Influence of rootstock and vine spacing on root distribution, vine growth, crop yield, fruit and wine composition, canopy microclimate and wine quality of Cabernet Sauvignon

In 1991 and 1992, the effect of seven rootstocks (AxR#l, 110R, 5C, 3309, 420A, 1616, and 039-16) grafted to Cabernet Sauvignon in combination with three between row spacings (2, 3, and 4 m) and two in-row spacings (1 and 2 m) on root and shoot growth, water utilization, leaf, fruit and wine composition, crop yield and wine quality were evaluated in a field plot trial established at the Oakville Experimental Vineyard in 1987. The data revealed that the above seven rootstocks can be divided into three groups based on rooting depth, pruning weights and crop yield. 110R, AxR, and 039-16 rootstocks had the deepest roots, made the most vegetative growth and had the highest crop yield; 5C, 3309, and 1616 were intermediate in growth and yield, and 420A had the least amount of shoot growth and lowest yield. Neutron probe measurements also showed that AxR, 039-16, and 110R were able to utilize water down to depths of 210 cm (-7 ft); 3309, 5C, and 1616 mainly used water at depths between 30 and 150 cm and 420A mostly used water at depths less than 120 cm. In another field trial comparing St. George, AxR, and 110R it was shown that St. George had greater root density and deeper roots than 110R and AxR#l. There were relatively little differences in fruit composition at harvest between the seven rootstocks. 039-16 consistently had the highest pH, K+, and malic acid of the seven rootstocks. 110R fruit was the first to ripen and had the highest titratable acidity and anthocyanin pigment per berry, however, on a per gram basis, the level of anthocyanin did not differ significantly between rootstocks. In leaf petiole analyses, 039-16 had the highest level of K\ Ca*+, NO;, and Ca/mg ratio, and 420A was consistently the lowest in K at both bloom and veraison. The average crop yield of vines from rows spaced 2, 3, and 4 m apart was 7.7, 5.9, and 5.1 tons/ac, respectively, and for in-row spacings of 1 and 2 m, 7.0 and 5.5 tons/ac, respectively. Fruits from vines spaced 3 and 4 m apart between rows were significantly higher in sugar and pH than 2 m row spacing, however, TA, malic acid, K, and anthocyanin in fruits did not differ between row spacing treatments. Fruits from vines spaced 1 m apart within rows were significantly higher in pH, K, malic acid, and anthocyanin/berry than fruits from vines spaced 2 m apart. Wines made from Cabernet Sauvignon grafted onto different rootstocks differed in composition. 039-16 wines had the highest pH and hue and less red and total coloration than 5C, 3309 and 110R. 5C wine had the lowest pH and hue and the highest level of anthocyanin and total coloration of the above four stocks. Wines made from vines at two meter spacing generally had higher titratable acidity and level of anthocyanin than four meter row spacing wines. Within row vine spacing had little effect on wine composition. Duo-trio tasting of wines made from the 1992 vintage showed that 5C and 3309 wines could generally be distinguished from 110R and 039-16 wines. 5C wine had the most fruity character, whereas 110R and 039-16 wines were more vegetative and astringent in character. 3309 wine had the most herbal/spicy character of the four rootstocks. For 5C rootstock, closer vine spacing (2 x 1 and 2 x 2 m) wines could be distinguished from wider vine spacing (4 x 1 and 4 x 2 m) with a preference for the closer vine spacing wines. However, for 110R rootstock, wines did not differ between row and vine spacing in duo-trio taste comparisons.

Field Evaluation of Winegrape Rootstocks

The objective of this project is to evaluate rootstocks for winegrape performance in a wide range of coastal, foothill and central valley production areas, and in sites which are infested with phylloxera, nematodes or both, or which have the potential for such infestations. In 1992-93, 9 rootstock trials were harvested. A total of 16 trials are mature enough for harvest in 1993-94. The VR hybrid rootstock trials in Alexander Valley and San Jose, indicate that the rootstock VR 039-16 is the best rootstock for sites infested with fanleaf degeneration complex. Improved vine growth and yield as well as decreased rate of fanleaf infection are seen for 039-16 in both sites. At this point there are no other rootstock recommendations which could be made for fanleaf sites. Recommendations for planting 039-16 outside of fanleaf sites cannot be made until more is known about phylloxera resistance mechanisms and the risk posed by this one-half vinifera rootstock. In other experiments, rootstocks seem to be showing site x genotype interactions. This is especially true for Teleki 5C and 110 Richter. In deep, fertile soils well supplied with water, 5C shows itself to be quite vigorous, producing about 0.8 lbs cane prunings/ft row versus 110R at less than 0.4 lbs. However, in a hillside site, 110R is one of the top-ranked rootstocks in both growth and yield. These types of site interactions mean that multiple trials will be necessary to help choose an appropriate rootstock for the wide range of coastal and northern production sites. Details of individual trials are given in the full report.

