TITLE:
Efficacy of 2,4-D, Dicamba, Glufosinate and Glyphosate Combinations on Selected Broadleaf Weed Heights
AUTHORS:
Dwayne D. Joseph, Michael W. Marshall, Colton H. Sanders
KEYWORDS:
Palmer Amaranth, Pitted Morningglory, Sicklepod, Synergism, Antagonism, Glufosinate, Dicamba, 2, 4-D, Glyphosate
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.6,
May
30,
2018
ABSTRACT: Palmer amaranth, sicklepod and pitted morningglory
are the three most common and troublesome weeds in soybean in South Carolina.
They exhibit very aggressive growth capabilities and if left uncontrolled in
fields will cause significant reductions in soybean yields. Dicamba and 2,4-D
herbicides are currently having a resurgence in usage due to the recent
commercialization of soybean trait technologies with tolerance to these
herbicides. Dicamba and 2,4-D when tank mixed with glufosinate and glyphosate
may offer additional weed control to resistant weeds through the process of
herbicide synergism. Greenhouse experiments were conducted in 2013 at Edisto
Research and Education Center near Blackville, SC to evaluate the efficacy of
glyphosate, glufosinate, dicamba and 2,4-D treatments alone and in combination
on Palmer amaranth, sicklepod, and pitted morningglory at selected heights.
Results suggested that glufosinate alone provided the overall best control for
all 3 weed species. Glyphosate alone provided the lowest control of all 3
species at all heights. Synergism or improved sicklepod control was observed
when glufosinate was tank mixed with dicamba. However, as sicklepod increased
in height, glufosinate + 2,4-D or dicamba combination offered the best control
compared to glufosinate alone (90% versus 86% in 20 cm plants and 87% versus
85% in 30 cm plant). In the 5 cm Palmer amaranth, decreased control was
observed when glyphosate or glufosinate was tank
mixed with 2,4-D. These experiments showed that glufosinate alone and/or in
combination with 2,4-D or dicamba was the overall best treatment on the three
broadleaf weed species.