As no-till acres have increased in Iowa, so have the acres infested with winter annual weeds. The primary cost associated with these weeds is interference with crop establishment and early-season growth. Some growers question whether it is better to control winter annuals prior to planting or just wait to deal with them at planting. In most situations, the best option will be to control winter annuals as soon as it is fit to get into the field.
Iowa State University
Hartzler, Robert G., "Managing Winter Annual Weeds in No-Till Fields" (2009). Integrated Crop Management News. 693.