Preemergence Herbicide Stewardship--ISU

The advent of herbicide-resistant (HR) weeds has increasingly led to the recommendation that producers should use preemergence (PRE) or soil-applied herbicides to increase the mode-of-action variability in the battle to control HR weeds.  PRE herbicides are applied to the soil to prevent weeds seeds from germinating and emerging.  Thus, the soil is the interceptor of these herbicides vs. the plant which is the interceptor of POST herbicides that are applied to emerged and growing weeds either before or after crop planting and emergence.  Dr. Bob Hartzler of Iowa State Univ. provides details about how PRE herbicides will react with soil and perform based on that reaction.