Influence of Site on Mesquite Mortality from 2,4,5-T

Abstract

Soil temperature at the 18-inch depth was the most important factor affecting response of honey mesquite to 2,4,5-T application. Temperatures at this depth in the high 60's F or low 70's F resulted in no mesquite kills with the best results obtained if temperatures were over 80 F. Phenological development was essentially as important with plants having mature leaves and seed pods being easiest to kill. Trees with small and blooming spikes and those without flowers or pods were hardest to kill with 2,4,5-T. Other variables usually considered important, such as soil moisture, were important only in combination with other variables. Mesquite trees growing on upland and sandy sites are apparently more susceptible to 2,4,5-T largely because the soil is usually several degrees F warmer than bottomland and clay sites.