Â Bordeaux is facing a new challenge with a vine disease, Flavescence dorÃ©e, threatening to be become a bigger problem than Phylloxera.Â
The disease is caused by phytoplasmas, microscopic plant pathogens similar to bacteria, but much smaller and lacking cell walls. They live in the vascular system of plants and are spread by sap-feeding insects, including leafhoppers and planthoppers.Â
Flavescence dorÃ©e infects only vinifera grapes and interspecific hybrids.Â Symptoms usually appear the year after infection and either get progressively worse until the vine dies or disappear in an apparent recovery.
Symptoms include delayed or no bud break and progressively shortened internodes. In summer, vines take on a weeping posture, and shoots become rubbery and fail to lignify. Characteristic black pustules may be seen in longitudinal rows near the bases of shoots. The leaves have golden yellow or reddish patches and curl downward. Growing points become necrotic, and flowers and fruit clusters shrivel up and fall.