This project continues to investigate the interactions of rootstocks with cultural decisions of pruning severity, and between-row or in-row spacing. The project was comprised of several experiments bearing on the interaction of rootstock with cultural practices. In combination with three between row spacings (6, 9, and 12 ft.), nine rootstocks (AxR#l, 110R, 039-16, 5C, 3309, 5BB, 1202, 1616, and 420A) grafted to Chardonnay were evaluated for effects on fruit composition, vine growth, and crop yield in a replicated field plot established at the Beringer’s Hudson Vineyard in Napa, CA. The stocks could be divided into four vigor groups based on the amount of shoot growth as measured by shoot length or lateral and primary leaf areas. 039-16 and 420 A were in classes by themselves as the highest and lowest vigor stocks, respectively. Between the two extremes, 110R, 1202, 5-C, AxR#l, and 1202 exhibited intermediate growth while 3309 and 1616 tended toward low vigor. In general vigor tended to be lower in stocks with V. riparia heritage. Crop loads per vine increased with wider spacing from 8.1 kg/vine at 6 ft to 9.7 kg/vine at 12 ft. The increase was due to larger clusters with more berries per cluster. When considered on a per acre basis, however, yield was 50%higher on the narrow spacing due to more vines per acre. The average yield per acre of the 6, 9, and 12 ft spacings were 9.2, 6.7, and 5.5 tons/acre, respectively. At Oakville, the interaction of rootstock and balanced pruning formula on Cabernet Sauvignon (Clone UCD #8) grapevines was examined for the second year. Results in the second year of study differed substantially from those of 1995. Fruit maturity was not significantly lower on 039-16 as in previous years. Soluble solids increased as crop load decreased whether due to pruning formula of rootstock. Crop yield was reduced on 039-16 relative to the other stocks due to lower clusters per shoot and by pruning formula through reduced shoot number. Yields were 5.6 kg/vine for 039-16 and an average of 8.1 for 110R, 3309, and 5-C. The 5, 7, 9, and 11 bud/lb treatments produced yields of 5.5, 7.1, 7.6, and 8.6 kg/vine, respectively. No other components of yield (berry weight, cluster weight and berries per cluster) were found to be compensating for cluster number. Please consult the complete Final Report for other results and remaining experiments.

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.

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.

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.