The effects of different rootworm control products, different planting times, and different crop rotation sequences on rootworm larval injury and rootworm adult emergence
Nathan L. Wentworth, firstname.lastname@example.org, Kevin L. Steffey, email@example.com, Michael E. Gray, firstname.lastname@example.org, and Ron Estes, email@example.com. University of Illinois, Crop Sciences Department, Urbana, IL
Trials were conducted in 2003 and 2004 to determine the effects of rootworm control products, planting dates, and crop rotation sequences on rootworm larval injury and rootworm adult emergence. The trials were planted in two crop rotation schemes: corn after corn and corn after soybeans. Each trial was designed as a split plot, with planting dates (May 13 and May 29 in 2003; April 15 and May 15 in 2004) as whole plots and rootworm-control products (Aztec 2.1G, Prescribe, and YieldGard Rootworm in 2003; Aztec 2.1G, Poncho 1250, and YieldGard Rootworm in 2004) as subplots. An untreated check also was included as a subplot. Larval injury was assessed using the Hills and Peters root rating scale (1971). In 2003, late-planted corn in both rotation schemes had less root damage than early-planted corn. Plants treated with rootworm-control products had less root damage than untreated plants. In corn after corn, more beetles emerged from early-planted corn than from late-planted corn. Fewer beetles emerged from YieldGard and Aztec-treated plots than from Prescribe or check plots. In corn after soybeans, fewer beetles emerged from YieldGard plots than from Prescribe or check plots. These results verify the importance of agronomic similarity (e.g., planting time, crop sequence) between YieldGard Rootworm corn and its associated non-Bt corn refuge. Peaks and patterns of rootworm adult emergence influenced by agronomic factors may influence the effectiveness of the refuge.