AnthracnoseTracer: A Spatiotemporal Model for Simulating the Spread of Anthracnose in a Lupin Field

ABSTRACT A spatiotemporal model has been developed to simulate the spread of anthracnose, initiated by infected seed, in a lupin field. The model quantifies the loss of healthy growing points of lupin in all 1-m(2) subunits of a field throughout a growing season. The development of growing points is modeled as a function of temperature using a 1-day time step, and disease-induced compensatory growth is accounted for. Dispersal of spores is simulated explicitly using Monte Carlo techniques. Spread of spores occurs during rainfall events on a 1-h time step. The distance traveled by spores is partially dependent on wind speed and is generated by adding the values selected from half-Cauchy distributions. The direction of travel of the spores is influenced by wind direction. The model has been employed to produce a theoretical assessment of damage from disease in two environments at five levels of seed infection. It was calculated that in a susceptible lupin cultivar with a 0.01% initial seed infection, anthracnose would cause approximately 15% loss of healthy growing points in a high rainfall environment in Western Australia. In a low rainfall environment, similar damage would be unlikely even with a much higher (1%) level of seed infection.