Cultural Control of Phylloxera in Existing Root Systems

Root system conversion methods were evaluated in small research blocks at the White Hills Vineyard near Santa Maria, CA and the Meridian Vineyard near Paso Robles, CA during the 1992 season. Larger scale commercial blocks were evaluated at the previously mentioned vineyards as well as the Douglas Vineyard near Santa Ynez, CA, the Cat Canyon Vineyard near Los Alamos, CA, and the Sierra Madre Vineyard near Santa Maria, CA. Varieties used in these experiments were Gewurztraminer (White Hills), Chardonnay (Cat Canyon, Douglas, Sierra Madre, and White Hills), Cabernet Sauvignon (Meridian) , and Syrah (Meridian). Root system conversion treatments included inverted side grafting using cuttings, approach grafting using a rooting, interplanting between existing vines using a benchgraft, and an ungrafted control. In certain experiments, the suitability of selected rootstocks for root system conversion was tested using inverted side grafting (cutting). Freedom, Harmony, Teleki 5C, Teleki 5A, Kober 5BB, and Couderc 1613 rootstocks were used in these experiments. Grafting was done in February 1992 by Ken Coates, Coates Grafting, East Wenatchee, WA. Periodic inspections of the plots were made during the growing season. The extent of graft union formation was subjectively assessed during these inspections. Data on the cost of grafting and after-grafting care in commercial scale blocks were collected by Hampton Farming Company personnel. Yield data for Gewurztraminer was collected when vines were harvested on September 9, 1992. Syrah vines were harvested and yield data collected on September 11, 1992. Harvest of Chardonnay vines occurred on September 25, 1992. Berry samples were collected at harvest and fruit composition determined. Percentage take was measured on December 2-4, 1992. Chardonnay and Gewurztraminer vines were pruned during February 1993. Approach grafting produced the highest {aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} take. The percentage take obtained for inverted side grafting using cuttings was extremely low as in 1991. This method of root system conversion is not recommended for further testing. Root system conversion method and rootstock had little effect on vine performance. Economic analysis of approach grafting indicated that it would cost approximately $5,210 / acre to achieve 100{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} conversion during a 5 year period with a 76{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} initial take. This is a conservative and high estimate. Factors influencing the estimated cost of root system conversion by approach grafting were vineyard density (83 0 vines/A), the initial {aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} take, and the cost of grafting which was relatively high at $3.00/vine.

Breeding grapevine rootstocks for resistance to soil-borne pests and diseases

Objectives: Continue a rootstock breeding program initiated in the Department of Viticulture and Enology, University of California, Davis in 1988, addressing resistance to soil-borne pests and diseases. Evaluate seedling populations from crosses with Muscadinia rotundifolia and a range of Vitis species of North American, Middle Eastern, and Asian origin for resistance to phylloxera, fanleaf degeneration, and root knot nematodes, and for viticultural characteristics such as propagatability. Increase of understanding of the nature of phylloxera and fanleaf degeneration resistance under Californian conditions, by utilizing tissue culture and whole plant methods, and apply the knowledge to seedling evaluations. Produce additional crosses, as indicated by preliminary information from seedling screenings, to further emphasize ease of propagation and enhanced resistance. Begin field evaluation of selected genotypes leading to the release of new rootstock cultivars. This project is a part of a broadly focused rootstock breeding program. This specific project emphasizes rootstocks tailored for use with wine grapes. Many of the objectives are shared with a similar project jointly funded by the California Table Grape Commission and the California Raisin Advisory Board which emphasizes table and raisin grape rootstock development.

