Evaluation of Selected Mediterranean Wine Grape Cultivars and Clones in Lake and

During the year 2000, phenological and harvest data were taken from three Mediterranean Winegrape Cultivar Test Plots in Lake and Mendocino Counties. Results indicate that there are tremendous differences in budbreak, yield and harvest dates between the cultivars and locations. In Lake County, all cultivars reached ripeness (23.5 brix) in the Red Hills plot, whereas only the earliest cultivars reached ripeness in the Highland Springs plot. This can be explained partially by the warmer climate of Red Hills, but also by the smaller crop size and lighter soils in that plot compared to larger crops and heavier, cooler soils found in Highland Springs. In general, the ripening sequence is as follows: Pinotage, Barbera, Dolcetto, Grenache, Nebbiolo, Cabernet sauvignon, Sangiovese, Cinsault, Syrah,. Harvest occurred from Sept. 15, to Oct. 27th, 2000. At Highland Springs, only Pinotage fully ripened during the 2000 harvest. At the UC Hopland Research and Extension Center, there is a greater number of cultivars being tested. Ripening sequence this year was Pinot gris, Viognier, Tempranillo, Cinsault, Grenache, Syrah, Sangiovese, Dolcetto, Viognier (“Bonny Doon” clone), Fiano, Freisa, Mourvedre, Nebbiolo, Corvina, and Aglianico. Canailo nero, Montepulciano and Marsanne failed to adequately ripen, and were lost due to rain damage. A research progress report of the UC HREC data is being prepared for a California Agriculture magazine issue featuring the 50th anniversary of the UC Hopland Research and Extension Center. In nearly all cases, quality of the fruit was quite high, showing adequate sugar (23.5 brix), good acidity, and very little rot. For the combined trials, 22 lots of wine are being fermented. It is clear that there are many cultivar options for quality winemaking in Lake and Mendocino Counties. We were not able to plant a clonal trial of Syrah during this season. Vines will be planted in 2001. Evaluations of 5 Syrah clones were made from commercial plantings at McDowell Valley Vineyards. Clones include Syrah noir (“Hermitage” clone), Shiraz (UC clone #1), McDowell clone, CTPS #877, and CTPS #174. Significant differences in cluster size, shape and yield per vines were noted, as well as must chemistry. Separate lots of wine were vinified, and there are definite organoleptic differences between the clones. While not statistically valid, these observations are still helpful in assessing differences between the Syrah clones. Information from this survey will be presented at the ASEV Syrah Symposium in San Diego in June, 2001.

Evaluation of Wine Grape Cultivars and Selections for a Cool Maritime Climate

The primary trial was established in 2000 at two vineyard plots, one located at Mount Vernon research station and one located with Louis Dailly at his vineyard near Concrete. A randomized block of 3 replications, with 5 plants per replication has been established. At the station site, plot size is 10′ rows with 6′ between plants, total area of the planting approximately 0.5 acre. The upriver plot is planted at 8′ rows with 6′ between plants. In addition, a preliminary evaluation, consisting of three plants per variety in two rows at each location, has been established to test certain other varieties/selections which can be added to the primary trial later if their performance warrants inclusion. A rootstock trial of Pinot Noir 2A has been planted in both locations, consisting of seven rootstocks plus self rooted plants, to test for earlier ripening potential. This trial includes five plants of Pinot Noir 2A on each rootstock, replicated three times, established at each plot location. Plants rooted in 1999 were planted in spring 2000. Irrigation lines, posts and wires have been installed and training vines will begin in spring 2001.

