By Jim Clarke

The vine looks confused: the leaves have turned red, even though it’s only July. Looking closer, the graft, where the vitis vinifera Syrah is attached to an American, phylloxera-resistant rootstock, is swollen – it looks like an injured knee. Perhaps there’s even a crack or two. The vine is not making good grapes, and will probably die in a few years.

Syrah – or, in its Australian incarnation, Shiraz – has been on the rise since the 90s, gaining popularity with winedrinkers and wine critics alike. Winegrowers in the New World have responded, and new plantings abound; in Washington, for example, the total acreage devoted to Syrah ballooned from 50 acres to approximately 2,000 over one decade. Bottlings of Syrah are also appearing on the shelves from unexpected places like Argentina and South Africa.

But at the same time, a mysterious ailment is attacking Syrah vineyards. The French call it “Syrah Decline;” in California, it goes by “Syrah Disorder.” It’s become a worldwide problem, and the causes remain unclear.

The vine’s appearance is one thing, but Syrah Decline also affects the wine, because the grapes do not ripen properly. The flavors don’t materialize, the sugars remain too low, the acidity drops, and even the color is light. Even if it weren’t Syrah – full-bodied, darkly-colored Syrah – these grapes wouldn’t make a good wine.

How widespread is Syrah Decline? A French report in 2004 said that all French Syrah vineyards 15 years or younger show some signs of the illness, with 1 to 15% of the vines infected in any given vineyard. Some growers in the Languedoc-Roussillon area have resisted government pressure to plant more Syrah, fearing that it could infect their Grenache and Carignane plantings. South Africa, California, and Oregon have also been affected; one expert estimates that in some Central Coast’s vineyards, 25% of the Syrah vines are dying from Syrah disorder each year. Australia remains remarkably unaffected, so perhaps there is something in calling it Shiraz after all.

Growers are mystified. Research has uncovered some common factors in cases of Decline across the world. Water-management is a point of agreement: vines that become stressed by drought, salinity, or lack of appropriate irrigation are more likely to develop symptoms (However, over-irrigation leads to its own drop in wine quality; some water stress leads to a concentration of flavor in the grapes.). Similarly, most agree that vascular function – the flow of liquids within the plant – is involved, especially at the graft union, which sometimes seems to be choking the vine. Syrah is more sensitive than most vines; under drought conditions, its leaves do not close their stomata (the breathing holes on the underside of the leaves), so more evaporation occurs and the vine loses more water.

However, other analyses are more contradictory. South Africa has found substantial differences in the susceptibility of various clones, with French clones succumbing most frequently. But a 2002 UC Davis survey of California Syrah vineyards included a dozen clones, a dozen rootstocks, and seven different field selections, and found no real pattern in the Syrah Disorder occurrences. Californian research is focusing on soil types and nutrients, especially phosphorus, potassium, and magnesium. No virus or bacteria has been found in association with the ailment.

While Syrah is not about to disappear from the shelves, the disease has been distressing for winegrowers, some of whom have hoped to jump on the train and take advantage of the grape’s popularity. Keep an eye on prices, though, if the spread of Syrah Disorder accelerates, costs could move up as well…except in Australia, since it doesn’t seem much affected. Hmm…I smell a possible conspiracy theory in the making.

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