Wine Grape Canopy Management Practices in the San Joaquin Valley

AVF Proj. ID: 9537 / /Cat.: ,
Primary Investigator(s): Peter Christensen, Nick Dokoozlianby

This report concludes a study conducted in the San Joaquin Valley toward determining the most effective vine training and pruning system for fruit composition, quality, and yield while being cost-efficient and adaptable to mechanization. Previous work was conducted on training system and trellis designs and the effects of fruit exposure on yield and fruit composition. The current study compared pruning systems which can be mechanized and are much different in crop level, vegetative development, and canopy configuration. Six systems involving bilateral and quadrilateral cordon training and hand, machine-hedge, and minimal pruning were compared with French Colombard and Barbera. 1995 was the third year of a 3-year study. The treatments included: bilateral (Bilat) and quadrilateral (Quad) cordon training under both hand (Hand) and machine (Mach) pruning; and minimal pruning (Minimal Pruning/Cordon Training = MPCT) is also being compared with and without hedging to adjust crop load after fruit set (MPCT-Adjust). Generally, the treatments with the lowest pruning severity (MPCT, followed by MPCT-Adjust, Quad Mach, Bilat Mach, Quad Hand, and Bilat Hand) produced the most clusters of least weight. Thus, the vines tended to adjust crop loads with smaller clusters and berries. This resulted in comparable yields from all treatments except for lower fruit weights form the bilateral cordon pruning treatments and MPCT Adj. in French Colombard and the hand pruning treatments in Barbera. Thus, the most restrictive pruning level (hand) and vine canopy training (bilateral cordon) systems still tend to be the most limiting to yield. Fruit composition effects from treatment in French Colombard were minimal except for a 2-week or more delay in harvest from MPCT. The bilateral cordon systems, whether hand or machine pruned, were restrictive in overall yield potential. Also, there were no advantages in the MPCT system over quadrilateral training or machine pruning. Adjusting crop load after fruit set in MPCT did not respond favorably; it reduced yield while not improving fruit composition. Overall, the data indicate the greatest advantages with quadrilateral cordon training in this vigorous cultivar. Machine pruning also showed benefit in increasing yields in some years with no adverse effects on fruit ripening or composition. 38 Barbera was most responsive to machine pruning, with large yield increases over hand pruning. While there was some delay in fruit ripening (10-15 days) from machine pruning the berries reached comparable fruit composition on their respective harvest dates. MPCT pruning showed no improved yields over machine pruning and ripened later with lower berry skin anthocyanin. Additionally, MPCT Adj. did not show any benefits from crop load adjustment after fruit set. The hand-pruned systems produced some trade-off effects. While there was higher anthocyanin in Quad Hand fruit Bilat Hand resulted in the most bunch rot. Overall, quadrilateral cordon training was the most favorable system for French Colombard and with the advantage that it could be machine pruned without affecting fruit composition. Barbera responded favorably to quadrilateral training when hand pruned but the greatest yield increase was from machine pruning, although with some delayed fruit ripening (2 out of 3 years). The MPCT treatments have been disappointing. While they may reduce or eliminate pruning costs, fruit ripening was delayed by two weeks or more and with lower fruit anthocyanin (Barbera). Adjusting crop load in MPCT after fruit set is not producing favorable crop thinning effects. This is not surprising, as the supportive shoots and leaf canopy are removed with the clusters.

Wine Grape Canopy Management Practices in the San Joaquin Valley

AVF Proj. ID: 9434 / /Cat.: ,
Primary Investigator(s): Peter Christensen, Nick Dokoozlianby

