Call Topic C : Grapevine Flavescence dorée

A call text for this topic is provided below. Please see the Applicants Guide for national eligibility, available national funding, and application processes

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Call topic title

Evaluation of the risk of spread of Scaphoideus titanus, the vector of Grapevine Flavescence dorée, with commercial grapevine propagation material

Background

Flavescence dorée (FD) is a yellows disease of grapevine, caused by phytoplasmas of the elm-yellows (16Sr-V) group. It is a quarantine disease in Europe. FD is graft transmissible and can be spread with grapevine propagation material. However, disease outbreaks depend on the presence of the vectoring leafhopper Scaphoideus titanus, a nearctic species that has been introduced to France presumably in the early 20th century. The vector is present around the 45th degree of latitude and spread already from France to Spain and Portugal, Italy and Slovenia. Recently, also Serbia and southern areas of Hungary, Austria and Switzerland have been colonized. S. titanus is currently extending its range to the north, presumably due to changing climate variables. However, studies of the genetic structure of European populations revealed dissemination with grapevine material as the most probable means of spread. This is possible, because this strictly ampelophagous species deposits its eggs in the bark of one and (mostly) two year old wood of grapevine, on which it fulfils its whole life cycle.

FD causes severe damage to viticulture in southern viticultural areas e.g. in France and Italy. In addition, efforts to minimize pesticide use are impeded by the regular insecticide treatments against the vector, which are required to disrupt the epidemic cycle. Preventing the further spread of S. titanus is therefore an important phytosanitary measure not only for countries that are completely free of this pest like Germany but also those where the distribution is still restricted. Additional information is required on the risk of introducing eggs of S. titanus with grapevine propagation material and the chance that viable populations could develop from those eggs in vector free areas.

The proposed project consists of the following parts:
Part I - Significance of rootstock and scion propagation material as carriers of S. titanus
Part II - Risk of establishment of viable populations of S. titanus after introduction

Based on the results of part I and II risk mitigation of S. titanus spread through insecticidal and heat treatments of propagation material may be evaluated in a further step. However, depending on the time scale of the project, this may be addressed in a separate project.

Research need

Information on the infestation of propagation material with S. titanus eggs

Information on the susceptibility of eggs to the propagation procedure

Estimation of the risk of spread of S. titanus with propagation material into vector free areas and its potential to establish in vine growing regions north of the 46th degree of latitude.

Expected benefits

The project will reveal additional information about the risk of introduction of S. titanus for vector-free areas. Data on the effects of the propagation process on S. titanus eggs and on the significance of waste wood for the dissemination of the vector will help nurseries to minimize the risks by adapting the propagation practice or appropriate treatment of the waste material.