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 Clingeleffer, 1993). Most of these reports showed that sugar concentration, as well as pH were reduced and total acid concen- Rising production costs in the national and international wine tration increased by minimal pruning. In terms of wine colour, industries essentialise the implementation of cost reducing flavour and quality, variable results were reported depending on methods and procedures. Labour costs are responsible for more climate and vigour. than 60% of total annual costs of wine grape production in South Africa ('Vinpro, 2005) and, therefore, the development of Research results on non-pruning are not abundant. Working labour saving techniques is of paramount importance. Most wine with seven different cultivars, Bakonyi (1987) reported increased grape vineyards in the Western Cape are pruned by hand. This yields, no obvious loss in quality but an increase in oIdium and makes an important contribution to the annual labour costs of vine scales compared to hand pruned control vines. The research producing wine grapes and, therefore alternative pruning methods of Martinez de Toda & Sancha (1988) on un-irrigated Grenache had to be investigated. These alternative pruning methods are showed that non-pruning increased the yield, dry matter and sugar mechanical spur pruning (May & Clingeleffer, 1977; Clingeleffer, production per vine. This was ascribed to a significant increase in 1988), minimal pruning (Clingeleffer, 1993) and non-pruning total leaf area per vine. On the other hand, sugar concentration (d'Armailhacq, 1867; Bakonyi, 1987). was reduced. Although general trends in the effect of alternative pruning Most reports on mechanical spur pruning showed an increase in methods on grapevine performance are visible from the research yield (Morris et al., 1975; May & Clingeleffer, 1977; Clingeleffer, results, the following pertinent questions needed answers under 1988; Reynolds, 1988; Reynolds & Wardle, 1993; Archer, 1999). the specific viticultural conditions prevailing in South Africa: 1) On the other hand, it reduced bunch and berry mass (Morris et al., Can these methods be used in producing top quality red wine from 1975; Morris et al., 1981; Reynolds, 1988), and sugar concentration a noble cultivar? 2) Are these methods applicable under different (Shaulis et al, 1973; Morris & Cawthon, 1980 and 1981; Anderson climatic conditions? 3) Are there response differences between et al., 1996). In general, wine quality was reduced mainly due to cultivars to these pruning methods? In an endeavour to answer a loss in colour with red grapes (Reynolds & Wardle, 1993). The these questions, this research project was undertaken in 1996. response of the vine to mechanical spur pruning varied according to cultivar (McCarthy & Cirami, 1990) as well as clone (Clingeleffer, MATERIALS AND METHODS 1988; McCarthy & Cirami, 1990) and virus infection (Clingeleffer The project entailed three field trials at three different localities: & Krake, 1992; Rühl & Clingeleffer, 1993). Trial at Elsenburg Research results on minimal pruning, compared to normal The one ha trial vineyard was planted in 1996 on an Oakleaf soil hand pruning, showed an increase in yield, number of bunch- form (Soil Classffication Work Group, 1991) with six cultivars: es and shoots (Cirami et al, 1985; Clingeleffer & Possingham, Chardonnay, Chenin blanc, Sauvignon blanc, Pinotage, Shiraz 1987; Clingeleffer, 1988 and 1989; McCarthy & Cirami, 1990; 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.

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107 108 Alternative pruning methods for some wine grape varieties

The treatments used were: control (hand pruned to two-bud spurs, vine), mechanical pruning (vines were pruned with mechanical 12 spurs per vine), mechanical pruning (vines were pruned with hedge cutters approximately 10cm above the cordon; no thinning of mechanical hedge cutters approximately 10cm above the cordon; spurs were done) minimal pruning (vines were mechanical skirted no thinning of spurs were done) and minimal pruning (vines were approximately 30cm above ground level during December and the mechanical skirted approximately 30cm above ground level dur- sides were trimmed with mechanical hedge cutters to keep the rows ing December and the sides were trimmed with mechanical hedge open for spraying. The tops were untouched) and non-pruning (no cutters to keep the rows open for spraying. The tops were un- pruning or trimming was applied). The pruning treatments were touched). Both cultivars and pruning treatments were randomised randomised in blocks and consisted of five replicates, each sepa- in blocks and consisted of three replicates each separated by buff- rated by buffer rows and vines. er rows. Before planting, the soil was criss-crossed with a shift delve Before planting the soil was criss-crossed with a shift delve plough to depth of 1 .30m after 12tIha calcitic lime was broad- plough to a depth of 1 .2m after 4.5t/ha calcitic lime was broadcasted on the soil surface (eventual soil pH = 5.9). Depending on casted on the soil surface. This resulted in a soil pH of 5.2 to the season and soil moisture measurements, a maximum of three 5.9 and the vineyard was cultivated without irrigation. Vines in irrigations were applied with micro-jets. Vines in the control plots the control plots were split-cordon trained (cordon height above were split-cordon trained (cordon height above ground = 0.70m). ground = 0.60m) on a standard four strand Perold trellis with Vines in the other plots were trained exactly the same as in the movable foliage wires (Zeeman, 1981). 'Vines in the other plots trials at Elsenburg and Robertson. were split-cordon trained (cordon height above ground = 1 .20m) MEASUREMENTS 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. Time studies Trial at Robertson Time studies to determine man hours needed for each operation were done during pruning, canopy management (suckering, posi- This two ha trial vineyard was planted in 1997 on a Hutton soil tioning of shoots, tipping, topping and leaf removal) and harvest- form (Soil Classification Work Group, 1991) with six cultivars: ing and from these the labour needed to manage the vines of each Chardonnay, Chenin blanc, Colombar, Sauvignon blanc, Ruby of the pruning systems was calculated (machine and machine op- Cabernet and Shiraz, all grafted onto Richter 99 rootstock. The erator costs not included). treatments used were: control (hand pruned to two-bud spurs, 14 spurs per vine), mechanical pruning (vines were pruned with me- Yield, bunch mass, peduncle mass, berry mass and berry chanical hedge cutters approximately 10cm above the cordon; no volume thinning of spurs were done) and minimal pruning (vines were During harvest, the physical condition of the grapes was visually mechanical skirted approximately 30cm above ground level dur- evaluated in all plots and the percentage rot, millerandage, etc. ing December and the sides were trimmed with mechanical hedge noted by the same person. Thirty vines per plot were harvested in cutters to keep the rows open for spraying. The tops were un- crates, weighed, and the average yield per vine calculated. One touched). Both cultivars and pruning treatments were randomised crate per plot was randomly selected, weighed, and the number in blocks and consisted of six replicates, each separated by buffer of bunches counted to calculate the average bunch mass. Five rows. Based on heat summation over the growing period (Sep- bunches from each of those crates were randomly selected and tember to March), this locality is in climatic region III (Saayman, stored at -20° C until after harvest to determine berry mass and 1981) at 330551 South latitude. Before planting, the soil was criss- volume. In the case of the trial at Nietvoorbij, five vines per plot crossed with a shift delve plough to a depth of 1.3m after 6.5t/ were harvested to determine yield per vine, bunch, pedicel and ha dolomitic lime was broadcasted on the soil surface (eventual berry mass as well as berry volume. The rest of the vines of the soil pH = 6.3). Irrigation was applied by means of micro-jets alternative pruned treatments were then mechanically harvested. and scheduled according to A-pan evaporation and crop factors. The mass of the frozen berries was determined by being thawed. Vines in the control plots were split-cordon trained (cordon height Using the methods as described by Van Schalkwyk (2004) to de- above ground = 0.70m) on a standard five strand Perold trellis termine bunch mass, peduncle mass, berry mass and berry vol- (Zeeman, 1981) with movable foliage wires. 'Vines in the other ume, five bunches of each plot were randomly sampled and the plots were split—cordon trained (cordon height above ground = frozen berries rubbed off in such a way that the pedicel were left 1 .20m) on a one strand hedge trellis (Zeeman, 1981). 'Vine spac- on the peduncles. Out of this sample, 100 berries were randomly ing in all cases was 3.Om x 1.5m, resulting in 2 222 vines per ha. counted and weighed using a laboratory balance with a sensitiv- The nutrition programme was managed in the same way as with ity of two decimals per gram. These berries were also used to the trial at Elsenburg. determine berry volume. A 1 000mL measuring cylinder was filled Trial at Nietvoorbij with enough water to cover 100 berries (e.g. 200mL). The berries were then added, a reading taken and the first reading subtracted This one ha trial was laid out in an existing Cabernet Sauvignon from the second to determine the volume of 100 berries. All five x Richter 99 vineyard on an Avalon soil form (Soil Classification bunches peduncles per sample were weighed after the berries work Group, 1991). Vme spacing was 2.75m x 1.5m resulting in were rubbed off and average mass calculated. 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 Cane mass and number of buds (1 .2m) one strand Hedge trellis according to the procedures de- During winter, the number of shoots per vine and internodes per scribed by Archer & Van Schalkwyk (1998). The following treat- shoot were counted. Cane length was measured using all the canes ments were applied: control (hand pruning to 12 two-bud spurs per of five vines per replicate and the average internode length was

