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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
This is the last in a series of four articles about the performance of the above four cultivars under South African conditions. Part 4 is dedicated to Tannat.
PART 4: Tannat
Origin and cultivation
Tannat’s home is in the southwest of France where it is the most important component in the wines of Madiran. It probably originated on the other side of the Pyrenees (which form the border between Spain and France) in the Basque provinces of Spain. At present Tannat constitutes less than 3 000 hectares in France, which is next to nothing in French terms. Madiran is situated approximately 120 kilometres south of Bordeaux (43 degrees northerly latitude) and influenced by similar climatic conditions. The climate can be described as maritime, consisting of cold, wet winters, like the Mediterranean climate, but with slightly more moderate summers and more rain. In summer westerly winds from the Atlantic Ocean have a cooling effect with positive results, although wind damage does occur from time to time. Although Tannat is mostly associated with Madiran wines, it is also cultivated in neighbouring Wine of Origin areas, the best known being the wines of Tursan, Côtes de St Mont, Irouléguy in the Pyrenees and Béarn. The soils are well-developed with an alluvial origin and sandy/stony topsoils on mixed limestone/clay subsoils with good water retention capacity. The only exception is the area of Irouléguy, which is situated on higher mountain slopes in the Pyrenees. The soils consist mostly of weathered sandstone with a clay mixture in the subsoil.
It is no coincidence that the name Tannat evokes "tannins". The Tannat wines are enormously rich in tannins, consequently they are used with Cabernet Franc and Cabernet Sauvignon in blends. The Madiran wines consist of at least 60% Tannat, the balance being Cabernet Sauvignon or Cabernet Franc, and are then matured in small wooden barrels for 20 months to "soften" the wine. A fair amount of Tannat is also used to make rosé wines, likewise with a sturdy structure. Apart from Madiran, the wines in which Tannat play a significant role are sold mainly in France.
Apart from the southwest of France, Tannat is the most important cultivar in Uruguay, South America, where a small wine industry exists with only 10 000 hectares of wine grapes. Here Tannat constitutes more than 2 000 hectares of total vineyards and is referred to as Harriague. Tannat spread to Uruguay with the Basque settlers from Spain in the course of the nineteenth century. Uruguay’s climate differs drastically from that of southwestern France in the sense that there is a lot more summer rain and the soils are heavy and rich in organic matter. As a result vigour is strong and difficult to control, causing a reduction in quality in most cultivars. Tannat is the ideal cultivar to use as a blending component in order to give structure to “thinner” red wines from Cabernet Sauvignon and Merlot grapes. Varietal Tannat wines are being marketed as Uruguay’s flagship wines. The wines have excellent structure and good colour, but volatility is only obtained when blended with the above-mentioned Bordeaux cultivars.
In addition to Uruguay, limited plantings are also found in Brazil, Argentina, California and Australia. As a varietal wine, however, it is encountered mostly in France and Uruguay.
South African conditions
Tannat, like Mourvèdre, has existed in South Africa for a long time, but due to the predominance of white wine cultivars during the biggest part of the 1900s, it was only “rediscovered” in the mid-1990s. Meanwhile wine has been made from commercial motherblock plantings for three vintages.
The most obvious characteristic of Tannat is probably the leaf shape, with the edges typically curling downward. The leaves are round and reminiscent of Malbec, bare below and have a dark green colour. Up to now the only experience of the cultivar in South Africa is limited to the foundation premises of KWV Vititec in Stellenbosch (approximately 100 vines) and the motherblock premises of Voor-Groenberg Nurseries in Wellington. In both instances the vines are planted on weathered shale soils with irrigation. Wellington, however, has much higher summer temperatures than Stellenbosch. In this article the emphasis will fall on the Wellington plantings, where 4 hectares have already been established.
Tannat is moderately vigorous and not in the same class as Cabernet Sauvignon, Cabernet Franc or Mourvèdre. The shoots have short internodes and are fairly thick, especially at the base. For this reason one could say that the cultivar is quite wind resistant. Shoot lengths are often uneven, it is therefore recommended that longer shoots be tipped early in spring so as to obtain evenness. The shoots have relatively few tendrils attached to the foliage wires, but are nevertheless sturdy and can be handled with two sets of moveable foliage wires on a trellis with a 2.1 metre pole. On more fertile soils a 2.4 metre pole may be used, but 3 sets of moveable foliage wires are unnecessary. Plant spacing of 1.2 metres between vines is sufficient and wider spacing will have to be considered with caution. The ideal distance between rows is what is practically possible, provided the use of the soil surface is optimised.
