MODELLING SPLASH DISPERSAL OF PLANT PATHOGENS WITHIN A CROP
Wageningen Agricultural University, Wageningen, The Netherlands
Background and objectives
The model incorporates the main mechanisms underlying the spatial spread of spores from a point source, that is: the probability per time unit of a spore being hit by a raindrop and splashed away; the probability per splash of being removed from the process; and a function for the spatial distribution of splashed spores.
Using these mechanisms, the effects of different crop characteristics on splash dispersal can be studied. We assume that spores can occupy four different sites in a crop, that is, the ground between plants, the ground underneath plants, leaves and fruit. Incorporating the above-mentioned mechanisms, a transition matrix is derived representing transition probabilities between the different sites in a canopy. To obtain reasonable parameter values for these transition probabilities, experiments are being performed using the rain tower facility at Rothamsted experimental station (Harpenden, UK). Oilseed rape plants infected with light leaf spot P. brassicae is the first system under study.
Previous field experiments showed that both horizontal and vertical dispersal of P.brassicae plays an important role in the spread of disease within the canopy . Data analysis showed that both the dynamics of the pathogen and the growth dynamics of the plant play an important role in potential disease development. Therefore, the purpose of this study was to develop a model that included both plant growth and splash dispersal of infectious units. This model will give further insight in spore movement within a plant canopy under different environmental conditions.