The Effect of Alternative Pruning Methods on the ... · Four different pruning methods, hand, ... Rising production costs in the national and international ... Alternative pruning

The Effect of Alternative Pruning Methods on the Viticultural and Oenological Performance of Some Wine Grape Varieties

E. Archer1 and D. van Schalkwyk2

Lusan Premium Wines, P0 Box 104, 7599 Stellenbosch, South Africa ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, South Africa

Submitted for publication: March 2007 Accepted for publication: May 2007 Key words: Grapevine, pruning, wine quality

Three different trials, at three different localities, each with different growing conditions, were conducted with nine different wine grape varieties. Four different pruning methods, hand, mechanical, minimal and no pruning were tested. Growth responses, grape composition and morphology, wine quality as well as labour inputs were evaluated. Huge labour savings were obtained with the alternative pruning methods compared to hand pruning. A reduction in vigour and increase in yield were evident in each variety. Wine quality was not decreased and in some cases even a quality increase was evident. Varieties differ in their adaptabifity to alternative pruning methods with Cabernet Sauvignon, Pinotage and Chardonnay performing well and Sauvignon blanc and Merlot poorly. Chenin blanc, Shiraz, Colombar and Ruby Cabernet showed acceptable performance. Alternative pruning methods proved to be viable, especially for the production of medium and low priced wines.

INTRODUCTION

Rising production costs in the national and international wine industries essentialise the implementation of cost reducing methods and procedures. Labour costs are responsible for more than 60% of total annual costs of wine grape production in South Africa ('Vinpro, 2005) and, therefore, the development of labour saving techniques is of paramount importance. Most wine grape vineyards in the Western Cape are pruned by hand. This makes an important contribution to the annual labour costs of producing wine grapes and, therefore alternative pruning methods had to be investigated. These alternative pruning methods are mechanical spur pruning (May & Clingeleffer, 1977; Clingeleffer, 1988), minimal pruning (Clingeleffer, 1993) and non-pruning (d'Armailhacq, 1867; Bakonyi, 1987).

Most reports on mechanical spur pruning showed an increase in yield (Morris et al., 1975; May & Clingeleffer, 1977; Clingeleffer, 1988; Reynolds, 1988; Reynolds & Wardle, 1993; Archer, 1999). On the other hand, it reduced bunch and berry mass (Morris et al.,

1975; Morris et al., 1981; Reynolds, 1988), and sugar concentration (Shaulis et al, 1973; Morris & Cawthon, 1980 and 1981; Anderson et al., 1996). In general, wine quality was reduced mainly due to a loss in colour with red grapes (Reynolds & Wardle, 1993). The response of the vine to mechanical spur pruning varied according to cultivar (McCarthy & Cirami, 1990) as well as clone (Clingeleffer, 1988; McCarthy & Cirami, 1990) and virus infection (Clingeleffer & Krake, 1992; Rühl & Clingeleffer, 1993).

Research results on minimal pruning, compared to normal hand pruning, showed an increase in yield, number of bunch-es and shoots (Cirami et al, 1985; Clingeleffer & Possingham, 1987; Clingeleffer, 1988 and 1989; McCarthy & Cirami, 1990;

Clingeleffer, 1993). Most of these reports showed that sugar concentration, as well as pH were reduced and total acid concen-tration increased by minimal pruning. In terms of wine colour, flavour and quality, variable results were reported depending on climate and vigour.

Research results on non-pruning are not abundant. Working with seven different cultivars, Bakonyi (1987) reported increased yields, no obvious loss in quality but an increase in oIdium and vine scales compared to hand pruned control vines. The research of Martinez de Toda & Sancha (1988) on un-irrigated Grenache showed that non-pruning increased the yield, dry matter and sugar production per vine. This was ascribed to a significant increase in total leaf area per vine. On the other hand, sugar concentration was reduced.

Although general trends in the effect of alternative pruning methods on grapevine performance are visible from the research results, the following pertinent questions needed answers under the specific viticultural conditions prevailing in South Africa: 1) Can these methods be used in producing top quality red wine from a noble cultivar? 2) Are these methods applicable under different climatic conditions? 3) Are there response differences between cultivars to these pruning methods? In an endeavour to answer these questions, this research project was undertaken in 1996. MATERIALS AND METHODS The project entailed three field trials at three different localities: Trial at Elsenburg The one ha trial vineyard was planted in 1996 on an Oakleaf soil form (Soil Classffication Work Group, 1991) with six cultivars: Chardonnay, Chenin blanc, Sauvignon blanc, Pinotage, Shiraz and Cabernet Sauvignon, all grafted onto Richter 99 rootstock.

*correponding author: VSchalkwykDarc.agric.za

Acknowledgements: The Wine Grape staff at Nietvoorb(j is thanked for their technical agsistance. Winetech and ARC Jnfruitec-Nietvoorb(j are thanked for their financial support. New Holland South Africa and Unique Agri Trade are thanked for harvesting the alternative pruning treatments of the Cabernet Sauvignon trial at NietvoorbU with Braud and Gregiore mechanical harvesters, respectively.

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007

107

108

Alternative pruning methods for some wine grape varieties

The treatments used were: control (hand pruned to two-bud spurs, 12 spurs per vine), mechanical pruning (vines were pruned with mechanical hedge cutters approximately 10cm above the cordon; no thinning of spurs were done) and minimal pruning (vines were mechanical skirted approximately 30cm above ground level dur-ing December and the sides were trimmed with mechanical hedge cutters to keep the rows open for spraying. The tops were un-touched). Both cultivars and pruning treatments were randomised in blocks and consisted of three replicates each separated by buff-er rows.

Before planting the soil was criss-crossed with a shift delve plough to a depth of 1 .2m after 4.5t/ha calcitic lime was broad-casted on the soil surface. This resulted in a soil pH of 5.2 to 5.9 and the vineyard was cultivated without irrigation. Vines in the control plots were split-cordon trained (cordon height above ground = 0.60m) on a standard four strand Perold trellis with movable foliage wires (Zeeman, 1981). 'Vines in the other plots were split-cordon trained (cordon height above ground = 1 .20m) on a one strand Hedge trellis (Zeeman, 1981). 'Vine spacing in all cases was 3.Om x 1 .5m, resulting in 2 222 vines/ha. Trial at Robertson This two ha trial vineyard was planted in 1997 on a Hutton soil form (Soil Classification Work Group, 1991) with six cultivars: Chardonnay, Chenin blanc, Colombar, Sauvignon blanc, Ruby Cabernet and Shiraz, all grafted onto Richter 99 rootstock. The treatments used were: control (hand pruned to two-bud spurs, 14 spurs per vine), mechanical pruning (vines were pruned with me-chanical hedge cutters approximately 10cm above the cordon; no thinning of spurs were done) and minimal pruning (vines were mechanical skirted approximately 30cm above ground level dur-ing December and the sides were trimmed with mechanical hedge cutters to keep the rows open for spraying. The tops were un-touched). Both cultivars and pruning treatments were randomised in blocks and consisted of six replicates, each separated by buffer rows. Based on heat summation over the growing period (Sep-tember to March), this locality is in climatic region III (Saayman, 1981) at 330551 South latitude. Before planting, the soil was criss-crossed with a shift delve plough to a depth of 1.3m after 6.5t/ ha dolomitic lime was broadcasted on the soil surface (eventual soil pH = 6.3). Irrigation was applied by means of micro-jets and scheduled according to A-pan evaporation and crop factors. Vines in the control plots were split-cordon trained (cordon height above ground = 0.70m) on a standard five strand Perold trellis (Zeeman, 1981) with movable foliage wires. 'Vines in the other plots were split—cordon trained (cordon height above ground = 1 .20m) on a one strand hedge trellis (Zeeman, 1981). 'Vine spac-ing in all cases was 3.Om x 1.5m, resulting in 2 222 vines per ha. The nutrition programme was managed in the same way as with the trial at Elsenburg. Trial at Nietvoorbij This one ha trial was laid out in an existing Cabernet Sauvignon x Richter 99 vineyard on an Avalon soil form (Soil Classification work Group, 1991). Vme spacing was 2.75m x 1.5m resulting in 2424 vine per ha, and the existing five strand Perold trellis as well as the vines (expect for the control plots) were converted to a high (1 .2m) one strand Hedge trellis according to the procedures de-scribed by Archer & Van Schalkwyk (1998). The following treat-ments were applied: control (hand pruning to 12 two-bud spurs per

vine), mechanical pruning (vines were pruned with mechanical hedge cutters approximately 10cm above the cordon; no thinning of spurs were done) minimal pruning (vines were mechanical skirted approximately 30cm above ground level during December and the sides were trimmed with mechanical hedge cutters to keep the rows open for spraying. The tops were untouched) and non-pruning (no pruning or trimming was applied). The pruning treatments were randomised in blocks and consisted of five replicates, each sepa-rated by buffer rows and vines.

Before planting, the soil was criss-crossed with a shift delve plough to depth of 1 .30m after 12tIha calcitic lime was broad-casted on the soil surface (eventual soil pH = 5.9). Depending on the season and soil moisture measurements, a maximum of three irrigations were applied with micro-jets. Vines in the control plots were split-cordon trained (cordon height above ground = 0.70m). Vines in the other plots were trained exactly the same as in the trials at Elsenburg and Robertson.

MEASUREMENTS

Time studies Time studies to determine man hours needed for each operation were done during pruning, canopy management (suckering, posi-tioning of shoots, tipping, topping and leaf removal) and harvest-ing and from these the labour needed to manage the vines of each of the pruning systems was calculated (machine and machine op-erator costs not included).

Yield, bunch mass, peduncle mass, berry mass and berry volume

During harvest, the physical condition of the grapes was visually evaluated in all plots and the percentage rot, millerandage, etc. noted by the same person. Thirty vines per plot were harvested in crates, weighed, and the average yield per vine calculated. One crate per plot was randomly selected, weighed, and the number of bunches counted to calculate the average bunch mass. Five bunches from each of those crates were randomly selected and stored at -20° C until after harvest to determine berry mass and volume. In the case of the trial at Nietvoorbij, five vines per plot were harvested to determine yield per vine, bunch, pedicel and berry mass as well as berry volume. The rest of the vines of the alternative pruned treatments were then mechanically harvested. The mass of the frozen berries was determined by being thawed. Using the methods as described by Van Schalkwyk (2004) to de-termine bunch mass, peduncle mass, berry mass and berry vol-ume, five bunches of each plot were randomly sampled and the frozen berries rubbed off in such a way that the pedicel were left on the peduncles. Out of this sample, 100 berries were randomly counted and weighed using a laboratory balance with a sensitiv-ity of two decimals per gram. These berries were also used to determine berry volume. A 1 000mL measuring cylinder was filled with enough water to cover 100 berries (e.g. 200mL). The berries were then added, a reading taken and the first reading subtracted from the second to determine the volume of 100 berries. All five bunches peduncles per sample were weighed after the berries were rubbed off and average mass calculated.

Cane mass and number of buds During winter, the number of shoots per vine and internodes per shoot were counted. Cane length was measured using all the canes of five vines per replicate and the average internode length was


Alternative pruning methods for some wine grape varieties 109

calculated. To calculate the cane mass per vine, 30 vines of each replicate were of the hand and mechanically pruned treatments were weighed. In one year the number of winter buds were count-ed on five randomly selected vines per plot. The same vines were used to count the shoots during spring and from this % bud burst was calculated. Berry skin, wine colour and phenols Berry skin (Hunter et al., 1991) and wine colour (Ribereau-Gayon et al., 2000) were only analysed for the red varieties at A420 nm and A520 nm using a LKB Biochrom Ultraspec II E UV/Visibile Spectrophotometer. Total phenolic compounds were quantffied using a HPLC (Ribereau-Gayon et al., 2000).

Wines At Elsenburg and Nietvoorbij wines were prepared from all three and five replicates, respectively of all the treatments of all the varieties. At Robertson grapes from replicates one and four, two and five, three and six, per treatment per variety were pooled re-spectively for wine making thus only three wines per treatment were made instead of six. Eighty kg of grapes were harvested per plot and used for wine making.

Grapes from the white varieties, Chardonnay, Chenin blanc, Colombar and Sauvignon blanc were harvested between 21 .0°B to 22.0°B and red varieties, Cabernet Sauvignon, Merlot, Pino-tage, Ruby Cabernet and Shiraz between 23.0°B to 24.0°B, re-spectively.