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 109 calculated. To calculate the cane mass per vine, 30 vines of each skins were separated from the juice using a pneumatic press and replicate were of the hand and mechanically pruned treatments pressed juice added to the free-run juice. Overnight settling was were weighed. In one year the number of winter buds were count- allowed at 14°C after adding 0.5gfhL Ultrazyme. Clear juice was ed on five randomly selected vines per plot. The same vines were drawn off into 20L stainless steal canisters and 50 g/hL di-ammo- used to count the shoots during spring and from this % bud burst nium phosphate added and inoculated with YiN 13 (30 gIHL). was calculated. Wines were dry fermented at 14°C at which point free SO 2 was ad- Berry skin, wine colour and phenols justed to 40mgfL, and 50gIHL bentonite added. Wines were cold stabilized at 0°C for at least one week, then racked and filtered Berry skin (Hunter 1991) and wine colour (Ribereau-Gayon et al., trough filter sheets. Free SO 2 was adjusted to 45mgfL at bottling. 2000) were only analysed for the red varieties at A420 nm et al., The wines were stored in 750mL bottles with screw-caps at 13°C and A520 nm using a LKB Biochrom Ultraspec II E UV/Visibile in a dark, temperature-controlled room directly after bottling. Spectrophotometer. Total phenolic compounds were quantffied using a HPLC (Ribereau-Gayon et al., 2000). The same wine making procedures were followed for Chardon- nay and Sauvignon blanc except that after crushing skin contact Wines was applied for four hours at 14°C. At Elsenburg and Nietvoorbij wines were prepared from all three During August/September each year these wines were sensori- and five replicates, respectively of all the treatments of all the ally evaluated by trained tasting panels. A ten-point-line-score- varieties. At Robertson grapes from replicates one and four, two card system was used to evaluate wine quality, colour, overall and five, three and six, per treatment per variety were pooled re- cultivar intensity, aroma, acid, tannins, hardness and fullness. spectively for wine making thus only three wines per treatment were made instead of six. Eighty kg of grapes were harvested per Statistical analysis plot and used for wine making. The data was subjected to an analysis of variance. Student's t least Grapes from the white varieties, Chardonnay, Chenin blanc, signfficant difference (LSD) values were calculated to facilitate Colombar and Sauvignon blanc were harvested between 21 .0°B comparison between treatment means. Means which differed at to 22.0°B and red varieties, Cabernet Sauvignon, Merlot, Pino- p0.05 were considered to be signfficantly different. tage, Ruby Cabernet and Shiraz between 23.0°B to 24.0°B, re- RESULTS AND DISCUSSION spectively. Trial at Nietvoorbij Wines were made according to the standard Nietvoorbij proce- All three alternative pruning methods significantly reduced labour dure for small-scale winemaking at the ARC Infruitec-Nietvoorbij cost for managing Cabernet Sauvignon compared to hand prun- Research Institute. The vinffication procedure for red wines was ing (Table 1). Not only was labour input for pruning reduced, but as follows: grapes were crushed, free SO 2 content was adjusted also for canopy management and harvest. Minimal and no prun- to 50mgfL before pressing and inoculated with YIN 13 (30gfhL) ing required significantly less labour than hand and mechanical and fennented to 0°B at 24°C. During this period the cap was pruning. It is imperative that mechanical harvesting is used when punched down three times a day. The skins were separated from any one of the alternative pruning methods are employed as it is the juice using a pneumatic press and pressed juice added to the extremely labour intensive and costly to harvest these systems by free-run juice. After fermentation was completed, the total SO 2 hand. content was adjusted to 85mgfL and 50gIhL bentonite added. More sunburn as well as berry shatter occurred when any one Wines were cold-stabilized for two weeks at 0°C, filtered and bot- of the alternative pruning methods were used (Table 2). With the tled in N2-filled bottles at room temperature with adjustment of hand pruned control plots, the shoots were vertically positioned as the total SO2 content to 85mgfL. The wines were stored in 750mL part of the canopy management programme, therefore, the bunch- bottles with screw-caps at 13°C in a dark, temperature-controlled es were better protected against direct sunlight. On the other hand, room directly after bottling. the open hanging shoots of the minimal and no pruning plots, ex- The vinification procedure for white wines was as follows: posed the grapes more to direct sunlight and in abnormally hot grapes from Chenin blanc and Colombar were crushed and the seasons (data not shown), this caused sunburn-damage. The higher free-run juice collected. Total SO2 was adjusted to 50mgfL. The 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.

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 110 Alternative pruning methods for some wine grape varieties ing, may be the result of a higher cluster exposure to wind during A significantly lower yield was obtained from the hand pruned flowering time (data not shown). No pruning induced less compact control vines (Table 3). A clear seasonal interaction with treat- bunches than any of the other pruning methods (Table 2). ments can be seen in Fig. 1A. In most years the hand pruned plots The alternative pruning methods decreased shoot length signifi- yielded less but at least it was relatively consistent from year to cantly compared to the hand pruned control (Table 3) and amongst year, while the alternative pruning treatments varied much more. them, the vines pruned mechanically had the longest shoots. The The 2003 season was extremely favourable for hiegh yields for internode length was affected similarly (Table 3). This can be re- alternatively pruned Cabernet Sauvignon. Over the five year trial lated to the fact that the capacity of alternatively pruned vines was period, this treatment accumulatively produced less grapes than expressed in signfficantly more shoots per vine than in the case of the other treatments (Fig. 1B) and of the alternative methods; no the hand pruned control (Table 3). As expected, the highest cane pruning produced significantly more grapes. mass was obtained from the hand pruned control vines. Although the bunch mass was significantly reduced by alterna- Bud counts made during one data year (data not shown), showed tive pruning, the increased number of bunches ensured that the that 24, 72, 191 and 227 buds per vine were left with hand, me- yield per ha increased. The hand pruned control vines produced chanical, minimal and no pruning respectively. This resulted in % signfficantly larger berries than the other pruning treatments budburst of 108%, 60%, 49% and 47% respectively. (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).

Parameter Hand pruning Mechanical pruning Minimal pruning No pruning 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

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Alternative pruning methods for some wine grape varieties 111

a 20 V

>- 15

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-)

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).

