Spread and Control of Biotype B Phylloxera

AVF Proj. ID: 9328 / /Cat.: ,
Primary Investigator(s): J. Granett, J. DeBenedictis, E. Weberby

Phylloxera variability: Four “non-A, non-B” strains from various resistant rootstocks survive on some rootstocks that are resistant to types A and B. In laboratory tests, one strain increased 15-fold on Harmony rootstock suggesting the potential for damage in the field. Field observations at the original collection site will evaluate the susceptibility of Harmony to this strain. The other strains grow slowly on resistant rootstocks in the laboratory. They appear incapable of damaging mature resistant rootstocks, but their effect on new plantings needs further evaluation. We assisted M. A. Walker with electrophoretic and DNA characterization of some of our laboratory colonies. His data indicate more variability than expected and suggest the need for better understanding of life cycles, biology, and worldwide variability in phylloxera. Characterization of variability is critical for testing breeding materials in Walker’s rootstock program. Additional DNA testing will begin in June. Potential for control other than with rootstocks: We evaluated several products in the laboratory. The toxicity of some insecticides justifies further testing. Several non-conventional products including microbes, plant extracts, nutritional supplements and surfactants appear to be incapable of killing phylloxera in the field and unable to protect plants by enhancing the natural defenses and vigor of vines. Continued screening of such products is necessary to detect any that has merit and to provide growers and farm advisors with scientific information on products they might encounter on the market. We found that infested vines grown in low fungi environments were less damaged than untreated infested plants grown. This suggests that fungi cause some and possibly much of the damage to vines. If so, insecticides might not cure damage because the secondary fungal infections could persist after phylloxera are eliminated. We began new greenhouse tests to evaluate several insecticides and determine which fungi cause damage. We are setting up a Sonoma Co. trial to test whether insecticides can slow spread of damage. Other field trials to investigate whether fungicides can be curatives awaits the new funding cycle. Factors that affect the spread of damage: Research with scientists at NASA, Robert Mondavi Winery and Chico State University is investigating whether remote sensing can detect phylloxera infestations. The initial analyses are cause for optimism. The method will be critical for understanding the highly variable rates of spread of phylloxera populations and damage. Remote sensing is potentially feasible commercially. The plots for the 1994 field season have been set up.

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

AVF Proj. ID: 9319 / /Cat.: ,
Primary Investigator(s): W.M. 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 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. The most significant new findings obtained in 1993 were the documentation of the differences in the patterns of root growth of the seven rootstocks at two different vine spacings (1 and 2 m) on the basis of root density (number of roots/unit volume) and root sizes at depths between ground level and 2 meters. The root mapping data showed that 039-16 stock had the greatest number of roots, 4m2 of soil surface area, and 1616 and 420A had the lowest root density. There was a positive relationship between the total number of roots per 4m2 of soil surface area and the amount of above ground growth of the different stocks. There were significant differences between stocks for total roots, small roots (< 2 mm root diameter) and large roots (5 to 12 mm and > 12 mm diameters). For all stocks, root density declined with soil depth and with closer vine spacing. However, closer vine spacing did not alter the root distribution of any rootstocks. Root maps by size and number to a depth of 2 m of all seven stocks are presented in the report. The stocks were divided into three groups based on the amount of shoot growth and crop yield; 110R. 039-16, AxR#l. and 1616 had the most shoot growth and highest yield; 5C and 3309 were intermediate, and 420A was lowest. The higher yielding stocks had greater number of shoots and clusters per vine and higher berry and cluster weights than lower yielding stocks. Shoot length, number of primary leaves, and leaf area of spur shoots of 110R, 039-16, and AxR#l were greater than the other four stocks. Pruning weight per vine of the seven rootstocks were in decreasing order of AxR#l, 110R, 039-16, 3309, 5C, 1616, and 420A. Yield: pruning weight ratios ranged between 3.84 and 4.85, all within an acceptable range for balancing shoot growth and crop yield. At harvest, 039-16 fruits were generally higher in pH, malate, and K than fruits form the other six 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. 8 Mineral petiole analysis at bloom and veraison revealed that 039-16 stocks continues to be the highest in K and lowest in Mg, whereas 420A is lowest in K and highest in Mg, the oilier 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. The average crop yield of 2, 3, and 4 m row spacing were 7.9, 6.0, and 5.2 tons/acre, respectively, and for 1 and 2 m vine spacing were 7.1 and 5.7 tons/acre, respectively. The higher yields were due to greater number of shoots and clusters per acre. Berry weight increased with wider row spacing, but did not differ between 1 and 2 m vine spacing. Closer row and vine spacing delayed accumulation of sugar in fruits and time of harvest. 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 wider row spacing than narrow row 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. Wines made from four rootstocks (5C. 110R, 3309, and 039-16) at two vine spacings (2×2 m and 4×2 m) in 1993, differed considerably in composition. However Duo-trio taste comparisons generally did not show rootstock differences between the wines (Tables 17 and 18). 039-16 wine had the highest pH and hue and the lowest litratahle acidity and color at both spacings. whereas 3309 wine was lowest in pH and highest in TA and color.