Evaluation of Winegrape Clones

This project evaluates 20 Pinot noir and 13 Chardonnay clones for their viticultural and enological attributes in production of base wines for sparkling wine production and five Merlot and three Malbec clones for their viticultural and enological attributes for production of red wine. Replicated plots of Pinot noir and Chardonnay clones have been established at Gloria Ferrer in Sonoma and of Merlot and Malbec at the Department’s Oakville Experimental Vineyard. Chardonnay mean harvest °Brix was 21.6 in 2000 and did not vary by more than 0.6 °Brix from the mean with the exception of the Wente clone that was harvested 1.2 °Brix above the mean. This compares with the three-year average that shows a mean harvest Brix of 20.8. The yield range was approximately 2x for the three-year data and in 2000. In 2000 clone 4 had a yield of 8.2 kg vine”1 and the Wente clone yield was 4.0 kg vine”l. For the majority of Chardonnay clones harvest date was correlated to vine yield with two notable exceptions. While clone 4 has the largest crop and latest harvest date, the harvest date appears to be delayed more than the yield would warrant when compared to the other clones. Likewise, the Wente clone with the lowest yield also has a much later harvest date than we would predict. These observations hold for both the 2000 and three-year data. Mean Pinot noir harvest °Brix for 2000 was 19.9. Harvest was completed over a 21-day period in 2000 and the two-year data shows a 19-day span. In both instances clone 4 was the first harvested and clone 780 the last. Yield ranged from 5.7 (clone 870) to 9.4 (clone 666) kg vine”1 in 2000. As in preceding years, Merlot clone FPMS 8 had the lowest yield (6.3 tons/acre) in the 2000 growing season compared to the other clones (9.2 to 10.3 tons/acre). The primary contributing yield component was berries per cluster (103 for clone FPMS 8 versus 151 to 164 for clones 1, 3, 6, 9) this was also consistent with past data. In 2000 clone FPMS 8 produced the smallest berries and second lowest number of clusters per shoot. Averaged over six years, clone FPMS 8 has produced approximately two thirds the yield of the other four clones due to smaller clusters caused by reductions in both number of berries per cluster and berry size. Mean yield for all Malbec clones was 4.9 tons/acre for the 2000 crop and was 40%above the average of the preceding 4 years (3.5 tons/acre). Clonal differences were evident in all components of yield except berry weight. In 2000, clone FPMS 08 was again the most fruitful in all components and produced 9.7 tons per acre compared to 4.1 and 2.2 tons per acre for FPMS 04 and 06. In each of the last four years, FPMS 08 has consistently produced the greatest crop and FPMS 06 has produced the least. Averaged over five years, yields were 3.0, 2.2, and 6.2 tons per acre for FPMS 04, 06, and 08 respectively.

Clonal Testing of Wine grapes in the San Joaquin Valley

This is an ongoing study to evaluate promising, virus disease-free FPMS clonal material for the San Joaquin Valley. Completion dates for past trials were: French Colombard and Chenin blanc (1994), Barbera (1995), and Muscat of Alexandria (1997), Grenache (1998), and Muscat blanc (1998). The Sangiovese trial was completed in 1999 with crop level comparisons. Data collection began with the Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel/Primitivo trials. These trials were planted with 6 clones each in 1997 in order to evaluate clonal differences in a warm climate region. Sangiovese. Clones 2 and 3 are recommended for warm climate sites, while Clone 4 is not recommended. Clone 4 was consistently of poorer fruit composition (lower T A, higher pH and the most bunch rot), even with an imposed lower crop level; most often it was of lowest yield during the 5-year study period. The differences between Clones 2 and 3 were fairly clear in this study, each having certain advantages and disadvantages. Clone 2 was more fruitful and often ripened later than Clone 3 (-1.3 °Brix at harvest over 4 years). This later ripening can be corrected with crop level adjustment, as demonstrated in the 1999 comparative crop level treatments. Clone 2 had the smallest berries, even with crop level adjustment; Clone 3 berry weights were always heaviest, sometimes with fewer berries per cluster. Thus, mean cluster weights were similar between Clones 2 and 3. Overall, it would appear that Clone 2 is preferable due to its smaller berry size. However, its higher fruitfulness may require more attention to crop level management to assure timely ripening of quality fruit. Cabernet Sauvignon. Berry weight, number of berries per cluster and cluster weight differences significantly influenced clone yield which, in turn, affected fruit soluble solids at harvest. Clones 8 and 22 were highest yielding, while Clones 2 and 24 were lowest; Clones 10 and 21 were intermediate. Clones 2 and 24 had the smallest berries and fewest berries/cluster. Merlot. Vine yields and cluster weights were similar among clones, and fruit composition and berry weight differences were minor. Zinfandel/Primitivo. The Zinfandel clones were all similar except for the smaller berries of Zinfandel 2; Zinfandel 3 had a lower bunch rot incidence as compared to Zinfandel 1 A. The Pnmitivo clones did not differ from one another. However, when compared to Zinfandel the Primitivo clones had smaller berries, fewer berries/cluster, and clusters of lower mass and earlier ripening and less rot (~3x less). Yields of Primitivo tended to be lower than those of Zinfandel. 54 Project Title: Clonal Testing of Wine grapes in the San Joaquin Valley (Continued) Chardonnav. Clone 4 was highest yielding, while Clones 6 and 37 were lowest, mainly the result of number of berries/cluster and cluster weight. Berry weight was highest in Clone 20 and lowest in Clone 4. Clone 4 had lower fruit soluble solids but higher TA and pH at harvest. The 1999 results of the ‘fighting varietals” – Cabernet Sauvignon, Merlot, Zinfandel and Chardonnay are preliminary, as they represent first crop data. However, it is interesting to note that significant clonal differences are demonstrated early in the study when crop levels are adjusted uniformly across clones for each cultivar. Thus, the differences reported are mostly the result of berry weight, berries/cluster and the final cluster weights.