Vines that were hand and mechanically pruned, produced The aroma profiles and overall quality of the wines are indi- grapes with a higher sugar concentration than minimally and non- cated in Figs. 2 & 3. Vintage played an important role and over pruned vines (Table 3). The grapes from the alternative pruning years succeeded in blanketing the treatment effects in the case of treatments had a lower pH than those from hand pruned vines and 6-month-old wines (Fig. 2). In spite of this, the wines from the this tendency was carried forward into the wine (Table 4) even hand pruned vines consistently showed the most pronounced veg- though it was not true for the juice after crushing (Table 3). This etative character. This is expected due to a higher canopy density higher pH in grapes and wine from hand pruned vines is ascribed (more shade) in the bunch zone. This tendency also held true in to higher shade levels in the bunch zone of these VSP trained most vintages for the 18-month-old wines (Fig. 3). These results plots (data not shown). In general, the alternative pruning meth- are in accordance with those of numerous other researchers who ods induced better colour in the skins and wines (Table 4) and this found a better expression of fruitiness in wines from alternative- is ascribed to better sunlight penetration into the bunch zone of ly prunes vines. In spite of this, an evaluation of overall quality these vines (data not shown). These results are in accordance with showed that the trained panel ofjudges had a preference for wines those reported by Clingeleffer (1988 & 1993). from the hand pruned vines (Table 5).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 112 Alternative pruning methods for some wine grape varieties

Trial at Elsenburg The number of canes per vine of the three white varieties were Hand pruning, together with the necessary canopy management increased with the alternative pruning methods, but the average as well as harvest, require 273.6 man hours/ha compared to 43.8 cane length was reduced (Table 7). This reduction could, in part, and 14.4 man hours/ha for mechanical and minimal pruning re- be ascribed to a reduction in internode length. The other cause of spectively (Table 6). This saving in man hours was true for all the the reduction in cane length with the alternative pruning meth- varieties and there is a clear economic advantage to use anyone ods could be found in the vigour reducing effect of an increased of the alternative pruning methods. During this trial, time stud- crop load. In this regard, interesting differences occurred between ies showed that it is not viable to harvest any of the alternatively varieties. Although the cane length of Chardonnay was not af- pruned plots by hand (data not shown). A mechanical harvester is fected by mechanical pruning, minimal pruning significantly de- a prerequisite when these methods are used. 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). Parameter Hand pruning Mechanical pruning Minimal pruning No pruning 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

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

TABLE 5 Effect of pruning method on the wine quality of 6 and 18 month old Cabernet Sauvignon wines at Nietvoorbij (2000 -2004). Parameter Hand pruning Mechanical pruning Minimal pruning No pruning

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

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

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- management 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.

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Alternative pruning methods for some wine grape varieties 113

Overall ndtivar intensity Overall cultivar intensity LSD(p0.05)5.6 100 LSD(p0.05)=6.4 LSD(p0.05)7.2 iixi LSD(p0.05)5.4 Quality Colour Quality Colou 100 100 80 > NS 80 . LSD (p 0.05) 3.6 - 100 / 100 80 80 80 awo 80 — LSD(p0.05)7A LSD(p<005)140 LSD(p0.05) 65 LSD (p <005) 7.3 ,,, 40 = Hardness 100 40 fl Vegetative Hardness 100 Vegetative 80 7 20 74! I <100 L60 4 \ 100 80 I1 80 / 60 2 2 20 60 / 80 100 40 .SD (p 80 - 40 0.05) = 9.8 * NS L NS \ 80 ' NS II 80 X Fullnes 40\ 80 100 fly Fullness 40 \ 100 Berry 60 80/2< 60 60 100 80 80 ioo/ 80 100 NS NS NS Acid Spicy Atid Spicy 100 - LSD (p 0.05) = 6.4 100 LSD (p 0.05) = 9.2 LSD (p 0.05) = 9.2 Other Other

Hand pruning Ti Mechanical pruning Hand pruning ri Mechanical pruring Minimal pruning No pruning F: Minirrl pruning 1 No pruning 2000 Vintage 2001 Vintage Overall cultvar intensity Overall cultivarintensity LSD(pe.e5)=1e.8 LSD(pe.e5)=6.8 LSD(p 0.05)=9.8 100 NS* 100 Quality Colour Qush ty Colour 100 100 80 >. LSD (p 0.05) 9.8 80 80 100 7180 80 / 80 60 se= )< NS* 60 80 NS 80 LSD (p 0.05) = 2.8 NS 40/10 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 20 100 -' 80 Fullness 40 100 Berry Fullness 40\ 100 Berry 60 40 6 ° LSD

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 NS Colour Quality Colour 100 100 80 100 NS NS -\ - - - ..—J'— 80 80 NS NS Hardness 180 Vegetative Hardness 100 40 Vegetative 80 80 )/ _ 60 20 4 100 2 100 80 80 60 60 NS NS 2040 80 100 20 LSD (p 0.05) = 83) 100 NS -.40/0 S 60 60 80 E:ii:iii:I:80 Fullness 40 100 Berry Fullness 40 100 Berry 40 'NS 40 NS 60 60' 80 80 60 60 8X.NS 100 80 \ NS 100 80 80 l0 NS 100 Add NS Spicy 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 2004 Vintage 2005 Vintage

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).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 114 Alternative pruning methods for some wine grape varieties

Overall cultivar innsity OraII cultivar intensity 100 NS* LSD(p<0.05)=6.0 100 LSD(p 0.05)6.1 Quality 100 NS Colour Quality Colour 100 6° 80 >. LSD(p0.05)8.4< 100 80 i00NS 80 / 6° / 60 80 LSD<0.O5)=4.9 LSD(p0.05)=67 6° LSD0.0=6.2< Hardness - Vegetalwe Hardness 100 I40 Vegetive 1 80 60 40 0 2 100 60 $j 100 80 80 60 60 NS 2

20 40 NS lOO 60 __k4 80 - 6° Fullnes 60 100 Ber Fullnes 40 \ 100 Berry

60k' LSD(p< 0.05) = 8 5 6° 80 \ 100 - 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 2000 Vintage 2001 Vintage Overall cultivar intensity Overall cultivar intensity LSD(p0.05)6.5 100 NS LSD(p<0.05)=8.5 100 Quality NS Colour Quality Colour 100 100 80 80 LSD(p0.05)=12.1 100 100NS LSD(p<005)=59 NS* \,, 40 Hardness 100 40 Vegetative Hardness 100 4( Vegetative 80 t6f40'\ so 60 00 /4 80 80 60 NS 60 LSD(p 0.05) 10.3

2 60 NS 80—' j 6040 80 'NS 100 ! 40 2O 20 40 2020 60 80 LSD (p 0.05) = 9.1 40 40 100 80 Fullrus 60 40 Berry 40 100 Berry 60 LSD (p o.) 60 80\ NS 100 100/ 80 100 : 100 LSD Add NS Spy (p 0.0 = 9.7 NS Acid Spicy 100 100 LSD (p 0.05) = 8.6 •NS Other Other

Hand pruning ii Mechanical pruning Hand pruning r I Mechanical pruning No pruning Minimal pruning D [j Minimal pruning Ii No pruning 2002 Vintage 2003 Vintage Overall ajlvar intensity ioo LSD(p 0.05)=4.6 Quality NS Colour 100 6080 80 NS* 80 /ioo 60 LSD(pO.O5)=5.6 40 HarJness 40 60 Vegetative 80 100 6 220 100 60 NS 40 JUa- - 20 NS 60 80 100 40 60 80 Fullnes 40 100 Berry 60 40 60 60 00 80 NS Ns NS Ac 100 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).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 115 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

Viticultural performance

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

Numbershoots/ 19c 31b 23c 41b 72a 22b 32b 71a vme 56a 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 24c 148a 20c 46b 172a bunches/vine 83c 60b

