The destructive louse phylloxera, an insect that devours grapevine roots, has now been found in every major New Zealand viticultural area. Last week, Te Kairanga Wines in Martinborough confirmed an infestation in a vineyard block situated close to the winery. This is the first discovery of phylloxera in Martinborough, a sub-region of Wairarapa, on the southeastern tip of the North Island.
Te Kairanga winemaker Peter Caldwell noticed problems in the block last year, when the vines were evidently ailing, but he thought the problem was due to water stress or possible nutrient deficiencies in the soil. This past February, Caldwell was concerned when Matahiwi Estate, a producer in Masterton, about 14 miles north of Te Kairanga, discovered phylloxera in its vineyards.
"I think it was inevitable it would come here," Caldwell said. "It was a little unusual in that it wasn't at the end of a row where there's more traffic, but in the center of the block," since phylloxera tends to spread on farm equipment or cars that were used previously in infested vineyards. "It could have been brought in by a contract worker," surmised Caldwell, who suspects the phylloxera probably arrived on the property about three years ago. The infestation has affected about 30 Pinot Noir vines to date, which were planted in 1985.
There is no cure for phylloxera, which feeds on the roots of European Vitis vinifera vine varieties. In France, phylloxera arrived in the Rhône Valley in 1862 and within 30 years had devastated vineyards throughout the country, and caused $1 billion of damage in California vineyards in the 1980s and 1990s. The only solution is to uproot susceptible vineyards and replant with vines grafted onto American rootstock species that are resistant to the louse.
Te Kairanga has a total of 247 acres, of which about 30 will require replanting. That puts the producer in a better position than many in the region, where 25 percent of the vines are ungrafted. But only 9 percent of New Zealand's total 58,000 producing acres are susceptible to phylloxera.
As soon as the infestation was confirmed, Te Kairanga notified the local growers association, which contacted other area producers. "A lot of people came down to check out the vines so they'll know what to look for. And we showed them how to look at the roots under the microscope," said Caldwell.
Te Kairanga currently makes about 40,000 cases a year, of which about three quarters is Pinot Noir (the rest is Chardonnay, Sauvignon Blanc, Riesling and Pinot Gris). Despite the infestation, there's a silver lining for Te Kairanga. Viticulture has improved significantly since the property was first planted, and better clones and vineyard design in the replants should translate to better wines. "There's some older Chardonnay on pretty average clones I'll be happy to see the end of," said Caldwell.