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. Data collection continued (third fruiting year in 2001) 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. A new Barbera trial was planted in 2000 and trained in 2001.

Chardonnay. Clone 4 was high yielding in 2001, as in 1999; its cluster numbers and yields were lower in 2000, suggesting an alternate bearing response. Clone yield differences in 2001could be largely attributed to differences in berries per cluster and cluster weight. While Clone 4 had the fewest clusters, they were the heaviest due to high berry numbers per cluster; its fruit composition was again among the best – – high soluble solids and TA, and low Ph. Clone 20 also tends to be high yielding, but with heavier berries of lower soluble solids. Clone 15 had the fewest berries per cluster and the lowest bunch rot incidence in 2001; it was also lowest yielding.

Cabernet Sauvignon. Clone 2 again had the fewest clusters and smallest berries. Clone 24 was also more similar to Clone 2 than the others. The others were similar to one another except for the heavier berries and higher fruit Ph of Clone 22. While the overall differences were not great, the trend toward smaller berries with Clones 2 and 24 and the larger berries of Clone 22 may be of importance to San Joaquin Valley growers. However, the smaller berry characteristics are accompanied with some sacrifice in yield, unless pruning practice can compensate for the lower cluster numbers in Clones 2 and 24.
Merlot. The Merlot clones showed significant differences in all of the measured parameters. Clone 11 produced the heaviest berries with the highest bunch rot. It also produced the highest fruit Ph in 1999 and 2000, all of which are undesirable characteristics for warm districts. Clone 14 again produced fewer clusters with smaller berries than some of the others, with corresponding lower vine yields and higher oBrix. Clone 10 was the most fruitful and had the highest fruit TA. It has also performed well in all yield and fruit composition parameters in previous years. Thus, Clone 10 has consistently shown good characteristics, while Clone 11 shows some unfavorable characteristics for warm climates. While Clone 14 has small berries, its lower yield is a disadvantage, unless this can be improved with higher pruning levels.
Zinfandel/Primitivo. Clonal differences were again not as distinct as they were in 1999 when the Primitivo clones had smaller berries, fewer berries/cluster and clusters of lower mass and earlier ripening and less rot as compared to the Zinfandel clones. However, the Primitivo clones continue to show some advantages over the Zinfandel clones in terms of higher cluster numbers, higher fruit {aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} soluble solids, smaller berry weights, and much less bunch rot in one clone, Primitivo 6. Primitivo 3 is again showing the highest yield potential of all of the selections, and with good fruit composition. Overall, clonal differences within the Zinfandel and Primitivo clone groups were small; they were greater between the two groups.
The clonal variations in response over time point to the importance of multiple year data collection in excess of 2 years of full production. At least 4 years of full production data are needed to determine longer term vine response.

PDF: Clonal Testing of Wine Grapes in the San Joaquin Valley

Clonal Evaluation of Cabernet Sauvignon Clones from Heritage, French, and Old California Sources

Funding was provided for nursery expenses in the first year of this work. Approximately 3000 cuttings of 110R rootstock were collected. Budwood from 20 different Cabernet Sauvignon clones from the FPMS collection, California Heritage sources and French ENTAV sources was collected and is currently being benchgrafted. The vineyard will be planted in a randomized design in Oakville, Napa Valley and data collection will begin in 2005/2006.

PDF: Clonal Evaluation of Cabernet Sauvignon Clones from Heritage, French, and Old California Sources

Clonal Evaluation of Cabernet Sauvignon Clones from Heritage, French, and Old California Sources

Funding was provided for nursery expenses in the first year of this work. Approximately 3000 cuttings of 11 OR rootstock were collected. Budwood from 20 different Cabernet Sauvignon clones from the FPMS collection, California Heritage sources and French ENTAV sources was collected and is currently being benchgrafted. The vineyard will be planted in a randomized design in Oakville, Napa Valley and data collection will begin in 2005/2006.