This work is a continuation of studies conducted in the San Joaquin Valley toward determining the most effective canopy management practices for fruit composition, quality, and yield while being cost-efficient and adaptable to mechanization. Previous work was conducted on training system and trellis designs and the effects of fruit exposure on yield and fruit composition. The current study compares pruning systems which can be mechanized and are much different in crop level, vegetative development, and canopy configuration. Six systems involving bilateral and quadrilateral cordon training and hand, machine-hedge, and minimal pruning are being compared with French Colombard and Barbera. 1994 was the second year of a 3-year study. The treatments include: bilateral (Bilat) and quadrilateral (Quad) cordon training under both hand (Hand) and machine (Mach) pruning; and minimal pruning (Minimal Pruning/Cordon Training = MPCT) is also being compared with and without hedging to adjust crop load after fruit set. Generally, the treatments with the lowest pruning severity (MPCT, followed by MPCT-Adjust, Quad Mach, Bilat Mach, Quad Hand, and Bilat Hand) produced the most clusters of least weight. Thus, the vines tended to adjust crop loads with smaller clusters and berries. This resulted in comparable yields from all treatments except for lower fruit weights from the bilateral cordon pruning treatments and MPCT Adj. in French Colombard and the hand pruning treatments in Barbera. Thus, the most restrictive pruning level (hand) and vine canopy training (bilateral cordon) systems still tend to be the most limiting to yield and without any improvements in fruit maturation and composition. Fruit composition was not affected in French Colombard except for a 2-week or more delay in harvest from MPCT. The bilateral cordon systems, whether hand or machine pruned, have been restrictive in overall yield potential while there was no advantage in the MPCT over machine pruning. Adjusting crop load after fruit set in MPCT has not responded favorably; it reduces yield while not improving fruit composition. Overall, this second year of data indicates the greatest advantages with quadrilateral cordon training in this vigorous cultivar, especially with machine pruning. Barbera is responding favorably to machine pruning in the-second year of treatment by producing maximum yields with comparable fruit composition to the hand-pruned systems. Overall, the two machine pruning treatments « Bilat. Mach and Quad Mach ~ produced the highest yields with favorable fruit composition. MPCT pruning showed no improved yields over machine pruning and ripened later with lower berry skin anthocyanin. Additionally, MPCT Adj did not show any benefits from crop load adjustment after fruit set. The hand-pruned systems produced a trade-off, ie. higher anthocyanin in Quad Hand but higher bunch rot in Bilat Hand. To date, quadrilateral cordon training with machine pruning is most favorable for French Colombard. Barbera showed some delay in fruit maturation from machine pruning in the first year; machine pruning is now producing maximum yields without delayed ripening. The MPCT treatments have been disappointing. While they may reduce or eliminate pruning costs, fruit ripening is delayed by two weeks or more and with lower fruit anthocyanin (Barbera). Adjusting crop load in MPCT after fruit set is not producing favorable crop thinning effects. This is not surprising, as the supportive shoots and leaf canopy are removed with the clusters.

Influence of Vine Trellis Training Systems on Growth, Yield, Fruit Composition, and Eutypa Incidence of Cabernet Sauvignon Grapevines

AVF Proj. ID: 9422 / /Cat.: ,
Primary Investigator(s): R. Keith Striegler, Dave Wineman, Greg Bergby

This is the third season of a long term study to investigate the influence of trellis / training system on vine performance and the incidence of eutypa dieback in a Cabernet Sauvignon vineyard. The goal of this experiment is to develop cultural practices which will reduce vine losses from eutypa and reduce production costs without a loss in fruit quality. Vines had good early season growth with the exception of vines which were head-trained and cane-pruned. These vines displayed poor development of buds in the middle of canes. Minimally-pruned vines grew well and appeared to develop a full canopy by May. We observed that early season leafhopper damage appeared to more severe on minimally pruned vines due to their early completion of shoot growth. Minimally-pruned vines were skirted (trimmed) at approximately 36″ above the ground to reduce crop and facilitate cultural practices during June. Also, an additional drip emitter (0.5 gallon) was installed for each minimally-pruned vine to compensate for the higher water requirements of this treatment, especially early in the season. Significant differences in yield and fruit composition parameters were observed in 1994. Minimal pruning and machine pruning treatments had significantly higher yield and number of clusters than the other treatments. The head trained/cane pruned treatment had significantly lower yield than the other treatments. Treatments .with the higher yield i.e. minimal and machine pruning displayed a slight delay in fruit maturation. Trellis / training system did not significantly affect total growth of vines as indicated by mature nodes per vine. Nodes retained were highest for the minimal and machine pruning treatments. Symptoms of Eutypa lata infection have not been observed in the experimental block.

Influence of Trellis-Training System and Rootstock on Optimum Spacing of Cabernet Sauvignon Vines Within Rows

