Alternative Wine Grape Cultivars for the San Joaquin Valley

A San Joaquin Valley wine grape trail block was established in 1992 at the UC Kearney Agricultural Center to evaluate potential Italian and Rhone regional cultivars of limited experience to the San Joaquin Valley. A collection of the most promising selections from Fay Triplett’s wine cultivar breeding program was included in another trial, as well as a collection of Muscat cultivars for premium dessert wine production. The first year of field data collection in 1996 is summarized as follows: 1. Rhone and Italian Cultivars ? Shiraz, Nebbiolo, Sangiovese, and Mouvedre showed the most promising characteristics of the black cultivars. Cinsault and Dolcetto were the least promising. Grenache and Barbera served as standard comparisons. Shiraz and Nebbiolo were comparatively early ripening, moderate yielding, small-berried, free of bunch rot, and of good fruit composition. Conversely, Cinsault and Barbera had large berries, high cluster numbers and yields and were late ripening with the highest bunch rot. Sangiovese also ripened later due to its high yield and had intermediate bunch rot incidence and fruit composition characteristics. Mouvedre was less promising than Sangiovese due to heavy clusters, more bunch rot, and poorer fruit composition. Viognier showed the most promise of the non-standard white cultivars tested, with early ripening small berries, low bunch rot, and satisfactory yields. Sauvignon blanc performed well except that it had a higher rot potential than Viognier. Marsanne was a disappointment due to heavy clusters with high rot and the poorest fruit composition. French Colombard, the standard, had the highest yield and best fruit composition, as might be expected. 2. Muscat Cultivars ? Muscat blanc, Orange Muscat, and Muscat Hamburg were somewhat similar in ripening period (mid August), yield and fruit composition. The exception was Muscat blanc’s higher titratable acidity and bunch rot incidence. Aleatico ripened almost one month later with a much heavier crop and more bunch rot that the others. Malvasia Bianca was comparatively low yielding due to low cluster numbers. A search for a better clone of Malvasia Bianca should be an industry priority. 3 Fay Triplett Wine Cultivar Selection ? sixteen black selections were in full production for data collection in 1996. Four had a fairly high bunch rot incidence while most of the others were almost rot-free. Nine cultivars ripened in mid to late August; five ripened in mid to late September while two were only 15.9 and 18.8 degree Brix by September 27. Most of the selections had very favorable titratable acidity levels for the San Joaquin Valley. Twelve of the selections were above 0.75 g/100 ml, 6 of which were above 1.0 g/100 ml. Most of the fruit pH’s were also very favorable, with 9 selections showing pH levels below 3.5. Many of the selections showed excellent viticultural characteristics such as open canopies, small berries and loose clusters, good fruit color, and varietal flavor characteristics. One more year of fruiting data will be collected in order to determine the best selections for wine making evaluation in 1998.