Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/6/2003
Publication Date: 7/1/2003
Citation: Greenberg, S.M., Showler, A., Sappington, T.W., Bradford, J.M., Carroll, S., Arnold, M., Parajulee, M., Brashears, A.D., Knutson, A. 2003. Postharvest mortality of boll weevils relative to tillage in fallen cotton squares and bolls. In: Proceedings of the Beltwide Cotton Conferences, January 6-10, 2003, Nashville, Tennessee. 2003 CDROM.
Interpretive Summary: The boll weevil is a destructive primary insect pest on cotton. Control of this insect is the key to successful cotton production. Chemical control programs that rely on broad-spectrum insecticides have associated environmental problems and can lead to insect resistance. Among important alternatives to insecticides are cultural control techniques. Integration of pesticides with cultural practices may provide opportunities for reducing insecticide input. Tillage operations modify soil habitats where many insect pests and beneficial insects reside during at least part of their life cycles. We studied the effects of conventional and conservation tillage on boll weevil mortality in postharvest cotton fields. The results indicated that extreme temperatures on the soil surface of conservation cotton fields are a major mortality factor of the boll weevil, while in conventional tillage, buried infested fruits can increase short-term survival during periods of excessively high surface temperatures. The knowledge of the effects of cotton postharvest treatments on boll weevil survival is necessary to an understanding of the development of individual insects within the overwintering population.
Technical Abstract: Studies were conducted to assess the effects of conventional and conservation tillage on boll weevil, Anthonomus grandis grandis Boheman, mortality in postharvest cotton fields. Samples taken just before harvest indicated that the number of fallen fruiting structures per M**2, the number of infested fruits, and the number of fruits containing live boll weevils were significantly higher in conventionally tilled fields than in conservation tillage fields. By seven days postharvest, boll weevil mortality in conservation tillage fields was 12.4-fold higher in infested squares, which remained on the soil surface than in those buried in conventional tillage fields. The major factor responsible for boll weevil mortality immediately after harvest in conservation tillage plots was high soil-surface temperatures. Mortality of boll weevils in small or medium size bolls (10-15 mm in diameter) on the soil surface was significantly lower than in squares, presumably because the bolls provided better insulation from the high temperatures. While in the large laboratory-infested bolls (equal to 20 mm in diameter), the mortality was higher than in small or medium sizes because in large bolls development of weevils was in difficulty. Our study showed the feasibility of cultural management of overwintered boll weevil control.