Damage symptoms
The American vine leafhopper is not directly harmful to grapevine but it is an important vector of ‘Candidatus Phytoplasma vitis’, the causal agent of Flavescence dorée, which is a Grapevine Yellows Disease that causes severe damage in European vineyards. Flavescence-dorée phytoplasma is a quarantine disease in the European and Mediterranean Plant Protection Organization (EPPO) region and control measures are mandatory in some European countries.
Leaves of grapevines infected with Flavescence dorée show yellowing discoloration and rolling down of leaf margins. Flowers wither and berries shrivel resulting in a reduction of quality and yield of the crop. Woody canes are poorly ripened and remain rubbery, giving the stock an overall 'weeping' aspect. Not enough young wood is produced and left for pruning. The plants rapidly decline.