Modeling spatial and temporal spread of Flavescence dorée in two Austrian vine growing areas

Abstract: A Monte Carlo model to simulate the natural spread of Flavescence dorée [FD] and of its vector Scaphoideus titanus was developed using the statistical software R. Simulations were run for two model domains with demarcated areas for FD, which differ in the average acreage of vineyards and the abundance of amenity grapevines in arbours and hedges that act as vector and disease reservoir. The model incorporates biological characteristics, the topography and different scenarios regarding the initial disease and vector infestation and can hence be used as a decision support tool for risk reduction options in specific outbreaks. The results confirm the vital importance of surveillance to detect outbreaks at an early stage and show that the main factors affecting the spread of FD are the initial disease and vector infestation, the abundance of untreated grapevines and the applied pest control measures: in locations with a high density of untreated amenity grapevines and severe initial outbreaks, the spread of FD within the region is only contained using strict phytosanitary measures that include vector treatments of larvae and adults in vineyards and amenity grapevines. In cases where outbreaks are limited to single plants the spread of FD can be contained using application against larval stages only, particularly in areas where amenity grapevines are rare.