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 continued (2nd fruiting year in 2000) 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. A new Barbera trial was planted in 2000. Cabernet Sauvignon. Clones 2 and 24 again produced smaller berries and clusters than the others, as in 1999. This corresponded with lower yields and earlier fruit maturation. These characteristics tend to be more prevalent in Clone 2. The other clones – 8, 10,21 and 22 – were all similar. Merlot. The Merlot clones showed significant differences in fruitfulness, berry weight, total vine yields, and fruit composition. Mostly, the differences were small. Some noteworthy responses included: heavier berries of lower pH in Clone 11; and lower vine yields from Clone 14 due to fewer clusters and smaller berries than some of the others. In contrast. Clone 10 produced 40{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} more yield than Clone 14 and with similar berry weight and fruit composition. Overall, Clone 10 performed very well, similar to Clones 3 and 9, except that it also produced smaller berries. Zinfandel/Primitivo. Clonal differences were not as distinct as they were in 1999 when the Primitivo clones had smaller berries, fewer berries/cluster and clusters of lower mass and earlier ripening and less rot as compared to the Zinfandel clones. The Primitivo clone vine yields also tended to lower than those of Zinfandel in 1999. In contrast, the Primitivo clones tended to produced higher harvestable yields than those of Zinfandel in 2000, possibly due to less rot per cluster. Fruit soluble solids were higher in P3 and P6 as compared to 1A and 3. This is similar to the 1999 data showing earlier fruit maturation in the Primitivo clones as compared to Zinfandel. Titratable acidity was also higher in several of the Primitivo clones (P5 and P6) as compared to Zinfandel 2 and 3. Overall, clonal differences within the Zinfandel and Primitivo clone groups were small; they were greater between the two groups. Chardonnay. Significant clonal differences were again measured in 2000, but the data is too preliminary to demonstrate important or consistent effects. For example, Clone 4 of outstanding performance in 1999, was of lower yield in 2000, the result of fewer clusters per vine. Vine yields were highest with Clones 15, 18, and 20 and lowest with Clones 4, 6, and 37. Yield differences could be largely attributed to differences in clusters/vine and/or cluster weight. Fruit maturation was largely influenced by total fruit weight. Clone 20 again produced the heaviest berries while Clone 6 produced the lightest clusters. The 2000 results of these trials are preliminary. They represent two years of data collection, the first of which was the 3rd leaf vine data in 1999.

Clonal Testing of Wine Grapes in the San Joaquin Valley

The San Joaquin Valley wine cultivar clonal evaluation study was initiated in 1987. It is an ongoing study to evaluate the most promising, virus disease-free clonal material being held or introduced as FPMS source material. French Colombard, Chenin blanc, and Barbera were completed in 1994 and 1995. Trial blocks of 3 clones each of Grenache, Sangiovese, Muscat blanc, and Muscat of Alexandria were established in 1993; data collection was initiated at harvest, 1995, in these new trials. Significant clonal differences have been measured over 3 years in all of the 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. Clone 4 was of higher fruit maturation than clone 3. Thus, clone 4 is the best performing selection at this point in the study. Grenache. These are all California selections. The trial includes a genetic comparison (Clone 1A vs. 3, both non-heat-treated) and a heat treatment comparison (1A vs 2, clone 2 being a 62-day heat treatment of Clone 1 A). Genetic differences have been more apparent than heat treatment differences, with clone 3 producing the highest yield, lowest fruit maturation and most bunch rot. Differences among clones 1A and 2 have been minor. While clone 2 has slightly better fruit composition, its rot potential was similar to Clone 3. Clones 1A and 2 are fairly comparable at this point. Sangiovese. This cultivar continues to demonstrate rather distinct clonal differences, with Clone 2 continuing to show the greatest promise due to its smaller berry size and high vine fruitfulness and yield. Clone 3 has the heaviest berries, fewest clusters, and lowest yield. Clone 3’s earlier ripening could be attributed to a lower crop load, as compared to Clone 2. Clone 4 has the poorest fruit composition and most bunch rot. Muscat of Alexandria. The California selection A3 has out-yielded both its Australian counterparts – J2 and G5 – with comparable fruit composition. Differences between the Australian clones were minor, with J2 having smaller berries than G5, overall. A3 was the most fruitful and vigorous, accounting for its high yield potential and fruit ripening capabilities. One more year of data collection in these trials is anticipated in order to determine consistency of differences over time. The Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel trials were planted in 1997 at the request of the AVF Research Committee. Six clones of each cultivar are to be compared for ‘fighting varietal’ data under warm climate conditions.