AVF Proj. ID: 9421 / /Cat.: ,
Primary Investigator(s): W. Mark Kliewerby

The second year’s data from five-year-old Cabernet Sauvignon vines grown at the south Oakville Experimental Vineyard comparing within row vine spacings of 1, 2, and 3 meters showed average crop yields of 8.8, 8.3, and 7.3 tons/acre, respectively, when data of six trellis systems and two rootstocks were averaged together. The higher yield of closer vine spacing was mainly due to greater number of vines, shoots and clusters per acre, and to a lesser extent, berry weight. The number of berries set per cluster and cluster weight decreased with closer vine spacing but this reduction was more than made up for by the increase in shoots and clusters per unit area of land from higher planting density. The differences in yield between in-row spacing treatments was only 20%in 1994 compared to 63%in 1993, suggesting that dif¬ferences in yield due to within row vine spacing may disappear as the vines become older. With wider vine spacing there was an increase in the number of shoots, leaf area and pruning weight per vine but reduction of these parameters per meter of row length. Shoot length, leaves/shoot, internode length, leaf area per shoot and leaf area per gram of fruit decreased with increasing distance between vines within rows. The overall effect of increasing distance between vines was a reduction in canopy density and an increase in the amount of photosynthetic light in the fruiting region. The total leaf area (m2)/m row length was reduced from 4.6 for 1 m vine spacing to 2.8 for 3 m spaced vines when averaged for all trellis systems and both rootstocks. Pruning weights were similarly reduced on a per meter of row basis from 1.5 for 1 m spaced vines to 0.8 kg/m for 3 m spaced vines. Increasing the distance between vines from 1 m to 3 m sig¬nificantly reduced the level of TSS, pH, malic acid and anthocyanin per berry in fruits at harvest, however TA, K, and anthocyanin per g berry weight did not differ significantly between vine spacing treatments. Increasing vine space also reduced wine pH (and for the GDC, wine TA) but did not significantly effect ethanol concentration, wine color density or wine hue. The yield of Cabernet Sauvignon or 110R rootstock averaged 9.0 tons/ac compared to 7.1 tons/ac for 039-16 stock. The higher yields obtained with 110 are compared to 039-16 stock was true for all vine spacing and trellising treatments. The higher yields produced with 110R stock was mainly due to greater number of shoots and clusters per vine and to a lesser extent to larger berries. Shoot length and leaf area per shoot of vines on 110R stock were about 30%greater than vines on 039-16 stock. Total leaf area per vine aver¬aged approximately 50%higher with 110R than 039-16 stock. Total pruning weight per vine and average shoot weight were almost doubled on 110R relative to 039-16. The greater density of 11 OR resulted in a reduction in the amount of light in the fruiting region, however, the level of light did not limit fruit bud formation and vine productivity. The ratio of leaf area/g fruit averaged 8.4 for 039-16 and 10.1 for 110R. Crop to pruning weight ratios were 9.1 for 039-16 and 6.2 for 110R. 110R fruit at harvest was significant¬ly higher in TSS, pH, K and anthocyanin than 039-16 fruit. Wines from Cabernet Sauvignon on 110R

Wine Grape Canopy Management Practices in the San Joaquin Valley

AVF Proj. ID: 9333 / /Cat.: ,
Primary Investigator(s): Peter Christensen, Nick Dokoozlianby

This work is a continuation of studies conducted in the San Joaquin Valley toward determining the most effective canopy management practices for fruit composition, quality, and yield while being cost-efficient and adaptable to mechanization. Previous work was conducted on training system and trellis designs and the effects of fruit exposure on yield and fruit composition. The current study compares pruning systems which can be mechanized and are much different in crop level, vegetative development, and canopy configuration. Six systems involving bilateral and quadrilateral cordon training and hand, machine-hedge, and minimal pruning are being compared with French Colombard and Barbera. 1993 was the first year of a 3-year study. The treatments include: bilateral (Bilat.) and quadrilateral (Quad.) cordon training under both hand (Hand) and machine (Mach.) pruning; and minimal pruning (MPCT) is also being compared with and without hedging to adjust crop load after fruit set. Generally, the treatments with the lowest pruning severity (MPCT, followed by MPCT-Adjust, Quad Mach, Bilat. Mach, Quad. Hand, and Bilat. Hand) produced the most clusters of least weight. Thus, the vines tended to adjust crop loads with smaller clusters and berries. This resulted in comparable yields from all treatments except for lower fruit weights from Bilat. Hand and MPCT Adj. in French Colombard and Bilat. Hand and Quad Hand in Barbera. Fruit composition was not affected in French Colombard except for a 2-week delay in harvest from MPCT. Thus, the Bilat. Hand treatment was restrictive in overall yield potential while there was no advantage in MPCT over machine pruning or adjusting crop in MPCT. Overall, this first year of data taking indicates comparable and most favorable fruiting responses among Bilat. Mach, Quad Hand, and Quad Mach with French Colombard. Bilat. Hand and MPCT Adj were lowest in yield and both MPCT treatments showed a 2-week delayed fruit maturation. Fruit composition was affected greatly in Barbera, especially by pruning method, with the hand pruning treatments ripening earliest followed by the machine pruning and then MPCT, much later. Overall, the two machine pruning treatments — Bilat. Mach and Quad Mach — produced the highest yields with favorable fruit composition. MPCT pruning showed no improved yields over machine pruning and ripened much later. MPCT Adj did show some crop adjustment after post-fruit set hedging with heavier clusters and a 1-week earlier fruit maturity as compared to MPCT. The Quad system out-performed the Bilat. system in yields with Hand pruning. However, Hand pruning increased bunch rot in Barbera over the mechanized systems, especially with Bilat. training. For both cultivars, machine pruning with either bilateral or quadrilateral (2′ cordon separation) might be considered the most favorable system overall in this first year. For hand pruning, the quadrilateral system is best. Additional work is needed to determine long-term effects, especially if MPCT may improve over time.

