Evaluation of Root System Conversion Methods in the Lodi-Woodbridge

AVF Proj. ID: 9513 / /Cat.: ,
Primary Investigator(s): R. Keith Striegler, David R. Winemanby

Root system conversion methods were evaluated in an own-rooted Sauvignon blanc vineyard in the Lodi-Woodbridge District. The root system conversion methods included in this study were approach grafting 1992 (rootstock rooting planted next to the vine and grafted in 1992), interplanting (rootstock rooting planted between vines in the row and budded in 1993), and an ungrafted control. Freedom rootstock was used in this experiment. Vines from the approach grafting 1992 treatment which failed to take were not regrafted in 1995. Also, the interplanting treatment was not rebudded. Our goal was to focus on the performance of converted vines. Growth and development of interplanted vines was limited due to shading from existing vines. Suckering was done twice during the growing season. Experimental plots were periodically inspected during the season. Yield data were collected at harvest on September 8, 1995. Berry samples were collected at harvest and fruit composition determined. Growth data were collected at pruning time on February 10, 1996. Percent conversion was also determined at pruning. Root system conversion method did not significantly affect yield, fruit composition, or growth during 1995. The number of approach grafted vines successfully converted has declined in most plots due to mechanical damage and weak rootstock growth. In addition, growth of interplanted vines has been poor due to shading. These results demonstrate the difficulty in managing young and mature vines planted in the same vine row. Under the conditions of this study (existing vines having a vigorous canopy), interplanting in the vine row was not an effective means of vineyard conversion.

Field Evaluation of Winegrape Rootstocks

AVF Proj. ID: 9517 / /Cat.: ,
Primary Investigator(s): James Wolpert, M. Andrew Walkerby

Data are presented for 12 rootstock trials throughout northern and coastal California and one trial from Kern County. The data indicate that there were wide variations in rootstock growth and yield components in these sites. Generally, growth differences (measured at pruning wts) were due to shoot wt (i.e. length) more than shoot number. Yield differences were due to berries/cluster, berry wt and cluster number, the importance of any one component varying among plots. Bloomtime petiole N and K also varied substantially among rootstocks. Juice potassium also differed significantly but no apparent relationship with petiole potassium or juice pH was noted. It is unclear from these data whether the differing performance of rootstocks from plot to plot is due to interactions of rootstock with site, scion or cultural practices. Readers are encouraged to consult the 1996 AVF Final Report to find data on the performance of particular rootstocks or in specific sites.

