Dynamics of acquisition and transmission of "flavescence dorée" phytoplasma in grapevine

A dynamic model of "flavescence dorée" phytoplasma (FD) in grapevine transmitted by the leafhopper Scaphoideus titanus was developed and tested. The model accounted for the biological life cycle of S. titanus on Vitis vinifera, epidemics progression in V. vinifera, vineyard setting, and agronomic practices aimed to control the epidemics. It was comprehensively tested against data sets of FD presence gathered in various vineyards in Piemonte, Italy, over nine years. The model achieved a correlation coefficient (R) and residual (NRMSE) against observations in the range R >= 91.3% and NRMSE <= 12.59%, respectively. A stochastic sensitivity analysis showed that FD progression was slightly more susceptible to uncertainty in S. titanus life cycle parameters than equivalent uncertainty in FD pathogen acquisition and transmission between plant and insect and initial conditions. Examples of analysis of outbreak scenarios and assessment of effectiveness of mitigation measures showed that combinations of insecticide applications and plant rouging were optimal to reduce FD progression within time scales of about 10 to 15 years. On a wider perspective, evidence validated by comparison with empirical data is presented for the potential use of epidemiological models in decision making when control strategies should be implemented in agronomic practices.