Influence of Canopy Density on the Performance of Vertically Shoot Positioned

The effects of leaf area density on the performance of vertically shoot positioned Chardonnay grapevines were examined over a three-year period. The experiment was established in 1996 in a mature, bilateral cordon trained and spur pruned vertically shoot-positioned Chardonnay vineyard located near Greenfield in the Salinas Valley. Primary shoot density was adjusted to 14, 28 or 40 shoots per vine (approximately 10 to 26 shoots per meter) following budbreak for three consecutive seasons (1996-1998). Cluster number and yield per vine increased with shoot density. Vines thinned to 14 shoots produced almost 5.4 tons per acre, while vines with 40 shoots produced about 11.7 tons per acre. Juice pH did not differ among the treatments, while berry weight, soluble solids and titratable acidity wee significantly lower for vines with 40 shoots compared to vines with 14 shoots. Total leaf area per vine and pruning weight increased with shoot density. Vines with 14 shoots had lower leaf layer numbers, greater numbers of canopy gaps, and higher percentages of exterior leaves and clusters, compared to vines with 28 and 40 shoots. Light penetration within the canopy declined as shoot number per vine increased. Despite dramatic effects on canopy density and light penetration, shoot density in 1997 had little effect on return fruitfulness during the course of this study. Little difference in wine quality among the treatments was found in 1998.

Evaluation of Trellis System and Subsurface Drip Irrigation for Wine Grape

This study is being conducted in a 15 acre Sauvignon Blanc vineyard located on the California State University, Fresno Agricultural Laboratory. The vines are grafted to Freedom rootstock and were planted on a spacing of 8′ x 12′ (vine x row) in 1992. Row direction is north to south with approximately 70 vines per row. The experimental design used is a randomized complete block and data are analyzed as a two-factor factorial. Treatment factors include four trellis systems and four irrigation methods. Trellis system treatments are as follows: 1) Bilateral Cordon (BC) on standard two-wire vertical trellis; 2) Open Lyre (OL); 3) Geneva Double Curtain (GDC); and 4) Minimal Pruning (MP). Irrigation scheduling treatments are as follows: 1) Above ground drip (AGD) with water application of 0.8 of crop evapotranspiration (Et); 2)Subsurface drip irrigation (SDI) with water application of 0.8 Et.; 3) SDI with water apphcation of 0.6 Et.; And 4) SDI with water application of 0.4 Et. The 1997 season represents the third year of data collection for this project. As in previous seasons, differences were observed in the management of the irrigation systems. Use of SDI allowed for reduced apphcation of herbicides. One or two applications of glyphosate could be avoided because berms were dry. Conversely, use of SDI required increased efforts for control of gophers. Flow reductions were noted in certain SDI plots during the 1997 season. Examination of the affected areas showed that flow rate was reduced due to root intrusion. The concentration of trifluralin in affected emitters was measured. Trifluralin levels were found to be lower than that required to prevent root intrusion. This problem was traced to improper installation of the SDI tubing. New tubing was installed in all SDI plots during the dormant season. Significant irrigation method effects on yield and fruit composition were observed in 1997. In general, as irrigation deficit increased, yield level decreased. However, the number of clusters per vine was not statistically different. Cluster and berry weights were lowest for the 0.4 Et^e SDI treatment. Fruit maturation was delayed for the 0.8 Etvine AGD treatment. Consequently, the 0.8 Etvine AGD treatment had the lowest soluble solids and pH while having the highest titratable acidity. Trellis system also had a significant impact on yield and fruit composition in 1997. Yields were highest for the OL and MP treatments. Increased yield generally resulted from higher numbers of clusters per vine. Cluster weights were highest for the BC training system. Bilateral cordon and OL trellis systems produced higher berry weights than the other trellis treatments. Fruit maturation was delayed significantly for those training systems which had the highest yields. Vines which were minimally- pruned had significantly lower pH than the other treatments. Fruit from GDC vines had the lowest titratable acidity. Trellis system had a greater impact on vegetative growth than irrigation method during the 1997 season. Shoots per vine were significantly higher for minimally pruned vines. Total vegetative growth as indicated by mature nodes per vine was greatest for the GDC, OL, and the MP vines and lowest for the BC vines. Irrigation method had no significant effect on vegetative growth.

