Control of a carrot weevil, Listronotus texanus (Coleoptera: Curculionidae): timing pesticide applications and response to selected pesticides

Insecticides and timing of applications were evaluated in southern Texas to determine optimal control strategies for Listronotus texanus (Stockton) on processing carrots, Dacus carota L. Results of evaluating seven insecticides indicated that applications of fenvalerate to experimental plots resulted in less damage than treatments of carbaryl, malathion, or in the untreated plots. Methyl parathion, the only other registered material, yielded equivalent control to fenvalerate in terms of damage but was not significantly better than the untreated check. Studies to determine optimal timing of applications of fenvalerate and methyl parathion indicated that a control program of 6 or 12 applications of either material spread throughout the season provided equivalent reductions of weevil damage. Carrots planted relatively late in the growing season (October and November) were subject to less damage, and a control program consisting of three or six late-season applications of either material provided control equivalent to 6 or 12 applications spread throughout the season