Phylloxera, the world's worst grapevine pest, originated in North America, where it lives in harmony with vines with natural resistance to the insect. In susceptible Vitis vinifera vines pale yellow sap-sucking aphid-like insects attack grapevine roots, gradually cutting off the flow of nutrients and water to the vine. Weakening of the vines usually takes between one and five years after the initial infestation, so by the time symptoms are noticed, the outbreak has probably spread within the vineyard and to other properties that share machinery, contractors or other possible agents.
In the late 19th century the phylloxera epidemic, introduced when botanists in Victorian England collected specimens of American vines, devastated vineyards in Britain and then moved to the mainland, destroying most of the European grape growing industry. Estimates suggest between two-thirds and nine-tenths of all European vineyards were destroyed. The only European grape resistant to phylloxera is Assyrtiko, which grows on the Greek volcanic island of Santorini although it is not clear whether the resistance is due to the rootstock itself or the volcanic ash on which it grows.
The louse has a complex life-cycle of up to eighteen stages and has proven to be extremely adaptable, as no one stage of the life cycle is solely dependent upon another for the propagation of the species, so there is no cure or treatment for phylloxera, and the only viable control strategy is to remove all vines and replace them with vines grafted onto resistant rootstocks. Unfortunately not all rootstocks are equally resistant. Modern phylloxera infestation occurs when wineries in need of fruit choose to plant ungrafted vines rather than wait for grafted vines to be available.
While most wine regions of the world are infested with phylloxera, Australia remains predominantly free of the pest, because of strict quarantine controls brought in when the pest was discovered, but the risk of spreading the pest from phylloxera infested zones is ever present, as over 85% of grapevines are planted on their own roots.
In Australia, phylloxera was first detected near Geelong in 1877, and nearly destroyed the Victorian wine industry in the 1880s. Until recently it was confined to areas in central and northeast Victoria, including Nagambie Lakes, Rutherglen and the King Valley), southeast New South Wales (Corowa) and Camden and Cumberland near Sydney. Over the past decade there have been several outbreaks in central Victoria including the Buckland Valley and Ovens Valley in 2003, Murchison and Yarra Valley in 2006 and Mansfield in 2010.
Phylloxera can be spread through grapevine materials, soil, whole grapes, machinery and vehicles and grape products such as must and juice. Natural spread within a vineyard is around 200 metres per year, while accidental human-assisted spread can be up to several hundred kilometres.
Pinot Grigio (variety)
Pinot Gris (variety)