Wines were made according to the standard Nietvoorbij proce-dure for small-scale winemaking at the ARC Infruitec-Nietvoorbij Research Institute. The vinffication procedure for red wines was as follows: grapes were crushed, free SO 2 content was adjusted to 50mgfL before pressing and inoculated with YIN 13 (30gfhL) and fennented to 0°B at 24°C. During this period the cap was punched down three times a day. The skins were separated from the juice using a pneumatic press and pressed juice added to the free-run juice. After fermentation was completed, the total SO 2 content was adjusted to 85mgfL and 50gIhL bentonite added. Wines were cold-stabilized for two weeks at 0°C, filtered and bot-tled in N2-filled bottles at room temperature with adjustment of the total SO2 content to 85mgfL. The wines were stored in 750mL bottles with screw-caps at 13°C in a dark, temperature-controlled room directly after bottling.

The vinification procedure for white wines was as follows: grapes from Chenin blanc and Colombar were crushed and the free-run juice collected. Total SO 2 was adjusted to 50mgfL. The

skins were separated from the juice using a pneumatic press and pressed juice added to the free-run juice. Overnight settling was allowed at 14°C after adding 0.5gfhL Ultrazyme. Clear juice was drawn off into 20L stainless steal canisters and 50 g/hL di-ammo-nium phosphate added and inoculated with YiN 13 (30 gIHL). Wines were dry fermented at 14°C at which point free SO 2 was ad-justed to 40mgfL, and 50gIHL bentonite added. Wines were cold stabilized at 0°C for at least one week, then racked and filtered trough filter sheets. Free SO 2 was adjusted to 45mgfL at bottling. The wines were stored in 750mL bottles with screw-caps at 13°C in a dark, temperature-controlled room directly after bottling.

The same wine making procedures were followed for Chardon-nay and Sauvignon blanc except that after crushing skin contact was applied for four hours at 14°C.

During August/September each year these wines were sensori-ally evaluated by trained tasting panels. A ten-point-line-score-card system was used to evaluate wine quality, colour, overall cultivar intensity, aroma, acid, tannins, hardness and fullness. Statistical analysis The data was subjected to an analysis of variance. Student's t least signfficant difference (LSD) values were calculated to facilitate comparison between treatment means. Means which differed at p0.05 were considered to be signfficantly different. RESULTS AND DISCUSSION Trial at Nietvoorbij All three alternative pruning methods significantly reduced labour cost for managing Cabernet Sauvignon compared to hand prun-ing (Table 1). Not only was labour input for pruning reduced, but also for canopy management and harvest. Minimal and no prun-ing required significantly less labour than hand and mechanical pruning. It is imperative that mechanical harvesting is used when any one of the alternative pruning methods are employed as it is extremely labour intensive and costly to harvest these systems by hand.

More sunburn as well as berry shatter occurred when any one of the alternative pruning methods were used (Table 2). With the hand pruned control plots, the shoots were vertically positioned as part of the canopy management programme, therefore, the bunch-es were better protected against direct sunlight. On the other hand, the open hanging shoots of the minimal and no pruning plots, ex-posed the grapes more to direct sunlight and in abnormally hot seasons (data not shown), this caused sunburn-damage. The higher percentage berry shatter that occurred with the alternative prun-

TABLE 1 Labour inputs for different pruning methods for Cabernet Sauvignon grafted onto Richter 99 at Nietvoorbij (2000 - 2004).

Labour (man hours/ha) Parameter

Hand pruning Mechanical pruning** Minimal pruning** No pruning**

Pruning 91.4 a* 20.4 b 0.7 c 0 c Canopy management 123.2 a 10.2b 11.4b 6.4 c Harvesting 97.5 a 1.5b 1.5b 1.5b Total labour input 312.1a 32.1b 13.6c 7.9c

* Figures followed by the same letter in the row do not differ significantly at pO. 05. ** Grapes from the alternative pruning plots were machine harvested.


110


ing, may be the result of a higher cluster exposure to wind during flowering time (data not shown). No pruning induced less compact bunches than any of the other pruning methods (Table 2).

The alternative pruning methods decreased shoot length signifi-cantly compared to the hand pruned control (Table 3) and amongst them, the vines pruned mechanically had the longest shoots. The internode length was affected similarly (Table 3). This can be re-lated to the fact that the capacity of alternatively pruned vines was expressed in signfficantly more shoots per vine than in the case of the hand pruned control (Table 3). As expected, the highest cane mass was obtained from the hand pruned control vines.

Bud counts made during one data year (data not shown), showed that 24, 72, 191 and 227 buds per vine were left with hand, me-chanical, minimal and no pruning respectively. This resulted in % budburst of 108%, 60%, 49% and 47% respectively.

A significantly lower yield was obtained from the hand pruned control vines (Table 3). A clear seasonal interaction with treat-ments can be seen in Fig. 1A. In most years the hand pruned plots yielded less but at least it was relatively consistent from year to year, while the alternative pruning treatments varied much more. The 2003 season was extremely favourable for hiegh yields for alternatively pruned Cabernet Sauvignon. Over the five year trial period, this treatment accumulatively produced less grapes than the other treatments (Fig. 1B) and of the alternative methods; no pruning produced significantly more grapes.

Although the bunch mass was significantly reduced by alterna-tive pruning, the increased number of bunches ensured that the yield per ha increased. The hand pruned control vines produced signfficantly larger berries than the other pruning treatments (Table 3).

TABLE 2 Effect of pruning method on the physical condition of Cabernet Sauvignon grapes at harvest at Nietvoorbij (2000 - 2004).

Parameter Hand pruning Mechanical pruning Minimal pruning No pruning

Dry rot (%) 0 a* 0.2 a 0.2 a 0.3 a Sourrot(%) 0 0 0 0 Bird damage (%) 0 a 0.2 a 0 a 0 a Sun burn (%) 2.2 c 6.6 b 9.7 a 9.9 a Berry shatter (%) 0.3 c 1.6 c 4.6 a 3.2 b Millerandage (%) 0.2 a 0.3 a 0.5 a 0.4 a Bunch compactness Well filled Well filled Well filled Loose Diseases/pests None None None None

* Figures followed by the same letter in the row do not differ significantly atpO.O5.

TABLE 3 Effect of pruning method on the viticulture performance of Cabernet Sauvignon at Nietvoorbij (2000 -2004).


Viticultural performance

Average shoot length (cm) 99.9 a* 70.9 b 19.7 c 18.6 c Number shoots/vine 26 d 43 c 93 b 108 a Average internode length (cm) 6.24 a 5.45 b 3.28 c 3.10 c Cane mass (tJha) 3.3 a 1.4 b nm nm Yield (tJha) 10.1 c 18.0b 16.4b 20.1 a Number of bunches/vine 33.8 d 83.4 c 106.6 b 140.9 a Bunchmass(g) 130.0 a 87.5b 64.6c 61.3 c Berrymass(g) 1.54 a 1.42b 1.18c 1.19c Berry volume (mL) 1.44 a 1.40 a 1.14 b 1.16 b

Grape composition Sugar concentration (°B) 24.0 a 24.0 a 22.9 b 22.8 b Acid concentration (g/L) 7.7 a 7.4 b 7.4 b 7.5 ab pH 3.66a 3.32b 3.27c 3.24c Sugar:acidratio 3.2b 3.3a 3.1b 3.1b

Must composition (after skin contact) Sugar concentration (°B) 24.2 a 24.6 a 23.4 b 22.8 c Acid concentration (g/L) 6.9 a 6.1 b 6.8 a 6.7 a pH 3.47b 3.58a 3.47b 3.45b Sugar:acidratio 3.6b 3.9a 3.5b 3.6b

* Figures followed by the same letter in the row do not differ significantly atpO.O5. nm = not measured



40

35

30

25

a 20

V

>- 15

10

2000 2001 2002 2003 2004

Vintage

•Hand pruning M Mechanical pruning W Mininial pruning 3 No pruning

Vertical bars followed by the same letter in the same vintage do not differ significantly at p 0.05.

120

B

100

80 0 0.

>' 60

E 40 E

C-)

20

2000 2001 2002 2003 2004

Vintage

Hand pruning MechanicaI pruning MinimaI pruning No pruning

FIGURE 1 The effect of alternative pruning methods on the yearly (A) and cumulative (B) yield per ha of Cabernet Sauvignon at Nietvoorbij (2000-2004).

111

Vines that were hand and mechanically pruned, produced grapes with a higher sugar concentration than minimally and non-pruned vines (Table 3). The grapes from the alternative pruning treatments had a lower pH than those from hand pruned vines and this tendency was carried forward into the wine (Table 4) even though it was not true for the juice after crushing (Table 3). This higher pH in grapes and wine from hand pruned vines is ascribed to higher shade levels in the bunch zone of these VSP trained plots (data not shown). In general, the alternative pruning meth-ods induced better colour in the skins and wines (Table 4) and this is ascribed to better sunlight penetration into the bunch zone of these vines (data not shown). These results are in accordance with those reported by Clingeleffer (1988 & 1993).

The aroma profiles and overall quality of the wines are indi-cated in Figs. 2 & 3. Vintage played an important role and over years succeeded in blanketing the treatment effects in the case of 6-month-old wines (Fig. 2). In spite of this, the wines from the hand pruned vines consistently showed the most pronounced veg-etative character. This is expected due to a higher canopy density (more shade) in the bunch zone. This tendency also held true in most vintages for the 18-month-old wines (Fig. 3). These results are in accordance with those of numerous other researchers who found a better expression of fruitiness in wines from alternative-ly prunes vines. In spite of this, an evaluation of overall quality showed that the trained panel ofjudges had a preference for wines from the hand pruned vines (Table 5).


112


Trial at Elsenburg

Hand pruning, together with the necessary canopy management as well as harvest, require 273.6 man hours/ha compared to 43.8 and 14.4 man hours/ha for mechanical and minimal pruning re-spectively (Table 6). This saving in man hours was true for all the varieties and there is a clear economic advantage to use anyone of the alternative pruning methods. During this trial, time stud-ies showed that it is not viable to harvest any of the alternatively pruned plots by hand (data not shown). A mechanical harvester is a prerequisite when these methods are used.

The number of canes per vine of the three white varieties were increased with the alternative pruning methods, but the average cane length was reduced (Table 7). This reduction could, in part, be ascribed to a reduction in internode length. The other cause of the reduction in cane length with the alternative pruning meth-ods could be found in the vigour reducing effect of an increased crop load. In this regard, interesting differences occurred between varieties. Although the cane length of Chardonnay was not af-fected by mechanical pruning, minimal pruning significantly de-creased the vigour of this variety. The explanation for this can be found in the yield/ha which was increased by 248% with minimal

TABLE 4 Effect of pruning method on the oenological performance of Cabernet Sauvignon at Nietvoorbij (1998-2005).


Alcohol concentration (vol %) 14.6 b* 15.1 a 14.9 a 13.8 c Extract (mg/L) 33.3 a 33.6 a 31.4 b 31.2 b Volatile acid (mgIL) 0.22 a 0.25 a 0.24 a 0.22 a Sugar concentration (g/L) 1.7b 2.0a 1.7b 1.7b Acid concentration (gIL) 6.5 c 7.0 b 7.0 b 7.3 a pH 3.86 a 3.74 b 3.61 b 3.58 b Skin colour (420nm) 0.227 c 0.267 b 0.292 a 0.280 a Skincolour(520nm) 1.000c 1.235b 1.358ab 1.328a Wine colour (420nm) 0.562 b 0.701 a 0.583 c 0.626 b Wine colour (520nm) 0.858 b 1.083 a 0.897 b 0.999 ab


TABLE 5

Effect of pruning method on the wine quality of 6 and 18 month old Cabernet Sauvignon wines at Nietvoorbij (2000 -2004).


Overall wine quality after 6 months (%) 56.5 a* 54.8 ab 52.1 b 52.3 b Overall wine quality after 18 months (%) 61.0 a 61.0 a 48.3 b 52.4 b Overall cultivar character after 6 months (%) 66.5 a 65.4 a 59.0 b 58.1 b Overall cultivar character after 18 months (%) 67.4 a 64.5 ab 61.5 b 61.0 b


TABLE 6 Labour inputs for different pruning methods for different varieties grafted onto Richter 99 at Elsenburg (2001 - 2004).

