Weed Management Update - Who Cares?

Despite the importance of glyphosate-based crop systems, there is a need for continued investigation and development of new tactics to manage weeds effectively and economically. It is interesting that larger farm size and higher percentage of income attributable to grain is associated with growers willingness to accept alternative weed management strategies and the adoption of integrated weed management programs (Hammond et al. 2006). The concern for timely weed management in order to protect crop yields becomes premiere in POST-based corn and soybean systems, whether based on glyphosate or any other herbicide (Halford et al. 200 l; Cox et al. 2006). Iowa State University recommends the use of herbicides that provide residual weed control in corn and soybeans. The early preplant application of residual herbicides is an excellent option to reduce weed management risks. Consider that the it is critical to reduce application timing risk; while many growers now have sprayers and combined with the custom herbicide application industry, the approximate 22 million acres of row crops in Iowa can receive a herbicide treatment in a relatively short period of time, there is still a major risk of making a timely POST application. The risk of making a timely POST herbicide application has less to do with controlling weeds and more to do with protecting potential crop yield. Recognize that herbicide applications are at the mercy of the environmental conditions, while weeds continue to grow irrespective of the weather. Furthermore, the ability to make a timely herbicide application is dictated on the ability to assess that which is impossible to predict - when weeds begin to compete with the crop yield potential. Thus, there is still an important role for new herbicides in weed management beyond the concerns caused by the evolution of herbicide resistant weed biotypes and weed population shifts. Some of the new herbicides and weed management issues facing crop production in 2007 will discussed below