Phylloxera (Daktulosphaira vitifoliae) is a tiny aphid-like insect native to North America that attacks grapevine roots. North American grapevine species have long coexisted with the insect, but when phylloxera reached Europe in the mid-19th century, local Vitis vinifera plants proved highly vulnerable. The pest nearly wiped out the entire European wine industry, and only decades after the first recorded outbreaks did recovery begin through the practice of grafting European vines onto resistant American rootstocks.
The first successful experiments are generally credited to French growers Léo Laliman and Gaston Bazille, who in the early 1870s began trialing grafting in the Languedoc. The practice initially faced resistance from purists, who feared American rootstocks would compromise a wine’s flavor. Yet the undeniable success of these early trials eventually led the French—and other governments—to officially endorse the method, fuelling its spread across Europe and, ultimately, the rest of the world.
Grafting has since remained the most effective means of managing phylloxera, and today the pest is often described as a threat of the past. But recent detections and new research suggest that way of thinking is far from the truth.
The modern face of an old threat
In Australia, for example, where strict quarantine measures have limited infestations partially or wholly to around five percent of the country’s vineyard area, the threat still persists. The quarantine measures are enforced using a well-defined zoning system: the Phylloxera Infested Zone (PIZ), where the pest is known to be present; the Phylloxera Exclusion Zone (PEZ), where it is confirmed absent; and the Phylloxera Risk Zone (PRZ), an intermediary area where surveillance is incomplete or the pest’s presence is unknown. Despite these scrupulous measures, phylloxera was discovered at Maroondah in the Yarra Valley in 2006, and subsequent detections led authorities to extend the PIZ to its current boundaries in 2023.
Further detections in regions that were historically unaffected have shown that phylloxera remains a genuine existential risk to the global wine industry. In 2019, the pest was identified in Washington State’s Walla Walla region. There, vines were not grafted as the sandy soils were thought to provide a sufficient barrier to its spread.
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