Submitted to: International Diabrotica Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/27/2002
Publication Date: 1/1/2003
Citation: IVEZIC, M., TOLLEFSON, J.J., RASPUDIC, E., HIBBARD, B.E., BRKIC, I. EVALUATION OF CROATIAN CORN HYBRIDS FOR TOLERANCE TO CORN ROOTWORM (DIABROTICA VIRGIFERA VIRGIFERA LECONTE) LARVAL FEEDING. INTERNATIONAL DIABROTICA CONFERENCE PROCEEDINGS. 2003. p. 205-212. Interpretive Summary:
Technical Abstract: The western corn rootworm (WCR) is a major pest of corn in the United States. It was first recorded in Yugoslavia in 1992 and arrived in Croatia in 1995. In the United States, insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to development of resistance. Growing corn that is resistant to corn rootworms would be a valuable alternative to use of insecticides. Ten Croatian (Institute of Agriculture, Osijek) and two Pioneer Hi-Bred Int., Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at four locations using a randomized complete block design with four replications. Two locations were in east Croatia (Gunja, Osijek) and two were in the United States (Iowa, Missouri). At the Missouri location, the plots were artificially infested with WCR eggs; the other locations had natural rootworm infestations. At all locations, root injury was rated using the Iowa State University Node-Injury Scale (0-3) with 0 representing no damage and 3 representing three nodes of roots pruned to within 3.8 cm of the stalk. The hybrids' tolerance to larval feeding was compared by evaluating root size and root regrowth. At the U.S. locations, tolerance was also measured by weighing root regrowth. Root injury, size, and regrowth were significantly different among hybrids and there was a significant location-by-environment interaction. Root injury ratings averaged 1.52 and 1.67 in Iowa and Missouri, respectively, and 0.07 and 0.36 in Osijek and Gunja, respectively. As a result of this study, European growers can choose among corn cultivars they are familiar with based upon corn rootworm tolerance in addition to other characters.