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

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 116 Alternative pruning methods for some wine grape varieties mal pruning increased the number of bunches for Chardonnay, ly decreased mainly because of a reduction in internode length Chenin blanc and Sauvignon blanc by 361%, 517% and 760% re- (Table 8). spectively (Table 9). Of the three white varieties, Sauvignon blanc Similarly to the white varieties, minimal pruning induced the showed the biggest decrease in beny mass and volume, bunch biggest changes in all measured parameters in the red varieties mass, cane length and internode length, while it showed the big- compared to hand pruning (Table 9). Merlot showed the biggest gest increase in number of bunches per vine, number of canes per increase in number of shoots for both alternative pruning meth- vine and the second largest increase in yield. After only four years ods and at the same time it showed the biggest decrease in cane of data this raises a question as to the adaptability of this variety length. Field observations showed that the shoot growth of this to alternative pruning methods. Taking the same parameters into variety came to a rather abrupt arrest during the middle of the account, Chardonnay seems to be better adaptable to alternative growing season even though the crop stress was not as high as in pruning. Further research into this aspect is necessary. the case of the other two varieties. Although Cabernet Sauvignon In the case of the red varieties, Cabernet Sauvignon reacted to showed the biggest decrease in internode length, it maintained mechanical pruning in a similar way than Chardonnay. Minimal shoot growth over a longer period. This, together with the fact that pruning significantly increased the number of canes per vine with it showed the biggest increase in bunch number and yield, points all three red varieties, but the average cane length was signfficant- 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 Parameters Hand Mechanical Minimal Hand Mechanical Minimal Hand Mechanical Minimal pruning pruning pruning pruning pruning pruning pruning pruning pruning

Viticultural performance

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

Number shoots! 24b 24b 52a 18b 21b 45a 26b 28b vme 63b 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 bunches!vine 38c 58b 78a 26c 45b 61a 23c 61b 98a

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

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 117

A B

70 - - 120 ; 1 60 E 100 .c so 80 0. •D 40 Ile 3. 60 30 ______40 20 E E 20 o 10

0J 2001 2002 2003 2004 2001 2002 2003 2004 Vintage Vintage

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

C - D

100 go-

70 6C 60 0. ______• 5C 50 4C 40 30- 30 20 E2c 0 10 0 2001 2002 2003 2004 2001 2002 2003 2004 Vintage Vintage

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

E - F

60 70 -

.c50 40 0. 40 JD 30 30

20 20 E E 10 o 10

o 1 2001 2002 2003 2004 2001 2002 2003 2004 Vintage Vintage

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

The bunch mass of Pinotage was least affected by alternative also was less expressed than for the other varieties, strengthening pruning and, combined with the relatively small change in the the observation that this variety may not adapt well to alternative growth habit, this indicates that this variety also adapts well to pruning. The cumulative yield of minimally pruned Chenin blanc alternative pruning methods. After only four data years it seems was the highest, while hand pruned Chardonnay and Cabernet that Merlot is the least suitable for alternative pruning. Sauvignon were the lowest. Except for Merlot and Pinotage the cumulative yield over four Although no clear pattern could be distinguished, important an- seasons for all varieties was highest for minimal pruning, pointing nual fluctuations in yield occurred (Fig. 5). As in the case of the to an earlier break even point than for the other pruning meth- trial at Nietvoorbij, 2003 season proved to be an excellent season ods (Fig. 4). The relative yield difference in the case of Merlot for alternative pruning methods for all varieties at Elsenburg. The

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 118 Alternative pruning methods for some wine grape varieties

A B

50 60 3 a 45 +4 50 40 4+ 1+4 a +4 1+4 35 40 a i•• a 30 +4 ra ++ 14+ ...... ++ b 25 4+ 35 CL b V , 20 a 20 ..•• >- 15 a a b ab 10 aaa

2001 2002 2003 2004 2001 2002 2003 2034 Vintage Vintage Duo 0 sOcro downy milcow 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 40 a a 35 50 a a 4+ 30 40 4+ ...... 4+ a a a 25 b ++ a

15 20

iliZ ii :i 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

25 40

35 20 30

25 ] a + 20 1I11': CL b

:jI bHLI4dLI4; r $; 2001 2002 2003 2004 2001 2002 iiiIi2003 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 chanically pruned Chenin blanc, mechanically and minimally (Region III) than the one at Nietvoorbij. This tendency was not pruned Sauvignon blanc showed a lower acid concentration (Ta- clearly shown for the Robertson (Region V) trial (see Fig. 13) ble 10). Hand pruning induced less colour in the skins and wines and it points to the possibility that climate plays an important role of Cabernet Sauvignon, while the colour of Pinotage was nega- in the performance of alternatively pruning methods. More data tively affected by alternative pruning methods (Table 11). Again, years are necessary to identify variety differences in this respect. more research is necessary to establish if this pattern will continue Different pruning methods had little effect on the oenological over the longer term. performance of the six varieties investigated (Tables 10 & 11). In three out of four years the citrus-like aroma of Chardonnay Minimally pruned Sauvignon blanc had lower extract, while me- wines was enhanced by minimal pruning (Fig. 6), while the tree

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 119

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 -9.0 a -18.Ob -21.0 a -40.0 b length (%) Cane mass -19.4 a nm -36.4 a nm nm nm nm -29.0 a nm (%) -35.8 a -38.0 a -55.0 a Yield(%) 113.Ob 247.8a 76.5b 155.0a 97.0b 230.0a 66.0a 71.0a 19.0a 8.0b 61.0b 115.0a Number of bunches/vine 128.0b 361.0 a 150.0b 517.0 a 130.0b 760.0 a 53.0b 105.0 a 73.0b 135.0a 165.0b 326.0 a (%) Bunch mass -1.1 a -13.4b -20.6a -42.0 b -22.0 a -32.0 b -16.0 a (%) -38.0 b -9.0 a -7.0 a -6.0b -30.0 b Berrymass -9.0 b -14.0 a 0.6a -14.0 b -2.0 a -18.Ob -7.0 a -18.Ob -4.0 a -16.0 b -4.0 a -12.0 b (%) Berryvolume -12.0 a -4.0 a -11.0b -1.4 a -17.0 b -4.0 a -16.Ob -15.0 b -15.0 b (%) -8.0 b -3.0 a -8.0 a

* 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 Parameters Hand Mechanical Minimal Hand Mechanical Minimal Hand Mechanical Minimal pruning pruning pruning pruning pruning pruning pruning pruning pruning Alcohol concentration (vol %) 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 Extract (mg/L) 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 Volatile acid (mg/L) 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 Free SO2 (g/L) 28a 27a 28a 27a 27a 28a 33a 29b 29b Total SO2 (g/I) 107a 101a 98a 88a 90a 88a 95a 95a 102a Sugar concentration (g/L) 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 Acid concentration (g/L) 5.4a 5.4a 5.1 a 7.1 a 5.8b 6.6a 6.9a 6.0b 6.3b PH 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

* 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 The vegetative character of Sauvignon blanc wines was en- vintages. This is ascribed to better fruit exposure brought about by hanced by hand pruning in two of the four vintages, probably be- alternative pruning methods (data not shown). cause of less fruit exposure (Fig. 8), while it improved the acid concentration of one year only. In one out of four years, the colour of Chenin blanc wines was improved by mechanical pruning (Fig. 7). During the same vin- Hand pruning decreased the colour of Pinotage wines in two tage, this pruning method decreased the acid concentration. Dur- of the four vintages, while it decreased the vegetative aroma and ing one year, minimal pruning decreased the overall quality of overall quality twice (Fig. 9). There is a tendency that the colour Chenin blanc wines. Chenin blanc wine did not benefit from al- is enhanced by mechanical pruning. These colour differences may ternative pruning. be ascribed to differences in fruit exposure and berry size.

