In 2000, Jim Oleson and Jon Tollefson, corn rootworm researchers at Iowa State University, developed a new method for evaluating root injury. They abandoned the traditional Iowa 1-6 scale that had been the standard by which all corn roots were evaluated since 1971 throughout the United States. In its place, they developed the Iowa State node-injury scale. This new scale more accurately reflects the relationship of injury from the low to the high end of the scale.
Iowa State University
Rice, Marlin E., "New method for understanding corn rootworm injury" (2003). Integrated Crop Management News. 1639.
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