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

AVF Proj. ID: 9420 / /Cat.: ,
Primary Investigator(s): W. Mark Kliewerby

The effects of seven rootstocks (AxR#l, 110R, 039-16, 5C, 3309, 1616, and 420A) grafted to Cabernet Sauvignon (clone #8) in combination with three between row spacings (2, 3 and 4 m) and two in-row spacings (1 m and 2 m) on root distribution, shoot growth, soil water utilization, leaf and fruit composition and crop yield were evaluated this past season in a replicated field plot established at the Oakville Experimental Vineyard in 1987. Rootstocks 110R, 039-16, 3309, 1616, 5C, 420A, and AxR#l were evaluated at both the UC Oakville Experimental Vineyard and at a rootstock trial on Beringer vineyards Hudson Ranch in Napa. This allowed for investigation of differences in the density and distribution of the rootstock root systems in two different soil environments. A high spring water table and lower soil redox values at the north east end of the Oakville Experimental Vineyard significantly correlated with a lower number of roots indicating that these conditions limit root distribution. Clay subsoils at the Hudson Ranch also limited root penetration. Percent soil gravel at the Oakville Experimental Vineyard correlated with root numbers at deeper depths suggesting that a high percentage of soil gravel allowed for improved root pene¬tration. Roots were counted and categorized into four size classes: small (< 2 mm), medium (2 to 5 mm), large (5 to 12 mm) and very large (> 12 mm). At the Oakville Experimental Vineyard, rootstock 420A had statistically the fewest small, medium and total roots, whereas, rootstock 039-16 had the most large and very large roots. At Beringer, rootstocks 1616 and 420A showed statistically the lowest density of large roots and 039-16 the highest density. Rootstock 039-16 also had a deeper root distribution than 420A at both sites. Vines at closer vine spacings had fewer total roots but higher root densities. Rootstocks 110R, 039-16, 3309, and AxR#l were more aggressive at establishing roots at the widervine spacing. The average crop yield of 2, 3 and 4 m row spacing were 8.1, 6.5 and 6.4 tons/acre, respectively, and for 1 m and 2 m vine spacing were 7.5 and 6.4 tons/acre, respectively. The higher yields were due to greater number of shoots and clusters per acre. Fruits from 1 m vine spacing had higher levels of malic acid than 2 m fruits at harvest. The level of anthocyanin in fruits was greater at 1 m vine spacing than 2 m vine spacing. Decreasing row spacing from 4 m to 2 m reduced pruning weight per vine and per meter of canopy length, whereas decreasing vine spacing from 2 m to 1 m reduced pruning weights per vine, but when compared on a per meter of row length basis, 1 m vine spacing had significantly higher pruning weight than 2 m vine spacing. Closer vine spacing within rows, however, did reduce average weight per cane. The stocks were devided into three groups based on the amount of shoot growth and crop yield; 110R, 039-16 and 1616 had the most shoot growth and highest yield; 5C and 3309 were intermediate, and 420A was lowest. The high¬er yielding stocks had greater number of shoots and clusters per vine and per acre than lower yielding stocks. Shoot length, number of primary leaves, and leaf area of spur shoots of 11 OR and 039-16 were greater than the other four stocks. Pruning weight per vine of the seven rootstocks were in decreasing order of 110R, 039-16, 3309, 5C, 1616, and 420A. At harvest, 039-16 fruits were generally higher in pH, malate, and K than fruits from the other five stocks. The levels of malic acid and titratable acidity in fruits at harvest were directly related to the total amount of shoot growth per vine. 420A, 1616, and 5C fruits were ripened earliest, 110R and 3309 ripened intermediate and 039-16 fruits were generally the last to ripen as measured by °Brix. Mineral petiole analysis at bloom and veraison revealed that 039-16 stock continues to be the highest in K and low¬est in Mg, whereas 420A is lowest in K and highest in Mg, the other stock ranging in between. Wider spacing between vines within rows increased the level of Ca and Mg and decreased K, however, row spacing had little effect on the mineral content of petioles at bloom and veraison.

Field Evaluation of Winegrape Rootstocks

AVF Proj. ID: 9417 / /Cat.: ,
Primary Investigator(s): James Wolpert, M. Andrew Walkerby

Rootstock performance is, to some degree, dependent on site and/or culture. For example, 039-16 was highest yielding in MEN1 but lowest in AMA2. AFV supporters are urged to obtain and closely examine a copy of the entire report. In the M0N1 site, 110R, 3309C and AXR#1 are showing the highest yield with cluster weight contributing more than cluster number. °Brix readings at harvest indicate that vines were well balanced. The exception was 3309 which was delayed by about 1 °Brix. Pruning wt differences were significant with 1202, AXR#1 and St. George having higher wts. In M0N2 and M0N3 sites, additional data will be necessary to establish a pattern of yield components. Thus far showing the greatest growth are 043-43, 5BB and Harmony in MON2, and 5BB and Freedom in M0N3. In NAP2, 039-16 is showing the greatest yield, while 101-14 has the least. This is the site of the apparent collapse of Harmony to phylloxera. In AMA1, a dry-farmed Zinfandel trial, 110R and St George and performing best and visually have the least stress, while 420A and 5C are showing the greatest visual signs of stress. In LAK1, a heavy clay soil, 5C and 5BB are showing the greatest growth, greatest yield and best maturity. These two rootstocks are also exhibiting the least visual symptoms of K deficiency. In SAC2, Chardonnay yielded most on SaltCreek, Freedom and 1103P, while in SAC1 Cab Sauv was relatively high yielding (10+ tons/ac) on all rootstocks. LAK1 and SNJ1 were concluded in 1994 and will be submitted for publication in 1995, in both scientific and trade publications.