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

120 Alternative pruning methods for some wine grape varieties

Overall cultivar intensity Citus 100 NS* 100 Quality NS Citrus 100 18° Fullness 80 80 100 100 LSD(pOO5)=58 o /m NS 80 Fullness Tree fruit Z4O 80 : 60 f .. 80 40

18° 80 60 .11 20 Acid I I I .1 I I ITropicalfruit ac 40 60 N 80 io Tropical fruit 40 20 20<\, :° 60/ 40 40\ 8° NS / t . 2< 60 80 60 100 80 60 so 100 Colour Ded •fl 100 Oth Drted fwit NS ioo o 100 NS Caramel Other Caramel

Hand pruning LI Mechanical pruning Li. Minimal pruning Hand pruning Li Mechanical prunng [] Minimal pruning 2001 Vintage 2002 Vintage** Overall cultvar intensity Overall cultivar intensity 100 100 NS* Quality NS J Citrus Quality NS I NS Citrus 1 00 I 8° 100 00 T 8° 100 80 LSD(pO.O5)=45 NS 8° ° 100 f +\J Fullness Tree fruit FulIn ess 80 / '\ .J 20 140 Tree fruit 10LSD(p0.05)=0.6 80 100

400

NS 00 60 NS X 60 NS ioyX Oif\ 8° 60t b y 60 100 °° 6o1c Acid eo\ Tropical fruit Add Tro pical fruit so 00 7L NS 100 100 100 NS 100 Other Caramel Other Caramel

[i] Hand prLning Mecharcal pruning Minimal pruning Hand pruning [I Mechanical pruning Minimal pruning Li 1 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).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 121

Overall cultivar intensity Fruity 100 NS* 100

Quahty NS Vegetaive :: : 100 80 100 NS Quality

60 80 20 40

1 °° 20; 40 NS

Fullness Tpical fit

60 80 80 Ilness 100 oI Atid Oth er

Hand prLning LI Mechanical pruning El Minimal pruning Hand pruning 2001 Vintage 2002 Vi ntage**

Overall culitvar intensity Overall cuWvar intensity 100 NS* - 100 NS LSD(p<0.05)=14 LSD(p<0.05)=10.2 NS Quality 80 Colour Quality - 80 Colour 100 100 />S100 80 .50 80 40

20 NS II 7\ X~ 40 NS S LSD (p 0.05) = 2 an / 20 20 1 NS o 7 Fullness I I 1Jree fruit Fullness I I I 1jree fruit 100 40 160

::I>, 60

100 100 Acid Tropical fruit Acid NS 8Ô Tropical fruit LSD (p 0.05) = 8.8 100 Other Other [1 Hand pruning Mechanicalpruning [] Minimalpruning El Hand pruning Li Mechanicalpruning [•_] Minimalprunig 2003 Vintage 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 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 Trial at Robertson of Merlot wines, except that minimal pruning was responsible for The same labour saving advantages obtained by alternative prun- wine colour reduction in three of the four vintages (Fig. 10) al- ing methods in the trials at Nietvoorbij and Elsenburg, were real- though the reduction was not significant. This cannot be explained ised in the trial at Robertson (Table 12). Hand pruning (including because no skin colour differences occurred (see Table 11). canopy management and harvesting) required 193.8 man hours/ In three of the four vintages, alternative pruning enhanced the ha, while 46.6 and 22.0 man hours/ha were used for mechani- colour of Cabernet Sauvignon wine compared to hand pruning cal and minimal pruning respectively. The man hours used for (Fig. 11). This was expected due to the improvement of the skin canopy management with the alternative pruning methods were colour obtained in the grapes (see Table 11). In spite of this, mini- for removing shoots on the trunks as well as mechanical trimming mal pruning produced the worst overall quality Cabernet wine in of shoots to open the work row. In the case of minimal pruning two of the three seasons. There is a tendency for wines form the summer trimming of the shoots 30cm above ground level is also hand pruned plots to be more vegetative in character and this is included under canopy management. It is again necessary to state probably due to the bunches not being as well exposed to sunlight that mechanical harvesting is a prerequisite when anyone of the as in the case of the alternatively pruned plots. This probably con- alternative pruning methods are used. tributed to the judges finding a higher overall cultivar intensity in The average cane length was significantly decreased by alter- the wines from the hand pruned plots. native pruning with minimal pruning producing the shortest in-

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 122 Alternative pruning methods for some wine grape varieties

Overall cultivar intensity Overall cultivar intensity NS - 100 NS-

80 LSD 0.05) iLl 80 NS (p = Quality Vegetative Quality NS Vegetative 100 100 60 60 80 100 NS 60 60 80 40 40 20 20 40 80 20

20 20 40 60 40 NS 60 80 NS 100 NS 100 20 40 60 60 20 80 20 80 Tpical fwit 100 Tpical fit Fullness 40 Fullness NS 40

60 60 6\ 60

100 NS 100 NS 100 Acid Other Acid Other

Hand pruining EI Mechanical pruning 11 Minimal pruning Hand pruining II Mechanical pruining Minnal pruning 2001 Vintage 2002 Vintage

Overall cultivar intensity Overall cultivar intensity i 100 LSD (p 0.05) = 4.5

80 80 1 NS Vegetative Quity Vegetative Quah ty 100 100 NS NS

60 40 60 II N 20420 20 2 20I20 40 NS 100 20 80 100 Fullness fruit Fullness 40 Tropical fruit NS 40 \ 60 60 60\ 80 80 80\ 80 NS 100 10 0/ LSD(p<0.05)=10.0 100 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 2003 Vintage 2004 Vintage

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

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 123

Colour Colour NS* 100 Overall culivar intensity NS 100 Quality Quality Overall culivar intensity 100 NS 100 NS NS 80 80 100 100 N S 80 , 80 80 80 NS Vegetative 60/ NS Tannins 100 Tainins ioo / Vegetative 40 . 60 40 60 80 40 80 0 100 100 NS 60 1 60 80 NS 80 20: 40 3L 20 60 60 - 40 40 NS 2 80 60 60 NS 100 100 80 40 60 : 80 100 40 60 80 Rilness 20 Berry Fullness 20 lao Berry NS NS 60 40 40 60 40 40 40 40 80 60 80 60 60 60 100 80 100 80 NS 60 LSD(pO.O5)=6.2 60 80 100 80 100 Acid Tree fruit Acid NS Tree fruit 80 80 100 NS 100 NS NS 100 NS 100 Other Dried fruit Other Dried fruit

Hand pruniig [1 Mechanical pruning Miniiial pruning El Hand prunhg El Mechanical prLning Minhial prunhg 2001 Vintage 2002 Vintage

Colour Colour LSD (p < 0.05) 21.6 LSD(

100 K 100 180 100NS 80 80 NS 80 6 NS Vegetative Tannins i Tannins 100 Vegetative 00 80 40 100 100 80 60 I NS* 80 NS 60 60 40 NS NS 40 00 Fullness Berry 40 80 Fullness 20 loo Berry LSD(p<0.05)=12.4 60

\ NS 100 80 0 80 : 100 60 NS 80 Tree fruit 100 Ad Tree Fwit NS 100 NS LSD (p 0.05) =2.7 100 IOOJNS NS 100 Other Dried fruit Other Dried Fruit

Hand pruning Liii Mechanical pruning Li Minimal pruning Hand pruning [1 Methanical pruning LI] Minimal pruning 2003 Vintage 2004 Vintage

