, followed by 1103P at 1.25 g/L (p < 0.0001). Total non-structural carbohydrate concentrations in the trunk during dormancy was the highest in 110R at 16.0% total dry weight (p = 0.0008). The larger trunk size and more extensive carbohydrate reserves suggest that green-growing benchgrafts using 110R or 1103P have a higher capacity and likelihood of establishment success. [ABSTRACT FROM AUTHOR]

Merlot grapes were harvested with three maturity levels (21.1, 23.1, and 25.1 Brix), and processed with or without the application of microwave-assisted extraction (MW). The detailed phenolic composition and color were followed during winemaking. The MW treatment did not affect the basic chemical composition of the wines. Upon crushing, MW caused a 211% improvement in anthocyanins in the wines of the first harvest and an 89% improvement in the wines of the third harvest. At bottling, MW favored the formation of pyranoanthocyanins and tannin-anthocyanin dimers. Tannin extraction was not affected by MW just after application of this process, but improvements of 30, 20, and 10% on MW-treated wines of the first, second, and third harvest, respectively, were recorded at pressing. The formation of polymeric pigments during aging generally increased along with harvest date and was only favored in MW-treated wines of the first and third harvest, with preferential formation of small polymeric pigments, in accordance with enhanced anthocyanin extraction in these wines. Initial improvements of wine color upon application of MW in the wines of the first, second, and third harvest were of 275, 300, and 175%, respectively. Although these differences subsided or disappeared for the wines of the second and third harvest during aging, the wines of the first harvest treated with MW retained 52% more color than Control wines at day 150 post-crushing. Results suggest the MW treatment was more efficient in extracting and retaining phenolics and color when applied to unripe fruit. [ABSTRACT FROM AUTHOR]

A two-year study was performed to evaluate the effects of the timing of cluster thinning on Pinot noir grapes and wines in the central coast of California. Vines were thinned to one cluster per shoot at three selected time-points during the growing season, and fruit was harvested and made into wine. No consistent effect of cluster thinning was found in wine phenolic profile or color across a cool (2016) and a warm (2017) growing season. The growing season had a more significant effect than the cluster thinning treatment for most parameters measured. There was no detectable overall sensory difference between the non-thinned control wines and any of the thinned treatment wines. Based on current results, Pinot noir vineyards on the central coast of California can support crop loads that result in Ravaz Index values from 3 to 6 without concern for impacting ripening potential or negatively affecting fruit composition. [ABSTRACT FROM AUTHOR]

• Extended maceration applied for 1 and 6 months (EM) and addition of pomace (DP). • Color, anthocyanins, and polymeric pigments affected negatively by EM and DP. • 6 months EM increased tannins by 13-fold and 1.6-fold in Pinot noir and Zinfandel. • DP and 1 month-EM did not affect tannin extraction. • Tannins extraction during EM appears to depend upon tannin desorption. Pinot noir and Zinfandel wines were produced with traditional maceration (Control), and extended maceration for one (1 month-EM), and six months (6 months-EM). Addition of an extra amount of pomace during EM was also evaluated through a treatment referred to as Double pomace. The application of EM and Double pomace decreased the chromatic as well as the anthocyanin and anthocyanin-derived pigment composition of the wines. Large polymeric pigments were favored in EM and Double pomace wines, but the total polymeric pigment content was not improved by any of the winemaking treatments. The 6 months-EM wines showed a 13-fold (Pinot noir) and a 1.6-fold increase (Zinfandel) in tannins, respectively, relative to Control wines. However, the 1 month-EM and Double pomace treatments did not affect tannin levels, suggesting that in these wines, the extraction of tannins during EM may depend upon desorption of previously extracted tannins during extended contact time. [ABSTRACT FROM AUTHOR]