Evaluation of Winegrape Clones

Pinot noir and Chardonnay. For Chardonnay, yields in 1999 were consistent with the 2-yr averages, in that Wente was the lowest at just over 3 kg/vine while 352 was among the highest at 5.2 kg/vine. Cluster number, berries per cluster and berry wt all played a role in yield differences. Cluster number varied from a low of 30 (clone 4) to a high of almost 44 (clone 352), berries per cluster from a low of 76 (clone 78) to a high of 107 (clone 4) and berry wt from a low of 0.94 (Wente selection) to a high of 1.59 (clone 4). Harvest in 1999 took place over a 9 day period from September 18 to 27. For Pinot noir, yield ranged from a low of 3.83 kg/vine (clone 13) to a high of 8.18 kg (clone 668). Cluster number varied from a low of 31 (clone 743) to a high of 54 (clone 2A), berries per cluster from a low of 74 (clone 13) to a high of 144 (clone 743) and berry wt from a low of 1.26 (clone 872) to a high of 1.57 (clone 13). Harvest occurred over a 17-day period from September 7 through September 24. Merlot and Malbec. Again in 1999, the major difference among Merlot clones was in the yield component of berries per cluster for clone 8, resulting in a significant decrease of more than 3 tons per acre. This trend corresponds precisely with the 5-year average. Despite the lower Brix of clone 8, it had the lowest Brix and highest pH both in 1999 and as a five-year average. The 1999 vintage was another difficult year for Malbec with yields on average being less than 4 tons/acre. Individually, significant differences could be seen among yields of the clones, with clone 8 showing 6.7 tons/acre versus 2.3 and 1.9 tons for clones 4 and 6, respectively. All yield components were involved including clusters per shoot, berry wt and berries per cluster. In 1999 the 11 OR rootstock showed a significantly greater yield than Malbec on 5C due to more clusters per shoot and heavier berries. There were few differences in fruit chemistry with the exception of significantly more potassium in Malbec 8 and all vines on 5C. Malbec values for the 4-year period show the dramatic yield differences among the years.

