|Ruberson, John - UNIVERSITY OF GEORGIA|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 30, 2001
Publication Date: June 1, 2001
Citation: Tillman, P.G., Ruberson, J.R. 2001. Grain sorghum as a trap crop for the corn earworm in cotton. Proceedings of the Beltwide Cotton Conference. p.1158-1159. Interpretive Summary: Since Bt cotton can be susceptible to corn earworm, and corn earworms have developed resistance to pyrethroids in isolated locations in the southeast, the corn earworm can be a serious problem in cotton in Georgia. Since grain sorghum is highly attractive to corn earworm moths, a grain sorghum strip crop was planted in cotton to determine if the grain sorghum could provide a trap crop for the corn earworm. Corn earworms were heavil attracted to the grain sorghum strips, laying over 300 times as many eggs in sorghum as in the 40 rows of cotton adjacent to the sorghum. In addition, 99.9% of the eggs laid in the sorghum failed to result in corn earworm pupae, demonstrating the effectiveness of natural enemies in the sorghum. These results suggest that grain sorghum may function as an excellent trap crop for corn earworms.
Technical Abstract: The ability of a strip crop of sorghum to serve as a trap crop for the corn earworm in cotton was investigated in Mystic, GA in 2000. A strip of sorghum, 8 rows by 400 feet, was planted in the center of a 2.4 acre cotton plot which was located at one end of a cotton field. Corn earworm populations were monitored in the sorghum strip, in cotton adjacent to the sorghum, and in cotton in a control plot located at the other end of the cotton field. The mean number of corn earworm eggs/acre was higher in the grain sorghum than in the cotton. These results demonstrated that the corn earworm was more attracted to sorghum than cotton, and thus grain sorghum was an effective trap crop for the corn earworm in cotton. Total real mortality (rx) of the corn earworm in sorghum was very high, and so the sorghum trapped the pest insect without becoming a source of the insect in cotton.