The foliage has a fairly "open" appearance and a single suckering action is sufficient. Few secondary sucker shoots bud after thorough early suckering. Even so, the leaves cover the bunches properly and the perception is created that the foliage is dense. Tannat is fertile and able to bear large bunches with equally well-developed shoulders. Production levels can easily exceed 4-6 kg/metre. All said and done, it makes sense to space bearers wide apart, closer to 15-18 cm between bearers. On a 1.2 metre plant width this boils down to 6 bearers - relatively few - per vine. Since fertility is high, normal two bud bearers are recommended as standard. In Uruguay lower fertility is experienced on short bearers and Tannat is pruned to canes. The same cannot be said of local conditions.
Bunches are sometimes carried high on bearer shoots. They are well-filled to compact and at times inclined to small, green seedless berries if the flowering period was cool or windy. Clonal differences are obvious and clones with this characteristic should be phased out. The berries are moderately large and firm when harvested. One of the most typical characteristics of Tannat grapes is the high fixed acid, especially around the seeds. The grapes are harvested at 25 degrees Balling with 8.5 grams/litre acid and pH of 3.4. These grape analyses are exceptional in a warm area such as Wellington. Ripening is between Shiraz and Cabernet Sauvignon. The bunch stems are thick and become woody easily, consequently the bunches are reasonably resistant to mechanical damage. The véraison period is drawn out as with Mourvèdre and may last 3-4 weeks before bunches colour evenly. The grapes do not have a particularly outspoken fruit character, but the powerful tannin structure is already evident when tasting the berry. Colour is always excellent.
At present there is too little experience of Tannat’s drought resistance to be able to express an opinion. There is one small trial planting in the Swartland where Tannat has been established as a dryland bush vine, but this vineyard will only start to bear in the 2004 harvest season. Although the shoots do not grow upright like Mourvèdre, the growth pattern is not as floppy as Merlot and will make an acceptable bush vine. As the vineyard matures one will get a better impression of the success of dryland and bush vine cultivation. In Uruguay summer rains are common and drought never really poses a threat. In the north of the country against the border with Brazil Tannat is cultivated on sandy soils that dry out quickly after rain; no drought symptoms are observed here.
The leaves have a leathery appearance and offer reasonable resistance to downy mildew and oidium. This is not good enough reason, however, not to follow preventive control programmes. Up to now there have not been affinity problems with the commercial rootstocks R99, R110, 101-14, SO4 or US8-7. In Uruguay Tannat is planted mostly on R110 and SO4. Two clones are currently available in South Africa, TT401 and TT399. Both these clones are considered keen producers (bigger berries and bunches), consequently new selections with smaller berries and bunches are currently being imported. TT401 is the original selection and presently the only commercial clone. TT399 from France is already undergoing virus cleansing, while a selection from Uruguay is still in quarantine.
General comments
Tannat’s biggest potential for South Africa is as a blend cultivar. Cultivar wine is characterised by exceptionally dark colour, high fixed acid and powerful tannins. It is considered to be fairly neutral, but South African Tannat wines of the past 3 seasons displayed characteristic strawberry and raspberry flavours. In Uruguay these same flavours are not obtained and the wine is rather neutral. It does make a contribution to colour, acid and structure in the thinnish Uruguayan Merlots and Cabernets. A small percentage in a blend makes the world of difference to the structure of a red wine.
Tannat’s potential lies in the warmer rather than the cooler areas. The reasons have to do with the high fixed acid content and hard tannins of the wine. The experimental wines from Stellenbosch had acids of up to 11 grams/litre compared to the 8-8.5 grams/litre in Wellington. Under warmer conditions, with lower acid levels, more acceptable wines might be made. The cooler areas of Stellenbosch, Constantia and Elgin should not establish this cultivar on cool slopes.
Tannat’s potential in the traditional irrigation areas of Worcester, Robertson, Klein Karoo and Olifants River valley should not be underestimated. Tannat can easily overproduce under irrigation if moisture management is not effective. Even with high productions, acceptable wines with good colour and tannins are made, but this could result in the demise of the cultivar. Overproduction may have a negative effect on vigour with uneven shoot lengths. Coarseness can easily occur if crop size is not controlled. Reduced deficit irrigation to control berry size should give good results. However, beware of too much early moisture stress which may result in delayed shoot growth. The removal of bunch shoulders in particular will constitute an important facet of crop control (considering the high production clones that are currently available).
Since the cultivar ripens just before Cabernet Sauvignon, is moderately vigorous and tends to overproduce, it is recommended that it be planted preferably on Karoo/lime/loam soils, instead of poor soils that dry out quickly (stone shale/broken hardpan). In France Tannat is planted mostly on alluvial soils. It is one of very few red wine cultivars that produce structured wines from these soil types.
Tannat is not a cultivar that will dominate the red wine market, but it has a definite place in the South African wine industry as a blend cultivar in the warmer areas. Tannat plantings currently constitute less than 10 hectares, mainly as a result of the unavailability of plant material. Bigger quantities of material are released annually.
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Andrew Teubes and Johan Wiese (pictured)
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