Honey Mesquite Control with Pelleted Hexazinone in Western Texas

Abstract

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione] applied as 1.2 cm3 (20% ai) pellets in a grid pattern at 2.2 kg active ingredient (ai)/ha killed 11 to 22% of undisturbed honey mesquite (Prosopis glandulosa var. glandulosa) 26 months after treatment in experiments at 3 locations in western Texas. Honey mesquite plants <1 m tall were less susceptible to grid pattern applications of hexazinone than were larger plants, probably because the smaller plants lacked sufficient root systems to contact herbicide columns in the soil. Efficacy of hexazinone applied in grid patterns for honey mesquite control increased as soil clay and organic matter contents decreased and as the amount of rock increased. Results from a single experiment indicated that hexazinone pellets applied at 0.8 g ai/plant near the stem base killed 48 to 60% of the honey mesquite plants <2 m in height, but this treatment did not control plants >2 m tall.