Joel Peterson on the Zinfandel grape
This show was published 09 March 2007
Joel Peterson is founder of Ravenswood, the largest producer of Zinfandel in the world. In this second interview with Joel we discuss the latest genetic research into the origins of the Zinfandel grape.
The research looks back at Zinfandel and shows that the grape is genetically the same as Primitivo but a different clonal variation. The researchers studied grapes in Croatia and found the grape Zirit clagingansie to be genetically identical to Zinfandel and to Primitivo but unlike Primitivo it was early ripening, more like Zinfandel.
This grape went from Croatia across the Adriatic to Italy in the early 1800s and was known as Primitivo. It then arrived in California via a collection from Austria.
The Zinfandel Heritage Vineyard is a 10 year project with UC Davis. They have collected number of vines planted before 1920 and are currently studying 90 different Zinfandel Clones of which they have narrowed the range to 20 interesting variations. Early indications are that there are at least 3 distinct variations based on very early data. The hope is this work will help improve planting in future, matching the correct clone to the right site.
Zinfandel is extremely important to California. It arrived in California in 1854 and by 1880 there were 30,000 acres planted. Today there are 50,000 acres. Zinfandel is clearly California's grape in terms of its fit with the environment - it is the right grape for the right place. It's big weakness is Zinfandel's uneven ripeness, picked too late you get wines with too much alcohol, while picked too early the wine is too light. When the vine is young it can yield 8/9T/acre. When very old still productive at 3T/acre. It tends to rot easily in high humidity or rain, but in California humidity is low so this doesn't happen very often.
The old bush vines are trained using the goblet system which is perfect for the larger Zinfandel grape clusters. The standard trellis system causes grape clusters to hang on top of each other so they don't get the right light and tend to rot more easily. The grapes are hand harvested and new plantings are trained in the same way as old vines and also hand harvested.
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