Simulation of potential epidemics of downy mildew of grapevine in different scenarios of disease conduciveness

The parameterisation process of a previously\r\ndeveloped modelling structure of the grapevine-downy\r\nmildew pathosystem is described. The model incorporates\r\nprimary and secondary infections, host crop\r\ngrowth and development, along with a linkage between\r\ndisease on foliage and disease on clusters. This processbased\r\nmodel was developed with a main objective of\r\nunderstanding the behaviour of the pathosystem under\r\ndifferent, variable, environmental conditions, or under\r\nclimate change. Six scenarios of disease conduciveness\r\nwere developed in order to capture the range of environmental\r\nconditions under which potential downy mildew\r\nof grapevine epidemics can develop. These climate\r\nscenarios were based on moisture and temperature factors.\r\nThe scenarios were translated into vectors of parameters\r\nfor primary and secondary infections in the\r\nmodel. Model testing was performed in three steps: (i)\r\nan analysis of potential epidemics was conducted from\r\nthe literature on grapevine downy mildew in order to\r\ndelineate the behaviour of the pathosystem under different\r\nscenarios; (ii) a simulation experiment was conducted\r\nto investigate the response of the model to different\r\npatterns of environmental conditions, corresponding to\r\nsix scenarios of disease conduciveness; and (iii) expected\r\nand simulated epidemics under these scenarios were\r\ncompared. In scenarios, the model mobilised existing\r\nquantitative information on downy mildew of grapevine\r\nand generated outputs that are congruent with expected\r\npatterns of potential epidemic. This study indicates that\r\nthe model is a reliable tool for simulating accurate and\r\nrobust potential epidemics of downy mildew of grapevine\r\nin a scenario analysis. This can have many applications,\r\nsuch as the understanding of the behaviour of\r\nthe pathosystem under climate change or when partial\r\nhost resistance is involved.