Clonal Testing of Wine Grapes in the San Joaquin Valley

This is an ongoing study to evaluate promising, virus disease-free FPMS clonal material for the San Joaquin Valley. Completion dates for past trials are: French Colombard and Chenin blanc (1994), Barbera (1995), and Muscat of Alexandria (1997). Trial blocks of 3 clones each of Grenache, Sangiovese, and Muscat blanc were established in 1993; data collection was initiated at harvest, 1995. Significant clonal differences have been measured over 3 or 4 years in these cultivars as follows: Muscat blanc. The Milan introductions, clones 3 and 4 have been distinctly better than clone 1, an older introduction into California. Clone 1 had fewer and heavier clusters with larger berries, less fruit yield, and more bunch rot. Overall, Clone 4 would be preferable because of its consistent high fruitfulness (3 years) of smaller clusters (1997 only) with less rot and earlier fruit maturation (compared to Clone 3), Clone 4 should be promoted, while Clone 1 should be discouraged, for all new plantings. Grenache. These were all California selections. The trial included a genetic comparison [Clone 1A (Gallo vineyard) vs. 3 (Jackson vineyard), both non-heat-treated] and a heat treatment comparison (1A vs 2, clone 2 being a 62-day heat treatment of Clone 1A). Genetic differences have been more apparent than heat treatment differences, with clone 3 producing the highest yield, lowest fruit maturation and most bunch rot. Clones 1 and 2 (heat treatment comparisons) were more similar, except for Clone 2’s heavier berries of slightly lower pH and higher TA and more bunch rot in one year (19988). Overall, Clone 1A would appear to be preferable due to its higher cluster numbers with smaller berry size and the least rot potential. For yield alone, Clone 3 would be preferable, but with some delayed fruit maturation and greater susceptibility to bunch rot due to heavier berries and clusters. Sangiovese. This cultivar demonstrated distinct clonal differences, with Clone 4 showing the least promise due to poor fruit composition (low TA and high pH), high bunch rot incidence, and low total anthocyanin content of experimental wine. Clone 2 may be preferred over Clone 3 due to its smaller berries and higher vine fruitfulness and yield. However, crop load management would be more important in Clone 2 as its fruit maturation was delayed as compared to less fruitful Clone 3. Further work is planned to determine if crop load adjustment of Clone 2 favors its fruit composition while retaining smaller berry size as compared to Clone 3. Experimental wine lots made from the clones in 1997 demonstrated minor differences in wine making or quality characteristics. Clone 4’s musts and wines were of lowest acidity and highest pH which were reflective of its harvest berry sample analyses. All wine samples were fairly low in color intensity. The Muscat blanc and Grenache trials are now complete. One more year of study with Sangiovese is anticipated to study crop load comparisons. This will determine under what conditions Clones 2 or 3 should be recommended for the best fruit composition with optimum yields. Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel/Primitivo trials were planted in 1997 at the request of the AVF Research Committee. Six clones of each cultivar will be studied for comparison under warm climate conditions.

Evaluation of Merlot and Malbec Clones

Data collected in 1998 in Merlot showed similarities to previous years. Clone 08 had the lowest yield (5.3 kg/vine) as a result of fewer berries per cluster and smaller berries. It also had the greatest pruning wt (2.4 kg/vine) as a result of heavier, not more, shoots. Clones 01, 03 and 06 were very similar in yield (about 7 kg/vine) but in growth FPMS 1 had the least at 1.98 kg. With the lower crop and greater pruning wt, clone 08 had a much lower yield:prunings ratio (2.17) versus the other clones (2.9 to 3.7). These values are dramatically different from 1997 when with higher yields and lower growth ratios were in the 5 to 8 range. Wines were made in cooperation with Duckhorn Vineyards. All wines will be initially evaluated informally at the winery. Three clones of Malbec, FPMS 04, 06 and 08, were compared on two rootstocks, 5C and 110R. Malbec had a the disastrous fruitset in 1998 similar to what it had in 1996. Yields in 1998 were 1 to 5 kg/vine. Under normal conditions, clone 08 shows a tendency to over-crop but with the poor set in 1998 it was not thinned. At these extremely low yields, pruning wts ranged from a low of 2.8 kg/vine for 08 to about 3.5 kg for clones 04 and 06. Vines on 11 OR yielded significantly more than 5C (3.4 vs 2.2 kg/vine, respectively), primarily due to more clusters per shoot and more berries per cluster. Even with the better crop load, 110R had a half degree higher Brix than 5C. Only clone 08, especially on 110R rootstock, had economically sustainable yields in 1998 with an average across rootstocks of 4.0 tons per acre versus 1.3 for 04 and 0.8 for 06.

Evaluation of New Pinot Noir and Chardonnay Clones for Sparkling Wine

Only the 13 Chardonnay clones were harvested, as the Pinot noir vines were too variable to include in 1998. Chardonnay clones were harvested over a 7-day period from September 7 through September 14. Juice yield (adjusted for the differing amounts of fruit) ranged from 135 gallons per ton (Clone 132) to 173 gallons (Clone 4 and Wente). Fruit yields in the difficult fruit-set year of 1998 were similar among clones, varying only from about 5.1 to 6.4 kg/vine, except for Wente which yielded only 3 kg/vine. With the exception of cluster number, Wente was the most radically different in other yield components, having the lightest cluster (75 g), 40 to 50%lighter than other clones. This resulted from having somewhat fewer berries per cluster (89) and 40%smaller berries (84 g per 100 berries). Among the remaining clones, cluster weights generally fell into two groups, one at about 150 g (4, 75, 96, 121) and another at about 130 g (76, 78, 118, 134, 130, 131, 132). Triplicate fermentations of each Chardonnay clone were made at UC Davis and will be further evaluated in 1999.