Field Evaluation of Winegrape Rootstocks

AVF Proj. ID: 9317 / /Cat.: ,
Primary Investigator(s): James Wolpert, M. Andrew Walkerby

Data on rootstock performance is presented for 13 trials, ranging from Ukiah to Amador to Bakersfield. Rootstock recommendations tend to be site specific so readers are urged to obtain a copy of the complete report. In general, the rootstock 110R is performing well in the dry-farmed site while Teleki 5C and Kober 5BB tend to do well in heavier soils well supplied with water. The rootstocks 3309C and 101-14 Mgt tend to be moderate vigor rootstocks in some situations but can be vigorous when used in fertile sites with plenty of water. The 420A is a lower vigor rootstock. These experiments point up the interaction between rootstock performance and grower management practice. Two of the VR rootstocks trials have been concluded and have supported the hypothesis that VR 039-16 is the only recommended rootstock for sites with fanleaf degeneration complex. This recommendation is holding as well for plots in the northern, central and southern San Joaquin Valley, although more data are needed in those sites. Future trials will focus on interactive effects of rootstocks with other cultural practices such as vineyard floor management, water availability and vineyard spacing.

Evaluation of Root System Conversion Methods in the Lodi-Woodbridge District

AVF Proj. ID: 9313 / /Cat.: ,
Primary Investigator(s): R. 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 graftinq 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 was used in all experiments. Vines from the approach grafting 1992 treatment which failed to take were regrafted in May 1993. Budding of interplanted rootstocks occurred in June 1993 and approach grafting 1993 vines were grafted in July 1993. The experimental plots were periodically inspected during the growing season. Yield data for Sauvignon blanc and Semillon were collected at harvest on September 20, 1993. Cabernet Sauvignon vines were harvested and yield data collected on September 29, 1993. Berry samples were collected at harvest and fruit composition determined. Percentage take and pruning weight were measured on January 11-12, 1994. Approach grafting done in 1992 and interplanting produced the greatest percentage conversion. Approximately 80%of vines in these treatment categories have been successfully converted to resistant rootstock. Root system conversion method did not significantly affect vine performance.

Effect of Rootstocks on grapevine mineral nutrition in the Central Coast Region

AVF Proj. ID: 9311 / /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. Four 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. 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) were also sampled at veraison in 1993. Analyses included 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 but higher CI; 1202 = higher P and Zn; 039-16 and 043-43 = higher N, Na, and CI; Freedom = higher N and K; Harmony = lower N, P, and Ca; St. George = lower CI but higher N and Mg; 5BB and 5A = mostly minor differences. Some of the differences were consistent with the generally good performance of St. George on a dryland site, the relatively poor performance of Harmony in Coastal sites, the general high nutritional status of Freedom, and the potentially high sensitivity of 039-16 to Na and CI problems. Additional information and recommendations should be forthcoming as the study progresses.

