Application of Herbicides on Rangelands with a Carpeted Roller: Evaluation of Four Herbicides for Control of Honey Mesquite

Abstract

A carpeted roller, designed to wipe herbicide solutions onto brush stems and foliage, was evaluated for control of honey mesquite [Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell] at 4 locations. Picloram (4-amino-3,5,6-trichloropicolinic acid) and clopyralid (3,6-dichloropicolinic acid) top-killed honey mesquite at all locations, whether applied in spring or fall. Mortality (root-kill) of plants treated with picloram varied from 38% of plants treated under drought conditions in south Texas to 97% of plants experiencing optimum growing conditions in central Texas. Clopyralid was equal to or slightly more effective than picloram, based on mortality near the end of the second growing season after treatment, whereas glyphosate [N-(phosphonomethyl)glycine] and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} were usually less effective. Solutions containing 120 g/L of herbicide active ingredient were more effective than solutions containing 30 g/L, but differences were sometimes slight. Small, widely spaced honey mesquites were more easily controlled with the carpeted roller than larger plants growing in dense stands.