As the end of April nears with little field work accomplished, getting the crop in the ground becomes the priority for many farmers. No-till farmers may plant fields prior to killing weeds with a burndown herbicide, with the intent of returning later to control the weeds with an early postemergence application. While this strategy can be effective, it is important to realize that planting into established weeds greatly shortens the time required for weeds to impact crop yields (critical period).