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

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

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

124 Alternative pruning methods for some wine grape varieties

Colour Colour 100 - 100 NS* Quality Overall cultivar charachter Quality rs Overall cultivar intensity 100 lao 80 80 7' 100 100 80 d 80/' )( NS 80 - 80 40 60 V60 Tarviins I'J40 Vegetative NS 80 Tannins 100 80 Vegetative 60 20 100 60 80 80 60 NS10 20 :80 0 10 NS 6ó 100 40 Fullness /C 100 Berry 80 6G" 40 °° Fullness 60 Berry 80 '7 60 NS ioo/ \ 80 100' NS 100 cid Spicy Acid Other 100 Other

Hand pruning El Mechaiical pruning Minimal pruning El Hand pruning El Mechanical pruning Minimal pruning 2001 Vintage 2002 Vi ntage**

Colour Colour 100 NS Quality NS Overall cultivar intensity Quality NS Overall cultivar intensity 1 00 I®

:/s 80 NS \s 60 Tannins Vegetative Tannins 100 40 Vegetative

60 20

60 NS 80 Fullness 46\ 100 Berry Fullness 40\ 100 Berry

NS IOO 86\), 100/ I 100 100 NS Acid Spicy Acid Spicy NS NS1 ®

Onther Other

Hand pruning El Mechanical pruning Minimal pruning Hand pruning II Mechanil pruning Minimal pruning 2003 Vintage 2004 Vintage

FIGURE 10 Effect of pruning methods on the aroma profiles and wine quality of Merlot wines of four different vintages at Elsenburg (2001 —2004).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 125

Colour Colour 100 NS 100 Quality NS Overall cultivar intensity Quality Overall cultivar intensity 100 100 80 '< 80 2' 100 80 O N < 6O 80 \ / 80 NS 40 Hardss I® 40 Vegetative Hardness I® 40 Vegetative 80 80 60 2(-2/\ l® --- 00 80 80 80 60 NS 60 20 60 NS 80 40 80 100 100 40 60 \40 20 80 Fullness 2040 40 I® Berry Fullness Berry 60 \ 60 NS 60 80 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 2001 Vintage 2002 Vintage Colour Colour LSD(p<0)5)12.O 100 NS* 100 NS* Quality Overall cultivar intensity Quality NS Overall cultivar intensity 100 80 100 80 1) (p 0.05) iLl 100 7100 so 80 I NS L so 80 NS Hardness 100 Vegetative Hardness o egeve

So 60 20 100 80 60 NS 40

LSD < 120 (p 05) 80 100 20 60 LSD(p<0.05)6A 100 80 Fullness 40 100 Be Fullss 100 Berry 60 60 40 \ NS NS 80/ NS 60 8 80' 100 100 : LSD(P<0.05)6 100 7 NS I 00 Acid NS Spicy Add a Spicy 100 NS 100ct NS Other Other

Hand pruning [1 Mechanical pwning LI] Minima pruning Hand pruning P1 Mechanical pruning I:] Minimal pruning 2003 Vintage 2004 Vintage

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).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 126 Alternative pruning methods for some wine grape varieties

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

Pinotage Merlot Cabernet sauvignon Parameters Hand Mechanical Minimal Hand Mechanical Minimal Hand Mechanical Minimal pruning pruning pruning pruning pruning pruning pruning pruning pruning 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 to the increases in yield (Table 13) compared to hand pruning. shoot length by 18% over all varieties, while minimal pruning Minimal pruned vines only yielded more than mechanical pruned was responsible for a 60% decrease (Table 14) compared to hand vines in the case of Chardonnay. Mechanical pruned vines per- pruning. At the same time internode length was reduced by 10% formed the same or better than minimal pruned vines in the case and 40% respectively. In all cases the number of nodes per cane of the other varieties. The possible yield reducing effect of a lower was significantly reduced by alternative pruning (data not shown) bunch mass in the case of the alternative pruning methods, was compared to hand pruning. The number of shoots per vine was more than offset by a significant increase in bunch number (Table signfficantly increased by the alternative pruning methods (Table 13). The cumulative yield over the six vintages of this trail showed 13), mechanical pruning increased it by 113% over hand pruning that Chardonnay and Shiraz profited by mechanical pruning, while and minimal pruning by 400% (Table 14) respectively. Changes Sauvignon blanc and Ruby Cabernet profited by minimal pruning in cane length (decrease) and number of shoots (increase) brought (Fig. 12). In the case of Chenin blanc and Colombar no distinc- about by mechanical pruning compared to hand pruning, resulted tion can be made between mechanical and minimal pruning. It in no change in cane mass/ha in the case of Ruby Cabernet and is, however, clear that these two alternative pruning methods had Shiraz (Table 14) repsectively. The overall reduction in vigour a yield advantage over hand pruning. No clear pattern emerged caused by alternative pruning methods could partly be ascribed when seasonal yields were compared between varieties (Fig. 13).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 127

Mechanical pruning increased the bunch number on average by With all the varieties, especially the two reds, sunburn and mill- 166% in all varieties, while minimal pruning was responsible for erandage were increased with alternative pruning and this tenden- an increase or 360% (Table 14). The smaller bunches obtained cy held true for all three trials. In all cases the bunch compaction with alternative pruning were not only caused by smaller berries was also reduced but no disease advantage could be monitored. (mass and volume), but also by a smaller physical size as shown CONCLUSION by the bunch stem mass (Table 13). Compared to hand pruning, alternative pruning methods (me- Pruning methods had no clear effect on sugar concentration and chanical, minimal and no pruning) are hugely labour saving and in the case of Chardonnay, Sauvignon blanc and Ruby Cabernet, contribute greatly to reducing production costs of wine grapes. A the acid concentration in the grapes was reduced (Table 13) com- prerequisite for these methods is the availability of mechanical pared to hand pruning. The effect of pruning method on must pH harvest machines because hand harvesting the resultant numerous was not clear and it differed between varieties. More research is small bunches by hand, is not viable. necessary to determine the effect of the alternative pruning methods on grape composition. Alternative pruning methods reduced the vigour of all varieties No clear trend in the effect of alternative pruning methods on the used in the three different trials, but the method as well as the wine composition of the different varieties could be found except variety differ in the extent to which these changes took place. Vig- for wine colour where these methods improved the colour of Ruby our reduction is ascribed to shorter canes with shorter internodes and the time of shoot growth arrestment varies between varieties. Cabernet and Shiraz wines (Table 15). This may be derived from the better skin colour (possible better skin: juice relationship of the Although berry mass and volume as well as physical bunch size smaller berries) obtained by alternative pruning with these varieties. were reduced by alternative pruning methods, resulting in lighter bunches, the increased number of bunches not only prevented a In two of the six vintages, the citrus aroma of the Chardonnay yield decrease, it was responsible for considerable yield increases wines was improved by minimal pruning, while mechanical prun- compared to hand pruning. Contrary to common believe that this ing achieved it in one season (Fig. 14). There is a tendency that may affect quality, wine quality in most cases was either not af- the citrus and tree fruit characters were enhanced by alternative fected or it was improved. Again, in this respect there are variety pruning. Pruning method had no clear effect on the wine aroma differences. of Chenin blanc (Fig. 15) and the same is true for Colombar (Fig. 16) which is also a neutral variety. Contrary to popular belief, Cabernet Sauvignon, Pinotage and Chardonnay seemed to minimal pruning enhanced the vegetative character of Sauvignon adapt the best to alternative pruning, while Sauvignon blanc and blanc wines in two of the six vintages, while it reduced the tropical Merlot (both varieties prefer cooler ripening conditions) were less fruitiness in one season (Fig. 17). The wines from the hand pruned adaptable. The perfonnance of Chenin blanc, Colombar, Shiraz plots showed a tendency to be fuller than that of the alternatively and Ruby Cabernet was acceptable making them good candidates pruned vines. In two of the six vintages the panel ofjudges found for alternative pruning especially when the economy is taken in a better colour in the Shiraz wines from the alternatively pruned account. Although not measured, practical vineyard observations vines (Fig. 18). Except for a tendency that alternatively pruning showed that inner trellis posts should not be planted further apart improved quality, overall cultivar intensity, fruitiness and spici- than 6.0m, while additional fertilization and irrigation will be ness, no clear pattern emerged in the wines of Shiraz (Fig. 18). needed when anyone of the alternative pruning methods is used. In four of the six vintages, there was a tendency that hand pruned Wider vineyard rows (3.Om to 3.2m) must be used when one vines enhanced the vegetativeness of Ruby Cabernet wine (Fig. or more of the alternative pruning methods are applied to provide 19). No other clear pattern emerged. enough room for the expansion of the permanent vine structure.

