Phylloxera is a nearly microscopic root louse or aphid, that primarily attacks the roots of Vitis vinifera grapevines, in much the same way an aphid attacks a tomato plant's stems and leaves, by puncturing the vessels and sucking out the plant's sap. Once infested with the phylloxera louse, the grapevine's root system can become severely impaired, making it difficult for the plant to absorb the needed water and nutrients to sustain a vine.
The final phylloxera outcome depends somewhat on the type of soil structure that the vine is growing in. Have clay soil and the vine is likely toast; sandy soil and the vine stands a chance of surviving the phylloxera invasion, because of decent drainage and an unwelcoming environment for the phylloxera bug to thrive.
Woe Is Phylloxera
During the mid to late 1800s, phylloxera infestation became an epidemic throughout France and most of Europe, destroying an unimaginable two-thirds of the continent's grapevines. Generations of winegrowers ripped out and burned heirloom vines in an aggressive attempt to quell the outbreak. Panic set in and solutions were sought far and wide. Ironically, both the initial cause and the eventual remedy to Europe's blight came from North America. After significant investigation, it was determined that the phylloxera louse originated in the U.S., though the native American vines were resistant to the bug's attack.
It was this resistance that would eventually be harnessed to provide a viable solution to Europe's phylloxera woes.
Researchers discovered that by grafting a European vine onto American rootstock, they could creatively keep the Phylloxera louse from feeding on the vine's root structure while maintaining the original vine's genetic material.
By allowing the vine to retain its innate character and quality atop a more resistant root, the new generation of vines would be set to thrive. This ambitious discovery led producers to undertake the enormous task of ripping out entire vineyards and replacing them with grafted vines. Old World vintners were forced to choose their top vines to graft onto the surrogate root systems, which bolstered overall quality throughout the continent.
Phylloxera's Unexpected Silver Lining
Fast-forward another hundred years and the regional roles are reversed. During the 1980s, California's vines were under attack from the mighty Phylloxera louse. Knowing the rootstock solution was the only viable option, producers braced themselves for the exorbitant costs of replanting with phylloxera resistant rootstock. With over a billion dollars invested in new plantings, California producers effectively hit the reset button and planted with intention. Grape varietals were now planted in climate zones and soils that were conducive to their specific growing requirements. The silver lining? Better wine, lower consumer costs, and ongoing research all due to that pesky phylloxera.