Cultural Control of Phylloxera in Existing Vineyards

Root system conversion methods were evaluated at the White Hills Vineyard near Santa Maria, CA and the Meridian Vineyard near Paso Robles, CA during the 1991 season. Varieties used in these experiments were Gewurztraminer (White Hills), Chardonnay (White Hills), and Syrah (Meridian). Root system conversion treatments included inverted side grafting using a cutting, approach grafting using a rooting, chip budding on the rootstock, interplanting between existing vines with a benchgraft and an ungrafted control. In certain experiments, rootstocks were evaluated using the inverted side grafting (cutting) and chip budding on rootstock methods. Harmony, Freedom, Teleki 5C, Couderc 3309, Salt Creek, Dogridge and Richter 110 rootstocks were used in these evaluations. Grafting was done in February 1991 by Ken Coates, Coates Grafting, East Wenatchee, WA. Periodic inspections of the plots were made during the growing season. The extent of graft union formation and rooting of cuttings were subjectively assessed during these inspections. Yield data for Chardonnay and Gewurztraminer were collected when the vines were harvested on October 7, 1991. Yield data were not available for Syrah vines. Berry samples were collected at harvest and fruit composition determined. Percentage take was measured on December 9-10, 1991 for Chardonnay and Gewurztraminer and on January 16, 1992 for Syrah. Vines were pruned and prunings weighed during January and February 1992. The {aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} take obtained during the 1991 season was low for the inverted side graft (cutting) and approach graft methods. This result was probably influenced by the rootstock wood used in grafting. Little suitable rootstock wood was available during 1991. Rootstock rootings or cuttings used for the inverted side graft or approach graft should have at least 6-8″ of 1/4″ minimum diameter cane. When rootstock wood meeting this criteria was used, inverted side grafting and approach grafting were successful. Chip budding on roots was a uniform failure and cannot be recommended for further evaluation. Root system conversion methods and rootstocks had almost no effect on vine performance. Yield and pruning weight were not significantly affected by treatment at any of the locations in the study. It is likely that differences in vine performance will become evident when the “new” rootstock becomes predominant over the existing root system.

Field evaluation of rootstocks for resistance to phylloxera and nematodes

Nine rootstock trials were harvested in coastal. Central Valley and foothill locations. Rootstocks were assessed for basic yield components and simple fruit maturity measurements. In sites where VR hybrid rootstocks are being tested for field tolerance to fanleaf degeneration complex, scions were tested by ELISA for presence of fanleaf virus. In Amador County, the Zinfandel rootstock trial is still maturing and hence crop is still being tightly regulated by pruning. The highest yielding rootstocks are AXR#1 and 1202, neither of which can be recommended for planting. Most of the remaining rootstocks are yielding approximately equivalent amounts, 16.2 to 18.9 lbs/vine. As the trial develops and becomes entirely dry-farmed this response will be monitored for change. In Lake County, the highest yielding rootstocks are 5BB, 5C and 420A, at 40-44 lbs/vine on the quadrilateral trellis. Also, 5BB and 5C, along with 101-14, are amongst the most vigorous (at 4.7 to 5.3 lbs/vine) while 110R is showing the poorest growth (2.8 lbs/vine). Severe shoot stunting was observed for the rootstocks 110R, 3309 and 101-14; the cause is unknown and will be investigated in the 1992-3 season. In Lodi, rootstocks grafted to Cabernet Sauvignon yielded 32 to 35 lbs/vine, except for St. George which yielded only 26 lbs per vine, pricipally because of fewer berries per cluster. Two VR hybrid rootstock trials were harvested in 1991, in Sonoma and Santa Clara counties. The results were similar. VR hybrids showed substantially more growth and yield than the AXR#1 controls in the fanleaf sites; the differences between the VRs and the AXR#I are greater in the older trial in San Jose. ELISA readings show that 039-16 has substantially less infection than either AXR#1 or 043-43. Therefore, 039-16 remains the only viable choice for fanleaf-infested vineyard sites. New rootstock trials have been established in Napa (Oakville Experimental Vineyard), Sonoma, Lake, Mendocino, and Monterey counties. Additional trials for San Luis Obispo, Santa Barbara, Merced, San Joaquin counties are being discussed.