Evaluation of Root System Conversion

AVF Proj. ID: 9413 / /Cat.: ,
Primary Investigator(s): Keith Striegler, David R. Winemanby

Root system conversion methods were evaluated in three vineyards using Cabernet Sauvignon grafted on Chenin blanc, Semillon grafted on Napa Gamay, and own-rooted Sauvignon blanc, respectively. The root system conversion methods included in this study were approach grafting 1992 (rootstock rooting planted next to vine and grafted in 1992), approach grafting 1993 (rootstock rooting planted next to vine and grafted in 1993 when canes had sufficient diameter for grafting), interplanting (rootstock rooting planted between vines in the row and budded in 1993), and an ungrafted control. Freedom rootstock were used in all experiments. Vines from the approach grafting 1992 and 1993 treatments which failed to take were regrafted in June 1994. The interplant/field bud treatments were not rebudded in 1994. Growth and percent take of the interplants was limited due to shading by existing vines. Yield data for Semillon and Sauvignon blanc were collected at harvest on August 22 and September 2, 1994, respectively. Cabernet Sauvignon vines were harvested and yield data collected on October 4, 1994. Berry samples were collected at harvest and fruit composition determined for all experiments. Growth data were collected at the time of pruning on January 20, 1995. Pruning weights were unavailable for Semillion. Percent conversion was also determined on January 20, 1995. Root system conversion method had little effect on yield, fruit composition, or growth during 1994. Based on previous research, we anticipate treatment effects, if present, would be detected during the next two seasons. The number of vines successfully converted has declined in most plots due to mechanical damage, shading, etc. This result demonstrates the difficulty in managing young and mature vines planted together in the same vine row.

Effect of Rootstocks on grapevine mineral nutrition in the Central Coast

AVF Proj. ID: 9411 / /Cat.: ,
Primary Investigator(s): Peter Christensenby

This study is comparing the differences in vine mineral nutrient status as influenced by rootstock in Central Coast wine grapes. Six rootstocks trials have been sampled to date to include Chenin blanc and Chardonnay in Soledad, Chardonnay at York Mountain (Paso Robles), and Cabernet Sauvignon at Santa Ynez, Soledad, and San Lucas. All are irrigated sites, except York Mountain, and compare 7 to 10 rootstocks, depending on location. All of the sites have been sampled at bloom while two of the sites (York Mountain and Santa Ynez) have also been sampled at veraison. Analyses include total N, N03-N, P, K, Ca, Mg, Na, CI, B and Zn. Generally, the results are demonstrating the strong influence that rootstocks can have on scion mineral nutrition. The information should be helpful in anticipating potential nutritional problems, guiding fertilizer recommendations, and selecting rootstocks partly on the basis of nutritional adaptability to the site. The information is preliminary, as additional years of sampling, including fruit analysis, will be needed to determine multi-season responses. However, some preliminary responses are worth noting, especially when they are showing some consistency among sites. They include: 5C = lower N, CI, and Zn; 110R = lower CI and K; 3309 = lower P and Ca; 1202 = higher P and N; 039-16 and 043-43 = higher N, Na, and CI; Freedom = higher N and K but lower Zn; Harmony = lower N, P, and Ca; St. George = lower CI but higher N and Mg; 5BB = lower K; 5A = lower N and K; Ramsey = higher N, P and Mg; and Schwarzmann = mostly minor differences. Many of the noteworthy differences showed some consistency among the irrigated sites. This included the relatively poor performance of Harmony (often noted in Coastal sites), the high nutritional status of Freedom and Ramsey, and the potentially high sensitivity of 039-16 to Na and CI problems. Generally, St. George performed well on the dryland site. Additional information and recommendations should be forthcoming as the study progresses.

