Control of Boll Weevils (Coleoptera: Curculionidae) Through Crop Residue Disposal: Destruction of Subtropical Cotton Under Inclement Conditions1

Abstract

Efforts to use areawide cotton-stalk destruction as a mandatory cultural control for the Lower Rio Grande Valley (LRGV) population of boll weevil, Anthonomus grandis grandis Boheman, have been seriously impeded by a current lack of means by which to destroy volunteer and regrowth cotton effectively under inclement conditions. The hazard posed by such cotton was demonstrated in studies that indicated a potential production of ca. 483,000 adult boll weevils per hectare on cotton regrowth from the time stalks were shredded (October 1985) until the subsequent production season (March 1986). Studies demonstrated the feasibility of two alternatives to conventional plowing: subsurface sweep tillage, which inflicted >99.9% mortality of mature cotton stalks occurring on dry and highly compacted soils; and application of two herbicides (paraquat and dicamba), which destroyed >95% of volunteer seedlings and may represent the only feasible means of stalk destruction in certain situations (e.g., on water-saturated soils). The role of optional stalk destruction strategies in an areawide pest management program directed against the LRGV boll weevil population is discussed.