Influence of Canopy Density on the Performance of Vertically Shoot Positioned Grapevines in the Central Coast

The purpose of this study is to examine the effects of leaf area density on the performance of vertically shoot positioned Chardonnay grapevines. The experiment was established in 1996 in a mature, bilateral cordon trained and spur pruned vertically shoot-positioned Chardonnay vineyard located near Greenfield in the Salinas Valley. Primary shoot density was adjusted to 14, 28 or 40 shoots per vine (approximately 10 to 26 shoots per meter) following budbreak in both 1996 and 1997. In the second year of the study (1997), cluster number and yield per vine increased with shoot density. Vines thinned to 14 shoots produced almost 4.5 tons per acre, while vines with 40 shoots produced about 7.5 tons per acre. Fruit soluble solids and pH did not differ significantly among the treatments, while berry weight was significantly lower and titratable acidity significantly higher, respectively, for vines with 40 and 14 shoots. Total leaf area per vine increased with shoot density, while pruning weight was lowest for vines with 14 shoots. Vines with 14 shoots had lower leaf layer numbers, greater numbers of canopy gaps, and higher percentages of exterior leaves and clusters, compared to vines with 28 and 40 shoots. Light penetration within the canopy declined as shoot number per vine increased. Despite dramatic effects on canopy density and light penetration, shoot density in 1996 had little effect on return fruitfulness in 1997.

Influence of Vine Training System on Growth, Yield, Fruit Composition, and

The 1997 season represents the sixth season of this study. The experiment being conducted is a long-term investigation of the influence of training system on vine performance and the incidence of Eutypa dieback in a Cabernet Sauvignon vineyard. Data for the 1997 season were analyzed by factorial analysis to show the effect of two distinct soil types within the experimental site. The soil change occurs in the middle of the vineyard, evenly dividing the experimental plots into either a high capacity soil (Columbia Silt Loam) or a low capacity soil type (San Joaquin Loam). Training system had a significant effect on yield and components of yield. Yield was highest for the minimal pruning treatment and lowest for head-trained, cane-pruned treatment. Minimally-pruned vines had the greatest number of clusters and the lowest cluster weight, berry weight, and number of berries per cluster when compared to the other treatments. Machine-pruned vines had yields greater than the hand pruned treatments but less than minimally-pruned vines. In general, large yield for the minimal pruning treatment resulted in delayed fruit maturation. Soluble solids and pH were lower for vines which were minimally-pruned while titratable acidity was higher. However, fruit composition for minimally-pruned vines was quite suitable for production of high quality red table wine. Fruit quality was significantly affected by soil type. Soluble solids and anthocyanin content were greater in the low capacity soil. Training system also had a significant effect on vegetative growth. Growth, as measured by mature nodes per vine, was lowest for bilateral cordon and head-trained, cane-pruned vines. Vines which were minimally-pruned had more shoots per vine than all other treatments. Symptoms of Eutypa infection were observed in the plot during Spring 1997 for the second consecutive year. As was the case in the 1996 season, Eutypa symptoms were only observed in hand-pruned, cordon-trained treatments.

Evaluation of Trellis/Training Systems and Subsurface Drip Irrigation for Wine Grape Production in California

This study is being conducted in a 15 acre Sauvignon blanc vineyard located on the California State University, Fresno Agricultural Laboratory. The vines are grafted to Freedom rootstock and were planted on a spacing of 8′ x 12′ (vine x row) in 1992. Row direction is north to south with approximately 70 vines per row. The 1996 season represents the second year of data collection for this project. Deficit irrigation scheduling treatments were fully implemented and statistical differences due to treatment were observed. As in 1995, differences were again observed in the management of the irrigation systems. Use of subsurface drip irrigation allowed for reduced application of herbicides. One application of glyphosate to perennial weeds could be avoided because berms were dry. Conversely, use of subsurface drip irrigation required increased efforts for control of gophers. Significant training system effects on yield and fruit composition were observed in 1996. Yields were highest for the open lyre and minimal pruning treatments. Increased yield resulted from higher numbers of clusters per vine. There was an inverse relationship between yield and berry weight or cluster weight, although the number of berries per cluster was not affected. Fruit maturation was delayed significantly for the training systems which had the highest yields. Vines which were minimally pruned showed significantly lower levels of titratable acidity. Irrigation method also had a significant impact on yield and fruit composition in 1996. In general, as irrigation deficit increased, yield level decreased. The number of cluster per vine followed a similar pattern, indicating that this parameter was the most important factor involved in determining yield level. Differences in berry weight and the number of berries per cluster were not statistically significant. Statistically significant differences in soluble solids and pH were observed. Soluble solids were highest in 0.8 Et SDI and lowest in 0.8 Et AGD, even though the amount of water applied was identical for each. There was a trend for increased irrigation deficit to significantly increase pH in the fruit. Training system had a greater impact on vegetative growth than irrigation method during the 1996 season. Shoots per vine was significantly higher for minimally pruned vines. However, total vegetative growth, as indicated by mature nodes per vine, was greatest for GDC vines and lowest for MP vines. There were few treatment effects on vine water relations except at veraison when differences due to irrigation method were detected. Vines with the SDI 0.4 Et treatment had lower stomatal conductance than vines with the SDI 0.8 Et. At this point in the project, significant differences between training systems and irrigation methods have been detected. Further research is needed to determine the reasons for the observed differences.