Evaluation of Merlot and Malbec Clones

Data collected in 1997 in Merlot showed similarities to previous years. Clone 08 had the lowest yield (8.0 kg/vine) as a result of fewer berries per cluster and smaller berries. It also had the greatest pruning wt (1.5 kg/vine) as a result of heavier, not more, shoots. Clones 01, 03, 06 and 09 were very similar in yield (about 10 kg/vine) and growth (1.2 to 1.4 kg/vine) and their components. With the lower crop and greater pruning wt, clone 08 had a much lower yield:prunings ratio (5.2) versus the other clones (7.2 to 8.2). Wines were made in cooperation with Duckhorn Vineyards. All wines exhibited a reduced character, as they did also in 1996, inhibiting the ability to draw distinctions among clones. Steps will be taken in 1998 to avoid this problem. If treatment lots improve over time, more distinctions will be made through sensory panels. Three clones of Malbec, FPMS 04, 06 and 08, were compared on two rootstocks, 5C and 11 OR. Malbec recovered from the disastrous fruitset in 1996 where all clones yielded less than 0.5 tons/acre. Yields in 1997 were 6.1 to 8.8 tons/acre in 1997. Under normal conditions, clone 08 shows a tendency to over-crop as a result of 2.37 clusters per shoot and average cluster wt 60{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} greater than either clone 04 or 06. Therefore, most of the Malbec 08 was thinned to 1.7 clusters per shoot, except for some unthinned vines kept as a control. Comparison of thinned and unthinned Malbec 08 indicate that the crop was reduced from 11.6 to 8.8 tons/acre and Brix at harvest improved from 19.9 to 22.5. Pruning wts ranged from a low of 1.59 kg/vine for thinned 08 to 2.33 kg for clone 06. Unthinned 08 pruning wt was 1.28 kg. The only effect of rootstock was that 110R had more clusters (64) than 5C (58). A significant effect of rootstock was not seen for any other growth or yield components, nor were there any rootstock x clone interactive effects.

Clonal Testing of Wine Grapes in the San Joaquin Valley

The San Joaquin Valley wine cultivar clonal evaluation study was initiated in 1987. It is an ongoing study to evaluate the most promising, virus disease-free clonal material being held or introduced as FPMS source material. French colombard, Chenin Blanc, and Barbera were completed in 1994 and 1995. Trial blocks of 3 clones each of Grenache, Sangiovese, Muscat Blanc, and Muscat of Alexandria were established in 1993; data collection was initiated at harvest, 1995, in these new trials, except for Muscat Blanc which was initiated in 1996. Significant clonal differences wee measured in all of the cultivars as follows: Muscat Blanc. The Milan introductions Clones 3 and 4 were distinctly better than Clone 1, an older introduction into California. Clone 1 had fewer and heavier clusters with larger berries and more bunch rot. Clone 4 was of higher fruit maturation than Clone 3. No clonal yield differences were shown. Thus, Clone 4 is the best performing selection at this point in the study. Grenache. These are all California selections. The trial includes a genetic comparison (Clone 1A vs. 3, 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. Although differences among Clones 1A and 2 were minor, Clone 2 is preferred at this point, due to its best overall fruit composition, as well as acceptable yield. Sangiovese. This cultivar continues to show rather distinct clonal differences, with Clone 2 continuing to show the greatest promise due to its smaller berry size, good fruit composition, and high vine fruitfulness and yield. Clone 3 has the largest berries, fewest clusters, and lowest yield; Clone 4 has the poorest fruit composition and most bunch rot. Muscat of Alexandria. The California selection A3 is out-yielding both its Australian counterparts – J2 and G5 – with comparable to superior fruit composition. Differences between the Australian clones were finally apparent in 1996, with J2 being more fruitful but with smaller berries of lower soluble solids than G5. Two more years of data collection in these trials are anticipated in order to determine consistency of differences over time. Propagation material has been obtained and the trial plots have been marked out for the Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel trials to be planted in 1997.

