Greenhouse and field experiments were conducted in east-central Texas to evaluate the influence of simulated rainfall on the availability of foliar-applied herbicides for huisache and honey mesquite control. The foliar activity of the amine salts of glyphosate, dicamba, picloram, clopyralid, and triclopyr was decreased on greenhouse-grown huisache when simulated rainfall was applied up to 240 min after herbicide treatment. The effectiveness of the butoxyethyl ester of triclopyr or 2,4,5-T was not reduced by rainfall washoff within 15 min after application. In natural huisache stands, injury from the ester of triclopyr or amine salts of picloram or clopyralid was not reduced by simulated rainfall at 60 min after herbicide treatment. In the greenhouse and field, honey mesquite leaves rapidly absorbed most herbicides, and triclopyr, 2,4,5-T, picloram, and clopyralid were highly phytotoxic even when simulated rainfall was applied within 15 min after herbicide treatment.