Influence of Canopy Density on the Performance of Vertically Shoot Positioned Grapevines in the Central Coast

The purpose of this study is to examine the effects of leaf area density on the performance of vertically shoot positioned Chardonnay grapevines in coastal regions. The primary objective is to develop quantitative guidelines for optimum canopy density and vine performance for vertically shoot positioned canopies. The experiment was established in 1996 in a mature, vertically shoot-positioned Chardonnay vineyard located near Greenfield in the Salinas Valley. The vines are bilateral cordon trained and spur pruned. Primary shoot density was adjusted to 14, 28 or 40 shoots per vine (approximately 10 to 26 shoots per meter) following budbreak. Additional adjustments were performed as needed during the growing season to maintain treatment integrity. Each treatment was replicated eight times using seven vine plots. The middle three vine spaces in each plot were used for light, canopy assessment, and vine performance measurements. In the first season of study, cluster number and yield per vine improved with shoot density. Vines thinned to 14 shoots produced approximately 2 tons per acre, while vines with 40 shoots produced about 5 tons per acre. Despite producing lower yields and having the greatest leaf area:fruit weight ratio among the treatments, fruit from vines thinned to 14 shoots had the lowest soluble solids in the experiment. Total leaf area per vine increased with shoot density (7 to 9 m2 for vines thinned to 14 shoots and 40 shoots, respectively), while pruning weight was lowest for vines thinned to 14 shoots. Vines with 14 shoots had lower leaf layer numbers, greater numbers of canopy gaps, and higher percentages of exterior leaves and clusters, compared to vines with 28 and 40 shoots per vine. Light penetration within the canopy declined as shoot number per vine increased. Cluster counts will be collected in spring 1997 to determine treatment effects on return fruitfulness.

Influence of Vine Trellis/Training System on Growth, Yield, Fruit

The experiment being conducted is a long term investigation of the influence of 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 reduction in yield or fruit quality. Warm weather produced excellent early season growth which enhanced canopy development and advanced fruit maturity. Minimally pruned vines were skirted in early June to reduce crop load and facilitate cultural practices. Symptoms of Eutypa infection were observed in the plot during Spring 1996 for the first time. Additional vines with foliar symptoms of Eutypa were identified during Spring 1997. Eutypa symptoms were only observed in hand-pruned, cordon-trained treatments. Training system had a significant effect on yield and components of yield in 1996. Yield was higher for the minimal pruning treatment and lowest for head trained – cane pruned treatment. High yield resulted from increased clusters per vine. Cluster number was greatest for minimally-pruned vines while cluster weight, berry weight, and berries per cluster were among the lowest when compared to the other treatments. In general, large yield for the minimal pruning treatment resulted in delayed fruit maturation. Soluble solids and pH were lower for vines which were minimally pruned. Potassium content was greatest for the Hudson River Umbrella treatment and lowest for the machine pruning with hand follow-up treatment. Titratable acidity and anthocyanin content did not differ significantly between treatments. Training system also had a significant effect on vegetative growth. Growth, as measured by mature nodes per vine, was greatest for bilateral cordon and lowest for minimally pruned or machine pruned vines. Vines which were minimally pruned had more shoots per vine than all other treatments.

