Alternative Wine Grape Cultivars for the San Joaquin Valley
A San Joaquin Valley wine grape trial 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 second year of field data collection in 1997 is summarized as follows: 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 had large berries of poor composition (high pH and low TA); Dolcetto had excessive cluster numbers which developed poorly (berry shrivel and drop) with the sparse vine canopy. Delayed fruit maturation with a high yield in Sangiovese demonstrates the need to adjust crop load in this large-clustered cultivar. Mouvedre was less promising than Sangiovese due to 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 again had heavy clusters with high rot and the poorest fruit composition. French Colombard, the standard, had the highest yield of the most balanced fruit composition, as might be expected. Muscat Cultivars ? Muscat blanc and Orange Muscat were again early-ripening. Malvasia Bianca and Aleatico were the highest and lowest yielding, respectively. The opposite was true in 1996, suggesting an >alternate bearing= response. Bunch rot was again high in Aleatico. Orange Muscat, Muscat blanc, Malvasia Bianca and Muscat Hamburg show the most promise but with a need to manage potential bunch rot. Aleatico has been the least suitable of the cultivars Fay Triplett Wine Cultivar Selection ? Sixteen black selections were in full production for data collection in 1997. Four had a high bunch rot incidence while the others were low-moderate to rot-free. Eleven cultivars ripened in mid September; four ripened exceptionally late and may not have ever achieved full-ripeness. Most of the selections had very favorable titratable acidity levels for the San Joaquin Valley. Nine of the selections were above 0.80 g/100 ml at harvest. Most of the fruit pH=s were also very favorable, with 8 selections showing pH levels below 3.5. Some 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.