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A Technical Guide for Wine Producers
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Practical viticultural experience of certain "new" cultivars
Viognier, Petit Verdot, Tannat, Mourvédre.
In this article, the first in a series of four, certain aspects of the cultivars Viognier, Petit Verdot, Tannat and Mourvédre are discussed based on a combination of literature and field experience. Experience is based on the performance of the cultivars in the establishment sites of KWV Vititec in Stellenbosch, the commercial mother block sites of Voor-Groenberg Nurseries in Wellington and commercial plantings in Stellenbosch, Malmesbury, Paarl, Worcester and the Southern Cape. Part 1 is devoted to Viognier.
Introduction
Over the past decade various old-world wine grape cultivars have been "newly" introduced to the industry. A large percentage of these cultivars did not necessarily make their début in South Africa, but were already imported in the first half of the 1900s. The reason for being withdrawn was largely a lack of market demand in an industry dominated by mass production. The exposure of South Africa to the international wine market since the 1990s has caused a rapid increase in the demand for a larger variety of cultivars. With local knowledge being limited or non-existent, the potential for some of these cultivars in South Africa was determined in the light of literature, overseas visits, or via international specialists.
Oenology in the New World has not yet developed to the same extent as in Europe, where there is a system of limiting cultivars to certain areas of origin, consequently a variety of cultivars is found in almost all wine regions. When a new cultivar is therefore introduced to an industry, its success is to a large degree determined by the environment and cultivation conditions of the area in which it is first established. Some cultivars have a wide application and have met with a positive reception from producers under widely divergent conditions, while others have very specific needs that, if not fully satisfied, may result in the unnecessary demise of such cultivars.
The theoretic evaluation of a cultivar's potential for establishment in a new environment is influenced by a variety of factors. The following may be singled out:
South Africa is in the privileged position to have wine regions with widely divergent soil and climatic conditions. The opportunity exists to plant a bigger variety of cultivars. Viognier, Petit Verdot, Tannat and Mourvédre are but a few of the cultivars to have emerged in the last decade. After some years' initial experimentation, followed by commercial cultivation, reasonable assumptions may be made concerning the potential of the above cultivars under South African conditions.
PART 1: VIOGNIER
Origin and cultivation
The origin of Viognier is uncertain, but some reckon the cultivar hails from Yugoslavia, whence it was brought to France in 281 BC. The Condrieu wines in the northern Rhône Valley are made from Viognier. Since the cultivar has been cultivated there for more than 1 000 years, the region is considered the historic home of Viognier. According to statistics from 1990, vineyards qualifying as Condrieu Wine of Origin constitute only 102 hectares. Only vineyards older than 3 years may be used for this purpose. The home of Viognier is therefore small and quite unique.
In Condrieu the vines are planted against steep (gradients of up to 70%) southerly and south easterly slopes that optimise exposure to morning sun. The Condrieu vineyards are situated in a zone with a continental climate, which means there are considerable differences between day and night temperatures during the ripening period. Maximum use of sunlight is obtained against the steep slopes facing the sun. Consequently sufficient heat is absorbed for the development of unique flavours in the grapes. The soils are of granitic origin, with sandy topsoils, thus making a further positive contribution to the satisfaction of heat demand during ripening.
Plant density is high at more than 6 000 vines per hectare. Production levels do not exceed 35 hectolitres/ha (less than 6 tons/ha; approximately 1 kg/vine), otherwise the risk of incomplete ripening becomes too big. It is clear that sufficient ripeness is one of the biggest challenges for producers in Condrieu. This is understandable, bearing in mind that the area is situated between 45 and 46 degrees northerly latitude, where the sun's angle of incidence is considerably smaller compared to lower latitudes. At such high latitudes, the gradient of the slope and the direction in which it faces have a noticeable effect on temperature.
South African conditions
In most South African wine regions, thanks to abundant sunlight and heat, it is not an issue to reach the desired levels of ripeness. The French select the warmest slopes in a relatively cool environment to plant Viognier. One wonders therefore whether locally a warm slope in a cool area, or a cool slope in a warm area, would produce similar results. There is not yet a satisfactory answer to this question, but up to now, regardless of the orientation of the slope, Viognier fares well almost everywhere in the warmer areas of Malmesbury, Paarl and Wellington. It should be borne in mind that the wine regions of South Africa have a predominantly Mediterranean climate with considerably smaller differences between day and night temperatures during ripening. The Western Cape is also situated at a lower latitude (between 33 and 34 degrees southerly latitude), which makes the sun's angle of incidence considerably bigger than in Condrieu.
Good quality and typical character are obtained in instances where producers wait patiently for ripening. Although the cultivar ripens early, at times even before Chardonnay, the higher sugar levels at which it is harvested might bring about a slight delay in the harvest date. On the whole one can accept that the time of ripening corresponds with that of Chenin blanc. The unique aromas of peach, apricot, flowers, etcetera only develop at sugar levels above 23.5 degrees Balling. It is not unusual to harvest the grapes between 25 and 26 degrees Balling, consequently the alcohol content is high. The appearance of the bunches and berries also changes with the onset of ripening. The berries acquire a brownish hue and start feeling slightly "mushy", reminding one of the shrinking that sometimes occurs in Shiraz. The berries are fleshy and the skin, although thin, has a leathery appearance with a strong phenolic character.
