Northern Corn Rootworm Field Test

October - December 2002

Paul Kassel , crops field specialist


Extended diapause of the northern corn rootworm reduced yields and caused harvest problems in northwest Iowa in 2001. Damage was extensive to northwest Iowa corn fields in terms of the number of fields affected, the percent of individual fields affected and the impact on corn yield. 


Joel DeJong, Todd Vagts and Paul Kassel identified some factors to evaluate in field scale research/demonstration project. They worked with Joyce Hornstein and Jon Tollefson to fine tune the project objectives. 
Plans were then made to evaluate the use of insecticide on first year corn versus an untreated check on the following factors:

- hybrids with good company ratings versus poor root ratings
- plant population
- root damage
- lodging
- grain yields
- ease of harvest

There are two kinds of plots to evaluate these factors
- side by side
- replicated trial with two hybrids


Plant population was evaluated for effect on plant population in the untreated check. Secondary pest damage may be more of an annual problem whereas corn rootworm damage may be sporadic. Results from this study showed that plant population increased from 29,587 to 30,121 when insecticide was used (preliminary data).
Root damage was minimal at all locations except one. In one location the untreated check was 0.49 on the node-injury scale versus 0.43 when insecticide was used.
Data from these plots will be shared at winter crop meetings and Private Continuing Instructional Course meetings.


Page last updated: July 10, 2006
Page maintained by Linda Schultz,