Variety Labour (man hours/ha)

Hand pruning Mechanical pruning** Minimal pruning**

Pruning Canopy Harvest Total Pruning Canopy Harvest Total Pruning Canopy Harvest Total manage- manage- manage-

ment ment ment

Chardonnay 37.8 a* 111.4 a 74.7 a 223.9 a 27.9 b 23.3 b 1.4 b 55.1 b 0 c 12.4 c 1.5 b 14.2 c Cheninblanc 88.4 a 162.7 a 107.0 a 358.1 a 19.7b 14.0b 1.4b 34.1 b Oc 16.0b 1.5b 17.5b Sauvigonblanc 71.4 a 125.1 a 94.3 a 2908 a 44.1 b 17.2 b 1.4 b 62.7 b 0 c 15.0 b 1.5 b 16.5 b Pinotage 36.5 a 130.3 a 136.2 a 3030 a 23.8 a 10.0 b 1.4 b 35.2 b 0 c 12.5 b 1.5 b 14.0 b Merlot 28.0a 74.3 a 78.1 a 180.4a 12.4b 6.4b 1.4b 20.2b Oc 8.8b 1.5b 13b Cabernet Sauvignon 82.7 a 134.3 a 63.3 a 285.3 a 41.3 b 12.8 b 1.4 b 55.5 b 0 c 12.4 b 1.5 b 13.9 c Average 54.5 a 128.9 a 92.3 a 273.6 a 28.2 b 14.0 b 1.4 b 43.8 b 0 c 12.9 b 1.5 b 14.4 c

* Figures for the same action in the row, followed by the same letter, do not differ significantly atpO. 05 ** Grapes from the alternative pruning plots were machine harvested.



Overall ndtivar intensity

LSD(p0.05)5.6 100 LSD(p0.05)=6.4 Quality Colour

100 80 > NS

80

- 100

awo

LSD(p0.05)7A 80

,,, LSD(p<005)140

Hardness 100 40 7 fl Vegetative 80

60

2

20 74! I <100

80 /

2

40 NS

100 - 40 II L.SD (p 0.05) = 9.8

Fullnes 40\ 80 100 fly

60 100 80

60

80

80 100 NS

Acid Spicy 100

LSD (p 0.05) = 6.4 Other LSD (p 0.05) = 9.2

Hand pruning Ti Mechanical pruning

Minimal pruning No pruning

2000 Vintage

80

Overall cultivar intensity

LSD(p0.05)7.2 iixi LSD(p0.05)5.4 Quality Colou

100 80 . LSD (p 0.05) 3.6

80 / 100

— 80

LSD(p0.05) 65 40

Hardness 100

LSD (p <005) = 7.3 Vegetative

L60 I14 \ 100 80

/ 60 20

80 * NS \ 80 ' NS

X 80

Fullness 40 \ 100 Berry

80/2<

60

NS ioo/

NS

Atid Spicy - 100

Other LSD (p 0.05) = 9.2

Hand pruning ri Mechanical pruring

F: Minirrl pruning 1 No pruning

2001 Vintage Overall cultvar intensity Overall cultivarintensity

LSD(p 0.05)=9.8 100 NS* LSD(pe.e5)=1e.8 100 LSD(pe.e5)=6.8

Quality Colour Qush ty Colour 100

80 >. LSD (p 0.05) 9.8 100

80

80 60

/ 100 80 7180 se= )< NS*

80

80 60 80

NS NS

40/10 LSD (p 0.05) = 2.8 NS

40 -. 40 Hardness 100 40 Vegetabve Hardness mo 40 VegetsOve

80 60 20 100 20 80LSD p( 0.05) = 7.1

80 60 60

LSD (p 0.05) 7.5 80 80

SD (p 0.05) 5.1 100 20

Fullness 60 40 40 100 Berry

-' 80 Fullness 6 40\ 100 Berry °

LSD<e.e5)113 7 80 60

/

60

100 80\ NS

100 '- LSDp(<e.e5)=73

LSD (p <0.05) 2.8 80

— Add Spicy

80 NS 100

Add Spicy 100 NS 100 NS

Other Other

Hand pruning Li Mechanical pruning Hand pruning Li Mechanical pruning

Minimal pruning Li No pruning L..... Minimal pruning [i No pruning

2002 Vintage 2003 Vintage

Overall cultivar intensity 100 LSD (p 0.05) = 13.9

NS 100 NS Quality Colour Quality NS Colour 100

80 100

100

NS NS

-\ — 80 - - - ..—J' 80

NS NS

Hardness 100 40 Vegetative

60 2 100

Hardness 180 Vegetative 80 80

20 4 10080

)/ _

60 80 NS 60 NS

E:ii:iii:I:

2040

100 -.40/0 20 LSD (p 0.05) = 83) 80 100 NS S 60 60 80

40 100 Berry Fullness 'NS

80 Fullness 40

40 100 Berry 40

80 60'

NS 80

60 60

60

100 80 \ NS 100 8X.NS

80 l0 Add NS Spicy

80 NS 100

Acid Spicy 100 NS 100 NS

Other Other

Hand pruning LI Mechanical pruning Hand pruning LI Mechanical pruning

Minimal pruning fl No pruning Minimal pruning F. No pruning


Statistical differences indicated in the figuies (p 0.05). *NS = non significant.

FIGURE 2

Effect of alternative pruning methods on the aroma profiles and wine quality of 6-month-old Cabernet Sauvignon at Nietvoorbij (2000-2005).


114


Overall cultivar innsity OraII cultivar intensity

100 NS* LSD(p<0.05)=6.0 100 LSD(p 0.05)6.1 Quality Colour 100 NS Quality

100 Colour

6° 80 >. LSD(p0.05)8.4 < 80 i00NS / 100 80

60 LSD<0.O5)=4.9

80 6° /

LSD0.0=6.2LSD(p0.05)=67 < Hardness - Vegetalwe Hardness 100 I40

6° Vegetive

80

40 60 0 2 100

1 80 60 $j 100

60 80 NS

2 60

40 NS lOO __k4 20 60 80

Fullnes 60 100 Ber - 6°

Fullnes 40 \ 100 Berry

60k' LSD(p< 0.05) = 8 5 6°

100 80 \ - NS - 100/ : NS

LSD (p 0.0 = 3.6 100 100 Add Spicy Add NS Spicy

100 100 - NS Other LSD (p 0.05) = 4.9 Other

Hand pruning Li Mechanical pruning Hand pruning P I MecInical pruning

Mirmal pruning No pruning Minimal pruning IJ No pruning


Overall cultivar intensity Overall cultivar intensity 100 NS LSD(p<0.05)=8.5 100 LSD(p0.05)6.5

Quality NS Colour Quality Colour 100 80

100 80 LSD(p0.05)=12.1

100NS 100

LSD(p<005)=59 \,, 40

NS* Hardness 100 40 Vegetative Hardness 100 4( Vegetative

80 so t6f40'\ /4 80

60 00

60 80

LSD(p 0.05) 10.3

40

60 NS

60 NS 80—' j 40

2

'NS 40 2O 20

80 ! 100 40 2020 60

80 80 LSD (p 0.05) = 9.1 Fullrus 60 40

40 100 Berry

60

60

40 100 Berry

60 LSD (p o.)

100 80\ NS 100/

: 80 100 Add NS Spy

100 NS 100 LSD (p 0.0 = 9.7

Acid Spicy

Other •NS 100

LSD (p 0.05) = 8.6 Other

Hand pruning ii Mechanical pruning Hand pruning r I Mechanical pruning Minimal pruning D No pruning

[j Minimal pruning Ii No pruning

2002 Vintage 2003 Vintage Overall ajlvar intensity

ioo LSD(p 0.05)=4.6 Quality NS Colour

100 80 NS*

60

80 /ioo 60

80

LSD(pO.O5)=5.6 40 60 HarJness

100

40 Vegetative 80

6

60 NS

220

100

40 JUa- - 20 NS 60

100 40 60 80

80

Ns

Fullnes 60 40 40 100 Berry

60 60

00 80 NS

NS 100 Ac Spicy

ioo NS

Other

HarO pruning ri Mmnic xuring

Li Minima pruling [J No pruning

2004 Vintage

Statistical differences indicated in the figures (p 0.05). *NS = non significant.

FIGURE 3 Effect of pruning methods on the aroma profiles and wine quality of 18-month-old Cabernet Sauvignon at Nietvoorbij (2000-2005).



pruning (Table 9). In the cases of both Chenin blanc and Sauvi- plications for fertilization and irrigation when alternative pruning gnon blanc, the vigour was signfficantly reduced by both the alter- methods are applied. native pruning methods. This reduction was partly caused by the The alternative pruning methods significantly increased the huge crop induced by mechanical (76% and 97% respectively) as yield in the case of all varieties (Tables 7 & 8) while bunch mass, well as minimal pruning (155% and 230% respectively) (Table 9). berry mass and berry volume decreased. The decrease in berry size Field observations showed that, especially in the case of Chenin and volume can be ascribed to a signfficant increase in the number blanc, shoot growth came to a rather abrupt arrest compared to of bunches per vine (Tables 7 & 8) as well as an increase in the both Chardonnay and Sauvignon blanc. This has important im- fruit mass: leaf surface area relationship (data not shown). Mini-

TABLE 7 Effect of pruning method on the viticulture performance of the three different white varieties at Elsenburg (2001 -2004).

Chardonnay Chenin blanc Sauvignon blanc

Parameters Hand Mechanical Minimal Hand Mechanical Minimal Hand Mechanical Minimal pruning pruning pruning pruning pruning pruning pruning pruning pruning


Average shoot 105.5 a* 100.3 a 64.7b 105.6 a 60.3 b 57.4b 118.7 a 82.9b 49.0 c length (cm)

Numbershoots/ 19c 31b 56a 23c 41b 72a 22b 32b 71a vme

Average intemodelength 5.78a 5.57a 4.04b 6.60a 4.31 a 5.22b 6.25a 5.53b 4.08c (cm)

Canemass(tlha) 3.1a 2.5b nm 3.3a 2.1b nm 5.3a 3.4b nm

Yield (tJha) 2.3 c 4.9b 8.0a 15.3 c 27.0b 39.0 a 7.3 c 14.4b 24.1 a

Numberof 18c 41b 83c 24c 60b 148a 20c 46b 172a bunches/vine

Bunchmass(g) 122.4a 121.0ab 106.0b 297.1 a 235.9b 185.1b 147.4a 135.4a 85.9b

Berrymass (g) 1.48 a 1.39b 1.27b 1.87 a 1.88 a 1.61 b 1.834 a 1.87 a 1.50b

Berry volume 1.42 a 1.31 b 1.251, 1.81 a 1.74 a 1.61 b 1.75 a 1.73 a 1.46 b

Grape composition

Sugar concentration 22.5 a 22.7 a 22.2 a 21.8 a 21.2 ab 20.1 b 22.2 a 22.2 a 21.5 a (°B)

Acid concentration 8.5 a 7.4 b 6.8 c 9.2 a 7.1 c 8.0 b 10.8 a 10.0 b 8.7 c (g/L)

pH 3.37 a 3.35 a 3.34 a 3.28 ab 3.29 a 3.20b 3.21 a 3.21 a 3.18 a

Sugar:acidratio 2.8b 3.1 a 3.3 a 2.4b 3.1 a 2.6b 2.1 b 2.2b 2.5 a

Must composition after skin contact

Sugar concentration 22.8 a 22.8 a 22.2 a nm nm nm 22.2 a 22.5 a 21.6 a (°B)

Acid concentration 7.4a 6.5b 5.9c nm nm nm 10.2 a 9.4b 8.1 c (g/L)

pH 3.50 a 3.52 a 3.49 a nm nm nm 3.22 a 3.21 a 3.19 a

Sugar:acidratio 3.2b 3.7a 3.8a nm nm nm 2.2b 2.5ab 2.7a

*Figures for different treatments per variety, followed by the same letter, do not differ significantly atpO. 05. nm = not measured


116 Alternative pruning methods for some wine grape varieties

mal pruning increased the number of bunches for Chardonnay, Chenin blanc and Sauvignon blanc by 361%, 517% and 760% re-spectively (Table 9). Of the three white varieties, Sauvignon blanc showed the biggest decrease in beny mass and volume, bunch mass, cane length and internode length, while it showed the big-gest increase in number of bunches per vine, number of canes per vine and the second largest increase in yield. After only four years of data this raises a question as to the adaptability of this variety to alternative pruning methods. Taking the same parameters into account, Chardonnay seems to be better adaptable to alternative pruning. Further research into this aspect is necessary.

