Table 1. Corn rootworm larva injury in first-year cornfields.
Iowa State University 1-to-6 root-rating scale used: 1 = no visible damage or only a few minor feeding scars, 2 = some roots with feeding scars but none eaten off to within 1.5 inches of the plant, 3 = several roots eaten off to within 1.5 inches of the plant but never the equivalent of an entire node of roots destroyed, 4 = one node of roots destroyed or the equivalent, 5 = two nodes of roots destroyed or the equivalent, and 6 = three or more nodes of roots destroyed. See issue no. 15 (July 7, 2000) of the Bulletin.