Influence of rootstock and vine spacing on root distribution, vine growth

Root profile mapping of Cabernet Sauvignon on AxR, 110R and St. George rootstocks grown at the Oakviiie Experimental Vineyard revealed that St. George had the greatest number of roots at most depths with AxR lowest and 110R intermediate. The general distribution of the roots of all three stocks were similar, even though the frequency of different size roots differed. There was a significant difference between rootstocks, in terms of both total root numbers and in the individual root classes of < 2 mm and > 2 and < 5 mm. Mean separation tests supported the observation that St. George is producing the most roots followed by 110R and then AxR. Liberal tests suggest a statistical difference between all three rootstocks. Root numbers always varied significantly with depth. There was a rootstock-depth interaction for all root sizes except for the largest class (> 12 mm). This indicates that certain rootstocks are more likely to be found at one particular depth. St. George was found more often at the deeper depths than the other two rootstocks. This agrees with our original hypothesis that rooting patterns are based in part on geotropic angles. Even in very homogeneous soils, slight changes in the gravel or clay fractions seem to alter root distributions, as do changes in water application. Neutron probe measurements of water utilization at different soil depths between 0 and 2 meters showed that AxR, 039-16, and 110R stocks utilized more water at deeper soil depths than 5C, 1616, 3309, and 420A 110R stock utilized more soil water between depths of 120 and 150 cm than 3309. 3309 made maximum utilization of water at depths between 90 and 120 cm. 3309 also appeared to effectively use water at depths down to 90 cm midway between vine rows, whereas 110R was more efficient at using water at deeper soil depths than 3309, i.e., depths greater than 120 cm. AxR#l appears to use the greatest amount of available soil water in defined active zones, while 039-16, 110R, 3309 and 420A display similar “active zones,” but at consecutively lower levels. Data from each of these five rootstocks suggest strong lateral root growth at a particular soil depth. The remaining rootstocks 5C and 1616 each demonstrate less of an affinity for a given depth, but rather a higher volume of water uptake throughout the entire soil profile. The multiple access tube sites of 110R and 3309 indicated the most active root zones for each of these two rootstocks. Distinct patterns existed with respect to common depths of activity. The rootstock 3309 showed greater root activity at shallow depths down to 120 cm, while 110R displayed greatest activity at 150 cm. 110R appeared to produce greater lateral root distribution than 3309. This was evident by the higher water use at greater distances from the vine. Each of the seven vines indicated root activity to depths of 150 to 180 cm, but 039-16 and 5C showed greater water use at 210 cm than the others, suggesting a deeper root distribution with these two varieties. AxR, 039-16, and 110R produced the most above ground vine growth, 420A the least, and 1616, 5C and 3309 were intermediate. The closer the row spacing, the greater amount of water utilized from soil at depths between 0 and 200 cm, however, spacing between vines within rows of 1 and 2 m did not differ in the amount of water that remained in the soil at various depths. The amount of vine growth did not differ between row spacings of 2, 3, and 4 m, but was significantly greater for vines spaced 2 m apart within rows than 1 m vine spacing. Crop yields of 039-16, AxR and 110R were highest, 420A lowest, and 1616, 5C and 3309 were intermediate. Per vine crop yield of 2 m in row spaced vines was greater than 1 m spaced vines, however, on a per acre basis, 1 m vine spacing was greater than 2 m spacing. Generally, fruits at harvest from the higher vigor rootstocks (AxR, 039-16, 110R) had higher titratable acidity and malic acid and lower pH than the lower vigor stocks (1616, 5C, 3309 and 420A).

Influence of Potassium Deficiency and Temporary Potassium Deficiency on Nitrogen Metabolism in Leaves and Berries of Wine Grapes

During the 1991 season work was conducted to develop a procedure for putrescine estimation that could be performed quickly with simple equipment. Since the putrescine level increases many fold in leaves affected by potassium deficiency, it seemed likely that a simple procedure could be developed for the rapid diagnosis of potassium deficiency even when symptoms are mild or not yet visible. We have been successful in developing a rapid screening procedure to evaluate putrescine in dried and fresh grape leaves; this method is also applicable to petiole and rachis tissue. We found that making a derivative of putrescine using 5-dimethylaminonapthalene-l-sulfonyl chloride (Dns-Cl) gave a compound that was highly florescent and could be readily separated from other amine derivatives by TLC. We have now optimized the conditions and volumes used for the assay so that putrescine in the normal range in just barely visible under the conditions of the assay. This means that samples with elevated putrescine show large florescent spots and are easily distinguishable from the samples with normal levels. The previously used HPLC procedure could only accommodate 6 to 8 samples per day and running the instrument was rate limiting. With the new procedure we can easily screen 60 to 80 samples in a single day and grinding the samples is now the rate limiting step in the operation. We have therefore increased throughput by an order of magnitude and with this capability we now feel that the survey work to characterize putrescine and potassium levels in California vineyards can now be carried out.