In the case of the red varieties, Cabernet Sauvignon reacted to mechanical pruning in a similar way than Chardonnay. Minimal pruning significantly increased the number of canes per vine with all three red varieties, but the average cane length was signfficant-

ly decreased mainly because of a reduction in internode length (Table 8).

Similarly to the white varieties, minimal pruning induced the biggest changes in all measured parameters in the red varieties compared to hand pruning (Table 9). Merlot showed the biggest increase in number of shoots for both alternative pruning meth-ods and at the same time it showed the biggest decrease in cane length. Field observations showed that the shoot growth of this variety came to a rather abrupt arrest during the middle of the growing season even though the crop stress was not as high as in the case of the other two varieties. Although Cabernet Sauvignon showed the biggest decrease in internode length, it maintained shoot growth over a longer period. This, together with the fact that it showed the biggest increase in bunch number and yield, points to the adaptability of this variety to alternative pruning methods.

TABLE 8 Effect of pruning method on the viticulture perfonnance of the three different red varieties at Elsenburg (2001 -2004).

Pinotage Merlot Cabernet sauvignon



Average shoot 86.6 a* 71.4b 52.2 c 77.1 a 60.0b 36.2 c 114.5 a 106.3 a 57.0b length (cm)

Number shoots! 24b 24b 52a 18b 21b 45a 26b 28b 63b vme

Average intemodelength 5.41 a 5.10ab 4.02c 5.51 a 5.00a 4.53b 6.74a 5.32a 4.07b (cm)

Cane mass (t/ha) 2.9a 1.8b nm 2.0a 0.9b nm 6.3a 4.5b nm

Yield (tlha) 8.3 b 13.8 a 14.2 a 9.8 b 11.7 a 10.6 ab 7.4 b 11.9 ab 15.9 a

Numberof 38c 58b 78a 26c 45b 61a 23c 61b 98a bunches!vine

Bunchmass(g) 111.2ab 118.8a 104.6b 161.2a 126.1b 109.4b 105.9a 88.7b 74.5c

Berry mass (g) 1.67 a 1.54 ab 1.38 b 1.49 a 1.43 a 1.25 b 1.40 a 1.33 a 1.23 a

Berryvolume 1.53 a 1.48 a 1.30b 1.39 a 1.35 a 1.19b 1.37 a 1.27 ab 1.17b

Grape composition

Sugar concentration 25.0 a 24.2 ab 23.3 b 23.0 a 23.2 a 23.3 a 24.1 a 23.5 a 23.1 a (°B)

Acid concentration 8.6 a 7.2 b 6.8 b 6.3 a 5.8 a 5.8 a 8.5 a 7.6 b 7.4 b (g/L)

pH 3.37 b 3.46 ab 3.57 a 3.32 b 3.41 a 3.36 ab 3.45 a 3.47 a 3.36 b

Sugar:acid ratio 3.0 b 3.6 a 3.8 a 3.6 b 4.0 a 4.0 a 2.8 b 3.2 a 3.2 a

* Figures for different treatments per variety, followed by the same letter, do not differ significantly atpO. 05. nm = not measured



A B 120

E 100

80

Ile 60 3.

40

E 20

2001 2002 2003 2004

Vintage

-4-Hand pruning -U-Mechanical pruning -*-Minimal pruning

C - D 100

go-

70

60

50

40

30

20

10

0

2001 2002 2003 2004

Vintage

--- Hand pruning -U-Mechanical pruning -*-Minimal pruning

E - F 70 -

.c50

40

30

20

E

o 10

2001 2002 2003 2004

Vintage

-4--Hand pruning --Meacal pruning Minimal pruning

FIGURE 4

Effect of alternative prunin g methods on the cumulative yield of six varieties at Elsenburg (2001 - 2004). A = Chardonnay; B = Chenin blanc; C = Sauvignon blanc; D = Pinotage; E = Merlot and F = Cabernet Sauvignon.

70 - -

60

.c so

; 1

0.

•D 40

30

_______________________________________

0J

20

E o 10

2001 2002 2003 2004

Vintage

--- Hand pruning -U-Mechanical pruning -A- Minimal pruning

6C 0.

• 5C ________________________________

4C

30-

E2c

0

2001 2002 2003 2004

Vintage

--Hand pruning -U-Mechanical pruning -h-- Minimal pruning

60

40 0.

JD 30

20

E 10

o 1 2001 2002 2003 2004

Vintage

--- Hand pruning -U-Mechanical pruning -a-Minimal pruning

The bunch mass of Pinotage was least affected by alternative pruning and, combined with the relatively small change in the growth habit, this indicates that this variety also adapts well to alternative pruning methods. After only four data years it seems that Merlot is the least suitable for alternative pruning.

Except for Merlot and Pinotage the cumulative yield over four seasons for all varieties was highest for minimal pruning, pointing to an earlier break even point than for the other pruning meth-ods (Fig. 4). The relative yield difference in the case of Merlot

also was less expressed than for the other varieties, strengthening the observation that this variety may not adapt well to alternative pruning. The cumulative yield of minimally pruned Chenin blanc was the highest, while hand pruned Chardonnay and Cabernet Sauvignon were the lowest.

Although no clear pattern could be distinguished, important an-nual fluctuations in yield occurred (Fig. 5). As in the case of the trial at Nietvoorbij, 2003 season proved to be an excellent season for alternative pruning methods for all varieties at Elsenburg. The


118


A B

50 60 3 a

45 +4 50

1+4 a 40 4+ +4 1+4

35 40 a i••

a 30 +4 a ++ 14+ r ......++ b 25

CL b 4+ , 35

V 20 a ..•• >- 15

20 a a b ab

10

aaa

2001 2002 2003 2004 2001 2002 2003 2034

Vintage Duo 0 sOcro downy milcow

Vintage fiesta sf10 grapos cou d bo harnostod horn the mooban eel and miiimaltrawnnants • Harrd pruoing R Mechari cal pruning M M nireal pwrring • Hard pruniog IS Mehonical puoiug U Mininl Paoio9

C D

60

a

40

35 a a

a 50

4+ 30

40 4+ a a 25 b

...... 4+ ++ a

a

15 20

ii :i iliZ

2001 2002 2003 2004 2001 2002 2003 2004

Vintage Vintage • Hand pruning EA Mechan cal pruning Minimal pruning • Hand pruning 0 Mechanical pruning N Mm real pruning

E F

40 25

35

20 1I11': 30

] 25 a + 20

CL b iiiIi :j bHLI4dLI4; $ ; I r 2001 2002 2003 2004 2001 2002 2003 2004

Vintage Vintage Duo to soco downy miidoo iniostat on no grapos oouid be hunts od hot rho hand tmatmont • Hand pruniug e Mechauical pruning El Mu mal prunng • Fland pruning a Mechanical pruning • Minimal pruning

Vertical bars followed by the same letter in the same vintage do not differ significantly at p< 0.05.

FIGURE 5

Effect of alternative pruning methods on the annual yield of six varieties at Elsenburg (2001 —2004). A = Chardonnay; B = Chenin blanc; C = Sauvignon blanc; D = Pinotage; E = Merlot and F = Cabernet Sauvignon.

trail was approximately 7 km away and in the same climate region (Region III) than the one at Nietvoorbij. This tendency was not clearly shown for the Robertson (Region V) trial (see Fig. 13) and it points to the possibility that climate plays an important role in the performance of alternatively pruning methods. More data years are necessary to identify variety differences in this respect.

Different pruning methods had little effect on the oenological performance of the six varieties investigated (Tables 10 & 11). Minimally pruned Sauvignon blanc had lower extract, while me-

chanically pruned Chenin blanc, mechanically and minimally pruned Sauvignon blanc showed a lower acid concentration (Ta-ble 10). Hand pruning induced less colour in the skins and wines of Cabernet Sauvignon, while the colour of Pinotage was nega-tively affected by alternative pruning methods (Table 11). Again, more research is necessary to establish if this pattern will continue over the longer term.

In three out of four years the citrus-like aroma of Chardonnay wines was enhanced by minimal pruning (Fig. 6), while the tree



TABLE 9 Effect of pruning method on the percentage difference in relation to hand pruning for different varieties at Elsenburg (2001 - 2005).

Chardonnay Chemn blanc Sauvignon blanc Pinotage Merlot Cabernet Sauvignon Parameters

Mechanical Minimal Mechanical Minimal Mechanical Minimal Mechanical Minimal Mechanical Minimal Mechanical Minimal

Averageshoot -4.9a -38.7b -42.7a -45.7a -30.1 a -58.7b -18.0b -40.0a -22.0a -53.0b -7.0a -50.0b length (%)

Number shoots/vine 63.0b 194.7a 78.3b 213.0a 45.5b 222.7a 0.0b 116.0a 17.0b 167.0a 8.0b 142.0a (%)

Average internode -3.6 a -30.1 b -34.7b -20.9 a -11.5 a -34.7b -6.0 a -26b length (%)

Cane mass (%) -19.4 a nm -36.4 a nm -35.8 a nm -38.0 a nm

Yield(%) 113.Ob 247.8a 76.5b 155.0a 97.0b 230.0a 66.0a 71.0a

Number of bunches/vine 128.0b 361.0 a 150.0b 517.0 a 130.0b 760.0 a 53.0b 105.0 a (%)

Bunch mass -1.1 a -13.4b -20.6a -38.0 b -9.0 a -42.0 b -7.0 a -6.0b (%)

Berrymass -9.0 b -14.0 a 0.6a -14.0 b -2.0 a -18.Ob -7.0 a -18.Ob (%)

Berryvolume -8.0 b -12.0 a -4.0 a -11.0b -1.4 a -17.0 b -4.0 a -16.Ob (%)

-9.0 a -18.Ob -21.0 a -40.0 b

-55.0 a nm -29.0 a nm

19.0a 8.0b 61.0b 115.0a

73.0b 135.0a 165.0b 326.0 a

-22.0 a -32.0 b -16.0 a -30.0 b

-4.0 a -16.0 b -4.0 a -12.0 b

-3.0 a -15.0 b -8.0 a -15.0 b

* Figures for the same variety and parameters in the row, followed by the same letter, do not differ significantly atp0.05. ** Not measured.

TABLE 10 Effect of pruning method on the oenological performance of the three different white varieties at Elsenburg (2001 -2004).

Chardonnay Chemn blanc Sauvignon blanc

Hand pruning

Mechanical pruning

Minimal pruning

Hand pruning

Mechanical pruning

Minimal pruning

Hand pruning

Mechanical pruning

Minimal pruning

13.9 a* 13.9 a 13.3 a 13.1 a 12.8 ab 12.1 b 13.6 ab 14.1 a 13.1 b

23.9 a 23.3 a 21.2 a 21.1 a 20.2 a 20.5 a 22.7 a 21.5 b 21.7 b 0.27 a 0.21 b 0.20 b 0.28 a 0.24 a 0.23 a 0.30 a 0.29 a 0.29 a 28a 27a 28a 27a 27a 28a 33a 29b 29b 107a 101a 98a 88a 90a 88a 95a 95a 102a 3.4 a 2.9 a 2.4 a 2.4 a 2.5 a 2.9 a 2.1 a 2.3 a 2.2 a 5.4a 5.4a 5.1 a 7.1 a 5.8b 6.6a 6.9a 6.0b 6.3b 3.62 a 3.61 a 3.47 b 3.35 a 3.38 a 3.24 b 3.24 ab 3.27 a 3.23 b

Parameters

Alcohol concentration (vol %)

Extract (mg/L) Volatile acid (mg/L) Free SO2 (g/L) Total SO2 (g/I) Sugar concentration (g/L) Acid concentration (g/L)

PH

* Figures for different treatments per variety, followed by the same letter, do not differ significantly atp0. 05.

fruit aroma benefited form mechanical pruning for two of the four vintages. This is ascribed to better fruit exposure brought about by alternative pruning methods (data not shown).

In one out of four years, the colour of Chenin blanc wines was improved by mechanical pruning (Fig. 7). During the same vin-tage, this pruning method decreased the acid concentration. Dur-ing one year, minimal pruning decreased the overall quality of Chenin blanc wines. Chenin blanc wine did not benefit from al-ternative pruning.

The vegetative character of Sauvignon blanc wines was en-hanced by hand pruning in two of the four vintages, probably be-cause of less fruit exposure (Fig. 8), while it improved the acid concentration of one year only.

