Effectiveness of hot water treatment against the eggs of Scaphoideus titanus Ball, vector of the Grapevine Flavescence dorée

The leafhopper Scaphoideus titanus is the vector of flavescence dorée, a severe grapevine disease spreading in Europe. The project PROPSCAPH brought together four European research institutes in order to improve risk management schemes against the spread of flavescence dorée’s vector on propagation material. Agroscope Changins-Wädenswil, coordinator of the project, studied the impact of hot water treatments on the development of S. titanus eggs. In autumn 2008, one-year-old and two-year-old cuttings were collected in S. titanus infested vineyards in France, Italy and Switzerland. Half of the cuttings were exposed to a hot water treatment and the hatching of S. titanus nymphs was assessed. Our observations confirmed the ability of S. titanus to lay eggs on propagation material. However, hot water treatments reduced the number of hatched nymphs, i. e. the exposure to hot water killed more than 90 % of deposited eggs. Thus, the hot water treatment of rootstocks and scions before grafting or of grafted plants before commercialisation is strongly recommended. This should ensure the distribution of plant material free of flavescence dorée and minimise the risk of vector’s spread.