2025 Post-Veraison in Pennsylvania - September 9

Report #2: samples taken the week of September 1, 2025

This is the second weekly report for the third season of Post-Veraison in Pennsylvania (PVIP), a grape maturation reporting system across Pennsylvania vineyards. Reports will 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; thanks to 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 and do not necessarily represent the exact maturity of the cultivars due to sampling methods. These reports are meant to provide updates on general trends; some fluctuation from "expected ripening trends" in metabolites will be expected. But trends over time should give a good depiction of grape maturation across Pennsylvania.

Of the counties from which fruit composition was measured for this report, Cabernet franc was more mature in Fayette and Chester Counties relative to Erie and Lehigh Counties; while Brix and pH from Snyder were on par with maturation patterns in. Fayette and Chester Counties, the TA in Snyder was the highest reported from last week (Table 1). While Brix levels from the week of September 1 were greatest in Fayette County, Brix increased more so in Erie (+2.2), Chester (+3.3), and Snyder (+3.7) Counties. Titratable acidity (TA) drastically dropped in Erie from last week's report (-14.85 g/L), resulting in lower TA in Erie relative to all other counties; relative to last week's report, TA increased only in Snyder County. This is the first report of Cabernet Franc fruit chemistry from Lehigh County, where numbers currently show the least advanced fruit maturity relative to other counties. Relative to the second week's report from 2024 (collected during the week of September 2), Brix levels in Erie, Fayette, and Snyder were lower in last week's (2025) samples. Compared to last week's (2025) samples, TA values were relatively greater in Erie (when TA was 9.15 g/L), but relatively lower in Fayette (when TA was 4.80 g/L) and Snyder (when TA was 8.25 g/L) during the week of September 2, 2024. Thus, overall, Cabernet franc maturity in 2025 currently appears to be a bit delayed relative to 2024.

Chambourcin, a later ripening, red-berried hybrid cultivar, generally had lower Brix and pH, and greater TA, relative to Cabernet franc grown in the same vineyards. In Chester County, Chambourcin Brix increased by 2.9 and TA dropped by 1.65 g/L relative to last week’s report, and in Fayette County, Brix increased by 1.7 and TA dropped by 2.77 g/L relative to last week's report. While Chambourcin TA precipitously dropped in Erie relative to last week’s report (-6.45 g/L), the low Brix and pH and high TA from this location revealed that it was still behind in maturity relative to other locations. Chambourcin fruit composition from Snyder County changed the last relative to last week's report. Chardonnay pH and TA were lower, and Brix was greater, in Lehigh relative to Snyder County; however, relative to last week’s report, Chardonnay Brix increased (+4.5) and TA decreased (-2.1 g/L) in Snyder County. Riesling was most mature in Fayette, where it gained 3.8 Brix and dropped 3.75 g/L TA relative to last week's report. Despite ripening at the fastest rate (experiencing a 6.6 Brix increase and 15.15 g/L TA decrease relative to last week's report), Riesling in Erie remained less mature than Riesling in Chester and Fayette Counties. While Vidal blanc in Erie experienced a 3.3 g/L reduction in TA, while Brix remained similar, and pH was lower compared to last week's report, in Snyder County, Vidal blanc pH and TA remained relatively stable, while Brix increased (+4.0) relative to last week's report.

Table 1. Fruit composition [soluble sugars (Brix), pH, and titratable acidity (TA)] for Cabernet franc, Chambourcin, Chardonnay, Riesling, and Vidal blanc during the week of August 25 and September 1. NOTES: (1) fruit composition from Snyder County was not measured in this report; (2) higher Brix and pH and lower TA are generally associated with more advanced maturity.

Pennsylvania stakeholders have already reported harvest for some cultivars in the 2025 vintage, including Albarino, Aromella, Cayuga White, Chancellor, Chardonel Chardonnay, Marquette, Pinot noir, Sauvignon blanc, and Seyval blanc. In some cases, cultivars were picked at relatively low Brix and pH and high acidity to produce sparkling or rosé wines. 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.