Assessment of Weed Management Practices and Problem Weeds in the Midsouth United States—Soybean: A Consultant's Perspective

Abstract

Th is report explores the impact of the adoption of genetically engineered (GE) corn, soybean, and cotton on pesticide use in the United States, drawing principally on data from the United States Department of Agriculture. Th e most striking fi nding is that GE crops have been responsible for an increase of 383 million pounds of herbicide use in the U.S. over the fi rst 13 years of commercial use of GE crops (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008).Th is dramatic increase in the volume of herbicides applied swamps the decrease in insecticide use attributable to GE corn and cotton, making the overall chemical footprint of today' s GE crops decidedly negative. Th e report identifi es, and discusses in detail, the primary cause of the increase --the emergence of herbicide-resistant weeds.Th e steep rise in the pounds of herbicides applied with respect to most GE crop acres is not news to farmers. Weed control is now widely acknowledged as a serious management problem within GE cropping systems. Farmers and weed scientists across the heartland and cotton belt are now struggling to devise aff ordable and eff ective strategies to deal with the resistant weeds emerging in the wake of herbicide-tolerant crops.But skyrocketing herbicide use is news to the public at large, which still harbors the illusion, fed by misleading industry claims and advertising, that biotechnology crops are reducing pesticide use. Such a claim was valid for the fi rst few years of commercial use of GE corn, soybeans, and cotton. But, as this report shows, it is no longer.An accurate assessment of the performance of GE crops on pesticide use is important for reasons other than correcting the excesses of industry advertising. It is also about the future direction of agriculture, research, and regulatory policy.Herbicides and insecticides are potent environmental toxins. Where GE crops cannot deliver meaningful reductions in reliance on pesticides, policy makers need to look elsewhere. In addition to toxic pollution, agriculture faces the twin challenges of climate change and burgeoning world populations. Th e biotechnology industry' s current advertising campaigns promise to solve those problems, just as the industry once promised to reduce the chemical footprint of agriculture. Before we embrace GE crops as solution to these new challenges, we need a sober, data-driven appraisal of its track record on earlier pledges.Th e government has the capability, and we would argue a responsibility, to conduct periodic surveys of suffi cient depth to track and accurately quantify the impacts of GE crops on major performance parameters, including pesticide use. While the USDA continued to collect farm-level data on pesticide applications during most of the 13 years covered in this report, the Department has been essentially silent on the impacts of GE crops on pesticide use for almost a decade. Th is is why the groups listed in the Acknowledgements commissioned this study by Dr. Benbrook, the third he has done on this t...

Agronomic factors involved in low-level wild poinsettia resistance to glyphosate

“…This result confirmed that the RS soybean producers prefer to use this technology, being that the adoption of this technology can be attributed to the fact of the simplicity and flexibility of the use of the herbicide (Riar et al, 2013b). Thus, for the most part, RS farmers use glyphosate consecutively as the only herbicide for RR ® crops, in some cases for up to nine years (Ulguim et al, 2013).…”

“…To this end, we observed in this study that the vast majority (90%) of the producers use herbicides associated with glyphosate in pre-sowing soybean desiccation ( Figure 5). In 61% of the RR ® soybean crop area in the South Central Region of the United States, an additional herbicide was used in the pre-sowing application of the crop, followed by glyphosate applications in post-emergence (Riar et al, 2013b). In comparison, between 2005 and 2010, most producers have introduced in their management systems the combination of additional herbicides and glyphosate in continuously cultivated areas with RR ® soybean (Prince et al, 2012), due to the increasing problems related to weed resistance to glyphosate.…”

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

“…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). The acetamides are widely used in corn, cotton (Gossypium hirsutum L.), sorghum [Sorghum bicolor (L.) Moench], and soybean for control of annual grasses and smallseeded broadleaf weeds.…”

Using Herbicide Programs to Control Weeds in Corn (Zea mays L.) and Cotton (Gossypium hirsutum L.)

“…Miller and Norsworthy [120] reported that the addition of a residual herbicide, such as trifluralin, would provide an additional effective herbicide mode of action for managing resistant Palmer amaranth. Applications of 2,4-D, glyphosate, and glufosinate alone or tankmixed represent broad-spectrum POST herbicides that have the potential to control 9 of the 10 most problematic weeds in the southern cotton and soybean production [121].…”