Preserving the Value of Weed Management Tools

Bob Hartzler, Professor, Agronomy


Weed management is critical for profitable production of corn and soybean.  As farm size increases and energy costs rise, farmers look for ways to minimize the number of trips across fields.  This need to utilize time efficiently has led to an increased planting of glyphosate resistant crops and reliance on glyphosate to control weeds. This heavy use of glyphosate places high selection pressure on weeds for biotypes resistant to glyphosate. The selection and spread of glyphosate resistant weeds could have serious economic impacts for Iowa farmers and result in increased tillage and use of herbicides.


Increase awareness of farmers and agribusiness personnel on the factors influencing the selection of herbicide resistant weeds and the potential costs associated with herbicide resistance.


A multi-pronged approach was undertaken to increase the awareness of herbicide resistance.  In addition to the traditional extension approaches (grower meetings, conferences, Internet articles, newsletters), a meeting was held in Indianapolis with extension weed scientists from throughout the North Central region.  The meeting led to all cooperating states developing a unified message regarding resistance management.  A series of bulletins is being developed that target specific issues of herbicide resistance.  Individual states will be able to use only those that are pertinent to their specific cropping systems.


As of 2005 no glyphosate resistant weeds have been documented in Iowa.  However, glyphosate resistance is a major problem in the Southeast and Mid-Atlantic regions of the U.S.   The consistent message provided by extension since the introduction of glyphosate resistant crops concerning the implications of herbicide resistance has helped reduce the number of farmers using glyphosate in a manner that increases the likelihood of selecting resistant biotypes.



Page last updated: July 9, 2006
Page maintained by Linda Schultz,