Soil Pest Profile for Grape Rootstocks

At this time we can present a ranking of sixteen rootstocks and indicate their deficiencies and attributes as a tool of nematode management. FREEDOM — {V. champini X 1613C by Weinberger/Harmon 1967). This is one of the best rootstocks for broad resistance to nematode species. It has excessive vigor and will perform best in sandy or loamy sand soils. Its single major nematode problem is a particular root knot nematode, M. arenaria pv. Harmony, which is rare in occurrence but may eventually build up on it and become a problem in the subsequent vineyard. Freedom performs as well as any rootstock against ring nematode and citrus nematode. It is reported to provide protection against Type A and Type B phylloxera. It does tolerate nematode feeding, though not as well as Ramsey. Sandy soils having ring nematode present should be fumigated before planting. RAMSEY — {V. champini formerly called Salt Creek). This stock imparts even greater scion vigor than Freedom. It should be considered for use in the sandiest soils where no pre-plant fumigation is planned (this needs testing). This stock is damaged most by M. arenaria pv. Harmony and is more susceptible to ring nematode than is Freedom. Propagation is somewhat difficult. Ramsey is one of the best sources of broad nematode resistance and has untapped utility as breeding stock. Ramsey generally grows better in the presence of nematodes than it does in their absence. TELEKI 5C — {V. berlandieri X V. riparia selected from Teleki 5A, 1924). Presumably, this stock does not impart as much vigor as Freedom or Ramsey. It has broad resistance to root knot nematodes, except H. arenaria pv. Harmony. It is susceptible to root lesion nematode and citrus nematode. It provides some protection against X. index build-up but not against the ring nematode or X. americanum. Observers have reported it to do best in the best soils but we find it to grow as well in sand or sandy loam. This rootstock should not follow plantings that host root lesion nematode or M. arenaria pv. Harmony. It provides

Spread and Control of Biotype B Phylloxera

Summary From the 1990-1991 Report: Known biotype B sites are concentrated in the lower Napa and Alexander Valleys, with scattered sites elsewhere in Napa and Sonoma Counties only. Type B was detected on ungrafted Vitis vinifera and as a mixed population with biotype A for the first time. Laboratory tests of rootstock resistance detected no other biotypes and indicated that some resistant rootstocks are considerably less susceptible to grape phylloxera than others. Based upon these tests, own rooted \A vinifera vines and AXR#1, 41B and 0 43-43 rootstocks do not provide sufficient resistance to phylloxera, and some popular rootstocks are not as strongly resistant as others. In a release based on our research, the Phylloxera Task Force recommended sanitation, choosing the most resistant rootstocks and strategies for replanting to minimize the threat of grape phylloxera to vineyards. The efficacies on grape phylloxera of two organic phosphate compounds, carbon bisulfide and Electracat, an electronic device, were evaluated in the laboratory. All but the last were capable of killing grape phylloxera. A field test of the experimental pesticide Enzone in flood irrigation was discontinued because of inadequate control, but two tests of Enzone applications in drip irrigation are on-going. Collaborative research on rootstock breeding and physiological mechanisms of resistance were initiated. From the 1991-1992 Report: Biotype B grape phylloxera continues to spread in Napa and Sonoma Counties but is still unknown in other counties. According to results of a recent questionnaire, over 2000 acres of vineyards have been replanted in Napa and Sonoma Counties and another 6100 are currently infested with type B. No significant areas of Napa County are uninfested, whereas it has not yet been detected in some parts of Sonoma County. One Amador County and four Napa County rootstock field trials were examined for phylloxera. Phylloxera were only found in two of the Napa Valley trials. Samples from one of these trials contain a new strain. Bioassays of this strain indicate that it is much less vigorous than either type A or B on ^ vinifera roots, similar or slightly more vigorous than type A on AXR#1 roots, and more capable than both biotypes of feeding on callus and new roots of Freedom, Harmony, Dog Ridge, 1613 C and 5C. In these laboratory tests, the population did not grow rapidly on mature roots of any resistant rootstock tested. This strain (Strain 1) is not well adapted to any tested grape root as host and therefore is not yet considered a biotype akin to our A and B designations. It is not likely to kill any tested resistant rootstocks, however, more rootstocks must be tested. We plan experiments to determine whether it might economically stunt root growth of some resistant rootstocks. A collection from St. George led to a second strain (Strain 2) which has similar characteristics as Strain 1. We hope to determine the viticultural significance of these strains and continue the search for others. Roots of three accessions of Concord grapes were susceptible to biotype A and B. Winged phylloxera (alates) from a collection from Concord roots in Washington laid eggs that hatched and developed into sexual females, but alates reared from two California collections laid only non-viable eggs. This work confirms the existence of a viable sexual cycle for phylloxera in the Northwest, and the absence of this in California. Tests of chemicals to control phylloxera populations continue. Enzone trials indicate that phylloxera may be impacted but timing of multiple applications has not been worked out. A systemic insecticide candidate has been tested in the laboratory and kills phylloxera; whole plant tests are now warranted. Carbon dioxide and sulfur dioxide were tested in the laboratory; carbon dioxide takes too high a concentration and too long to kill and does not appear to be a good possibility for use in control programs. Sulfur dioxide kills phylloxera at a concentration of 10{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} in nitrogen for as short as 5 minute exposure. Further testing on potted plants and a vineyard is planned.