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 128 Alternative pruning methods for some wine grape varieties

140 160 120 140 ______120 C,'- 100 C, 100 80 C, 2 80 60 ______60 40 40 E 20 20

0 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 1 40 iz0 i z0 C, - 100 CL 100 .80 ______° 80 60 60 40 4 0 E 20 20 0 2001 2002 2003 2004TT 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 140 140 120 120 -c

C,'-______100 C)'- 100 80 80 C) C) 60 60 Z 40 40 E 20 E 20

I I I I I I I I I 2001 2002 2003 2004 2005 2006 2001A 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.

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 129

15 1 0 10

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

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

1 0 1 0 400%% —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

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

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

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

130 Alternative pruning methods for some wine grape varieties

Overall culvar intensity Overall cultivar intensity LSD(p<0.05)10.1 100 * 100 Quality Colour NS 100 LSD(p

60 20 NS 80 40 100 445\ 40 NS 80 60 100 °° #dd Add 80 60 60

80 NS 100 100 NS 100 L k100 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 100 100 LSD(p<0.0543 NS* LSD (p <0.05) = 4.0 Quality NS Citrus Quafi ty Citrus 100 . 80 100 80

80 80 - 60 80 so 60 \ NS 60 NS 40 Fullness 100 80 NS Te fruit Fullness Tree fruit

80 100 10 -*-----_ 60 20 40 20 NS

60 20 60 20 40 ao2 4q/ NS NS 60 60 100 ' 40 NS 100 40 NS / 80 °° 60 100 Add Tropicalfruit Acid 60 Tpical fruit 80 80 OO\ 100 l001 \ NS NS NS io 100 Other Caramel Other Caramel

Hand pruning [ Mochnici pruning 1-1 Minimal pruning Hand pnjng 1 MwhankA p,ning Minirni pruning 2005 Vintage 2006 Vintage

Statistical differences indicated in the figures (p 0.05). *NS = non significant. FIGURE 14 Effect of pruning methods on the aroma profiles and wine quality of Chardonnay, wines of six different vintages at Robertson (2001 —2006).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 131

E o CO o .0 CO 0 .0 0 0 CO CO CtC ' C O C O C11 fl M C-i - ,j c . wi 9 - -

CO .0 ,a ca Co Pa ca .0 CO ca Co CC .0 C N c' 00 C C .0 n - -

CO '0 CO Co Co CO CO o N Co Co N 00 - N - 00 00

Pa E o CO o CO CO 0 0 0 0 0 .0 00 N C' C\ - 00 0 • 00 .- ocS cq 0 CO .0 .0 .0 CO CO .0 CO .0 CO 00 C C C M 00 9wl o

CO '0 CO CO CO CO CO CO C CO 0 o C o - c C

PR 0 0 0 0 CO CO .0 CO .0 CO E 't 00 a 'r o', c' •-. N 0 C\ 0' , 00 N N i Cl! C11 - - - 6

.0 CO CO CO 0 .0 CO .0 .0 .0 - o CrC C n N 0 C CO 9

CO .0 CO CO CO CO .0 .0 I '0 0 CO CO 0 00 _ CO o 0 C C'> N CO C O C Ci C. C

PR 0 CO .0 CO 0 0 0 0 0 .0 CO .0 CO E l 00 C'> C'> N 0 CrC C'> Cfl N C'> C'> - - C'>

.0 CO .0 .0 .0 .0 CO CO C .0 CO CO .0 CO CO CC N cq 0 Ci VI CO C11 - - C'> CO

CO '0 CO 0 CO CO .0 CO CO CO ' CO CO CO 0 c - 00 - 00 C'> CO C'> Cfl 00 N C'> C C'> C a, C i C'> C'> CrC - -

PR 0 CO .0 CO CO 0 0 0 0 CO CO CO E CrC C1' 00 C'> - C'> 0 CO .0 .0 CO .0 .0 .0 CO CO CO CO CC 00 . 00 a, N 00 O 00 0 0 CrC • CrC C 00 en •• •-• 0 CO C'> .0

CO .0 CO CO CO CO CO CO '0 0 CO CO 0 00 CO CO 0 c N CrC C'> 00 C CO CrC N c C'> C C'> C'> C . - - N C'>

PR 0 0 CO CO 0 CO .0 CO CO 0 .0 0 CO E Cl 00 - C " c "R C11 C'> N - - - C'> 1401 0 0 .0 CO .0 CO .0 .0 0 CC .0 C'> N s CrC C Cfl N C' Cl CO '> - - C'> .0

* 0 CO CO CO CO CO '0 CO 0 CO CO 0 - CO .0 0 0 Cl CO 00 C'> O s C'> C'> Cfl 00 C'> - - -

.0 1 C

1401 0 CO 0 E 1>1> C Of> 0 0 CO CO 01> 0 <.9L) Z H

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 132 Alternative pruning methods for some wine grape varieties

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- Mniimal Minimal Mimalm Minimal Minimal Minimal meal nieal meal meal meal meal 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.

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 133

CO CO CO CO CO CO .0 .0 E 00 00 en wl s c' n O O C 0 o S u- d d d

ca CO CO CO .0 N Ci en - .r j U d d

'0 CO CO -' , CO CO - CO 0 00 00 C,5 CO o c n S O C - fl C,5 d d d d c'

CO CO PR .0 CO .0 .0 CO CO O S S E C11 S o as as C 00 0 00 - 00 C' C d wi 0 CO CO .0 .0 ' .o' CO CO CO CO CO CO C C, O O CO c C o c c' S C C 0 C c? .E ,- i,.; Cl! CO - n -. d - ' , CO '0 ,OM CO CO CO CO CO C, S C' S O 00 O S C Cl! 00 c C en C - C

PR CO CO CO , E 00 C -0 C,; 0 CO ' PR CO , CO CO 0 cc ' CO © C 00 en C .0 C .0 d 0 ',cC CO r, o , CO CO CO CO CO 0 C., O en

CO CO ... ,C CO .0 - CO o c c . en - c. n C

CO CO CO , CO .0 - ' . o . o • © I Pa CO en L) rd '0 CO CO CO CO CO CO . CO - C-i en d CO , CO CO E CO CO CO 00 C . Cl! C11 Ci Cf 0 0 44 , PR CO ,0 , , CO CO '0 o .0 0 . 0 S en ) E CO 0 0 .0 c .0

'0 CO CO , CO CO CO o 00 CO 00 C,-; Cl - C. -. Cfl C

•0 PR CO , CO 0 a CO 0 c as 00 wl ,

;

I- •0

E ne z J **

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 134 Alternative pruning methods for some wine grape varieties

Colour Fruitiness NS 100 160 NS

Quab(p Guava 60 80

40 Fullness '00

80 6\0 NS 80

NS 100 Acid 80 Tropical fruit NS 1 60 Fullness Other NS 100 Other Hand pruning Meuhaneal pruning Mnnnal pruning Hand pruning [1 Mechanical pruning II Minimal pruning [I Lii 2001 Vintage 2002 Vintage