Evaluation of Trellis Training Systems and Subsurface

The 1995 season represents the initial year of data collection for this project. Irrigation method had little effect on vine performance or fruit composition in 1995. Above ground and subsurface drip irrigation performed in a similar manner for yield and quality parameters. However, some differences were noted in the management of these irrigation systems. Use of subsurface drip irrigation allowed for reduced application of herbicides. One application of glyphosate to perennial weeds could be avoided because berms were dry. Conversely, use of subsurface drip irrigation required increased efforts for control of gophers. Significant trellis/training system effects were observed in 1995. Yields were highest for divided canopy systems and minimal pruning. Increased yield resulted from higher numbers of clusters per vine. There was an inverse relationship between yield and berry and cluster weight. Fruit maturation was delayed significantly for the trellis/training systems which had the highest yields.

Influence of Vine Trellis Training Systems on Growth, Yield, Fruit

The 1995 season represents the fourth season of this study. The experiment being conducted is a long term investigation of the influence of trellis/training systems 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 reduction in yield or fruit quality. Results obtained in 1995 differed somewhat from results in the 1992-1994 seasons. This was in part due to the unusual environmental conditions which occurred during the 1995 growing season. Heavy spring rains and cool temperatures contributed to reduced early season growth and delayed canopy development. Unseasonable temperatures and wide fluctuations in temperature were experienced through most of the season. Minimally-pruned vines were skirted in June to reduce the crop level and facilitate cultural practices. Due to environmental conditions and crop level, harvest occurred much later (November 4) than in previous seasons. Yield was higher in 1995 than during 1992-1994 for hand-pruned treatments. As a result, there were no significant yield differences between the treatments. Significant differences were observed for components of yield. Vines which were minimally-pruned or machine-pruned had more clusters than hand-pruned vines. Berry weight, cluster weight, and berries/cluster displayed an inverse relationship with clusters/vine. Hand-pruned vines exhibited higher berry weight, cluster weight, and berries/cluster than minimally-pruned or machine-pruned vines. Trellis/training system had little effect on fruit composition in 1995. Vines which were minimally-pruned had more shoots per vine than vines receiving the other treatments. However, total vegetative growth was greatest for control (bilateral cordon) vines and was the lowest for minimally-pruned vines (mature nodes/vine). Symptoms of Eutypa infection were not observed in the plot during 1995. This result is not surprising in that symptoms of Eutypa usually first appear approximately 6-8 years after vineyard establishment. Therefore, treatment effects on Eutypa incidence should become evident in the next few years.

Interaction of Rootstock With Crop Load, Trellis System and Planting

This project proposed to investigate the interactions of rootstocks with cultural decisions such as pruning severity, trellis selection and spacing of vines within rows. The project was comprised of three experiments bearing on the interaction of rootstock with cultural practices. The three experiments were: Part A. Interaction of rootstock with crop load in Cabernet Sauvignon at the Oakville Experimental Vineyard. Part B. Interaction of rootstock with vine spacing on six trellis systems in Cabernet Sauvignon at the Oakville Experimental Vineyard. Part C. Interaction of rootstock with planting density in Chardonnay at the Beringer Hudson Ranch Vineyard. Data from Part A indicated that rootstocks reacted differentially to increasing bud number (cropping severity) at pruning. 039-16 was unable to ripen heavier crop loads as well as the other rootstocks. Increasing crop load for all rootstocks decreased all measures of growth. Data from Part B indicated that crop increased with canopy division whether that division was vertical (SH or TK2T) or horizontal (GDC, U and V), and that crop yield per acre increased as spacing between vines narrowed from 3 m to 2m to lm. Increase in yield for both factors was due to greater shoot numbers and cluster numbers per unit length row. In this case, 11 OR rootstock outyielded 039-16 by one ton per acre due primarily to greater numbers of shoots and clusters. Data from Part C indicated that the nine stocks could be divided into four vigor groups based on the amount of shoot growth as measured by shoot length, lateral and primary leaf areas and pruning weight. 039-16 and 420A were in classes by themselves as the highest and lowest vigor stocks, respectively. Between the two extremes, 1202, 110R, 5-C, 5BB, AXR exhibited intermediate growth while 3309 and 1616 tended toward low vigor. Shoot numbers did not vary, reflecting a constant bud number retained at pruning time but yields differed based on numbers of clusters/shoot. While crop loads per vine increased at wider spacing (due to more berries per cluster), the crop per acre was greatest at the higher planting density afforded by the 6 ft. Rows. Readers are encouraged to consult the Final Report for a complete analysis of the data.