Hand pruning decreased the colour of Pinotage wines in two of the four vintages, while it decreased the vegetative aroma and overall quality twice (Fig. 9). There is a tendency that the colour is enhanced by mechanical pruning. These colour differences may be ascribed to differences in fruit exposure and berry size.


120


Overall cultivar intensity Citus

Quality NS 100 NS* Citrus 100

10018° Fullness 80

100

LSD(pOO5)=58 80

o /m NS 80 100

Fullness Tree fruit

80 60 f

: .. Z4O

80 40

:°

18° 80 Acid I I

60 20 I

.11 .1 I I ITropicalfruit

40 N 60 80 io Tropical fruit 40 20 20<\,

60/ 40

ac

NS 100

/ t 40\ 60

60

. 80

80 2< 8° 60

Colour so 100

Ded •fl Oth

100 Drted fwit

NS ioo o

Other NS Caramel 100

Caramel

Hand pruning LI Mechanical pruning Li. Minimal pruning Hand pruning Li Mechanical prunng [] Minimal pruning

2001 Vintage 2002 Vi ntage**

Overall cultvar intensity 100


Quality 00

NS J NS* 1 I

Citrus Quality

100

NS I NS 100

Citrus

T8° 8° 100 00

8°

80 LSD(pO.O5)=45

NS +\J f ° Fullness Tree fruit FulIn ess 100 80 / '\ .J 20 140 Tree fruit

10LSD(p0.05)=0.6 80 100

400

NS 00

b y

X 60 8°

NS ioyX 60t

Oif\ 60 NS

Add 60

00 6o1 c 100

Tro pical fruit Acid eo\ so

°° Tropical fruit

NS 7L

100 100

NS 100 100

Other Caramel Other Caramel

Hand pruning [I Mechanical pruning [i]

Minimal pruning Hand prLning Li Mecharcal pruning 1 Minimal pruning

2003 Vintage 1 2004 Vintage

Statistical differences indicated in the figures (p 0.05). *NS = non significant. ** Downy mildew caused severe damage in 2002 and wine could not be made from all the treatments and replicates thus no statistical analyses was applied.

FIGURE 6 Effect of pruning methods on the aroma profiles and wine quality of Chardonnay wines of four different vintages at Elsenburg (2001 —2004).



Overall cultivar intensity Fruity 100 NS* 100

NS

::

Vegetaive :

Quahty

100 80

NS Quality

100

80 40

20

60

1 °° 20; 40 NS

Fullness Tpical fit

Ilness

60 80

80

100 oI

Atid Other

Hand prLning LI Mechanical pruning El Minimal pruning Hand pruning

2001 Vintage 2002 Vi ntage**

Overa ll culitvar intensity Overall cuWvar intensity 100 NS*

100 NS -

LSD(p<0.05)=14 LSD(p<0.05)=10.2

Quality 100

80 Colour NS

Quality - 80 100

Colour

80 .50 />S100

80 40

X~ 40

NS II 7\ an / 20 20 1 NS

20 NS

o 7 S LSD (p 0.05) = 2 Fullness I I 1Jree fruit Fullness I 160 I I fruit 1jree

40 100

::I>, 60

Acid 100

Tropical fruit 100

Acid NS 8Ô Tropical fruit LSD (p 0.05) = 8.8

100

Other Other

Hand pruning [1 Mechanicalpruning [] Minimalpruning El Hand pruning Li Mechanicalpruning [•_] Minimalprunig



FIGURE 7 Effect of pruning methods on the aroma profiles and wine quality of Chenin blanc wines of four different vintages at Elsenburg (2001 — 2004).

No clear pattern is obvious form the aroma and quality profiles of Merlot wines, except that minimal pruning was responsible for wine colour reduction in three of the four vintages (Fig. 10) al-though the reduction was not significant. This cannot be explained because no skin colour differences occurred (see Table 11).

In three of the four vintages, alternative pruning enhanced the colour of Cabernet Sauvignon wine compared to hand pruning (Fig. 11). This was expected due to the improvement of the skin colour obtained in the grapes (see Table 11). In spite of this, mini-mal pruning produced the worst overall quality Cabernet wine in two of the three seasons. There is a tendency for wines form the hand pruned plots to be more vegetative in character and this is probably due to the bunches not being as well exposed to sunlight as in the case of the alternatively pruned plots. This probably con-tributed to the judges finding a higher overall cultivar intensity in the wines from the hand pruned plots.

Trial at Robertson

The same labour saving advantages obtained by alternative prun-ing methods in the trials at Nietvoorbij and Elsenburg, were real-ised in the trial at Robertson (Table 12). Hand pruning (including canopy management and harvesting) required 193.8 man hours/ ha, while 46.6 and 22.0 man hours/ha were used for mechani-cal and minimal pruning respectively. The man hours used for canopy management with the alternative pruning methods were for removing shoots on the trunks as well as mechanical trimming of shoots to open the work row. In the case of minimal pruning summer trimming of the shoots 30cm above ground level is also included under canopy management. It is again necessary to state that mechanical harvesting is a prerequisite when anyone of the alternative pruning methods are used.

The average cane length was significantly decreased by alter-native pruning with minimal pruning producing the shortest in-


122


Overall cultivar intensity Overall cultivar intensity

NS - 100 NS-

NS 80 LSD (p 0.05) = iLl 80

Quality 100

Vegetative 60

Quality NS 100

Vegetative 60

80 100 NS

60 60 80

40 20

80

40

20 40 20

NS 40 20

60 40

20 60

NS 100 80 20 40 NS

Fullness 20

40

60 80

100

Tpical fwit Fullness NS 20

40

60 80 100 Tpical fit

60 60

60 6\

100

NS 100 NS 100 Acid Other Acid Other

Hand pruining EI Mechanical pruning 11 Minimal pruning Hand pruining II Mechanical pruining Minnal pruning



i 100 LSD (p 0.05) = 4.5

1 Quah ty

NS 80

Vegetative Quity

80

100 Vegetative

100 NS NS

60 40 60 II N 20420

20 2 40

20I20

100 NS

Fullness 20 80

fruit Fullness 40 100 Tropical fruit

60

NS 40 \

60

\ 80

80\

60 80

0 80

10 / NS LSD(p<0.05)=10.0 100

100 LSD(p0.05) =2.5 NS 100

Acid Other Acid Other

Haiti pninig 1 Mechaical pruiing Minima uning Haiti xining II Mechanical pruining Minima xining



FIGURE 8 Effect of pruning methods on the aroma profiles and wine quality of Sauvignon blanc wines of four different vintages at Elsenburg (2001 —2004).



Colour

Quality NS* 100

Overall culivar intensity 100 NS

NS 80 100 80 ,

80

Tannins 100 NS Vegetative

80 40 40 60 .

NS 60 1 100

20: 80 60

40

80 60 -

NS 100

Rilness 40

20 60

80 100 Berry NS 60 40 40

80 40 60

100 60

60 80

LSD(pO.O5)=6.2

Acid 80 100

Tree fruit 80

100 NSNS 100

Other Dried fruit

Hand pruniig [1 Mechanical pruning Miniiial pruning

2001 Vintage

LSD(<O.05)=113 Colour LSD (p < 0.05) 21.6

Quality 100

Overall cuWvar intensity 100 LSD(p <0.05)= 11.6

100

NS

80

6 80

Tannins i 00

Vegetative

80 60 I 100 80 NS*

60

Fullness Berry

LSD(p<0.05)=12.4 60

\ 100

0 : 80 NS

NS 80 Tree fruit NS

100 NS 100

Other Dried fruit

Hand pruning Liii Mechanical pruning Li Minimal pruning

2003 Vintage

Colour

Quality NS 100

Overall culivar intensity

N S

100 80

NS 100

80

60/ / 80

NS Vegetative Tainins ioo 40 60

80 0 100 NS

60 40 3L 20 80

60 40

100 80 60 2

NS

Fullness :

40 20

60 80 lao Berry NS

60 40 40

80 40 60

100 60

60 80 NS

Acid NS 80 100

Tree fruit 80

100 NS NS 100

Other Dried fruit

El Hand prunhg El Mechanical prLning Minhial prunhg

2002 Vintage

Colour

Quality NS

K 100 1 80 100NS


80 100NS

NS Tannins 100 Vegetative

80 40 100

NS 60

40 NS

NS

Fullness 40 20

40 00 80 loo Berry

100 80

Ad

60 100

Tree Fwit

LSD (p 0.05) =2.7 IOOJNS NS

100

Other Dried Fruit

Hand pruning [1 Methanical pruning LI] Minimal pruning

2004 Vintage


FIGURE 9 Effect of pruning methods on the aroma profiles and wine quality of Pinotage wines of four different vintages at Elsenburg (2001 —2004).


124


Colour - 100 NS*

Quality rs Overall cultivar intensity

lao 80

80/' 100

- 80 NS

40NS V60

Tannins 100 80 60

Vegetative

10 60 80 NS

NS 100 40 '7 6ó

80

Fullness 60 °° Berry

Colour 100

Quality100

Overall cultivar charachter 80

80 d 7' 100

)( 80

Tarviins

:80

I'J40 60

60 20

Vegetative 80

100

Fullness

80

20 0

10

/C 6G" 40

100 Berry

80 60

NS ioo/ \ NS 100

Acid Other

Hand pruning El Mechaiical pruning Minimal pruning

2001 Vintage

80 100' cid Spicy

100

Other

El Hand pruning El Mechanical pruning Minimal pruning

2002 Vi ntage**

Colour Colour 100 NS

Quality NS Overall cultivar intensity Quality NS Overall cultivar intensity 1 00 I®

\s :/s 80

Tannins 60

Vegetative

NS Tannins 100 40 Vegetative

60

20

NS 60

Fullness 80

46\ 100 Berry Fullness 40\ 100 Berry

100/ I 100

Acid NS

Spicy

Onther

Hand pruning El Mechanical pruning Minimal pruning

2003 Vintage

86\),

Acid NS1

NS Spicy100

NS IOO

®

Other

Hand pruning II Mechanil pruning Minimal pruning

2004 Vintage


** Downy mildew caused severe damage in 2002 and wine could not be made from all the treatments and replicates thus no statistical analyses was applied.

FIGURE 10

Effect of pruning methods on the aroma profiles and wine quality of Merlot wines of four different vintages at Elsenburg (2001 —2004).



Colour Colour

100 NS 100

Quality NS Overall cultivar intensity Quality Overall cultivar intensity

'< 100

80 100

80

80 O N 2' 100

< 6O 80 \ / 80

NS

Hardss I® 40

80

Vegetative Hardness I® 40 40

Vegetative 80

60 60 2(-2/\

80

--- 00 l®

60 80

NS 60 80

60

40

20

NS 80 100 40

20

40 60

80 60

100 \40 20

Fullness 60

40 \ I® Berry Fullness 60

80 Berry

NS

80 60

80/ 60

00 100 Acid NS Spicy Acid Spicy

NSIOO 100

Other Other

El Hand pruning El Mechanical pwring Minimal pruning Mechanical prunin [1 Minimal pruning


Colour Colour LSD(p<0)5)12.O 100 NS* 100 NS*

Quality 100

Overall cultivar intensity Quality NS 100

Overall cultivar intensity 80

so 100

1) (p 0.05) iLl 80 7100

L 80 I NS

so 80

NS Hardness 100 Vegetative Hardness o egeve

So 60 20 80

100

60 NS 40

LSD (p < 05) 120 80 100 20 60

80 LSD(p<0.05)6A 100

Fullness 60 40 100 Be Fullss 60 \

100 Berry

80/

NS 40

NS

NS 8

: 100

60 80' 7 100

LSD(P<0.05)6 100

NS I

act 00 Acid NS Spicy Add Spicy

NS 100 NS 100

Other Other

Hand pruning [1 Mechanical pwning LI] Minima pruning Hand pruning P1 Mechanical pruning I:] Minimal pruning



FIGURE 11 Effect of pruning methods on the aroma profiles and wine quality of Cabernet Sauvignon wines of four different vintages at Elsenburg (2001 —2004).



TABLE 11 Effect of pruning method on the oenological performance of the three different red varieties at Elsenburg (2001 -2004).

