Correlation of Honey Mesquite Response to Herbicides with Three Plant Variables and Soil Water

Abstract

Honey mesquite [Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell] response to sprays of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid) and picloram (4-amino-3,5,6-trichloropicolinic-acid) + 2,4,5-T was evaluated and correlated with maximum daily photosynthetic rate, upward movement of methylene dye, xylem pressure potential, and percent soil water. Picloram + 2,4,5-T was superior to 2,4,5-T alone for killing honey mesquite from May 15 through August 4. Time of day the herbicide was applied had no significant effect on control. Maximum daily photosynthetic rate varied from 32.9 to 10.1 mg ${\rm CO}_{2}\ {\rm dm}^{-2}$ leaf area hr-1 and was highly correlated (r = 0.89 to 0.92) with honey mesquite control with herbicides. Rate of upward movement of methylene blue dye in the xylom varied from 295 to 44 cm hr-1. (MPa) while soil water content varied from 11.5 to 18.6%. Upward movement of methylene blue dye, xylem pressure potential and percent soil water were not significantly correlated with honey mesquite control.