Cultural Control of Phylloxera in Root System Conversion Treatments

AVF Proj. ID: 9409 / /Cat.: ,
Primary Investigator(s): Keith Strieglerby

Root system conversion methods were evaluated at the White Hills Vineyard near Santa Maria, Ca. This study consisted of two experiments which utilized Gewurztraminer and Chardonnay in separate locations. Root system conversion treatments included inverted side grafting using cuttings, approach grafting using rootings and an ungrafted control for Gewurztraminer. The Chardonnay experiment investigated the suitability of selected rootstocks for root system conversion using the inverted side graft and approach grafting. Freedom, Harmony, Teleki 5C, Teleki 5A, Kober 5BB, and Couderc 1613 were the rootstocks used in this experiment. Yield data were collected for Chardonnay on October 6, 1994. The Gewurztraminer experiment was harvested and yield data collected on October 13, 1994. Berry samples were collected at harvest and fruit composition determined for both experiments. Vine growth and graft union assessment data were collected for Chardonnay on January 27, 1995. Graft union assessment data for Gewurztraminer were collected on January 27, 1995. As in previous seasons, the type of rootstock used was not an important factor in the response of Chardonnay vines to rootsystem conversion. Rootstock treatment had little effect on growth, yield or fruit composition. Gewurztraminer vines displayed a positive response to root system conversion in 1994. Vines which had been converted using approach grafting or inverted side grafting produced significantly higher yield than control vines.

Characterize virulence and life cycles of new phylloxera strains

AVF Proj. ID: 9405 / /Cat.: ,
Primary Investigator(s): J. Granett, J. De Benedicts, E. Weberby

Summary:

  1. Characterize virulence and life cycles of new phylloxera strains ‘Non A/non B’ strains were tested in the laboratory and shown to have increased aggresivity on some rootstocks. Based on the population growth data, overall aggresivity was too low for us to predict that these strains would cause economic losses to strongly resistant rootstocks with no V. vinifera parentage. A ‘Harmony’ adapted strain (strain 4) from Napa Co. had high population growth in the laboratory tests and was observed to cause damage to field vines. This strain represents a new biotype and this finding supports recommendations not to use this rootstock for phylloxera control. A German strain, reported to be damaging to 5C there, has been established in the laboratory and the first tests indicate that it is probably not virulent enough to cause field losses. The tests completed to date were plagued by technical problems and will be repeated. We can not guarantee the permanent stability of phylloxera resistance in rootstocks; understanding variation in phylloxera aggresivity from California and the world will help us evaluate the risks for the future. People from Andy Walker’s and our laboratory, made comparisons of phylloxera DNA. Results indicate that at least several strains of biotypes A and B exist. Our work failed to identify markers for biotypes or for geographical origin of strains. One interpretation of these data is that biotype B was selected more than once (rather than spreading from a single epicenter). We conclude from this interpretation that AXR#1 is not safe to use anywhere in California and quarantines will not prevent new occurrences of biotypes.
  2. To determine the potential for control tactics other than rootstocks Mocap tests in large planter boxes failed to control phylloxera or protect vines. Greenhouse studies demonstrated that Fusarium and Pythium fungi contribute to vine damage associated with phylloxera feeding. Although vine damage is caused by phylloxera alone, presence of secondary fungi increased damage about two-fold. The two most common fungi observed in the greenhouse studies were also found to be present in phylloxera-caused feeding wounds on field vines. The contribution of fungi to phylloxera based vine damage makes economic injury levels difficult to establish for this insect. This work also suggests that curative insecticide treatments in the field will not result in rapid reversal of vine-damage symptoms. We are collecting field data in a Sonoma County experiment to determine whether prophylactic insecticide treatments will slow spread of phylloxera or prevent damage. The first year’s data are encouraging. We have been screening new chemical and biological control agents in the laboratory. Some manufacturers are encouraged by the tests and are planning to test some with field trials. Others will not.
  3. To evaluate the factors that affect phylloxera populations, damage and spread Work on temperature thresholds for grape phylloxera suggests that temperature dependency of population growth is complex. Temperature thresholds vary with the insect stage and change with pulses of unseasonable temperatures. These results argue against use of a day-degree model for this insect.