Pinotage Merlot Cabernet sauvignon


Alcohol concentration (vol %) 15.0 a* 14.5 a 14.1 a 14.5 a 14.4 a 14.6 a 14.2 a 14.6 a 14.0 a Extract(mg/L) 33.8a 32.6a 31.9a 30.4a 29.6a 29.8a 34.7a 35.1 a 31.6b Volatile acid (mgIL) 0.44 a 0.37 b 0.38 b 0.25 b 0.26 b 0.35a 0.22 a 0.23 a 0.20 b Free S02 (g/L) 55a 56a 54a 42a 41a 41a 45a 42b 43ab Total S02 (9/L) 68a 71a 69a 81a 81a 83a 81a 77b 78ab Sugar concentration (g/L) 2.0a 2.0a 1.8a 1.6b 1.7ab 1.8a 1.8a 1.7ab 1.6b Acid concentration (gIL) 6.8 a 6.0 b 6.4 ab 6.1 a 6.3 a 6.3 a 6.2 a 6.8 a 6.9 a pH 3.82 a 3.86 a 3.81 a 3.62 a 3.60 a 3.54 a 3.93 a 3.88 a 3.68 b Skin colour (420nm) 0.359 a 0.388 a 0.449 a 0.480 a 0.451 a 0.506 a 0.271 b 0.339 a 0.355 a Skin colour (520nm) 1.623 a 1.749 a 2.059 a 2.270 a 2.141 a 2.078 a 1.214 b 1.603 a 1.717 a Wine colour (420nm) 0.763 a 0.741 ab 0.604 b 0.688 a 0.749 a 0.723 a 0.669 b 0.915 a 0.740 b Wine colour (520nm) 1.263 a 1.120 ab 0.986 b 1.134 a 1.202 a 1.185 a 0.885 b 1.284 a 1.145 a

* Figures for different treatments per variety, followed by the same letter, do not differ significantly atp0. 05.

TABLE 12 Labour inputs for different pruning methods for different varieties grafted onto Richter 99 at Robertson (2001 -2006).

Labour (man hours/ha)

Hand pruning Mechanical pruning** Minimal pruning** Variety

Canopy Canopy Canopy Pruning manage- Harvest Total Pruning manage- Harvest Total Pruning manage- Harvest Total

ment ment*** ment***

Chardonnay 52.4a 54.5a 86.5a 193.4a 19.6b 18.9b 1.4b 39.9b Oc 17.4c 1.5b 18.9c Cheninblanc 61.9a 51.1 a 90.5a 203.4a 22.7b 21.9b 1.4b 46.0b Oc 20.1 c 1.5b 21.5c Colombar 57.3 a 34.0 a 76.8 a 168.1 a 22.2 b 17.0 b 1.4 b 40.7 b 0 c 16.2 b 1.5 b 17.7 c

Sauvignonblanc 67.5a 38.6a 89.5a 195.6a 22.9b 31.5b 1.4b 55.8b Oc 27.5c 1.5b 29.0c

RubyCabemet 66.2a 27.5a 111.4a 205.2a 25.1b 17.4b 1.4b 43.9b Oc 15.9c 1.5b 17.4c Shiraz 63.1 a 47.4a 86.5a 196.9a 22.2b 29.4b 1.4b 53.0b Oc 25.7c 1.5b 27.2c Average 61.4a 41.9a 90.2a 193.8a 22.5a 19.9b 1.4b 46.6b Oc 20.5b 1.5b 22.0c

* Figures for different treatments per variety, followed by the same letter, do not differ significantly atp0. 05. ** Grapes from the alternative pruning plots were machine harvested. *** Shoots on the vine trunks were removed. In the case of minimal pruning, shoots hanging down were trimmed to about 30cm above soil level. Shoots of the mechanical and minimum pruned vines were also trimmed to open up the workrow.

ternodes (Table 13). On average, mechanical pruning reduced shoot length by 18% over all varieties, while minimal pruning was responsible for a 60% decrease (Table 14) compared to hand pruning. At the same time internode length was reduced by 10% and 40% respectively. In all cases the number of nodes per cane was significantly reduced by alternative pruning (data not shown) compared to hand pruning. The number of shoots per vine was signfficantly increased by the alternative pruning methods (Table 13), mechanical pruning increased it by 113% over hand pruning and minimal pruning by 400% (Table 14) respectively. Changes in cane length (decrease) and number of shoots (increase) brought about by mechanical pruning compared to hand pruning, resulted in no change in cane mass/ha in the case of Ruby Cabernet and Shiraz (Table 14) repsectively. The overall reduction in vigour caused by alternative pruning methods could partly be ascribed

to the increases in yield (Table 13) compared to hand pruning. Minimal pruned vines only yielded more than mechanical pruned vines in the case of Chardonnay. Mechanical pruned vines per-formed the same or better than minimal pruned vines in the case of the other varieties. The possible yield reducing effect of a lower bunch mass in the case of the alternative pruning methods, was more than offset by a significant increase in bunch number (Table 13). The cumulative yield over the six vintages of this trail showed that Chardonnay and Shiraz profited by mechanical pruning, while Sauvignon blanc and Ruby Cabernet profited by minimal pruning (Fig. 12). In the case of Chenin blanc and Colombar no distinc-tion can be made between mechanical and minimal pruning. It is, however, clear that these two alternative pruning methods had a yield advantage over hand pruning. No clear pattern emerged when seasonal yields were compared between varieties (Fig. 13).



Mechanical pruning increased the bunch number on average by 166% in all varieties, while minimal pruning was responsible for an increase or 360% (Table 14). The smaller bunches obtained with alternative pruning were not only caused by smaller berries (mass and volume), but also by a smaller physical size as shown by the bunch stem mass (Table 13).

Pruning methods had no clear effect on sugar concentration and in the case of Chardonnay, Sauvignon blanc and Ruby Cabernet, the acid concentration in the grapes was reduced (Table 13) com-pared to hand pruning. The effect of pruning method on must pH was not clear and it differed between varieties. More research is necessary to determine the effect of the alternative pruning meth-ods on grape composition.

No clear trend in the effect of alternative pruning methods on the wine composition of the different varieties could be found except for wine colour where these methods improved the colour of Ruby Cabernet and Shiraz wines (Table 15). This may be derived from the better skin colour (possible better skin: juice relationship of the smaller berries) obtained by alternative pruning with these varieties.

In two of the six vintages, the citrus aroma of the Chardonnay wines was improved by minimal pruning, while mechanical prun-ing achieved it in one season (Fig. 14). There is a tendency that the citrus and tree fruit characters were enhanced by alternative pruning. Pruning method had no clear effect on the wine aroma of Chenin blanc (Fig. 15) and the same is true for Colombar (Fig. 16) which is also a neutral variety. Contrary to popular belief, minimal pruning enhanced the vegetative character of Sauvignon blanc wines in two of the six vintages, while it reduced the tropical fruitiness in one season (Fig. 17). The wines from the hand pruned plots showed a tendency to be fuller than that of the alternatively pruned vines. In two of the six vintages the panel ofjudges found a better colour in the Shiraz wines from the alternatively pruned vines (Fig. 18). Except for a tendency that alternatively pruning improved quality, overall cultivar intensity, fruitiness and spici-ness, no clear pattern emerged in the wines of Shiraz (Fig. 18). In four of the six vintages, there was a tendency that hand pruned vines enhanced the vegetativeness of Ruby Cabernet wine (Fig. 19). No other clear pattern emerged.

With all the varieties, especially the two reds, sunburn and mill-erandage were increased with alternative pruning and this tenden-cy held true for all three trials. In all cases the bunch compaction was also reduced but no disease advantage could be monitored.

CONCLUSION

Compared to hand pruning, alternative pruning methods (me-chanical, minimal and no pruning) are hugely labour saving and contribute greatly to reducing production costs of wine grapes. A prerequisite for these methods is the availability of mechanical harvest machines because hand harvesting the resultant numerous small bunches by hand, is not viable.

Alternative pruning methods reduced the vigour of all varieties used in the three different trials, but the method as well as the variety differ in the extent to which these changes took place. Vig-our reduction is ascribed to shorter canes with shorter internodes and the time of shoot growth arrestment varies between varieties. Although berry mass and volume as well as physical bunch size were reduced by alternative pruning methods, resulting in lighter bunches, the increased number of bunches not only prevented a yield decrease, it was responsible for considerable yield increases compared to hand pruning. Contrary to common believe that this may affect quality, wine quality in most cases was either not af-fected or it was improved. Again, in this respect there are variety differences.

Cabernet Sauvignon, Pinotage and Chardonnay seemed to adapt the best to alternative pruning, while Sauvignon blanc and Merlot (both varieties prefer cooler ripening conditions) were less adaptable. The perfonnance of Chenin blanc, Colombar, Shiraz and Ruby Cabernet was acceptable making them good candidates for alternative pruning especially when the economy is taken in account. Although not measured, practical vineyard observations showed that inner trellis posts should not be planted further apart than 6.0m, while additional fertilization and irrigation will be needed when anyone of the alternative pruning methods is used.

Wider vineyard rows (3.Om to 3.2m) must be used when one or more of the alternative pruning methods are applied to provide enough room for the expansion of the permanent vine structure.


128


AB

140 160

120 ______________________________________

'- 100 C,

80

140

120 C,

100 C, 2 80

60 60

___________________________________ 40 40

E 20

0 20

0 I I

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage Vintage

---Hand pruning —U—Mechanical pruning —h—Minimal pruning ---Hand pruning —U—Mechanical pruning —h-- Minimal pruning

C -- D

160 160 -

140 40 1 i iz0 z0

C,

CL - 100 100

__________________________ .80 ° 80

60

_______________ 60

40 TT 0 4 E 20

0

20

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage Vintage

—4-- Hand pruning —U— Mechanical pruning —h-- Minimal pruning —4-- Hand pruning —U— Mechanical pruning —*— Minimal pruning

E F

140 140

120 -c '-______________________________________ C, 100

120

100

80

'- C)

80 C) A C)

60

Z 40

60

40

E 20

I I I I I I

E 20

I I I

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage Vinatge

—4--Hand pruning —U— Mechanicalpruning —- Minimalpruning —--Hand pruning —U— Mechanicalpruning —4--Minimalpruning

FIGURE 12 Effect of alternative pruning methods on the cumulative yield of six varieties at Robertson (2001 —2006).

A = Chardonnay; B = Chenin blanc; C = Colombar; D = Sauvignon blanc; E = Ruby Cabernet and F = Shiraz.



15 1 0 10

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage

• Hand pruning

Vintage

E1 Mechanical pruning 00 Minimal pruning • Hand pruning 63 Mechanical pruning LI Minimal pruning

400%%

10

0 1 0 —1% 1

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage Vintage

• Hand pruning 0 Mechanical pruning 0 Minimal pruning • Hand pruning n Mechanical pruning El Minimal pruning

E F

25

20

2001 2002 2003 2004 2005 2006 2001 2002 2003 2004 2005 2006

Vintage

U Hand pruning

Vintage

E Mechanical pruning Minimal pruning • Hand pruning ni Mechanical pruning Id Minimal pruning

Vertical bars followed by the same letter in the same vintage do not differ significantly at p< 0.05.

FIGURE 13 Effect of alternative pruning methods on the annual yield of six varieties at Robertson (2001 —2006).

A = Chardonnay; B = Chenin blanc; C = Colombar; D = Sauvignon blanc; E = Ruby Cabernet and F = Shiraz.



Overall culvar intensity

LSD(p<0.05)10.1 100 *

Quality Colour 100 LSD(p<O.05)5.S

80

O Fiilness 100

80 100

us

80 °

100 6,/ç / / 1 k LSD (p <0.00) 8.5

100 80 60 , 40

NS

Acid NS

60

00 Trae fruit

100

80 60'N 60

\ 00NNS

Other NS 80 100

80 Tropical fruit

100 NS

Caramel Dried fruit

Had prrng Mchr,cI prrng El MnI prnng

2001 Vintage

Overall cultivar

Qualty 100 NS

00

eo NS

Fullness 100

\40

00 60

40

NS

40 / i

Add /

00/

NS100 7 Other

00

100

Hond Pn Mochornca

2002 Vintage

Caramel

intensity 100

NS Cour 00

100

/ NS 00

Otrus

100

4NS 40

NS

40 100 Te fruit ra

60 00

NS 100

NS Tcal fruit

Li MnrrIprunng

Overall ajltKr iflteflslty Overall cultivar intensity 100

LSD(p<0.05)8.6 100 LSD (p <0.05) 23

Quality NS Citrus 100 80 Quality Citrus

100 80

80 2' 100LSD (p <0.05) = 12.0 -\ / 100 2< 80 NS

80

NS 60

-.