Cdour Coloir 100 NS* IOONS

Quality - Overall cultivar intensity Quality uo Overall cuttivar intensity 1 1010 "° 80 NS / 80 60 40

11 40 a NS 100 60 Fullness 160 I 1Tme fruit Fullness i 21 (1

Y60 -40 66 40 60 80 66 100 80 NS 100 60 66 LSD(p

100 NS 100 Other Other Hand pruning LI Mechanical pruning Minimal pruning Hgod pruning LI Mechanical pruning L Minirl pruning 2003 Vintage 2004 Vintage

Coloir Colour

100 100 LSD(p

100 100NS

>(ID so LSDO-7.4 LSD(p

160 60 00 60100 LSD(p

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

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

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

Alternative pruning methods for some wine grape varieties 135

Colour Fruitiness 100 100 NS* T NS* S Quality Overall cultivar intensity I 52 100 60\ 100 NS 80 40 \ NS 40 100 Guava 40 20 100 lOS 80 100 80 60 A 0 20 60 40 Fullness I I I (I I 4 I I I Treefruit 80 100

0 20

40 6<\ 60 60 100/60 100 40 NS NS 100 Add 80 Tropical fruit / \ 100 Ns 100 Fullrross Other Other

Hand pruning Mechanical pruning Mininal pruning Li Li pruning LI Medlanical pruning !! MininSi pruning 2001 Vintage 2002 Vintage

Cour Cdour 100 100 lOS. lOS NS Quality 00 Overall cultivar intensity Quality NS Overall culbvsr intensity 100 100

60 160 160 lOS 80 NS 40 40 40 60 60 lOS S LSD(p

100 NS 80 100 Acid 00 Tropical fruit Acid 00 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 2003 Vintage 2004 Vintage

Colour Cdour 100 lOSt 100 T Npr Quality lOS 00 Overall culitvar intensity I so 100 Qity Overall cultivar intensity 160 lOS 80 - iso 00 40 i 40 60

100 00 60 ' 40 20 20 Ns Fullness 20 I I I I 1 1 5Q 160 ITreefruit L )( .00.05) 40 80 160 / • 80 Fu Ilness Tree fruit 40 60 90 100 60 60 lOS 80 100 Acid 00 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 2005 Vintage 2006 Vintage

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)

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 136 Alternative pruning methods for some wine grape varieties

Overall cultivar intensity Overall cultivar intensity rOONS* 180LSD(p<055)10.4

Quality Quality //)(/X

NS GO LSD(p

80 /n.\\ Fullness Tropical fruit Fullness 2 Tropical fruit 40 GO

80 \ NC Acid Other Acid Other

Li Hand nuning LI Medranicd pruning Li MinirHa pruning Li Hand prunne LI Meohencel pruning Mnnr6I pruning 2001 Vintage 2002 Vintage

Overall cultivar intensity Overall cultivar intensity

60 40

vu Fullneu o 20 80Tropi: t Fullness 100 Tl fruit

o 40

NS Acid Other Acid Other NS

Li Hund prunire LI MeohHnioHI prHa5 Li Mininhel pruning Li Hand pruning Li Mechanical pruning I] Mininl pruning 2003 Vintage 2004 Vintage

Overall cultivar intensity Overall culhvar intensity LSD (p

80 Quality Qenlity vegetauve r r

80 80 - 80 80 50 60 50 20 00' / 00 00 60

60 80 80 80 Nropicai 60 Nropicai 80 ruu roc fwit Fullness it Fullness :80 80 60

80 NS roc NS roc NC Acid Other Acid Other

Hand ruining El Mednar6od prunrig Mininnd prurrrg Hand prunina Li Mechanical phrnina Li Mirnal prunina Li Li 2005 Vintage 2006 Vintage

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

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

Alternative pruning methods for some wine grape varieties 137

Colour Colour NB LSD (p 0.05) = 11.1 iuu 10 * NS Quality Overall cultivar intensity Quality Overall cultivar intensity iuu NS 100 0 / iuuNS l00NS \ OO 1 amp 80 80 LSD(p

NB 80 60 40 60 NB 100 40 NB 100 no 80 Fullness 60 Scy Fullness no NBscy

NB no 100 NB NB / 10 at I 'NS Add Smoky Add Smoky -- INS 100 100 Other Other LBD (p <0.05) = 10.4

Hand pruning [1 Mechanical pruning Li Minimal pruning Hand pruning [1 Mechanical pruning [] Minimal pruning 2001 Vintage 2002 Vintage

Colour Colour NB* NS* 100 100 NB NB Quality Overallcultienrintenalty Quality Overall cultivar intensity 100 NB 100 100 buNS 80 60 00 no 80 LSD(p

Cour Colour LBD (p <0.05) = 12.0 100 NS* NS LBD (p <0.05) = 15.8 100 Quahty Overall cultivar intensfty Quality Overall cultivar intensity 100 80 100 ...• /ioo NS LBD(p<0.05)=8.4 ec 100 . . \ tso / NS NB o Tannins 40 Berry Tannins Barry so 80 S 100 00 NB NB

20 I 2 20 NS 60 LBD (p 0 so 80 100 20 0 100 60 NS 40 .00 NB so no Fullness 40 100 Spicy Fulness 40 100 Spicy 40 P I no NS 1: 1c\ , ( 00+ 80 I I 80\ 100 NB ioo NS NS Acid Smoky AcC 100 100 NB NB Other ogler

Hand pruning [1 Mechanical pruning [7 Minimal pruning Hand pruning 11 Mechovical pruning Uj Minimal pruning 2005 Vintage 2006 Vintage

Statistical differences indicated in the figures (p 0.05). *NS = non significant. FIGURE 18 Effect of pruning methods on the aroma profiles and wine quality of Shiraz wines of six different vintages at Robertson (2001 —2006).

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

138 Alternative pruning methods for some wine grape varieties

Colour Colour LSD(p50.05)8.3 LOD(p

/LSD(p<0.05)6.9 7100 100 -\ 80 - -\ 00 oo'7-' )( 80 00 NS NS 18.7 Tannins Vegetative Tan,4ra 0'\F 100 1t40 4>: t

NO 40 NO _/ (p <0.05) 7.2 1oo__ 40) '00ad ed ad 80 40\\ 100 Fullness 100 Berry 40 BerrY LSD(p<0.05) 00.4

NS NO Acid NuttY Acid Nutty NS ira NO Other Other Hand pruning El Mechanical pruning MIninnal Pruning Hand pruning ri Mechanical pruning . 1 Mininnal Pruning [.11 2001 Vintage 2002 Vintage

Colour Colour 100 NS LSD(p

LOD(p

Hand pruning Mechanical prraing I Mininral pruning Hand pruning Mechanical prraing Mininial pruning El I ] El Ci 2003 Vintage 2004 Vintage

Colour Colour LOD (p <0.05) = 8.7 100 100 NO* Quality NO Overall cultivar intensity Quality Overall cultioar intensity 10 r

100 s ' 80 80 LSD(p

40 j 40 LSD(p5O.O5)4.0 80 80 20 NO 40 20 eo NO 100 Be Fullness 100 Berry Fullness ° r ry 60 ° eo

80 80 100 NO : 100 NO 100 Add NO Nutty Add NS Nutty 100 100 Other Other

Hand pruning LI Mechanical pruning I MHinal pruning Hand pruning LI Mechanical pruning Mirinnal pruning 2005 Vintage 2006 Vintage

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

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).

S. Afr. J. Enol. Vitic., Vol. 28, No.2,2007 Alternative pruning methods for some wine grape varieties 139

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