HOST MIXTURE EFFICACY IN DISEASE-CONTROL - EFFECTS OF LESION GROWTH ANALYZED THROUGH COMPUTER-SIMULATED EPIDEMICS

Lesion growth varies among foliar parasites and in order to study the effect of lesion growth on the efficacy of host mixtures to control ep idemics, we altered the epidemic simulator Epimul by integrating a les ion growth function into the model. A theoretical study was performed by simulating epidemics caused by parasites with different lesion grow th rates, spore dispersal gradients and multiplication rates. We found that increases in lesion growth rates resulted in large decreases in the effectiveness of mixtures for disease control and interacted stron gly with parasite multiplication rate and spore dispersal gradient. Th e decline in mixture efficacy for epidemics with high lesion growth ra tes was reduced when parasite multiplication rate was higher and spore dispersal gradient steeper. Our results suggested that the lower numb er of infections on susceptible plants in the mixture as a result of i noculum loss on resistant hosts was partially compensated by lesion gr owth.