Identifying Varieties and Clones by DNA Typing

In 1997 we conceived and founded the Vitis Micro satellite Consortium, a group of 18 cooperating grape research groups in 10 countries that are sharing the costs and labor to develop 100 to 200 new grape SSR DNA markers. Although we already have enough DNA markers for routine grape variety identification, these additional markers will be used for genome mapping and may also be of value for distinguishing closely related varieties and possibly for identifying clones. We were not able to initiate a proposed new approach to clone discrimination until late in the 1997-98 period because of insufficient funding but will actively pursue this avenue during 1998-99. Our cultivar database has continued to grow and now contains 111 cultivars that have been typed with 13 to 18 DNA markers. This geographically balanced database not only provides us with references against which to compare unknowns, but is also the basis for estimating the statistical probability that a DNA-based identification is correct. We have also developed a database of 300 French cultivars that we will keep separate for statistical purposes so as not to bias the original database geographically. This database will be useful for verifying the identity of new French vine importations and for identifying unknowns in California vineyards (see Carmenere below). In order to continue to investigate the hypothesis that Zinfandel is the Croatian variety Plavac Mali, we obtained three accessions of this variety from the Croatian island of Brae. As we had earlier found with two Plavac Mali accessions growing in our UC Davis collection, none of these three is identical to Zinfandel. They are, however, very closely related to Zinfandel. We now know that the variety Plavac Mali is not genetically uniform and contains several related sub-types. (We have detected three.) We think that we have not yet seen all the Plavac Mali sub-types and that analysis of additional Plavac Mali samples is warranted. If Zinfandel is found in Croatia, then we may have a source of needed clonal diversity for California Zinfandel. If Zinfandel is not found, then any attempts to market Croatian Plavac Mali wine as Zinfandel can be countered with strong scientific evidence. In collaboration with a visiting Chilean researcher, Dr. Patricio Hinrichsen, we investigated the identity of some vines in Merlot vineyards in Chile that have been identified ampelographically as the old Bordeaux variety Carmenere, as well as an FPMS vine originally labeled as Cabernet Franc but also suspected to be Carmenere. All were confirmed as true Carmenere by comparison to an authentic DNA reference obtained from Montpellier France (see French database above).

Evaluation of Merlot and Malbec Clones

Five Merlot clones were compared for a second year. In 1996, clone 8 was the lowest yielding clone and clone 3 was the highest. Pruning wts. were the converse, with 3 being lowest and 8 being highest. Shoot numbers did not differ, indicating that average shoot wt was the critical factor. Clone 8 also had the lowest cluster wt and fewest berries per cluster. Cluster numbers did not differ in 1995 but in 1996 clone 8 had the lowest number while others did not differ. Clones 8 and 9 were higher in Brix than the other three clones, although TA did not differ. K+ levels tended to mirror pH values with higher K+ being associated with higher pH. With respect to wines, no significant differences were seen with regard to anthocyanins. Wine TA was lower for clone 8. Wine pH differences were similar to those for juice values. VA was well below threshold sensory values. Ethanol values were small, as predicted given the small Brix differences seen at harvest. Significant differences were seen in all co-pigmentation values including the amount of anthocyanin in copigment form, amount of free anthocyanin and amount of polymeric anthocyanin, with clone 8 being highest in copigment and free while being lowest in polymeric form. Malbec clones were not harvested in 1996. The rains and cool weather during bloom, as well as severe pruning designed to correct some training errors, resulted in disastrous fruitset. Only about 400 lbs of fruit were harvested from the entire 1.4 acres. Therefore, the data were meaningless. Initial observations in 1997 seem to mirror those in 1995 with clone 8 have the appearance of more and heavier clusters than that of clone 4 or 6.