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Practical viticultural experience of certain "new" cultivars:

Viognier, Petit Verdot, Tannat, Mourvédre.

Andrew Teubes and Johan Wiese (pictured)
Voor-Groenberg Nurseries
Key words: Petit Verdot, Origin, Cultivation, Production, Wine potential

This is the third in a series of four articles about the performance of the above four cultivars under South African conditions. Part 3 is dedicated to Petit Verdot.

PART 3: Petit Verdot

Origin and cultivation

Petit Verdot is one of the five classic red wine cultivars of the Bordeaux region in France. Together with Malbec its significance faded in due course of time, while Cabernet Sauvignon, Cabernet Franc and Merlot took over as the predominant red cultivars in Bordeaux. It seems as though Petit Verdot had its origin in Bordeaux where it was cultivated exclusively for centuries. The fact that Petit Verdot is harvested much later than Cabernet Sauvignon means that it does not ripen sufficiently in cooler growing seasons. Compounding the problem of insufficient ripening, Petit Verdot is also inclined to have small, green, seedless berries if weather conditions during flowering are unfavourable. This is quite possibly where the name stems from - petit (small), and verdot (green). The inability to produce constant quality in cooler and at times even more inclement climatic conditions is probably the reason why it went out of fashion in Bordeaux. However, if Petit Verdot ripens fully, it has the ability to produce concentrated wines with lots of tannins and a deep colour.

Total plantings in Bordeaux currently amount to a few hundred hectares only (which is not much for Bordeaux). Since it is planted here only, it is therefore a very insignificant cultivar in France. Small quantities of plantings occur exclusively on the lower lying, light sandy soils of the Medoc area. It makes a valuable contribution to several of the famous red wines from this area. Petit Verdot makes up between 2% and 7% in the well-known blends of Pauillac, St Julien and Margaux. It is not clear whether Petit Verdot has been planted here because these light, sandy soils favour optimum ripening, and whether the full, more structured wines of Petit Verdot are necessary in the predominantly Cabernet Sauvignon blends. Quite possibly it plays an important role in the blends, otherwise it would have disappeared a long time ago! In the Gironde at Chateaux Palmer, where Merlot constitutes the biggest percentage of the blend, 10% Petit Verdot is used in the blend. According to the winemaker the powerful tannins, high fixed acid and extract quality of Petit Verdot balance the softening quality of the Merlot.

The practice of planting small quantities of Petit Verdot to make high quality blends also occurs outside France. In the south of Spain, near Toledo, Marques de Grinon (Dominio de Valdepusa) produces an outstanding quality Petit Verdot wine from 2.5 hectares of vineyard on a lyre trellis. In Peru at Vina Tacama Petit Verdot constitutes an important part of the red blend together with Merlot and Malbec. Here the vineyards have been trained on a T-type system. In Australia, more than any other country, Petit Verdot is marketed as a cultivar wine. The Pirramimma of McClarenvale and Lennard's Crossing in South Australia are both described as full-bodied, rich wines with intense fruit and length. In California and more specifically Napa small volumes have been planted. South Africa currently has two wines on the market. Nederburg and Signal Hill both received a four star grading in the Platter wine guide. Both are intense wines with good length.

Traditionally Petit Verdot is cultivated in temperate to cool climatic regions with a mild summer climate on sandy and gravelly soils that ensure ripening. It seems as though this cultivar will also perform well in warmer climatic regions with sufficient irrigation.

In some countries Verdot - not to be confused with Petit Verdot - is cultivated. This is an entirely different cultivar (Gros Verdot) with its own unique characteristics.

South African conditions

Given the correct choice of terrain any late cultivar will ripen in South Africa as a result of sufficient sunshine and heat units, as well as the fact that rain is not common during the ripening period. Petit Verdot therefore ripens sufficiently in the majority of South Africa's traditional and newer wine growing areas. Seasonal differences will necessarily occur in cooler climatic regions, areas where summer rainfall occurs in some years or where strong winds prevail during flowering. With South Africa's drier Mediterranean climate the probability that Petit Verdot will ripen is very good and there is actually no reason for concern. Climatically only areas that have been identified for the cultivation of high quality Sauvignon blanc should be considered as potentially risky areas for the establishment of Petit Verdot.

Petit Verdot has various positive characteristics such as even colour, relatively small berries, high fertility and a particularly high fixed acid. Although bunches are slightly compact in certain years, the berries colour well right up to the berry stem. Bunches are carried very much like Merlot, close to the base of the shoot, with the result that the bunches are easily clumped together. Due to the high fertility of as many as four bunches per shoot, some of the bunches do occur higher on the shoots. The removal of base bunches during crop control ensures better distribution of the bunches. Fully ripe grapes with prominent ripe fruit flavours will be obtained if the soil moisture late in the season is sufficient for optimum ripening of the grapes.

