A survey on Maltese vineyards for Grapevine Flavescence Dorée Phytoplasma : a preliminary step in the process for the acquisition of a protected zone for the Maltese Islands

Abstract

The entire official action programme for the acquisition of a protected zone status for the Maltese Islands with regards to grapevine flavescence dorée phytoplasma was analysed. During 2007, the Plant Health Department, within the Ministry for Resources and Rural Affairs, which is the National Plant Protection Organisation, carried out an extensive survey on local grapevine cultivation to determine the presence or absence of this harmful organism as listed in Council Directive 2000/29/EC and amendments. The aim of this survey is to serve as a preliminary step in the process for the acquisition of a protected zone for the Maltese Islands. Grapevine flavescence dorée phytoplasma belongs to the elm yellow group 16Sr-V subgroups C and D. This pathogen has a narrow host range mainly limited to Vitis vinifera though Vitis riparia can also be infected naturally. In 2004 Clematis vitalba L., was also found to be infected with flavescence dorée. The main vector of grapevine flavescence dorée phytoplasma is the leafhopper Scaphoideus titanus Ball. This disease spreads epidemically because both the larvae and adults feed only on grapevine, where they acquire the phytoplasmas from infected vines and transmit them to other vines. Flavescence dorée is a very senous grapevine disease and is considered as a quarantine disease in the European Community. This disease spreads rapidly and has caused severe damage in the viticulture industry of France, Italy and Spain. Without good control measures Flavescence dorée can affect 80 to 100 per cent of the vines within a few years where it can cause a reduction of fruit setting on grapevines and inferior quality of grapes. This was the first survey performed for the detection of grapevine flavescence dorée phytoplasma in Malta. A total of 26 different vineyards amounting to 56 hectares IV spread around Malta and Gozo where visually inspected out of which 139 samples were collected and tested by molecular diagnostic techniques. As part of the survey, monitoring of the vector S. titanus was performed in 26 different vineyards. All the tests and observation of traps were carried out at the Plant Health Department within the Ministry for Resources and Rural Affairs. During the last few years grapevine cultivation with special reference to the viticulture sector has become very popular and is now at its thriving stages. An overview of the status of grapevine flavescence done phytoplasma in Malta will provide necessary tools for the possibility of acquisition of a protected zone status. This will give the Maltese Islands more protection against the introduction of this disease which will help in keeping this disease at bay.