Clonal Testing of Wine grapes in the San Joaquin Valley

The San Joaquin Valley wine cultivar clonal evaluation study was initiated in 1987. It is an ongoing study to evaluate the most promising, virus disease-free clonal material being held or introduced as potential FPMS source material. 1994 was the sixth and last year of evaluating three selections each of French Colombard and Chenin blanc. Each cultivar comparison involves two different selections which are registered (indexed as virus free) but not heat treated. Additionally, each cultivar includes a heat treated selection. Thus, we have been studying the possible influence of heat treatment on virus-free material of French Colombard and Chenin blanc. Barbera was in its fourth year of data taking. This compares an Italian selection, Rauscedo 6 (FPMS Clone 2), with Marshall (FPMS Clone 1). The Marshall clone presently involves much of the present commercial acreage but was found to contain mild leafroll after many plantings were completed. French Colombard. Overall, all three clones were fairly similar in response for consideration in commercial plantings. However, Clone 2 could be considered to be the most favorable selection due to minimal bunch rot problems and consistency in yield and fruit characteristics over the years of study. Differences due to heat treatment were found when comparing Clone 1 (no HT) and Clone 2 (91 day HT). Clone 2 had heavier berries, fewer berries per cluster, and a trend towards lower bunch rot incidence as compared to Clone 1. There were no significant differences in wines made from the clones in 1993. All three clones are being maintained by FPMS with Clone 2 “Registered” for qualification as California Foundation Stock. Chenin blanc. Clonal and heat treatment differences were greatest with Chenin blanc. Heat treatment resulted in higher cluster numbers and yield with Clone 4 and without corresponding negative effects on fruit composition. For this reason, Clone 4 is recommended above non-heat-treated Clone 1. Clone 5 was a big disappointment. Its higher cluster numbers with smaller berries and clusters were thought to be potential characteristics for lower bunch rot and higher wine quality. However, the clusters were very compact and showed almost twice the bunch rot potential as the other clones. Also, sensory analysis comparisons of the wines in 1993 showed no significant differences. Currently, recommended Clone 4 is “Registered” for qualification as California Foundation Stock. Barbera. Clone 2 (Rauscedo 6) would appear to be the recommended choice for future planting, given its virus-free status and higher yields as compared to Clone 1 (Marshall). However, there has been some delay in fruit maturation, a higher potential for rot, and lower wine color with Rauscedo in past years. Differences were relatively minor in 1994, with no yield differences between the clones and with Rauscedo only having heavier berries and clusters as compared to Clone 1. One more year of field data and wine quality comparison will enable us to make a more definitive recommendation. The problems with Rauscedo point to the need to clean-up Marshall with shoot tip culture as well as the importation of additional Barbera clonal material. Grenache. Sangiovese. Muscat blanc. and Muscat of Alexandria. Trials with 3 clones each were established in 1993 and will begin fruiting for data collection in 1995.

