Grain Sorghum as a Trap Crop for the Corn Earworm

1. Grain Sorghum as a Trap Crop for the Corn Earworm Glynn Tillman, USDA, ARS, Crop Protection & Management Lab, Tifton, GA pgt@tifton.cpes.peachnet.edu 229-387-2343 John R. Ruberson, UGA, Entomology Department, Tifton, GA CEW Eggs on Sorghum Trap, Cotton Trap, Field Cotton Associated with Sorghum and Cotton Trap, and Cotton in Control Fields INTRODUCTION Since Bt cotton is less resistant to the corn earworm (CEW) and these pests have developed resistance to pyrethroids in isolated locations, the CEW can be a serious problem in cotton. Grain sorghum is highly attractive to CEW moths, and thus this plant species may be an effective trap crop for this pest. Percentage of Sorghum Plants in each Head Stage with CEW Eggs and Percentage of CEW eggs for each Head Stage This study was designed to evaluate grain sorghum as a trap crop for the CEW. Specific objectives were 1) determine the attractiveness of grain sorghum as an ovipositional site and 2) determine if the grain sorghum serves as a sink for the CEW. This presentation reports results of data on the 1st objective. Both Trap Crop Cotton Fields and Control Cotton Fields were adjacent to a corn field. Sorghum and Cotton Traps were planted only in Trap Crop Fields. Plants were sampled for CEW eggs throughout the cotton season in the Sorghum Trap, Cotton Trap, Trap Crop field cotton associated with their perspective traps, and cotton in Control Fields. See plot plan below. Sorghum was planted at 3 dates. Mean Number of CEW Eggs in Sorghum Trap for each Planting Date (PD) and Combined Planting Dates Mean Number of CEW Eggs on Sorghum and Cotton Trap over Time 1. CEW eggs were higher in the Sorghum Trap than in the Cotton Trap. 2. No difference in CEW eggs was found on cotton between the Cotton Trap and Field Cotton associated with the Sorghum and Cotton Trap. 3. No difference in CEW eggs was found on cotton between Field Cotton associated with the Sorghum Trap and Field Cotton associated with the Cotton Trap. 4. CEW eggs were higher on cotton in Control Fields than in Trap Crop Fields. Grain Sorghum served as an effective trap crop for the CEW in cotton fields. Conclusion