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A Technical Guide for Wine Producers
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VINPRO (SA) / WINETECH Vineyard Practice Evaluation 2002
Evaluation Of A Few Practices That Were Judged
1. INTRODUCTION
The Vineyard Practice Evaluation is funded by Winetech as a technology transfer project on an annual basis. VinPro (SA) acts as co-ordinator of the project and covers the running costs. The evaluators are not remunerated for time spent on evaluation or on the so-called "farmers' days"; their participation is most highly appreciated by both Winetech and VinPro (SA).
I should also like to make use of this opportunity to thank all the judges who offered their services during the 2002 evaluation.
The goals of the project may be summarised as follows:
Altogether 55 entries were received for the 2002 competition. The districts from which most entries were received, were Worcester with 10 and Malmesbury with 8 entries.
Each district's blocks were evaluated by various judging panels, appointed annually on a rotation basis. Direct comparisons between districts must therefore be made with circumspection. Evaluation took place according to a pre-composed evaluation form. A minimum of five entries per district are required to make the evaluation valid.
The evaluation occurs in three sections. The evaluation form makes provision for long term techniques, short term techniques and general appearance. The focus of this article will be the specific practices for which the lowest average points in all the districts were allocated.
2. LONG TERM TECHNIQUES
The practices evaluated below are soil preparation, cultivar adjustment to the resources, growth, row direction, hereditary quality, spacing, trellis system, vine shape and irrigation system.
The practice for which the lowest marks were allocated, is vine shape. Two different evaluation forms are used for trellised and bush vines respectively. With trellised vines, vine shape constitutes a score of 9 out of the total of 100 and is evaluated according to the following criteria:
The evaluation of bush vines occurs according to the following criteria (11 points of the total score out of 100):
Only a few bush vine vineyards were entered and therefore the scoring is applicable mainly to trellised vineyards. Figure 1 indicates the judges' evaluation in the various districts. Stellenbosch (84%) in particular fared very well in this section, while Worcester (78%) deserves to be commended. In Paarl (58%), Orange River (65%), Robertson and Klein Karoo (70%) and Malmesbury and Olifants River (71%) vine shape certainly warrants more attention.
3. SHORT TERM TECHNIQUES
The practices evaluated below are fertilisation, irrigation, winter pruning, canopy management, weed control and crop protection. Figure 2 shows that in general, the score for maintenance fertilisation was very disappointing. The following scores indicate that no district obtained more than 70%:
Worcester - 50%
The evaluation form for both bush vine and trellised vineyards allows a maximum of 4 points for maintenance fertilisation. The use of soil analyses and application of fertilisation, taking into account vigour and/or pruning system, are used as criteria for the allocation of points.
Too little or too much fertilisation has a big influence on the vigour of vines and eventually also in the final quality of the grapes and wine. In addition to the short term disadvantages of excessive fertilisation (overly vigorous growth, rot, etcetera) there are also long term disadvantages such as infertility caused by foliage compaction.
The direct cost per hectare of fertilisation and the percentage it constitutes of production cost per hectare for the 1998 and 2001 production years are as follows:
FERTILISATION
COST (R/ha) %
OF TOTAL PRODUCTION COST 1998 2001 1998 2001 Orange
River 423 158 7% 2% Olifants
River 599 520 8% 7% Malmesbury 333 302 4% 3% Paarl 333 302 4% 3% Klein
Karoo 334 668 5% 7% Robertson 498 503 8% 5% Stellenbosch 258 370 3% 3% Worcester 462 481 6% 5%
The figures show that in general, the cost of fertilisation, in relation to total production cost, either decreased or remained constant. The exception is Klein Karoo, where the cost of fertilisation as a percentage of production cost increased.
The cost of fertilisation did not increase above a maximum level of 7% in any of the districts. It is obvious, moreover, that over or underfertilisation in monetary terms does not make a big contribution to the total production cost per hectare. Instead, the result should be quantified to gauge quality, and be reflected in the selling price of the wine.
4. GENERAL APPEARANCE
This category evaluates vigour, compared to soil potential, evenness of the block, appearance of the foliage during ripening with a view to wine quality, appearance of the crop during ripening and the general appearance of the farm.
A subsection that carries much weight (11 points out of a total score of 100) as far as the allocation of marks is concerned, is the appearance of the crop during ripening. The following aspects are evaluated:
Figure 3 shows that generally the regions fared better in this section. The following scores were allocated: Stellenbosch (84%), Klein Karoo (83%), Robertson (82%), Worcester (79%), Olifants River (77%), Paarl (74%), Malmesbury (71%) and Orange River (55%).
5. SUMMARY
The best application of natural resources, as well as the application of short and long term practices, with a view to the cultivation of high quality wine grapes, are the most important aspects to be evaluated. Considering the market's requirement of quality wines and the growth in the demand for wines made from noble cultivars, the viticultural practice evaluation is an excellent opportunity to get a panel of specialists to give their opinion about your own viticultural practices. All participants also receive the judging panel's comments to enable them to adjust and improve their viticultural practice.
The evaluation also serves as an important extension aid since annual workshops or farmers' days are held at the winning blocks in the various districts. The correct application of the various practices is demonstrated and critically evaluated in situ, while at the same time other topical and relevant issues regarding the cultivation of wine grapes are also discussed.
The subsections which received the highest scores (vine shape, fertilisation and appearance of the foliage during ripening) were also conveyed to the Viticultural Forum of the South African Society for Enology and Viticulture (SASEV) as suggested topics of discussion for their viticultural meetings in the course of the next year.
6. VITICULTURAL PRACTICE EVALUATION 2003
The evaluation of vineyard blocks will continue in all eight KWV districts in 2003. Interested parties who want to enter may contact the following convenors in the various districts:
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