1. Netherlands Institute for Vectors, Invasive Plants and Plant Health, Netherlands Food and Product Safety Authority, Wageningen, the Netherlands
2. Laboratory of Plant Pathology, TERRA, Gembloux Agro-Bio Tech, University of Liege, Liege, Belgium
3. Plant Sciences Unit, Research Institute for Agriculture, Fisheries and Food (ILVO), Merelbeke, Belgium
4. Virology-Phytoplasmology Laboratory, Agroscope, 1260 Nyon, Switzerland