How do differences in herbicides affect a grower’s options for weed control?
Decisions about weed management may well be the most complex decision that growers must make, because each weed control option has trade-offs and affects the feasibility of using other options. The first constraint a grower faces is herbicide spectrum. A grower almost always has a number of weed species that must be controlled. Therefore the broader the spectrum, the better for cost effective weed control, because the grower can use fewer herbicides. However, herbicides with the broadest spectra also may injure crop plants. Spectrum differences also affect a grower’s freedom to use the “wait and see” approach advocated by Integrated Weed Management. Because of their past experiences, most growers assume they will have a weed problem caused by both grass and broadleaf weeds. Once the crop emerges, they are limited to using a selective herbicide that does not harm the crop (post-emergence). Unfortunately, the selectivity also means it will only control certain weeds and not others. There
