Excellent quality Zinfandel wines are made from “old vines” in California. Often the source of wood for these vineyards is unknown. It is unclear whether these vineyards are different selections or clones of Zinfandel, or if they produce superior quality because of age, vineyard site, stress, viticultural or management differences. Virus disease symptoms, especially Leafroll have long been associated with many “old vines”. As laboratory testing for virus disease becomes more sophisticated even “asymptomatic” popular selections prove to be diseased. While the University of California and FPMS continue to promote certified stock, there is still strong industry interest in duplicating the success of “old vine” selections of Zinfandel, regardless of virus status or proven performance outside of the origin vineyard. By growing these selections in one location under uniform cultural practices, we will be able to evaluate any differences in these field selections.
A research block was established Amador County. In 1998, budwood was collected from nine “old vineyard” Zinfandel selections in Amador, Calaveras, and El Dorado Counties. Primitivo was also collected since there is growing interest in this cultivar. Wood was collected from 4-5 vines that appeared to be free of any virus symptoms. The wood was grafted onto St. George rootstock. Plants were grown during the summer at Sunridge Nursery in Kern County and the research vineyard was planted in March 1999. Selections include: Aparicio, Dal Porto, Deaver, Eschen, Upton, Ghirardelli, Higgins, Lubenko, Primitivo, Steiner (same Source as Grand Pere).
Each plot consists of 32 vines (4 rows x 8 vines) and each plot is replicated in 8 blocks across the 3 acre field. The blocking is laid out to follow soil types. Large plots were established so that wine samples could be made from the selections.
In March 2001, the first pruning weights were collected from 4 data vines per plot. Pruning weights will be collected each year to determine vine vigor. Other data to be collected includes; clusters/vine, vine nutrient status (beginning in 2003), and harvest data including; yield, berry weight, cluster weight, brix, titratable acidity, pH.
When vines are mature and yielding sufficient fruit, wine will be made from the plots. Fruit from all 256 vines of each selection will be harvested, divided and small wine lots will be made by two Amador County wineries. Sample wines will be evaluated.
Vines will be monitored for virus symptoms and PCR testing will be conducted as time and expense allow.