2025 Post-Veraison in Pennsylvania - October 7

Report #6, Samples taken the week of September 29, 2025

This is the sixth weekly report for the third season of Post-Veraison in Pennsylvania (PVIP), a grape maturation reporting system across Pennsylvania vineyards. Reports consist of weekly grape ripening updates from cultivars that are planted widely across Pennsylvania (PA) vineyards (as based on feedback documented within Cultivars in the Commonwealth). Henceforth, PVIP reports will review the ripening patterns of some, or all, of the following cultivars: Cabernet franc, Chambourcin, Chardonnay, Riesling, and Vidal blanc. Due to the time required for grape samples to be shipped, processed, and measured, weekly reports will reflect maturation from the previous week. Participating stakeholders for the 2025 edition of PVIP manage vineyards in the following Pennsylvania counties: Chester, Erie, Fayette, Lehigh, and Snyder. We thank these stakeholders for their participation and collaboration on this project. If you have a commercial vineyard in Pennsylvania, please let us know if you are interested in participating in a future edition of PVIP.

Note that these fruit samples are sent in from commercial vineyards; due to sampling methods and other factors, the samples may not necessarily represent the overall maturity of each cultivar across the entire block. These reports are meant to provide updates on general trends; some fluctuation from "anticipated ripening trends" in metabolites will be expected. Nonetheless, trends over time should give a good depiction of wine grape maturation across Pennsylvania. To date, Chardonnay has been harvested in Lehigh and Snyder Counties, and Riesling has been harvested in Chester and Fayette Counties.

Primary fruit composition: soluble solids (Brix), pH, and titratable acidity.

Cabernet Franc samples collected on September 29 indicated that fruit maturity was highest in Fayette County, moderate in Lehigh and Chester Counties, and lowest in Erie and Snyder Counties (Figure 1). Compared to the previous week, Brix levels either minimally changed or decreased. For example, Brix dropped significantly in Lehigh County (-2.0) and Snyder County (-4.0), while changes in Erie and Snyder Counties were more moderate. Relative to last week, the pH increased by a range of 0.02 to 0.14 across Lehigh, Erie, and Chester Counties, but decreased drastically (-0.48) in Snyder County. The lowest titratable acidity (TA) values were measured in Erie County (5.70 g/L) and Fayette County (4.35 g/L). While TA minimally changed in Lehigh and Chester Counties relative to last week, it increased by 3.15 g/L in Snyder County, which parallels the decrease in juice pH observed from that location.

Note - the three counties that participated/are participating in PVIP in 2024 and 2025 are Erie, Fayette, and Snyder Counties. Average fruit composition from these counties is used to compare last year's and this year's editions of PVIP (except for this report, which averages across Fayette and Snyder Counties since grape samples were not received from Erie County). Relative to the sixth week's report from 2024 (samples collected during the week of September 20), last week's samples showed: lower average Brix (-1.6), lower average pH (-0.13), and lower average TA (-0.68 g/L). Except for the lower TA values, these differences suggest that Cabernet franc primary fruit composition in 2025 is again relatively delayed compared to the same period in 2024. This contrasts with last week's report, which indicated that 2025 trends were "advanced relative to 2024." It is possible that the rainy and cloudy weather from last week has slowed maturation, perhaps via rain uptake and subsequent dilution of soluble solids, as reflected by the decrease in Brix levels.

Based on primary fruit composition, Chambourcin was most mature in Fayette and Snyder Counties. Brix levels were relatively greater in Fayette County, while Snyder County fruit had the highest pH and the lowest TA (Table 1). Relative to samples from last week, Brix increased only in Fayette County (+1.0) and decreased in Chester County (-3.6) and Snyder County (-1.0). Chambourcin pH increased at all locations relative to last week’s samples; while the increase was minimal in Fayette and Chester Counties, a more pronounced increase was measured in Snyder County, where pH increased by 0.53. In contrast, pH marginally decreased in Fayette and Chester Counties. Relative to last week’s report, Chambourcin TA decreased at all locations: -2.10 g/L in Fayette County, -1.35 g/L in Chester County, and -5.1 g/L in Snyder County.

The only Riesling sample received last week was from Erie County; since no samples were collected from this location the week prior, comparisons with earlier data cannot be made. Vidal blanc maturity was relatively more advanced in Snyder County when compared to Erie County, as observed by the greater Brix and lower TA in Snyder County. The only Vidal blanc sample received from one site over the last two weeks was from Snyder County; when compared to the previous week's values, only modest changes in fruit composition were observed and the only metric that showed some advancement to maturity was a minimal decrease in TA (-0.30 g/L).

Pennsylvania stakeholders have reported harvest for the following cultivars in the 2025 vintage: Albariño, Aromella, Cabernet Dorsa, Cabernet Franc, Cayuga White, Chambourcin, Chancellor, Chardonel, Chardonnay, Gruner Veltliner, Marquette, Merlot, Noiret, Pinot grigio, Pinot noir, Pinotage, Riesling, Sauvignon blanc, Seyval blanc, and Traminette, Vignoles, Vidal blanc, and Zweigelt. If you have harvest updates you wish to be included in this report, please email them to viticulture@psu.edu.

The data in this report is possible due to the funding and support of the Pennsylvania Wine Marketing and Research Program. The authors and collaborators are grateful for the support.