Spotted lanternfly (Lycorma delicatula White; SLF) is a phloem‐feeding planthopper invasive to the Eastern United States that can feed on a range of wild and cultivated plant species. Since its 2014 introduction in the United States, large infestations and subsequent economic damage have been reported in cultivated grapevines, but no studies have detailed grapevine physiological responses to SLF phloem feeding. This study investigated grapevine‐SLF interactions, detailing how different infestation densities affect leaf gas exchange and end‐season concentrations of nonstructural carbohydrates and nitrogen in vegetative and perennial tissues of two Vitis species. Effects on fruit ripeness parameters and dormant bud freeze tolerance were examined, in addition to other year‐after effects. Phloem feeding by low densities (≤4 SLF shoot⁻¹) had minimal effects, whereas greater densities (5–15 SLF shoot⁻¹) increasingly affected carbohydrate and nitrogen dynamics in both Vitis species. Phloem feeding substantially affected starch and, to a lesser extent, total nitrogen concentrations of woody roots. Prolonged exposure strongly reduced leaf gas exchange. We conclude that intensive late‐season phloem feeding by large adult SLF population densities (≥8 SLF shoot⁻¹) can induce carbon limitation, with the potential for negative year‐after effects in cases of severe belowground carbon depletion. This work presents novel insights into SLF‐grapevine interactions, identifies avenues of future SLF‐plant research, and assists the development of action thresholds for SLF management in vineyards.

Background and goals Early leaf removal (ELR) is a canopy management practice that can reduce bunch rot and improve fruit maturity by modifying cluster architecture and fruit zone microclimate. The goal of this study was to identify an ELR threshold that balances improvements to fruit quality and reductions in yield for a highly vegetative and high-yielding Vitis vinifera cultivar grown in the eastern United States, Grüner Veltliner. Methods and key findings Over two consecutive years, we applied a wide range of ELR severities (three to 12 leaves per shoot) at trace bloom (Eichhorn-Lorenz [E-L] stage 19) and evaluated relationships between increasing ELR severity and fruit set, yield parameters, fruit maturity, bunch rot, and juice volatile composition at harvest. In the first year, increasing ELR gradually reduced fruit set, subsequently lowering yield via reducing berry number and cluster weights. Additionally, ELR increased fruit ripeness while reducing rot incidence. However, extreme ELR (10 to 12 leaves per shoot) negatively affected inflorescence floret number and fruitfulness in the following year. In the second year, only high ELR severities (eight to 12 leaves per shoot) reduced yield parameters, and improvements in fruit ripeness or bunch rot were not observed, likely because of poor weather conditions during fruit ripening. The impact of increasing ELR severities on juice volatile composition was largely limited to benzaldehyde (a volatile phenylpropanoid), which was negatively affected by ELR in both years. Conclusions and significance Removal of six to eight leaves per shoot appeared to be the optimal ELR severities for grapegrowers seeking crop management and rot reduction for high-yielding cultivars like Grüner Veltliner. However, as reported in the second year of this study, the effects of ELR may vary by year and be limited by unfavorable weather conditions.

The influence of cultural and environmental factors on the sensory and chemical profiles of wines has been the subject of research investigation for many years, and an examination of these relationships can help determine whether wine regional trends exist. The present study investigated the chemical and sensory factors that drive regional differences in Pennsylvania Grüner Veltliner wines through a controlled winemaking study across two vintages in 2018 and 2019. Descriptive analysis was used to identify key sensory attributes of Pennsylvania Grüner Veltliner. Intensities of these attributes were evaluated in wines vinified under identical conditions from grapes harvested across nine Pennsylvania vineyards. Chemical profiles of finished wines were examined through volatile, phenolic, and color analyses. Significant sensory differences were found between wine regions, with some trends consistent across both vintages; however, regionality based on compositional analyses was less clear. As the first study to examine Pennsylvania Grüner Veltliner wines sensorially, results revealed sensory characteristics that can be useful for wineries and their tasting room staff in marketing these lesser-known white wines to wine consumers as the variety grows in popularity in the state.

Background and goals The spotted lanternfly (SLF), Lycorma delicatula White, is an invasive sap-feeding planthopper that can negatively affect grapevine carbon assimilation and allocation, but it is unclear if such negative effects persist postinfestation. This study examined whether adult SLF feeding affects carbon allocation after SLF removal, with the aim to determine if starch storage in young vines was negatively affected by prolonged adult SLF feeding. Methods and key findings ¹³C pulse labeling was used to measure ¹³C content of vegetative tissues in young, container-grown Cabernet franc grapevines. We measured total nonstructural carbohydrates in stems and roots. Feeding by SLF affected carbon allocation: SLF-infested vines had about two times greater ¹³C content in stems and over four times less ¹³C in roots than control vines, 12 days after SLF removal. We confirmed that SLF feeding can inhibit carbon allocation to roots, as demonstrated via reductions in root ¹³C. Conclusions and significance This study demonstrates that the effects of adult SLF feeding on carbon allocation may persist following SLF removal, suggesting that carbon reserve refilling may be limited following substantial late season feeding. These results highlight the importance of controlling the exposure time of vines to high populations of adult SLF to avoid negative effects on carbon allocation and storage.