A field day focusing on the impacts of crop rotation on weed population dynamics will be held Monday, August 16, near Boone, Iowa. The event will be held at the site of a 21-acre experiment involving 3 crop rotations (corn - soybean; corn - soybean - small grain/red clover; corn - soybean - small grain/alfalfa - alfalfa). Information on why weeds respond differently to the rotation systems will be presented. Speakers include Matt Liebman, Bob Hartzler, and Andy Heggenstaller from the Iowa State University Department of Agronomy; weed management practitioners; and others. Refreshments will be served after the field day.