Fullne 60

Tree fruit Tree fnjit

80 100

LSD (p 5 0.05) = 6.3 80

100 NS

60 20 NS 80 40

100 445\ 40 NS 80

#dd 60

100 Add 60 60 °°

80

80

100 NS 100 L k NS 100 100

Other Caranel Other Caramel

Hard purng [ MchonIcoIprunIr ii MInInoIp.,nIng Hand pnIng MeohonIIprnIng Minimal pruning

2003 Vintage 2004 Vintage Overall cultivar intensity Overall cultivar interity

100 LSD (p <0.05) = 4.0

100 LSD(p<0.0543

Quality NS*

100 . 80 NS Citrus Quafi ty Citrus

100 80

80 - 80 60 60 80 so \

NS 40 60

Fullness 100 80 NS Te fruit Fullness

NS Tree fruit

100 10

-*-----_ 80

20 40 60 20 NS

NS ao2 100 '

60 20

4q/ 60

40 NS /

NS

100

60 20 40

60 NS 40 80 Add °° Tropicalfruit

80 \

Acid 60

80 60

100 Tpical fruit

100 OO

l001 NS \ io NS NS 100 Other Caramel Other Caramel

Hand pruning [ Mochnici pruning 1-1 Minimal pruning Hand pnjng 1 MwhankA p,ning Minirni pruning



FIGURE 14 Effect of pruning methods on the aroma profiles and wine quality of Chardonnay, wines of six different vintages at Robertson (2001 —2006).


Pa CC

'0

.0

E CO

o CO o .0 CO 0 .0 0 0 CO CO CtC

C-i ' 9

C O C -

O ,j

C11 c

fl . M

wi - -

ca .0 00

.0 CO C

CO

C

.0 C N

,a c'

ca ca Co Co

n - -

CO N

CO 00

CO - N

o CO N - 00

Co Co Co Co 00

o CO o CO CO

00

0 00

0 N ocS

0 0 C'

0 C\ -

.0

00 • .-

cq

.0 CO CO .0 00

.0 .0 .0 C

CO CO CO C

M 00 wl 9 o C

CO o CO CO c C o

CO

C

CO - CO CO C CO 0

CO .0 CO 0 0 0 0 .0 CO CO

C\ 0' , 't 00

00 a N

'r N

o', i

c' Cl!

•-.

6 N

C11 - - -

.0 -

CO o

CO .0 CrC

.0 C

.0 n

CO CO N

9 C

CO 0 CO CO .0 0 CO CO CO CO .0 CO .0 o

C O C 00 _ C'> N Ci C C. C

0 l

CrC

CO 00

.0 CO

'>

0 0

Cfl

0

N

0 C'>

0 C'>

.0 CO .0 N

CO

CC'> C'> - - C'>

.0 N .0 CO CO CO

cq .0

.0 .0 .0 .0 CO CO CO CO

C11 - - C'> Ci

CO 0 CO CO .0 CO CO CO CO ' CO CO CO c -

C'> C'> C

Cfl C'>

00

C

-

CrC

00 00 -

N - a,

C'>

C i C'> C'>

0

00

CO CrC

.0 C1'

CO CO 0 0 0 0 CO CO CO

C'> - C'>

00 CrC . CO

00 .0 a, en

.0 N

.0 00

.0 O •

CO 00

CO CO CO

CrC C 00 •• •-• C'>

CO 0 CO CO .0 0 CO CO CO CO CO CO CO CO

c C'> C C'>

00 CrC C'>

N C .

CrC N -

C'> -

00 C N

c

C'>

0 Cl

CO 00

.0 -

CO C

CO 0 .0 "

0

c

0 CO

"R 0 CO CO

C11 C'> N - - - C'>

.0 .0 CO .0 CO C'> .0 .0

N 0

s CrC C N

Cfl C'

'> Cl - - C'>

* CO CO CO 0 CO CO CO CO CO CO .0 0

00 0

C'> C'>

O Cl C'>

0 s Cfl

-

00 C'> - - -

.0 1

C

0 CO 0

1>1> C Of> 0 0 CO

01>

<.9L) Z 0

E

'0

C

VI

1401

1401

CO

H

Pa E 0

0

.0 0

0

I

0 CO .0 0 0

.0

PR E 0

CO

'0 0 CO

PR E 0

CC 0

CO

'0 0 CO

PR E

CC 0

CO

'0 0 CO

PR E

0 0

CO .0

CC

'0 0 CO




TABLE 14 Effect of pruning method on the percentage difference in relation to hand pruning for different varieties at Roberston (2001 - 2006).

Chardonnay Chenin blanc Colombar Sauvignon blanc Ruby Cabernet Shiraz

Parameters Meeha- Meeha- Meeha- Meeha- Meeha- Meeha- meal Mniimal nieal Minimal Mimal m meal meal Minimal meal Minimal meal Minimal

Average shoot -21.0 a -61.7b -22.8 a -63.0b -13.5 a -51.2b -14.1 a -60.9b -15.1 a -62.6b -23.4 a -59.7b length (/o)

Number shoots! 110.9 b 420.2 a 134.5 b 379.8 a 130.5 b 488.3 a 87.0 b 314.3 a 97.1 b 422.3 a 115.1 b 369.2 a vme (%)

Average internode -18.8 a -41.5 b -17.2 a - 44.9b -8.9 a -32.7b -4.3 a -42.51, -1.1 a -46.2b -13.2 a -37.6b length (/o)

Cane mass (%) -16.7 a nm -30.0 a nm 0 a nm 0 a nm -5.3 a nm -9.5 a nm Yield(%) 91.0a 56.3b 72.6a 62.8a 59.8a 49.0a 101.9a 100.4a 26.5a 33.2a 57.5a 43.9b Number Of 174.9 b 265.3 a 179.5 b 420.2 a 170.4 b 370.6 a 206.0 b 477.3 a 113.6 b 327.9 a 153.6 b 295.9 a bunches/vine (/o)

Bunch mass -27.1 a -50.9 b -35.7 a -64.2 b -34.0 a -60.5 b -30.4 a -56.9 b -33.5 a -60.4 b -29.8 a -55.4 b

Berrymass -13.2a -26.4b -14.6a -29.9b -16.5a -35.4b -12.8a -29.9b -9.5a -33.0 b -20.8a -31.1b

Berryvolume -13.0 a -25.1 b -15.0 a -29.4b -17.5 a -35.7b -10.8 a -29.1 b -9.2 a -32.5 b -15.9 a -30.1 b

* Figures for different treatments per variety, followed by the same letter, do not differ significantly atpO. 05. nm = not measured.


E

PR

0

j U '0 0 CO

E 0

0

' .o' CO .EC c c? 0

CO

'

'0

E 0 -

0 CO

'

PR

PR 0 cc ©

.0 0

',cC CO o r, , 0

I Pa

- ' ©

CO

L) rd

'0

CO

E

0 44 , PR o .0

PR

.54

0 ) E CO

0 .0 c .0

'0 o CO a

J !©

I-


CO CO .0 .0 CO CO

00

CO CO

s c' 00 n o

O S

en O

u- wl C

d d d

CO CO

N Ci

CO .0 ca

- en .r d d

CO 00

CO 00

-' -

,

o

CO

c CO

CO

n C,5 S O C - fl C,5 d d d d c'

C11 S CO o

CO as

.0 as

CO C

.0 O

00

.0 S

CO S

CO

C' C d 00 - 00 wi

CO CO CO CO CO CO .0 .0

C C

CO o

CO c i,.;

c' C, S Cl!

O C

O C

- n ,- -. d -

,OM CO CO CO , CO

S CO O

CO 00 C Cl!

C, 00

S O c

C' SC en

C - C

CO CO CO , 00 C

C,;

CO

en

' C

CO 00

, CO CO

C .0 C d

CO CO CO CO CO C., O

en

CO o

CO c

... - c

,C CO

CO .

.0 en

- c. n C

CO .

CO o

CO .

, CO o

.0 •

en

CO CO CO CO CO CO

.

- C-i en d

CO 00

CO C

CO

Ci

,

. Cf

CO CO

Cl!

CO

C11

CO .

,0 0

, , CO S

CO en

0 '0

0

CO CO CO CO , 00 Cl

CO

C,-; 00

- C. -. Cfl C

•0 CO ,

as c CO 00 ,

0 wl

CO 0

0 00 CO .0

C11

- c-i

00

en Cl -

CO CO CO CO

CO

00 00 cli

- C

S t- c'

* *

en d

C

;

•0

E ne z

**



Colour NS

Fruitiness 100 160 NS

80

Quab(p 60

Guava

'00 40

Fullness

80 6\0 NS 80

Acid NS 80 100

Tropical fruit NS 1 60

NS 100

Fullness Other

Other

Hand pruning [1 Mechanical pruning II Minimal pruning Hand pruning [I Meuhaneal pruning Lii Mnnnal pruning


Cdour Coloir 100 NS* IOONS

Quality 1

- Overall cultivar intensity Quality "°

uo 1010

Overall cuttivar intensity

80

/ 80 NS 60 40

40 a 11

100 60 NS

Fullness 160 I 1Tme fruit Fullness (1 i 21

Y60 -40 40

66

100

60

80 NS 100

80 66

60 66 LSD(p<O.O5)7.8

NS Atid 80

100 Tropical fruit Add NS 100

80 Tropical fruit

100 NS 100

Other Other

Hand pruning LI Mechanical pruning Minimal pruning Hgod pruning LI Mechanical pruning L Minirl pruning


Coloir Colour

LSD(p<O.5)1O.S 100

LSD(p<O.5)=O 100

Quality a) Overall cultvar intensity Quality 100


so

100 100NS

>(ID

K412

LSDO-7.4 LSD(p<M5)8.7

'60 '60 ITroefruit 1

ITreeit '42D4

. 40

160 60 00 60100

LSD(p<G.66)7S 100 Add

NS Tropical fruit Add Tropicalfruit

LSD(p<G.O5)2S 00

100 NS

(p 0.05) 14.3 Other other

El Hand pruning [1 Machelical prunirg 1 Mninral pruning Hand pruning El Meuhancal punng Mnnrmal pruning



FIGURE 15 Effect of pruning methods on the aroma profiles and wine quality of Chenin blanc wines of six different vintages (2001 —2006).



Colour Fruitiness

Quality

100 NS*

S Overall cultivar intensity

100 T NS*

I 52 100

60\ 100 NS

40 \ 80 NS

40 100 Guava 20

40

100 80 60 A 0 20 lOS 100

80 60

Fullness I I I (I I 4 I I I Treefruit 80 100

40

0 20

40 6<\ 60

100/60

/ \ Add NS 80 100

Tropical fruit 40 NS

60

100

100 Ns

100 Fullrross Other

Other

Hand pruning Li Mechanical pruning Li Mininal pruning pruning LI Medlanical pruning !! MininSi pruning


Cour Cdour 100

lOS lOS.

100 NS

Quality 00 100

Overall cultivar intensity Quality NS 100

Overall culbvsr intensity

60 160

lOS 160

80 NS 40 40

lOS

40 60

S

all all

60 X 10000

LSD(p<O.O8 2r1:I NS

Fullness I I I Tree fruit I I ITreefruit 40 60 00 100 20

If

00 00 160

II

40 20 2u4J

all

60 40" 40

1uu./)<

00

00

00 Ns

00

160

80 Acid 00

100

Tropical fruit NS

Acid 00 100

Tropical fruit

uu LSD(p<0.05)6.1 100 NS

Other Other

Hand pruning D Mechanud pruning Minirna pruning Hand pruning LI Mechanical pruning ] Mininlal pruning


Colour Cdour 100 lOSt 100

T Npr

Quality lOS 00 Overall culitvar intensity I so 100 Qity Overall cultivar intensity

lOS 160

80 - iso

40 00

i 40 60

100 00 60 ' 40 20 20 Ns 20 Fullness I I I I 1 40 1 5Q 160 ITreefruit L )( .00.05)

/ • 160

80 80

Fu Ilness

60 40

Tree fruit

60 100 60 lOS 80

90

Acid 00 100

Tropical fruit 100

LSD (p <0.05) 100 - Other Tropical fruit Other

Hand pruning LI MechanHal pruning Minirnd pruning Hand pruning Li Mechar.cal prurng Li Mnrul pruning


Statistical differences indicated in the figures (p:90.05). *NS = non significant.

