Influence of application variables on efficacy of glyphosate

• Published in: Weed technology 1997-04, Vol.11 (2), p.354-362
• Main Authors: Jordan, D.L, York, A.C, Griffin, J.L, Clay, P.A, Vidrine, P.R, Reynolds, D.B
• Format: Article
• Language: English
• Subjects: 2,4-D; ABUTILON THEOPHRASTI; ACIFLUORFEN; ACIFLUORFENE; AMARANTHUS; AMARANTHUS RETROFLEXUS; AMMONIUM SULPHATE; ANNUAL WEEDS; APPLICATION DATE; APPLICATION RATES; Biological and medical sciences; CASSIA OBTUSIFOLIA; CHEMICAL CONTROL; CHLORIMURON; CHOIX DE LA DATE; Clay soils; CLORIMURON; CONTROL QUIMICO; Crop science; DATE D'APPLICATION; DESHERBAGE; DEVELOPMENTAL STAGES; DOSE D'APPLICATION; DOSIS DE APLICACION; ELECCION DE LA EPOCA; ESCARDA; ETAPAS DE DESARROLLO; FECHA DE APLICACION; Fundamental and applied biological sciences. Psychology; GLIFOSATO; GLYPHOSATE; Hemp; HERBICIDAS; HERBICIDE; HERBICIDE MIXTURES; HERBICIDES; IPOMOEA; IPOMOEA LACUNOSA; IPOMOEA WRIGHTII; LOUISIANA; LOUISIANE; LUISIANA; LUTTE CHIMIQUE; Parasitic plants. Weeds; PHARBITIS HEDERACEA; Phytopathology. Animal pests. Plant and forest protection; Plants; Quaternary ammonium compounds; SESBANIA; SESBANIA EXALTATA; SIDA; SIDA SPINOSA; Soybeans; STADE DE DEVELOPPEMENT; SULFATE D'AMMONIUM; Sulfates; SULFATO DE AMONIO; TIMING; WEED CONTROL; Weeds
• ISSN: 0890-037X; 1550-2740
• DOI: 10.1017/S0890037X00043062

Field experiments were conducted from 1993 to 1995 to compare weed control by the isopropylamine salt of glyphosate at 0.21, 0.42, 0.63, and 0.84 kg ae/ha applied at three stages of weed growth. Weed control by glyphosate applied at these rates alone or with ammonium sulfate at 2.8 kg/ha was also evaluated. In other experiments, potential interactions between glyphosate and acifluorfen, chlorimuron, and 2,4-DB were evaluated. Velvetleaf, prickly sida, sicklepod, pitted morningglory, entireleaf morningglory, palmleaf morningglory, and hemp sesbania were controlled more easily when weeds had one to three leaves compared with control when weeds had four or more leaves. Glyphosate controlled redroot pigweed, velvetleaf, prickly sida, sicklepod, and barnyardgrass more effectively than pitted morningglory, entireleaf morningglory, palmleaf morningglory, or hemp sesbania. Increasing the rate of glyphosate increased control, especially when glyphosate was applied to larger weeds. Greater variation in control was noted for pitted morningglory, palmleaf morningglory, prickly sida, and velvetleaf than for redroot pigweed, sicklepod, entireleaf morningglory, or hemp sesbania. Ammonium sulfate increased prickly sida and entireleaf morningglory control but did not influence sicklepod, hemp sesbania, or barnyardgrass control. Acifluorfen applied 3 d before glyphosate or in a mixture with glyphosate reduced barnyardgrass control compared with glyphosate applied alone. Chlorimuron did not reduce efficacy. Mixtures of glyphosate and 2,4-DB controlled sicklepod, entireleaf morningglory, and barnyardgrass similar to glyphosate alone.