Tolerance of Apple and Peach Trees to Triclopyr

Abstract

The tolerance of newly planted apple (Malus domestica Borkh.) and peach [Prunus persica (L.) Batsch] trees to the postemergence herbicide triclopyr was evaluated infield trials. Apple and peach trees were not injured by triclopyr applied at rates ranging from 0.28 to 1.12 kg acid equivalent (a.e.)/ha as a directed spray to soil. No injury was observed following direct application of 10 ml of a triclopyr solution at 2 g a.e./liter to the lower bark of either tree species. Applications of that solution to an individual branch injured or killed the treated apple or peach branch but did not affect the rest of the tree. No reduction in tree growth or injury was noted 1 year after triclopyr application. Applications of 10 ml of a glyphosate solution at 15 g a.i./liter to an apple branch caused severe injury and a growth reduction by 1 year after application, and killed all treated peach trees when applied to one branch. No triclopyr or 2,4-D treatment had affected apple or peach trunk diameter, number of branches, or tree size 1 year after application. Chemical names used: N-(phosphonomethyl)glycine (glyphosate); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); (2,4-dichlorophenoxy)acetic acid (2,4-D).