Cultural Control of Phylloxera in Existing Vineyards by Root System Conversion

AVF Proj. ID: 9308 / /Cat.: ,
Primary Investigator(s): R. Keith Strieglerby

Root system conversion methods were evaluated at the White Hills Vineyard near Santa Maria, CA during the 1993 season. The 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. The Chardonnay experiment also investigated the suitability of selected rootstocks for root system conversion. Freedom, Harmony, Teleki 5C, Teleki 5A, Kober 5BB, and Couderc 1613 rootstocks were used in these experiments. Regrafting of vines not previously successfully converted was done in February 1993. Periodic inspections of the plots were made during the growing season. Graft union formation, rootstock growth, and vine growth were assessed during these inspections. Yield data were collected for Chardonnay when the vines were harvested on September 16, 1993. Gewurztraminer vines were harvested and yield data collected on September 30, 1993. Berry samples were collected at harvest and fruit composition determined. Gewürztraminer and Chardonnay graft unions were assessed (%conversion) on April 9, 1994 and June 2, 1994, respectively. Approach grafting increased the percentage conversion for Chardonnay vines. Approximately 80% of vines have been successfully converted. For Gewurztraminer, the percentage conversion remained approximately the same. We observed that a number of rootstocks died between the 1992 and 1993 seasons which had a negative impact on percentage conversion. Root system conversion method and rootstock had little effect on vine performance.

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

AVF Proj. ID: 9304 / /Cat.: ,
Primary Investigator(s): Andrew Walkerby

Progress in rootstock breeding was made in a variety of areas in 1993. The best of the 1989 seedlings, crosses of rupestris x rotundifolia, and one solonis x rotundifolia, have almost completed testing at the UC Kearney Ag. Center in Mike McKenry’s nematode tanks with 3 of his most aggressive Meloidogyne races. Several of the 1989 seedlings have good resistance. Dormant cuttings of some of these seedling selections have been grafted with Chardonnay and are destined for planting in a nematode/phylloxera trial in Ripon. These were also grafted to Flame Seedless for establishment in a root knot trial in Fowler. 926 1992 seedlings of an original 1,888 were recently planted in the new breeding block. 1,671 1993 seedlings have also been planted in this block. Ninety three new crosses designed for the production of nematode (both dagger and root knot) resistant rootstocks were produced in 1993. These utilized selections that L.A. Lider produced utilizing arizonica, candicans, champinii, and longii. We crossed these Lider selections with species selected to improve rooting, nematode resistance and drought tolerance. We also made 55 crosses designed to allow study of the taxonomic relationships among the North American Vitis species. Some of these may also prove very valuable as potential rootstocks. The 1994 pollinations emphasized the same objectives as the 1993. Thus far, forty-four crosses have been made. We completed the second round of a screening of Vitis and Muscadinia for resistance to Meloidogyne incognita. Resistance was common in aestivalis, champinii, and rotundifolia, it was also found in cinerea and rufotomentosa. Evaluation of an embryo-rescued population of Thompson Seedless seedlings for resistance to fanleaf virus continues, thus far all seedlings allow virus replication. This was expected since resistance to fanleaf appeared to be a rare recessive trait in earlier studies. We have made significant progress in developing an in vitro co-culture system for phylloxera using only root cultures. This system is now being tested to confirm that resistant and susceptible species act as expected in tissue culture. We have had trouble finishing our studies of DNA diversity in phylloxera, but procedures are now working and the data ready for final analysis. Preliminary examinations of the data show that phylloxera are variable within and among biotypes. There are no consistent A or B genetic markers. This suggests that B type phylloxera are not spreading, but that they are selected for at different AXR#1 sites.