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

AVF Proj. ID: 9404 / /Cat.: ,
Primary Investigator(s): Andrew Walkerby

About 8,000 seeds from the 1993 crosses were planted during the winter of 1993-94. We planted 6,675 of these seedlings in the vineyard during the summer of 1994. Over half of these seedlings were from crosses designed to produce resistance to a variety of nematodes including root knot, dagger and nematode complexes; tolerance to drought and salinity; combining phylloxera resistance in all backgrounds; and appropriate levels of vigor. Fifty-four crosses were made in 1994 to address these same issues; 2326 seeds were produced from these crosses, about 1,000 are ready for planting as soon as the vineyard site is prepared. Progress with the 1989 seedlings has been slow because of repeated failures with the bench-grafting crew. These mistakes have been identified and the same series of materials is being bench-grafted again this winter. Grafting success with these seedlings has been good, however the soil mix into which they are planted after callusing, and the greenhouse culture they have been receiving, has been poor. These problems have been remedied, however they will not be completely solved until I have my own field and grafting crew. Mike McKenry, at the UC Kearney Ag Center, has completed screening the best of these seedlings for resistance to a complex nematode population consisting of his most aggressive root knot races. Three of these seedlings 8913-02 (rupestris A. de Serres X rotundifolia Trayshed), 8913-21 and 8916-02 (rupestris Wichita Refuge X rotundifolia Dixie) did well in his screen and are ready for field testing. A paper detailing a screening of Vitis species for resistance to root knot nematode has been published (Walker, Ferris and Eyre. 1994. Resistance in Vitis and Muscadinia species to Meloidogyne incognita. Plant Disease 78:1055-1058). Several interesting new sources of resistance were discovered and we are preparing to use them in crosses next year to improve rooting ability of known resistant species that root poorly. A graduate student of mine finished a manuscript (Fong, Walker, and Granett. RAPD assessment of California phylloxera diversity. Journal of Molecular Ecology, In Press), which details our discovery that phylloxera biotype definitions are groups of genotypes and not single types. This means that B type phylloxera are not spreading from a single point of origin, but are capable of evolving wherever AXR#1 is used. We have also begun a project to examine the genetic variability in dagger nematode (Xiphinema index) populations across the state. We have completed collections from San Joaquin, Sonoma, Napa, Monterey, Kem and Fresno counties. This study will examine the diversity that exists in populations of X. index, (high levels would not be expected from a predominantly parthenogenetic and imported pest) and will lead to studies on their ability to vector fanleaf virus and damage grape roots. We will then be able to utilize the most aggressive nematode populations in screening tests and be able to study differences in GFLV that may exist.

A broad Nematode Screen to Evaluate Four Potential Nematode Resistant Rootstocks

AVF Proj. ID: 9401 / /Cat.: ,
Primary Investigator(s): M.V. McKenryby

In 1994 we completed our three-year screening effort for “Broad Nematode Resistance.” We have identified three USDA-Fresno rootstocks having completely different parentages but each possessing broader resistance to nematodes than any of the 20 conventional rootstocks we have screened to date. In this final year our work was primarily to finish screening among the ectoparasitic nematodes Xiphinema index and several X. americanum populations. In conducting these studies we used X. index containing grape fan leaf virus. Based on ELISA tests conducted by Andy Walker we learned that three years after inoculation grape fan leaf virus was not yet present in samples from USDA 6-19B. After two years’ exposure the USDA 10-23B was ELISA positive and USDA 10-17A was ELISA negative. There are at least two exciting aspects to our results. First, in comparison to “tolerance,” which is nematode buildup without vine damage, “resistance,” which is low or no nematode buildup, reduces the opportunity for biotype development. At this time we are not aware of any nematode species of statewide importance with the ability to reproduce satisfactorily on these three rootstocks. Second, the commonality of nematode biotype development has prompted our notion that the rootstock selected to follow one vineyard should not have parentage similar to the previous rootstock. For example, we would suggest that parentage such as V. rupestris in the first vineyard should not be followed by V. riparia x V. rupestris parentage in the second vineyard. These three new rootstocks provide options for growers wishing to follow such a pest management strategy. These three rootstocks are now ready for field evaluation. Almost nothing is known about their viticultural characteristics or their susceptibility to other soil pests or soil problems.