Dossier Zinfandel: Zinfandel’s Origins Demystified

Dossier Zinfandel Panel
Discussion panel after the screening of Dossier Zinfandel: Dr Carole Meredith (right), David Gates from Ridge Vineyards (left), and Yountville former mayor in red.

Last thursday was the premiere screening of Dossier Zinfandel at the third annual Napa Valley Film Festival. Directed by Mika Barisic, the documentary tells the compelling story of Zinfandel, “California’s own grape,” and the search for its mysterious origins.

When Croatian-born winemaker Mike Grgich arrived in Napa Valley in 1958, he noticed that the Zinfandel vines looked familiar and very similar to Plavac Mali, a native variety from the Dalmatian Coast of Croatia. He was convinced at the time that Plavac Mali and Zinfandel were the same grape.

Mike Grgich
Mike Grgich at the Dossier Zinfandel reception hosted by Grgich Hills Estate

With his support, UC Davis professor and grapevine geneticist Carole Meredith started a collaboration with the University of Zagreb. In May 1998, she traveled to Croatia to meet scientists Ivan Pejic and Edi Maletic and the three of them started exploring the Dalmatian coast. Eventually, they collected 150 samples that Dr Meredith brought back to UC Davis so that they could be identified in her lab using DNA fingerprinting.

Carole Meredith
Carole Meredith at the Dossier Zinfandel reception

While Meredith’s team was able to confirm that the Italian grape Primitivo and Zinfandel were clones of the same variety, they found out that Plavac Mali was not a good match. Instead, they identified the Croatian grape as an offspring of Primitivo/Zinfandel.

It is only in 2001 that Pejic and Maletic finally discovered the correct match when they sampled an almost extinct indigenous grape called Crljenak Kaštelanski (Kaštela Red) in an old vineyard in Kaštel Novi in Central Dalmatia. Only nine Crljenak Kaštelanski vines were found in the vineyards. More vines known locally as Pribidrag were eventually discovered near the coastal town of Omiš. Finally, they were able to identify a 90-year-old dried Tribidrag leaf from the Natural History Museum in Split as being identical to Pribidrag/Crljenak Kaštelanski/Primitivo/Zinfandel.

There are references of Tribidrag being cultivated in Croatia as far back as the early 15th century. At the time, Tribidrag was an important part of the wine trade between Dalmatia and Venice, which makes Zinfandel one of the oldest grape varietals from which wine is still being made.

Ridge Vineyards played a crucial role in the import of the Croatian grapes to California via the Foundation Plant Services at UC Davis. After undergoing virus elimination treatment, these grapes are now available for planting. The Crljenak Kaštelanski clone is called Zinfandel 42.1 and the Pribidrag clones are called Zinfandel 43.1 and Zinfandel 44.1.

Meanwhile in Croatia, Zinfandel is back to its roots. Zinfandel, Primitivo, and virus-free Crljenak Kaštelanski from UC Davis are now planted side by side in an experimental vineyard where Pejic and Maletic are studying how each clone behaves on the same terroir and in the same climate.

David Gates
David Gates, Vice President, Vineyard Operations at Ridge Vineyards, and Frank at the Dossier Zinfandel reception