Use of Soybean Production Surveys to Determine Weed Management Needs of South Carolina Farmers¹

Abstract

Soybean producers of South Carolina were surveyed in 2000 through mail and on-farm visits to determine which production practices limit seed yields the most. Production systems have direct implications on weed management practices, difficulties, and future problems. When asked to describe two extension and research focus areas that would improve current soybean production, the number one response was improved weed control strategies. Fifty-seven percent of the respondents indicated that weeds were the pest that most limited soybean yield. Sicklepod, Palmer amaranth, morningglory species, common cocklebur, yellow nutsedge, and Texas panicum were considered the most problematic weeds. More than half the producers (68%) used glyphosate-resistant soybean, with one-half of these farmers producing soybean in row widths > 51 cm. Of the farmers who grew conventional soybean, 10% used narrow rows (≤ 51 cm), whereas 22% used wide rows (> 51 cm). Only 27% of the farmers who planted glyphosate-resistant soybean used a soil-applied herbicide. Forty-three percent of farmers based the need for a postemergence herbicide on weed size, 21% used no repeatable method, 21% relied on days after soybean emergence, 11% depended on soybean size or groundcover, and only 4% used a combination of weed density and size. Thirty-five percent of the farmers did not rotate soybean with another crop. In fields where soybean parasitic nematodes reduced soybean growth or caused plant death, late-season weed infestations were often exacerbated, especially in the absence of nonresidual herbicides. Specific reasons for difficulty in managing weeds in soybean may include a diverse weed spectrum, which is difficult to control with a single herbicide, the use of wide-row soybean, the lack of crop rotation, the prevalence of nematodes that directly affect crop development and, in turn, weed management, the lack of an appropriate criterion for timing postemergence herbicide applications, and the greater attention paid to production of more valuable crops. Educational efforts addressing weed management problems and association of such problems with other production practices are needed if weed management is to be improved and weed-induced yield losses minimized.

Evaluation of 2,4-D-Choline Based Herbicide Systems in 2,4-D Tolerant Soybean (<i>Glycine max</i> L.)

“…Resistance may occur naturally due to selection or it may be induced through such techniques as genetic engineering [13]. Currently, (L.)], are some of the weeds that are the most difficult to manage in soybean fields in South Carolina [16]. The discovery of glyphosate and ALS-resistant Palmer amaranth biotypes in South Carolina has exacerbated the issue.…”

Weed control and crop tolerance of micro-encapsulated acetochlor applied sequentially in glyphosate-resistant soybean

“…is the most widely grown field crop in the United States (United States Department of Agriculture 2012). Weed management is an important component of soybean production to secure higher yields (Norsworthy 2003). Application of pre-emergence (PRE) and/or postemergence (POST) herbicides is the primary method for weed control in soybean (Riar et al 2013).…”

Palmer Amaranth (<i>Amaranthus palmeri</i> S. Wats.) and Pitted Morningglory (<i>Ipomoea lacunosa</i> L.) Control in Dicamba Tolerant Soybean (<i>Glycine max</i> L.)

“…Palmer amaranth and pitted morningglory (Ipomoea lacunosa L.) are among the most common and troublesome weeds to manage in South Carolina soybean fields [9]. Palmer amaranth biotypes with resistance to glyphosate and ALS-inhibitors have become an economic burden under predominately glyphosate-based postemergence weed management systems in the Southern US.…”