Influence of Trellis-Training System and Rootstocks

AVF Proj. ID: 9320 / /Cat.: ,
Primary Investigator(s): W.M. Kliewerby

The first year’s data from four-year-old Cabernet Sauvignon vines grown at the South Oakville Experimental Vineyard (OEV) comparing in-row vine spacings of 1. 2, and 3 meters showed average crop yields of 4.4, 3.7, and 2.7 tons/acre, respectively, when data of seven trellis systems and two rootstocks were averaged together. Closer vine spacing reduced the number of clusters per vine and slightly reduced the number of berries per cluster and cluster weight but had little effect on berry weight. The greater number of vines and clusters per acre, as a result of closer vine spacing, more than compensated for the fewer clusters per vine and berries set per cluster, accounting for the higher crop yield of closer vine spacing. Decreasing the distance between vines from 3 to 1 m significantly increased the level of titratable acidity and malic acid in fruit at harvest, but °Brix, pH, K, and anthocyanins in berry skins did not differ between vine spacing treatments. With wider vine spacing, there was an increase in the number of shoots, leaf area and pruning weight per vine, but a reduction in leaf area and pruning weight per meter of row length. With an increase in vine spacing from 1 m to 3 m there was a 33%decrease in average shoot length and also a reduction in number of leaves/shoot, internode length, primary and lateral leaf area per shoot and percentage of total leaf area accounted for by lateral leaves, resulting in a reduction in canopy density. The amount of leaf area per gram of fruit was also significantly less at 2 and 3 m vine spacing than at 1 m vine spacing. Data obtained in 1993 comparing the performance of 039-16 and 110R rootstocks grafted to Cabernet Sauvignon at vine spacings of 1, 2, and 3 m showed that 110R rootstock produced significantly more shoot growth, pruning weight, and crop yield than 039-16. UOR stock produced 20%more shoots per vine than 039-16 and shoot length was also about 20%longer on 110R grafted vines compared to 039-16. Pruning weights per vine of 110R stock was more than double that of 039-16. The yield/pruning weight ratio of vines on 110R stock was significantly less than 039-16 for each of the seven trellis systems. Cabernet Sauvignon on 110R stock produced 3.8 tons/ac compared to 2.87 tons/ac on 039-16. Wider vine spacing generally resulted in wines of lower pH and titratable acidity for all trellis systems. However, vine spacing had no significant effect on the level of ethanol and wine color. Duo-trio taste comparisons of wines made from the in-row vine spacings revealed that 1 m vine spaced wines could be distinguished from 3 m vine spaced wines for two of the four trellis systems, namely the GDC and Shoot Positioned Vertical trellises. Wines made from the V-trellis showed that 2 m vine spaced wines differed from 3 m vine spaced wines. In no case was the taste panel able to show significant differences between 1 and 2 m vine spaced wines.

Wine Grape Canopy Management Practices in the San Joaquin Valley

AVF Proj. ID: 9231 / /Cat.: ,
Primary Investigator(s): Peter Christensen, Nick Dokoozlianby

