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68 P R A C T I C A L W I N E R Y & V I N E YA R D July 2015 W I N E G R O W I N G clusters or berries that ripen earlier or later. Cuttings from these altered shoots can be propagated into vines and vineyards with the new characteristic. Genetic vari- ation is most commonly seen as changes in berry color or flavor, disease suscepti- bility/resistance, shoot growth behavior or sugar accumulation. 2013 harvest results One goal of this study was to identify such genetic variation that had occurred in selections of California Heritage Zinfandel. The results of the 2013 data were consistent with previous observations and analysis collected by Mike Anderson and Wolpert in the years 2005–12. Across the enological and viticultural traits of titratable acidity, malic acid, YAN, bud break scores, pruning weights and fresh berry weight, there were no significant differences found among the selections of Heritage Zinfandel or Primitivo. Significant differences were observed in five parameters in 2013. The Primitivo selection had a lower cluster weight (344.0 g) than all of the Zinfandel selec- tions (374.3–479.5g), and there were fewer berries per cluster. One heritage selection had a significantly larger clus- ter weight and therefore more berries per cluster. Differences for these traits among the traditional FPS selection and the other five heritage selections were not significant. The same Primitivo selection had a significantly higher Brix value (24.8°) on the same day of harvest than all of the other Zinfandel selections (22.7°–23.6°), and a higher pH (3.45) compared to the Zinfandel selections (3.31–3.42). Conversely, the heritage selection 89 had a lower Brix (22.7°) and lower pH Heritage Zinfandel selection 80 was selected from a San Joaquin County vineyard. PHOTO BY MICHAEL PENN Heritage Zinfandel selection 55 was selected from a Napa County vineyard. PHOTO BY MICHAEL PENN