With the list of classes for this year's Five Nations Wine Challenge almost finalised, the judges from the participating countries - Argentina, Australia, Chile, New Zealand and South Africa - have been working through the strengths and weaknesses of their wine industries.

The Australians, unsurprisingly, feel they manage any of the likely combinations. With temperate zones promising good viticultural potential across much of the continent, they are confident there will be a sufficient number of quality wines to fill whatever varietal list is decided upon.

The Kiwis are less sanguine: much of the country's vineyard area lies at the outermost limit of successful viticulture. New Zealand cannot boast much in the way of southern European cultivars. Climate change may have helped the prospects of Cabernet, for example, but there are still very few producers trying their hand at Bordeaux blends, Port-style fortifieds, or many of the Mediterranean varieties.

The Argentineans know they will be light in the aromatic white wine classes, where the Kiwis are particularly strong, but they can manage many of the well-known varieties and expect to waltz home with Malbec.

The Chileans have moved beyond the simplistic supermarket exports of Sauvignon Blanc, Chardonnay and Cabernet Sauvignon. For example, as Jancis Robinson pointed out recently, it has several producers specialising in old-vine Carignan.

South Africa is in curious territory. Like the Australians, we have a long history of fortified wine production; unlike the Argentineans, we have considerable experience across a range of red varieties; like the New Zealanders, we have an international reputation for our Sauvignon Blancs. Still, we lack depth the moment we move outside the standard export cultivars: vineyard variety has been sacrificed on the altar of British supermarkets.

In the 1980s, Cinsaut dominated our red wine plantings. Today it has all but vanished, replaced by the ubiquitous Cabernet Sauvignon, Merlot and Shiraz believed to make up the bulk of what is desirable to UK trade buyers. There are about 8000 different wines rated by the Platter guide. Of these, there are fewer than 20 different bottlings of Barbera, Carignan, Cinsaut, Gamay, Gewurztraminer, Grenache Blanc, Grenache Noir, Mourvèdre, Nebbiolo, Pinot Blanc, Pinot Gris, Roussanne, Sangiovese, Sylvaner, Tannat, Tinta Barocca, Tempranillo or Verdelho.

You can easily understand why the average producer has no desire to risk the R100000 to R150000 it costs to plant a hectare of grapes if all that awaits him is the uncertainty of how a new variety might perform, and whether there will be a market for it. Already grape-growers ( farmers who sell their fruit to wine producers) are under-recovering on real farming costs. The best most can hope for is that their annual revenue exceeds their expenditure. This leaves no margin for speculative plantings. As Ken Forrester, who farms his own grapes as well as buying from other farmers, put it, "buying fruit from people who never include replanting as an overhead is like slaughtering a cow a day from a herd of 200 and expecting to do so for ever".

In an environment like this, no one is going to grub up hundreds of hectares of unsuccessful Merlot and give the great southern European cultivars a chance. This is why we still have so few varietal bottlings of Grenache, Mourvèdre, Cinsaut (and very few Chateauneuf-type blends), virtually no Carignan, Tempranillo or Sangiovese, and not a single example of the now fashionable Aglianico.

It's a comfort that two of our Five Nations rivals are generally no better off. With much the same offering between us, no wonder we can't beat our £4-£29 average UK price-point, which translates to less than R12 a bottle for the producer. For this, we are going to need something more exciting than the "biodiversity of the Cape's floral kingdom" to win the hearts and minds of wine-drinkers around the world.

From Business Day, 17 February 2012