Does weed control by precision spray technology favour the emergence of resistance?

Weed control by precision farming is recommended both by economic and ecological reasons. It is still unclear whether precision weed control favours the emergence of herbicide resistant biotypes. To investigate this, the cellular automaton model of Sandt et al. (2008) for the simulation of precision weed control was extended to resistant biotypes and their genetic interactions. The model is capable of simulating the emergence of resistant biotypes in dependence of weed control thresholds, application rates and initial distribution of biotypes. Examples are shown for the case of polygenic inheritance of resistance involving three loci and thus 27 biotypes. Preliminary simulation results hint that precision farming can delay the emergence of resistance at high weed control thresholds.