In the vineyard the cultivar grows vigorously to very vigorously when planted on high potential soils. Otherwise the vigour is balanced. The shoots are delicate and easily blown about by the wind. The bunches are particularly resistant to wind damage. There is a shortage of tendrils to attach the shoots properly to the trellis wires, therefore a trellis system with sufficient wires is recommended. For high potential terrain: 2.4 metre poles, 5-7 wire extended Perold with 2-3 sets of moveable wires. For medium potential terrain: 2.1 metre poles suffice. It is recommended that the first set of wires be placed at 20-25 cm in order to protect the young shoots from wind damage. Wires must be carefully raised and attached since the shoots are brittle and easily damaged. To a certain extent, this reminds one of Shiraz.
Although fertility and berry set are deemed problematic in France, the same cannot be said for South Africa. Crop control under luxurious conditions is required in many seasons, but under medium potential conditions, production levels of between 6 and 8 tons/ha (2.5 metres between rows) are easily obtained. There are exceptions, however, with local producers complaining about the fertility of the base buds in particular (with accompanying production levels of less than 5 tons/ha), while others obtain production levels of up to 15 tons/ha (how to answer this question?). Poor set has not been observed.
Although the cultivar is grown without irrigation in France, the availability of water under local conditions is a big advantage and without it quality is reduced, especially in the warmer regions where the cultivar is currently grown. In the Swartland, where some plantings grow as bush vines without irrigation, production levels are very low (below 5 tons/ha). The "floppy" nature of the shoots that fall open readily can easily result in sunburn. It is therefore strongly recommended to undertake severe topping actions early in the season in order to stimulate lateral shoot growth, which may offer protection. The bunches are small and light, but extremely concentrated in taste. Since Viognier is harvested almost without exception at high sugar levels, cultivation on loam soils, or soils with heavier clay sub soils and good water retention ability, is highly recommended.
Although the cultivar reaches top potential under warmer conditions, it is nevertheless sensitive to drought. Sugar levels increase rapidly during the second half of January, with pressing usually in the first two weeks of February. At sugar levels of 25-26 degrees Balling, acids are usually between 6 and 6.5 grams/litre and pH around 3.4. Sometimes symptoms of potassium and magnesium deficiency occur on the older leaves towards the end of ripening. This is not a dangerous sign provided the levels of these elements in the soil are within acceptable norms.
Viognier's sensitivity to rot is particularly low, given the compactness of the bunches. However, beware of heavy alluvial soils resulting in large berries and high production levels. Sensitivity to oidium is normal, while downy mildew may be a bigger problem due to the softness of the leaves. Up to now the cultivar has not displayed any affinity problems with the commercial rootstocks R99, R110, 101-14 and US8-7. Three (3) clones are currently available in South Africa. VR1, VR2 and VR642 are all French in origin. It seems as though VR642 is the more constant achiever of the three. Bird damage occurs due to the early ripening. Therefore an attempt should be made to avoid planting the vineyard near a lane of trees or natural bush.
General comments
There is a definite place for Viognier in the South African wine industry. The cultivar has already proved itself commercially and is well received by the wine public. Currently all cultivar wines have a fairly high alcohol content and are strongly wood driven, making the price significantly higher. As a cultivar wine the market is therefore limited, but it has good potential when blended with Chardonnay. It may even be fermented with Shiraz, as in the Rhône (the only complication is the different ripening times of the two cultivars). Viognier is one of the few white wine cultivars that displays a prominent cultivar character in warmer areas.
In the vineyard, Viognier must be properly managed in order to reach its full potential. Normal pruning and suckering practices must be followed, with the accompanying balanced production levels of 2.0-2.3 kg/metre. Even ripening is the key to success and this is only achieved if the above practices are correctly executed. Unevenness sometimes occurs if the flowering period is cool and rainy, as is the case in some South African regions.
Producers in dryland areas must beware of planting the cultivar on marginal soils, due to the low production levels that are obtained. The economic viability of the cultivar under such conditions is questioned if the grapes are to be sold at normal commercial prices.
South Africa must develop its own style Viognier. It is impossible (and undesired) to strive for the same style as Condrieu, considering the different conditions. The challenge of Viognier is to select the picking time carefully, so that the unique flavours of the grapes may be transferred to the wine. Too early and the wine is thin and characterless, too late and there is the danger of the wine becoming "heavy and unguent", without the freshness that makes Viognier so unusual.
Viognier already fares well in warmer environments, but there is certainly potential to establish the cultivar in cooler areas where ripening will occur slightly later. In cooler regions the potential is there to make unwooded wines. It is essential to compile annual ripening profiles by tasting the grapes on a daily basis, so that the correct moment may be identified to harvest.
According to the latest SAWIS statistics of 30 November 2001, altogether 94.54 ha have already been planted in South Africa, almost 50% of which may be found in Paarl and Malmesbury.
Acknowledgements and literature
KWV Vititec for providing access to its establishment sites
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Andrew Teubes and Johan Wiese
A typical Viognier bunch approximately 10 days before the harvest.
Andrew Teubes and Johan Wiese
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