Aims: Under global warming, the desynchrony between technology maturity and phenolic maturity of wine grapes is a worthy concern. Late winter pruning (LWP) has been proved to be an effective way to delay the grape phenological stages. The aim of this study was to evaluate the effects of LWP at different phenological stages (based on Baillod & Baggiolini system) on the delay of the grape ripening, on vine yield components as well as on berry composition, among others, the anthocyanin to sugar ratio. Methods and results: The two-year (2015 and 2016) trial was conducted in Rioja wine region (North of Spain) on Maturana vines and in each year, four pruning treatments were carried out taking apical buds/shoots as reference: (1) winter pruning at stage A (WPA; dormant bud); (2) LWP at stage C (LWPC; green shoot tip) in 2015 and at stage F (LWPF; inflorescence clearly visible) in 2016; (3) LWP at stage G (LWPG; inflorescences separated); (4) LWP at stage H (LWPH; flowers separated). LWPC failed to delay the late phenological stages and did not exert important influence on vine yield and berry composition. LWPG and LWPH succeeded to delay all the phenological stages of grapes to a great extent and created a considerably cooler and longer ripening period compared to WPA. Vine yield was not affected by LWPF and was reduced significantly (averagely by 41%) by LWPG. LWPH lead to great losses in yield (averagely by 67%), especially in 2015. LWPG did not change the fruit composition while LWPH increased the ratio of anthocyanin to sugar and helped to maintain a relatively high level of acidity in berries. Conclusions: The primary cause of the decline in production seems to be the losses of flowers and/or the reduction in fruit set percentage in the current season, instead of the losses in inflorescences within buds in the previous season. For Maturana grapes, LWP after the stage F would reduce the vine yield and could be applied as an alternative to the time consuming cluster thinning to meet the needs of yield control. Delaying the winter pruning to stage H could improve the fruit quality in spite of the greater risk of botrytis and a serious decline in production.

The application of unmanned aerial vehicles (UAVs) in viticulture is becoming increasingly popular. To the best of our knowledge, there are no studies comparing the effects of UAV spraying to manual spraying in high-slope vineyards. The goal of this study was to evaluate the effects of UAV spraying on droplet average diameter, droplet area percentage, and droplet density for vines grown using vertical shoot positioning (VSP) and Y-shaped trellis systems and to compare them with the effects of manual spraying via an electric knapsack sprayer. The results showed that manual spraying led to the greatest area of droplets for the VSP trellis system, and the uniformity and penetration of droplets with the UAV spraying method were higher than those for manual spraying for this trellis system. Regarding the Y-shaped trellis system, the UAV spraying method yielded lower droplet diameters, higher droplet density, and better uniformity and penetration than manual spraying. Moreover, conducting UAV spraying twice showed no statistical differences in droplet area percentage compared to manual spraying, and the effect of UAV spraying even once was similar to that of manual spraying on the abaxial sides of the leaves in this respect. Our research indicates that UAV spraying was not very suitable for VSP trellis systems, but it could be a good alternative for Y-shaped trellis systems since it is safe and cost-effective by reducing labor, time, and the dosages of the solutions applied.

(1) Background: Beibinghong is a grapevine variety that is well distributed in Northeastern China due to its adaptation to extreme cold conditions and vine diseases. Nonetheless, Beibinghong wines are extremely acidic and rich in phenolic compounds. The aim of this research was to study the effects of leaf removal at véraison and foliar K⁺ applications on Beibinghong vines to reduce the acidity and increase their polyphenol content. (2) Methods: Beibinghong berries were harvested when they reached close to 20 °Brix, and the physicochemical parameters were determined. (3) Results: Leaf removal at véraison plus K⁺ foliar applications to Beibinghong vines decreased the titratable acidity and increased the total phenolic and phenolic acid contents compared with the control. Moreover, the titratable acidity in the Beibinghong berries was negatively related to their total contents of phenols, proanthocyanidins, and anthocyanins. (4) Conclusions: Leaf removal at véraison performed with foliar K⁺ applications to vines could be an interesting alternative for Beibinghong production under cold-climate viticulture because it allows for a decrease in the acidity and an increase in the phenolic content of the berries, without incurring the risk of sunburn.