One of the primary benefits of site-specific agricultural technologies is the potential to reduce the use of polluting inputs, thereby minimizing ecological damage. Weeds are often found in patches, so site-specific (field scale) management offers a straightforward opportunity to minimize ecological effects related to wasteful broadcast use of herbicides. Beyond possible efficiencies related to accurate targeting, site-specific technologies, through a process of parameterizing management decision models for each field, may improve ecological understanding of weed populations and thus encourage ecologically based management. This hypothesis was assessed with a simple model that combined economic injury–level prediction with a single parameter (growing season precipitation) to represent environmental variability. Model simulations of crop yield in response to weed density at a virtual farm and six surrounding regional experiment stations suggested that localized (on-farm field) parameter estimation may help to circumvent the variability associated with damage function extrapolation from small-plot experiments at experiment stations and thereby improve predictive accuracy for site-specific weed management (SSWM) strategies. Thus, remote sensing and SSWM technologies may allow producers to reduce the risk associated with the reduced use of purchased inputs and greater reliance on natural weed population–regulating mechanisms. Effective ecologically based weed management may be dependent on local parameterization of models.