Evaluation of Zinfandel Heritage Selections

AVF Proj. ID: 318 / /Cat.: ,
Primary Investigator(s): James Wolpertby

Data were taken for the first time in 2005 on ?Phase 2? of the Zinfandel Heritage Vineyard which is the large, replicated group of 22 clones taken from the Phase 1 vineyard.

Objective(s) and Experiments Conducted to Meet Stated Objective(s):

  1. Viticultural evaluation of Zinfandel Heritage selections
  2. Evaluation of wine made from a select number a Zinfandel Heritage Selections.
  3. Viticultural and enological evaluation of Zinfandel Heritage Selections in the new replicated trial.

Summary of Major Research Accomplishments and Results (by Objective):

In consultation with Zinfandel Advocates and Producers? (ZAP) Research Committee, a decision was made to set aside objectives 1 and 2 in preference to Objective 3. Additional investment in data from the unreplicated vineyard and of small lot fermentations did not make sense in light of the better data and larger wine lots available. Objective involved the viticultural and enological evaluation of Zinfandel Heritage Selections in the new replicated trial.

Twenty-two selections were evaluated for yield components. Yields varied from 2.8 to 6.0 kg/vine. While clusters per vine are somewhat regulated (particularly in young vines relative to vine vigor) they still varied from a low of 14 to a high of 18. The

greatest difference in yield (as is typical for clones) was due to cluster weight, varying about two-fold, from 182 g to 374 g. Berries per cluster varied by about two fold as well, from a low of 89 berries to a high of 181. Berry wt values varied remarkably little from 2.0 to 2.2. Clones were picked on two dates September 9 and September 20. Berry sample Brix at harvest varied from a low of 22.6 to a high of 25.4. An attempt was made to harvest the plots at lower sugar values because of previous years? difficulties completing fermentations in high Brix juices. Values for pH with the Zinfandel at the Oakville Station Vineyards, were low ranging from 3.08 to 3.23 which was consistent with historical values, and TA levels ranged from 6.63 to 7.56.

Wines were made at the Ravenswood winery under the direction of Don Williams and Joel Peterson. Wine data will be available later in the spring. Pruning weight data will be taken later in the winter.

This larger trial will be the source of the most important data from the Heritage Vineyard, as the wine lots will be large enough to give more relevant experience with wines. However, it is too early to place a great deal of value on this data. As vines mature and additional years of data are collected, we will be better able to develop stronger conclusions about the zinfandel selections from the larger replicated trials with greater confidence.