Evaluation of Winegrape Clones

Thirteen clones or selections of Pinot noir were harvested for sparkling wine. Large differences were seen in maturity. Plots picked at 19 Brix were harvested over a 3-week period from August 21 through September 10. Yield was correlated more with cluster wt and cluster number than with berries/cluster. Among the clones, large differences were seen in virtually all measured parameters, including pruning wt, the several yield components, and in juice yield/ton of fruit. Duplicate wine lots were made from each clone or selection. Three clonal wines were rejected (both lots): one clone was defective in its aroma and two clones were lost because they underwent malo-lactic fermentation. The remaining 10 clones or selections are undergoing duo-trio analysis and further evaluation by cooperating winemakers. Further analysis of previous years’ data from two Chardonnay plots and one Cabernet Sauvignon plot reveals a close correlation of yield with cluster wt, more so than cluster number. For both varieties, there was a slight negative trend of pruning wt with yield, indicating that some yield increases were obtained at the expense of growth or that the yield:prunings ratio could have been altered by formula pruning, i.e. adjusting the buds retained at pruning based on the pruning wt. The Zinfandel clonal trial suffered heat damage and fruit shriveling prior to harvest skewing the data and resulting few reliable differences. Other trials with Merlot, Cabernet Sauvignon and Chardonnay are maturing and will be available in the near future.

Clonal Testing of Winegrapes in the San Joaquin Valley

An on-going San Joaquin Valley wine cultivar clonal evaluation trial was initiated in 1986 and planted into the first trial block in 1987. Location is the University of California Kearney Agricultural Center, Parlier where cultural conditions and practices can be closely monitored. All of the selections are indexed FPMS sources, most of which are registered. None have ever been compared in clonal studies in California. Thus, industry would benefit from performance information on available selections. This study utilizes 15 single-vine replicates in randomized complete blocks for each cultivar. 1992 was the fourth year of comparison for three selections each of French Colombard and Chenin blanc. Each cultivar compares two different selections which are registered (indexed as virus free) but not heat treated. Additionally, each cultivar includes a heat treated selection. Thus, we are studying the possible influence of heat treatment on virus-free material of French Colombard and Chenin blanc. Barbera was in its second year of data taking. This compares an Italian selection, Rauscedo 6 (FPMS Clone 2), with Marshall (FPMS Clone 1). Barbera Clone 1 presently involves much of the present commercial acreage but was later found to contain mild leafroll. French Colombard. Clone 5 was the only selection to show significant differences in 1992, with higher yields due to heavier clusters. The heavier clusters were due to more berries per cluster. This higher yield also contributed to lower fruit soluble solids of about l°Brix as compared to Clones 1 and 2. These results were different from those of past years when Clone 1 and Clone 5 were highest and lowest in yield, respectively. Clone 2 was the best overall selection in previous years but showed no benefits in its performance in 1992. Therefore, two more years of data taking are anticipated in order to better determine long-term differences. Chenin blanc. Clone 5 again produced the smallest berries and clusters of earliest maturity. However, rot also continues to be highest with this selection. Clone 4 continues to appear to be the best selection as it has had the highest yield and lowest rot incidence in the past. It was also more fruitful than Clone 1 in 1992. Clone 4 is a heat treatment of Clone 1. This is an interesting comparison, as the heat treated selection (Clone 4) has more favorable vine yield characteristics than Clone 1. 10-1 Barbera. These two selections were included to compare the widely planted Clone 1 (Marshall) with the only registered and recently introduced Clone 2 (Rauscedo). Because of its virus-free status, Clone 2 would appear to be the recommended choice for future planting. However, its larger berry size and higher yields contribute to later fruit maturity and lower fruit anthocyanin content. Thus, harvests in future years will be made at the same stage of fruit maturation rather than calendar date. This will enable us to more accurately compare fruit composition effects on wine quality. Wines were made from all of the selections in 1992. These results will be reported at a later date when sensory analyses have been completed. Zinfandel was eliminated in 1991 due to inclusion of a misnamed selection. Grenache, Sanqiovese, and Muscat blanc trials were established in 1993 with 3 selections of each cultivar.