Crop control is very important for the production of high quality wines. This is obtained by wider bearer spacing and consequently limited bearer shoots per vine, or by the removal of bunches. Spurs can be comfortably spaced 17 to 20 cm apart. Annual removal of bunches is then no longer so important because they hang further apart and there is also a lower bunch count per vine. Bunch stems are thin and brittle and bunches break off easily, even after veraison. When bunch clumps are thinned out the utmost care should be taken to limit damage to neighbouring bunches. The grapes are easily harvested as a result of the long bunch stems. Large-scale bunch damage/losses have not been observed in windy areas. Damage is likely to occur in the case of wind gusts, but in the light of the shoots' sensitivity to wind damage, Petit Verdot should preferably not be planted in areas that are prone to squalls.

Ablactation of berries has not been observed as a problem. On the contrary, under luxuriant cultivation conditions very compact bunches can be a bigger problem. Small, seedless green berries were observed in a few bunches, however, following the cool weather conditions in November 2002 (flowering).

Ripening at 24-25 °B sugar content is easily achieved. Even in the Southern Cape near the coast this sugar level is achieved. At this degree of ripeness the acid at the time of harvest ranges between 8.3 and 8.7 grams per litre, with pH values from 3.3 to 3.4. In the 2002 and 2003 vintages in Wellington Petit Verdot was harvested approximately 4 to 7 days after Cabernet Sauvignon at 25.1 and 24.8 °B respectively. In parts where the soil is drier, there is less vigour and the grapes tended to shrink in these areas. It is obvious that heat on its own does not have a negative effect on the quality of the grapes, whereas it does when combined with low soil moisture conditions.

The creeping, trailing growth pattern and thin, floppy shoots require a well-planned, intensive trellis system. Shoots are extremely brittle and break easily when handled during the growing season (for example tucking in of shoots or hooking up of foliage wires). Some shoots are also inclined to grow in an almost horizontal direction after budding and not necessarily in a vertical direction. The ideal trellis system is a parallel set of foliage wires at the 20 cm position above the cordon wire, with a further two sets of parallel foliage wires higher up spaced 30 cm apart. The use of a single foliage wire (as with a normal hedge trellis) is strongly discouraged due to the fact that the shoots are floppy with limited tendrils for support. Under prolific growing conditions a 2.4 m pole must be used, but in the majority of instances a 2.1 m pole will suffice. Under no circumstances should the distance from the cordon wire to the top set of foliage wires be less than 90 cm.

General comments

Sensitivity to drought as well as poor vigour on low potential soils are negative factors under South African conditions. Petit Verdot gives ready clues as to spots of poor soil in a block by highlighting variation in vigour in these zones. Special attempts should be made to ensure even vigour on spots of poor soil within a block. Plant width adjustment within the row is one example. More ideal, however, is that establishment should only occur on deep, well-drained, high potential soils. Petit Verdot tends to grow thin, short shoots on drier or shallower parts of the block. Although it has not been observed on sandy soils (as a result of limited plantings), it can be expected just as on any other dry soil types.

Sensitivity to drought conditions is a characteristic of the cultivar that must be carefully managed and requires further evaluation. In the light of present experience cultivation without irrigation cannot be recommended categorically. Even on deep, well-drained soils in temperate climatic regions such as Stellenbosch, irrigation after veraison seems to be very important. Due to the water demand late in the season, dark colour, good fixed acid and tannin structure, it is an interesting cultivar for the traditionally warmer irrigation areas.

This cultivar is not a good bush vine due to its trailing growth pattern. At this stage dryland establishment in the Swartland cannot be recommended.

The use of Petit Verdot in South Africa is likely to be entirely different than in France. It is unlikely that a significant number of cultivar wines will be produced. Petit Verdot is able to produce dark, well-structured wines with intense fruit in regions with high February temperatures, even better than Cabernet Sauvignon. For this reason the use of Petit Verdot in blends is probably the cultivar's biggest appeal. Whether the intense flavour might be too overbearing in blends only time will tell.

Sufficient volumes of grafting material are available. Two French clones are currently being used in South Africa. Clones PR400 (the only and best known clone in France, currently distributed by ENTAV) and PR8719 both perform very well under South African conditions. Very few differences have been noted so far and producers can feel free to plant either. Although Petit Verdot has lower take percentages in the nursery, no affinity problems with any of the commercial rootstocks has been experienced.

According to SAWIS statistics of November 2002 more than 300 hectares have been established in South Africa, mostly in Stellenbosch, Paarl and Worcester.

Literature

The Great Winebook, Jancis Robinson
Guide to French Wines, Steven Spurrier
The Oxford Companion to Wine, Jancis Robinson
Grapes & Wines, Oz Clarke & Margaret Rand
Terroir, James E Wilson

Wynboer is incorporated in WineLand, magazine of the SA wine producers.

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