A broad Nematode Screen to Evaluate Four Potential Nematode Resistant Rootstocks

AVF Proj. ID: 9301 / /Cat.: ,
Primary Investigator(s): M.V. McKenryby

In 1993 we were unable to secure as many plants of 10-17A, 10-23B and 6-19B as we would have liked. We did, however, have enough for six replicates of each rootstock in the presence of two X. americanum populations and one A”, index population. May 1994 root observations reveal tip galls by X. index on the Cabernet Sauvignon and Sauvignon Blanc comparisons but not on the above three rootstocks. May 1994 soil samples revealed inadequate nematode populations to determine the levels of resistance in the rootstocks. This technical problem can be solved with time and more sampling. Sixteen Ramsey x Schwarzmann seedlings are currently being screened against a dozen different nematode species. Two of the 16 seedlings exhibit poor rooting ability. All work should be completed by the target date of January 1995. One can see from Table 1 how some of the more interesting rootstocks performed in comparison to industry standards of Ramsey, Freedom, Teleki 5C and Harmony. In the screening process a number of farm advisors provided us with vineyard soil having root knot nematode problems. These mixed populations revealed that although 8-1 OB performed well against three of our most aggressive root knot populations it did not succeed against common field populations of root knot. It also shows the results of a two-year study involving those rootstocks and ring nematodes indicating that each has performed at least as well as Harmony. Our data for other ectoparasites will be available within months. Based on the numbers in Table 1 we have three rootstocks with very broad nematode resistance. These include 10-17A, 10-23B, and 6-19B. Each of these has differing parentage which is an asset when it comes time to make rootstock decisions at the farm level. The 6-19B rootstock roots well but may have some vigor problems. To have a successful rootstock one must be able to protect against all root knot populations present in the field. That is the “lofty” goal of this work.

Spread and Control of Grape Phylloxera Biotype B

AVF Proj. ID: 9224 / /Cat.: ,
Primary Investigator(s): J. Granett, J. DeBenedictis, M.A. Walker, J Wolpert, E. Weberby

Objective 1: Variability in resistance of rootstocks to phylloxera In California’s viticultural regions we previously found two variants, biotypes A and B from own-rooted and AXR#1-rooted vines. This year we found 3 additional variants by searching on other rootstocks, St. George, Freedom and Dog Ridge. The new strains (named 1, 2 and 3) are less vigorous than the standard colonies of biotypes A and B on V. vinifera roots (Cabernet Sauvignon), but are able to form many galls on immature roots of some resistant rootstocks. Strains 1 and 2 grow poorly on AXR#1 as does biotype A, but strain 3, like biotype B, grows well on AXR#1. Based on our field and laboratory observations, these strains are not likely to kill resistant rootstocks but we are investigating whether they may be debilitating in the long-term. Analytical biochemical methods of M. A. Walker indicate that our biotypes A and B are genetically variable suggesting that biotype B may have arisen more than once, and that the capacity for biotype B arising anywhere is prevalent. If so, quarantines of biotypes are not useful and the potential for other strains to evolve is real. This work is continuing. Objective 2: Spread and hosts of biotype B Biotype B has been found in Napa, Sonoma, Lake, Alameda, Santa Clara, San Joaquin and Sacramento Counties, . The biochemical methods developed by M. A. Walker will enable us to track phylloxera variability more closely, but have not yet been able to distinguish Biotype A from B. We have observed phylloxera populations on alternative rootstocks at replant sites. Feeding is restricted to new roots and any reduction in vigor is apparently temporary. These observations are forcing us to reconsider the Phylloxera Task Force recommendation against interplanting. Objective 3: Alternative tactics to control phylloxera Besides our work with Enzone, we have evaluated (or will evaluate) Mocap (Rhone-Poulenc), imidacloprid (Bayer-Mobay), C02 and S02 (independent developer, Liquid Carbonic), four numbered experimental pesticides (Sumitomo Corp., Sankyo Co.). one numbered experimental compound (ISK Corp.), one experimental mixture of natural products (“Thunder,” Natural Earth Technologies, Inc.), one experimental material (Cidal Corp.) and an electronic method (HVT Corp.). We have decided not to evaluate other offered tactics because of limitations in resources and/or apparent lack of scientific basis. Enzone (Unocal) clearly kills phylloxera, however, the 1-2-year duration of the experiments has not enabled us to evaluate properly for ultimate improvements in vine health which we now know may not be seen within the first or second year of treatment. Our research provided some of the data necessan/ for the temporary registration of Enzone in Napa, Sonoma and Mendocino Counties. Our work with other therapeutic methods has not progressed to definitive field trials. In 3-4 year studies, we will determine population growth and damage on vines in large planter boxes to evaluate the potential of therapeutic methods in general. We are collaborating in a NASA and Mondavi funded project to evaluate remote sensing of phylloxera and development of geographic information system (GIS) to characterize phylloxera epidemiology.

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: 9216 / /Cat.: ,
Primary Investigator(s): W.M. Kliewerby

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.