Recent wine grape vine training and trellising studies in the San Joaquin Valley have demonstrated the influence of cordon height, foliage support wires, and quadrilateral training on vine yield, fruit composition, and wine quality. Concurrent studies in other districts have also demonstrated the beneficial effects of cluster exposure through leaf removal and other canopy management practices on grape composition and reduced fungal disease incidence. The purpose of this study was to determine the influence of several leaf removal techniques and shoot hedging on wine grape cultivars and trellis systems suitable to the San Joaquin Valley. Three leaf removal treatments — Hand, Window, and Hedge — and a check, no leaf removal were compared with French Colombard and Barbera. Leaf removal increased fruit zone light exposure in French Colombard temporarily due to its continued vigorous growth. This resulted in no fruit zone light environment differences at veraison and harvest. There were no significant fruit composition or bunch rot effects from any of the treatments in this cultivar. Hand leaf removal reduced vine yields, presumably due to berry loss from sun exposure soon after the treatment was imposed. Greater treatment effects were measured with Barbera. This could be explained by the more extreme and persistent effects of leaf removal in this less vigorous cultivar. Window leaf removal increased sunlight exposure through veraison while hand leaf removal was effective through harvest. However, this improved fruit exposure was not accompanied by any benefits in fruit composition, including soluble solids, pH, or anthocyanin content. The only treatment effects on fruit composition were reduced berry weight and titratable acidity in the Window and Hand treatments, respectively. The only positive effect was a reduction in bunch rot incidence from all of the leaf removal treatments as compared to Check. This included Hedge which did not improve fruit zone light environment at any time. This would suggest that hedging may provide adequate air circulation to reduce bunch rot while not changing the fruit zone light environment. Overall, the results further demonstrate that canopy management leaf removal has the potential to reduce bunch rot in the San Joaquin Valley. However, the rapid regrowth of vigorous French Colombard may reduce or eliminate this effect unless practiced at a later date during fruit ripening. The mechanical methods of Window and Hedge were as effective as Hand, cluster-region leaf removal in reducing rot. Thus, they would be preferable under San Joaquin Valley conditions due to economics. Leaf removal did not improve fruit composition as has been reported in cooler, coastal region studies. In fact, some leaf removal methods reduced berry weight, and titratable acidity in Barbera and yield in French Colombard. This was especially true of the more severe Hand leaf removal treatment where fruit exposure in this hot region caused berry burn. Thus, leaf removal canopy management practices in the San Joaquin Valley can be recommended for bunch rot control but are of questionable, if not detrimental, benefit to fruit composition and yield.

Trellises for Wine Grape Canopy Management in the San Joaquin Valley

AVF Proj. ID: 9136 / /Cat.: ,
Primary Investigator(s): Peter Christensenby

A wine grape trellis trial was designed and planted in 1986 at the U.C. Kearney Agricultural’ Center in the San Joaquin Valley. The purpose was to determine the most suitable trellis system for optimum fruit production and composition in cultivars of major importance to the area; ease and economics of vine management and mechanization were also considerations. Two cultivars, French Colombard and Barbera, were tested on 8 trellis designs suited to mechanization over 3 years, 1989-91. Data collection involved measurements of vine growth and light environment and fruit characteristics and composition; wine making, must and wine composition, and wine sensory analysis were also performed. Contrast analysis was conducted on major comparisons of vine training and trellis configuration for individual years and all 3 years (overall effects). The addition of one foliage support wire above bilateral cordons (11″ distance) increased pruning brush weights; vine yield was also increased through increased berry and cluster weights and with little or no effect on fruit composition in both cultivars. Similar effects were also obtained by increasing the bilateral cordon height by 11″ in both cultivars and with some advanced fruit maturation in Barbera.

Vineyard canopy management practices for improving grapevine

AVF Proj. ID: 9139 / /Cat.: ,
Primary Investigator(s): W. M. Klicwerby

The main conclusions from a four-year study of trellising, row spacing and pruning level of Cabernet Sauvignon at the Oakville Experimental Vineyard are as follows: 1. Reducing row spacing from 12 feet to 8 feet increased crop yield by 35%or 2.8 tons/acre with little or no significant difference in fruit composition. 2. At each of the three row spacings, quadrilateral cordon (QC) trellised vines produced approximately two tons/acre higher yield than bilateral cordon (BC) trellised vines averaged over a period of four years. 3. At the same level of “Brix at harvest, QC fruit had lower pH and higher levels of anthocyanins than BC fruit. 4. The higher level of anthocyanins in QC fruits than BC fruits was correlated to greater amount of photosynthetic active radiation in the fruiting region of the former treatment. 5. Increasing the pruning level from 24 to 60 buds per vine increased crop yield from 6.6 tons/acre to 11.0 tons/acre. 6. With increase in the number of buds per vine from 36 to 60 there was an average of 7 to 10 days delay in ripening. 7. At harvest, fruits from vines pruned to 48 and 60 buds/vine had lower pH, TA, malic acid and K and higher anthocyanin than vines pruned to 24 and 36 buds per vine. 8. Dividing the canopy, reducing distance between rows, and increasing the number of buds per vine all reduced shoot length, shoot weight, pruning weight per vine, and primary and lateral leaf area per shoot and increased the cropping efficiency. 9. The canopy density of QC trellised vines was significantly less than BC trellised vines. 10. Sensory analysis showed that BC wines could be distinguished from QC wines. 11. Sensory analysis could not distinguish between low crop wines (24 buds/vine) and high crop wines (60 buds/vine).