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LOGO: Journal of Cotton Science


Weed Response to 2,4-D, 2,4-DB, and Dicamba Applied Alone or with Glufosinate

Authors: Rand M. Merchant, Lynn M. Sosnoskie, A. Stanley Culpepper, Lawrence E. Steckel, Alan C. York, L. Bo Braxton, and Jill C. Ford
Pages: 212-218
Weed Science

Cotton tolerant of 2,4-D, glufosinate, and glyphosate or dicamba, glufosinate, and glyphosate is in development. This technology will give growers additional tools to manage glyphosate-resistant weeds. A field experiment was conducted across six environments in Georgia, North Carolina, and Tennessee to determine the response of 13- to 20-cm weeds to 2,4-D, 2,4-DB, and dicamba applied alone or mixed with glufosinate. Palmer amaranth (Amaranthus palmeri S. Wats) was controlled 59 to 78%, 68 to 80%, and 59 to 83% by 2,4-DB dimethylamine (560-1120 g ae ha-1), 2,4-D dimethylamine (530-1060 g a.e. ha-1), and dicamba diglycolamine (280-1120 g ae ha-1), respectively, and 74% by glufosinate ammonium (430 g ae ha-1). Control was improved (89-97%) with all auxin/glufosinate mixtures when compared to respective herbicides alone. Glufosinate controlled Benghal dayflower (Commelina benghalensis L.) only 68%; 2,4-D at 530 g ha-1 and dicamba at 1120 g ha-1 controlled this weed at least 90%. Combinations of glufosinate and auxin herbicides were beneficial when control by auxin herbicides was 90% or less. Carpetweed (Mollugo verticillata L.) control by auxin herbicides ranged from 50 to 66%; glufosinate alone or in mixtures completely controlled carpetweed. All treatments completely controlled morningglory (Ipomoea spp.). Auxin herbicides had no activity on grasses. Texas millet (Panicum texanum [Buckl.] R. Webster) and broadleaf signalgrass (Brachiaria platyphylla [Nash] R. Webster) were controlled 89 to 90% by glufosinate alone. Both 2,4-D and 2,4-DB mixed with glufosinate reduced Texas millet control, and 2,4-D reduced broadleaf signalgrass control.