Flavescence dorée
Flavescence dorée (from French "Flavescence" : yellowing and "dorée" : golden) is one of the most important and damaging phytoplasma diseases of the vine with the potential to threaten vineyards. The bacterial agent has recently been named Candidatus Phytoplasma vitis, and its vector is the leafhopper, Scaphoideus titanus. Infection may kill young vines and greatly reduce the productivity of old vines. It is classified as a phytoplasma disease belonging to the group generically termed grapevine yellows. Occurrences are in sporadic epidemics, and varieties vary in their sensitivity to it. There is no cure at the moment and the way to manage its spread is by uprooting infected plants and by using selective insecticides in an area-wide pest management approach in order to reduce the hemipteran vectors. Symptoms The incubation period between infection and obvious symptoms is usually one year or more, depending on the response of the plant to both pathogen and environmental circumstances. Flavescence dorée has the following symptoms: leaves become yellow or red, depending on the variety downward rolling of leaves drying of stems and grapes there is no cold hardening Some plants affected with Flavescence dorée may die, some may be asymptomatic while some, depending on the