The root injury illustrated demonstrates how the Node-Injury Scale quantifies progressive feeding by corn rootworm larvae. The actual sequence of feeding will vary visually depending on a variety of conditions such as planting date, corn variety, degree days, soil moisture, insecticide application and placement, genetically modified roots, soil conditions, etc. The secondary roots (root hairs) are displayed only when no injury is represented; they have been removed to facilitate better viewing of the injury once larval feeding is simulated.
(Oleson, J.D., Y. Park, T.M. Nowatzki, and J.J. Tollefson. 2005. J. Econ Entomol. 98(1): 1-8)
To use the interactive node-injury scale, click on the image above. The scale will appear in a new window. Once the scale has loaded, use arrow keys for precise movement: up and down to increase/decrease root injury and left and right to rotate the root.
The scale is a large file (9 MB) and requires QuickTime 4 or later.
(Hills, T.M. & D.C. Peters. 1971. J. Econ. Entomol. 64: 764-765)
|1||No damage or only a few minor feeding scars|
|2||Feeding scars evident, but no roots eaten off to within 1 1/2 inches of the plant|
|3||Several roots eaten off to within 1 1/2 inches of the plant, but never the equivalent of an entire node of roots destroyed|
|4||One node of roots completely destroyed|
|5||Two nodes of roots completely destroyed|
|6||Three or more nodes of roots destroyed|
|This page is part of the Iowa State Entomology site.||Published November 26, 2001. Last updated March 2, 2005 by John VanDyk|