FIGURE 16 Effect of pruning methods on the aroma profiles and wine quality of Colombar wines of six different vintages at Robertson (2001 —2006)

135



Quality

NS

Fullness

Li Hand nuning


rOONS*

//)(/X

GO NS

80 Tropical fruit

GO

Acid Other

LI Medranicd pruning Li MinirHa pruning

2001 Vintage

Quality

LSD(p<e.eN=u25 80

Fullness

Li Hand prunne


180LSD(p<055)10.4

60 IQ-

L5D(p<o.es)=u2.0

/n.\\ Tropical fruit

40

80

2 \ NC

Acid Other

LI Meohencel pruning Mnnr6I pruning

2002 Vintage


60

40

Fullneu o 20

so

80Tropi t : 100 Fullness vu Tl fruit

40

o

Acid NS

Other NS Acid Other

Li Hund prunire LI MeohHnioHI prHa5 Li Mininhel pruning Li Hand pruning Li Mechanical pruning I] Mininl pruning


Overall cultivar intensity Overall culhvar intensity

rocNC LSD (p <e.ea) = a.e

Quality r

80

Qenlity r

- vegetauve

80 80 80

/ 80

20 50 60 50

00' 00 00 60

60

80 80

Fullness 80

Nropicai 80 80 roc fwit Fullness

Nropicai 60 ruu it

:80

60

80 roc NS

roc NC NS

Acid Other Acid Other

Hand prunina Li Mechanical phrnina Li Mirnal prunina Li Hand ruining El Mednar6od prunrig Li Mininnd prurrrg



FIGURE 17 Effect of pruning methods on the aroma profiles and wine quality of Sauvignon blanc wines of six different vintages at Robertson (2001 —2006).



Colour NB

iuu * Quality

iuu NS Overall cultivar intensity

OO \ 1 iuuNS /80

LSD(p<O.O=9.8 Tannins iuu

80 Berry

20 40 iou NB

NB 80 60 100 40

40 60 NB

Fullness

--

60 80 Scy

NB / 100

no

NB

Add 100

INS

10 Smoky

Other

Hand pruning [1 Mechanical pruning Li Minimal pruning

2001 Vintage

Colour 100 NS*

Quality NB Overallcultienrintenalty 100 NB

100 80 60

LSD(p<O.05)=7.8

Tannins NB Berry no

100

00 40 i awo

NB100 80 h'O NB 60 80

Fullness / :

L 40\

no

100 spicy

80

NB LSD(p<O.05) 4.4

Acid los I NS Smoky

Other

El hand pruning I Mechanical pruning L] Minimal pruning

2003 Vintage

Cour 100 NS*

Quahty NS 100

80

Overall cultivar intensfty

ec .

...• /ioo NS .

tso

NS Tannins

so 40 Berry

100

NB

NS 60 20

so 100 20 0

60 NS

Fullness 40 so

100 Spicy

NS : 1c\1 , 80

100 NS

Acid Smoky

100 NB

Other

Hand pruning [1 Mechanical pruning [7 Minimal pruning

2005 Vintage

Colour LSD (p 0.05) = 11.1

NS 10

Quality

l00NS

Overall cultivar intensity100

amp

80

NB

0

LSD (p < 0.05) 5.1 Tannins

100 40 Berry

100

80 60

40

NB 100

NBscy no

Fullness no

I 'NS Add

NB at

100

Smoky

Other LBD (p <0.05) = 10.4

Hand pruning [1 Mechanical pruning [] Minimal pruning

2002 Vintage

Colour NB*

NB

100

Quality 100


00 no

buNS

NB 140

80

Tannins 100 80

I\+

\/ / 40

Berry

100 80 NB

j640 NB 80

100

Fullness 40l 40 \ 00

100 5piy

NB

00 00±

80 NB

iu~ Add

100 I NB Smoky

Other

Hand pruning [1 Mechanical pruning Li Minimal pruning

2004 Vintage

Colour LBD (p <0.05) = 12.0 LBD (p <0.05) = 15.8 100

Quality Overall cultivar intensity 100 \ LBD(p<0.05)=8.4

100 / NB

Tannins 80 S

o Barry

00

NB

I 2 20

LBD (p 80

0

100 40 00 NB no

Fulness 40

P I

40

no

100 Spicy

NB ioo ( 00+

I I 80\

.

NS

AcC 100

NB ogler

Hand pruning 11 Mechovical pruning Uj Minimal pruning

2006 Vintage


FIGURE 18 Effect of pruning methods on the aroma profiles and wine quality of Shiraz wines of six different vintages at Robertson (2001 —2006).



Colour

LOD(p<O.05)=3.O 100 NO*

Quality 100 Overall cuOloar interndty

-\ 80 7100 -

80 NS

Tannins

100 1t40

Vegetative

NO 40

NO _/

Fullness 100 Berry

ad ed

NO Nutty

Acid ira NO

Other

Hand pruning ri Mechanical pruning . 1 Mininnal Pruning

2001 Vintage

Colour LSD(p50.05)8.3

Qualty NS Overall culivar intensly

'00

-\ 00

/LSD(p<0.05)6.9

100

00 oo'7-' )(

NS

Tan,4ra 0'\F 4>: t

18.7

1oo__ 40) (p <0.05) 7.2ad

80

LSD(p<0.05) 00.4 40

40\\ 100 BerrY

Acid NS NS NuttY

Other

Hand pruning El Mechanical pruning [.11 MIninnal Pruning

2002 Vintage

Colour Colour 100 NS LSD(p<O.O5)7.O 100 NS

Quality 100 NS Overall cultivar intensity so

Quality Overall cultivar intensity

so 100

NO 60

so

P80/4/ rk 60

100 NS*go

NS NO Tannins 100

80

40 Vegetative Tannins

80

40 Vegetative

40 80

NS 80

I'S806

LOD(p<O.05)6.680 00: ! 1 ,00 20 40 20 00 NO

040 NO60

Fullness 100 Berry

80 eO

00

Fullness 80

100 Berry

100 80

NS

80

so NO

Acid NO

Nutty Acid NO

Nutty

ioo NS 100

Other Other LOD (p 8.05) = 8.3

El Hand pruning I Mechanical prraing I ] Mininral pruning El Hand pruning Ci Mechanical prraing Mininial pruning


Colour LOD (p <0.05) = 8.7 Colour

100 100 NO*

Quality NO Overall cultivar intensity Quality 10 r Overall cultioar intensity

100 s ' 80 80

LSD(p<O.O5)3.2 NO

Tannins 100 40 ve Tannins 100 80

40 80 40

80 20 1 : 100

80 60 60

j 40 40 LSD(p5O.O5)4.0 80 80

NO 40 20 20 eo NO

Fullness 100 Berry 60 Fullness ° °

eo

:

100 Ber ry

100 80

NO 80

Add NO 100

NO Nutty Add NS 100

100 Nutty

100

Other Other

Hand pruning LI Mechanical pruning I MHinal pruning Hand pruning LI Mechanical pruning Mirinnal pruning



FIGURE 19 Effect of pruning methods on the aroma profiles and wine quality of Ruby Cabernet wines of six different vintages at Robertson (2001 —2006).



LITERATURE CITED Martinez de Toda, F. & Sancha, J.C., 1988. Long-term effects of zero pruning on

Anderson, P.C., Sims, C.A. & Harrison, J.M., 1996. Influence of simulated mecha- Grenache vines under drought conditions. Vitis 37, 155- 157.

nized pruning and hand pruning on yield and berry composition of Vitis mtundb- McCarthy, M.G. & Cirami, R.M., 1990. Minimal pruning effects on the perfor- ha Noble and Welder. Am. J. Enol. Vitic. 47, 292-296. mance of selections of four E'itis vinifera cultivars. Vitis 29, 85-96.

Archer, E., 1999. Meganisering van snoei by wingerd: Vereistes gestel aan die wingerd en reaksie van wingerdstok. KJ7nboer Tegnies 117, 46- 48.

Archer, E. & Van Schalkwyk, D., 1998. Die omskakeling van die prieelstelsel sowel as wingerdstokke vir meganiese snoei van wyndruiwe. ff5inboer Tegnies 102,10-11.

Bakonyi, 1., 1987. Non-pruning: a new technique in vineyard management. Austr. Grapegrower & Winemaker 280, 112- 113.

Cirami, R.M., McCarthy, M.G. & Furkaliev, D.G., 1985. Minimum pruning of Shiraz vines - effects on yield and wine colour. Austr Grapegrower & Winemaker 263, 24 -26.

Clingeleffer, P.R., 1988. Response of Riesling clones to mechanical hedging and minimal pruning of cordon trained vines - implications for clonal selection. Vitis 27,87- 83.

Clingeleffer, P.R., 1989. Update: Minimal pruning of cordon trained vines. Austr. Grapegrower & Winemaker 282, 78- 83.

Clingeleffer, P.R., 1993. Vine response to modified pruning practices. In: R.M. Pool (ed). Pruning mechanization and crop control. Proc. 2Ne1son J. Shaulis Gr. Symp., July13- 14, Fredonia New York, 20-30.

Clingeleffer, P.R., & Possingham, J.V., 1987. The role of minimal pruning of cor-don trained vines in canopy management and its adoption in Australian viticulture. Autr Grapegrower & Winemaker 280,7- 11.

Clingeleffer, P.R. & Krake, L.R., 1992. Responses of Cabernet franc grapevines to minimal pruning and virus infection. Am. J. Enol. r'itic. 43, 31 -37.

d'Armailhacq, A., 1867. De la culture des vinges dans le Médoc. 3me ed. P. Chau-mas, Libraire-éditeur, Fossés du Chapeau-Rouge, 34 Bordeaux.

Hunter, J.J., De Villiers, O.T. & Watts, J.E., 1991. The effect of partial defoliation on quality characteristics of Vitis yin ([era L. cv. Cabernet Sauvignon grapes. II. Skin color, skin sugar, and wine quality. Am. J. Enol. Vitic. 42, 13 -18.

May, P. & Clingeleffer, P.R., 1977. Mechanical pruning of grapevines. Austr Wine Brew. Spirit Rev. 96(11), 36- 38.

Morris, J.R., Cawthon, D.L., & Fleming, J.W., 1975. Effect of mechanical pruning on yield and quality of Concord grapes. Ar/c Farm. Res. 24(3), 12.

Morris, J.R.& Cawthon, D.L., 1980. Mechanical pruning and node adjustment of cordon trained Concord grapevines. J. Am. Soc. Hort. Sci. 105,310- 313.

Morris, J.R. & Cawthon, D.L., 1981. Yield and quality response of Concord grapes (Vitis Labrusca L.) to mechanized vine pruning. Am. J. Enol. Vitic. 32, 280-282.

Reynolds, A.G., 1988. Response of Okanagan Riesling vines to training system and simulated mechanical pruning. Am. J. Enol. Vitic. 39, 205-212.

Reynolds, A.G. & Wardle, D.A., 1993. Yield component path analysis of Okana-gan Riesling vines conventionally pruned or subjected to simulated mechanical pruning. Am. J. Enol. Vitic. 44,173 - 179.

Ribenreau-Gayon, P., Glories, Y., Maujean, A. & Dubourdieu, D., 2000. The chemistry of wine and stabilization and treatments. In: John Wiley & Sons Ltd.. Handbook for Enology, Vol. 2. 129- 185.

Ruhl, E.H. & Clingeleffer, P.R., 1993. Effect of minimal pruning and virus inoculation on the carbohydrate and nitrogen accumulation in Cabernet franc vines. Am. .1 Enol. Vitic. 44, 81 - 85.

Saayman, D., 1981. Klimaat, grond en wingerdbougebiede. In: J. Burger & J. De-ist (reds), Wingerdbou in Suid-Afrika, 48- 66.

Shaulis, N.J., Pollock, J., Crowe, D.E. & Shepardson, ES., 1975. Mechanical pruning of grapevines: progress 1968 - 1972. Proc. New. York State Hort.. Sci. 118,61-69.

Soil Classification Work Group, 1991. Soil classification - A taxonomic system for South Africa. Memoirs on natural resources of South Africa no. 15. Dept. Ag-nc. Developm., Pretroria.

Van Schalkwyk, D., 2004. Metodes om korrelmassa, korrelvolume en trosmassa te bepaal. KJinboer 182, 115- 116.

Zeeman, AS., 1981. Oplei. In: J. Burger & J. Deist (reds), Wingerdbou in Suid-Afrika, 185-201.


Documents

The Effect of Alternative Pruning Methods on the ... · Four different pruning methods, hand, ... Rising production costs in the national and international ... Alternative pruning