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April 2017 WINES&VINES 19 WINE INDUSTRY NEWS For more information contact your sales representative or email us at info@seguinmoreau.com D avis, Calif.—The grape va- rieties grown in Califor- nia's warm Central Valley were chosen largely based on their overall popularity, growing quali- ties and tradition, not rigorous research. As a result, some variet- ies may not be optimum for the area's warm climate, particularly as the earth grows ever warmer. To address this issue, Lindsay Jordan, the UC Cooperative Ex- tension's viticulture advisor for Madera, Merced and Mariposa counties in the San Joaquin Valley, has been conducting research on wine grape varieties for warm- climate wine production. J o r d a n p r e s e n t e d a b r i e f summary of her findings Feb. 13 at the Current Wine and Wine- grape Research seminar held at the University of California, Davis. She noted that nine vari- eties accounted for about three- fourths of the total 2015 crush, but opportunities may exist for other varieties. "We can grow quality wine grape varieties in the San Joaquin Valley," Jordan said. "We just need to find those naturally suited to the characteristics we want." Desirable characteristics in- clude good yield potential, adapt- ability to mechanization/minimal management, appealing flavor and wine-quality attributes like aro- matic or high-acid whites and aro- matic/flavorful or colorful reds. Jordan is conducting trials at the Kearney Agricultural Center in Parlier, Calif., and as of 2016, the test varieties included 25 red varieties and 26 white varieties. Fiano, a white wine variety originating from southern Italy, exhibits high acid and good flavor, for example. It was consistently a high-quality wine producer and had 7.0-9.2 titratable acidity over four years. It ripened early with an average calculated yield over four years of approximately 9.4 tons per acre, with a calculated average of 5.2 tons per acre in 2016. It also exhibited no rot. Morrastel, a European red variety that is a crossing of the vinifera grape Graciano, ripens fairly early (Aug. 22- Sept. 6). Its average calculated yield over four years was approximately 11.1 tons per acre (8.4 tons per acre in 2016) with low inci- dence of rot, including none in two years. The researchers applied me- chanical pruning to part of the vines for the past few years to see if yields could be increased, and they were: The yield increased to 13.7 tons per acre compared to 8.4 for spur pruning. The incidence of rot was sig- nificantly lower for most mechani- cally pruned vines and the yields were higher. In Arneis, for exam- ple, rot was 3% for mechanically pruned vines compared to 60% for spur pruned, even though yield was 18.3 tons per acre compared to 11.7 tons per acre. —Paul Franson Choosing Better Grapes for Warm Climates " We can grow quality wine grape varieties in the San Joaquin Valley. We just need to find those naturally suited to the characteristics we want." —Lindsay Jordan, University of California Cooperative Extension