This thesis examines, in both an experimental and theoretical context, the conditions under which site- specific management is likely to be advantageous. Initially, site-specific and broadcast herbicide treatments were applied in a large-scale block design , then subsequently compared using site-specific yield data. I calculated the net return as a function of the proportion of field treated and determined the theoretical threshold necessary to make site-specific weed control profitable. Using supplemental quadrat count data, I parameterized a relationship describing the competitive effect of wild oat on spring wheat using the site-specific yield data. I suggest that creating locally parameterized stochastic functions may improve the accuracy of input response prediction over regional small-plot experiments because of field-specific effects, which are not calibrated by regional small plot experiments. Lastly, I investigated the importance of weed demography in weed control decisions and developed an analytical approximation to the long-term economic threshold based on the population growth rate.