Grain Sorghum as a Trap Crop for the Corn Earworm

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Grain Sorghum as a Trap Crop for the Corn Earworm
Glynn Tillman, USDA, ARS, Crop Protection
Management Lab, Tifton, GA pgt_at_tifton.cpes.peachne
t.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