ArticleLiterature Review

Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact

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Abstract

Genetically modified (GM) crops have been and continue to be a subject of controversy despite their rapid adoption by farmers where approved. For the last two decades, an important matter of debate has been their impact on pesticide use, particularly for herbicide-tolerant (HT) crops. Some claim that these crops bring about a decrease in herbicide use, while others claim the opposite. In fact, since 1996, most cultivated GMOs have been GMHT crops, which involve the use of an associated herbicide, generally glyphosate. In their very first years of adoption, HT crops often led to some decrease in herbicide use. However, the repetition of glyphosate-tolerant crops and of glyphosate only applications in the same fields without sufficient alternation and herbicide diversity has contributed to the appearance of glyphosate-resistant weeds. These weeds have resulted in a rise in the use of glyphosate and other herbicides. This article explores this situation and the impacts of herbicide-resistant weeds, using an interdisciplinary approach and drawing on recent data. The paper analyzes the spread of GMHT crops worldwide and their consequences on herbicide use in the USA in particular. It then addresses the global development of glyphosate-resistant weeds and their impact, particularly focusing on the USA. Finally, the last section explores how industry, farmers, and weed scientists are coping with the spread of resistant weeds. The concluding comments deal more widely with trends in GM crops.

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... Glyphosate resistance has since been identified in seventeen weed species in the United States (Heap 2020). The rise of glyphosate-resistant weeds (GRWs) has led to a growing literature on best practices to delay and manage the onset of herbicide resistance in weeds (e.g., Beckie 2006;Evans et al. 2015;Bonny 2016;Beckie and Harker 2017). The increased use of tillage for weed control is frequently found among these recommendations. ...
... Meanwhile, agrochemical companies have responded to GRWs by developing new crop seed genetics resistant to other herbicides (Mortensen et al. 2012;Green 2014;Bonny 2016). Farmers remain optimistic that agrochemical companies will develop new solutions that will maintain the simplicity of glyphosate-based weed management (Dentzman and Jussaume 2017), and indeed a revival of interest in pesticide research has led to recent mode-of-action discoveries (Kahlau et al. 2020). ...
Article
Full-text available
Conservation tillage in American soybean production has become increasingly common, improving soil health while reducing soil erosion and fuel consumption. This trend has been reinforced by the widespread adoption of glyphosate‐based weed control systems. Many weed species have since evolved to resist glyphosate, reducing its effectiveness. We provide evidence that the spread of glyphosate‐resistant weeds is responsible for significant reductions in the use of conservation tillage in soybean production. We estimate reduced‐form and structural probit models of tillage choice, using a large panel of field‐level soybean management decisions from across the United States spanning 1998–2016. We find that the first emergence of glyphosate‐resistant weed species has little initial effect on tillage practices, though by the time that eight glyphosate‐resistant weed species are identified, conservation tillage and no‐till use fall by 3.9 percentage points and 7.6 percentage points, respectively. We further find that when ten glyphosate‐resistant species are present, the predicted adoption rate of non‐glyphosate herbicides rises 50 percentage points, and that the availability of non‐glyphosate herbicides facilitates continued use of conservation tillage as glyphosate‐resistant weeds proliferate. Using a simple benefits transfer model, we conservatively estimate that between 2008 and 2016 farmers' tillage responses to the spread of glyphosate‐resistant weeds have caused water quality and climate damages via fuel emissions valued at nearly $245 million. This value does not account for climate damages due to carbon released during soil disruptions and is likely to grow as glyphosate resistance becomes more widespread and more farmers turn to tillage for supplemental weed control.
... The release of genetically modified crops resistant to highly effective and non-selective herbicides has greatly impacted weed management. Even though chemical control was the main weed control method prior to the release of transgenic crops, herbicide-resistant crops allowed farmers to rely on a single herbicide site of action to control weeds, which reduced the diversity of weed management practices and chemistries used in a crop season (Bonny 2016;Duke 2005;Mazur and Falco 1989;Owen 2016;Vencill et al. 2012). Herbicide resistance in weeds is a consequence of evolution through herbicide selection pressure. ...
... Reports of dicamba failures have been increasing in the US mid-south, specifically in Tennessee(Steckel 2020). There is an undeniable correlation between the release of herbicide-resistant crops with the increased evolution of weed resistance to the same herbicide used on such crops due to the decrease in number of chemistries used and tremendous selection pressure on weed populations(Bonny 2016;Brookes 2014).ppo2 Mutations Among Survivors. ...
Thesis
Palmer amaranth (Amaranthus palmeri S. Wats.) is one of the most problematic agronomic weeds to control in fields across Arkansas. Thus far, this species has evolved resistance to several herbicides, including protoporphyrinogen IX oxidase (PPO) inhibitors. The majority of PPO-resistant Palmer amaranth populations harbor a target-site mutation (substitution or deletion of amino acids). The objective of this thesis was to identify the level of fomesafen resistance conferred by PPO2 mutations from Palmer amaranth. The experiments conducted aimed to (1) characterize the level of resistance conferred by the transgene Palmer amaranth ppo2 carrying ΔG210 mutation into the wild type rice (Oryza sativa cv. ‘Nipponbare’); and (2) study the resistance level of Palmer amaranth plants having a single mutation (ΔG210 or G399A) or a combination. For objective 1, ‘Nipponbare’ rice was transformed with Palmer amaranth ppo2 ΔG210 gene via particle bombardment. The presence of the transgene in T0 plants was confirmed, and seeds (T1) were harvested. After selection with foliar treatment of fomesafen (0.78 kg ai ha-1), T1 plants carrying the mutation and showing low injury were maintained to produce T2 seeds. Soil-based assay was conducted with T2 seeds and the survivors were cultured to produce T3 seeds. Seeds from each surviving plant were kept as a separate line. The insertion of Palmer amaranth ppo2 ΔG210 conferred resistance to fomesafen in rice. The data suggests that only homozygous transgenic plants had full resistance to fomesafen. For objective 2, one susceptible and six resistant accessions were used to conduct dose response assay with the PPO-herbicide, fomesafen, and to test cross resistance or multiple resistance. Selected survivors from these tests were genotyped for the two expected mutations. Homozygosity of ΔG210 was correlated with high fomesafen resistance. At higher fomesafen rates, survivors carrying ΔG210 in both alleles or accumulating ΔG210+G399A recovered better than heterozygous ΔG210 plants. Populations with higher frequency of individuals with these mutation profiles were also less sensitive to the other two PPO-herbicides tested, saflufenacil and trifludimoxazin.
... Many studies note the rise of agricultural biotechnology as a key factor behind growing glyphosate use (e.g. Benbrook, 2016;Bonny, 2016). This paper makes the case that while agricultural biotechnology is certainly a key piece of the explanation, it is only part of the story of glyphosate's increasingly central role as an agricultural input. ...
... As these regulatory and market dynamics unfolded, the agricultural input firms increased their investment in technological innovations that would at least partially address the growing concerns about the chemical even while continuing to rely on it. Glyphosate resistant weeds had by this time become a major problem in the sector that the firms could not deny or ignore (Bonny, 2016). The agricultural input firms began to introduce genetically engineered crops that are resistant to the application of multiple types of herbicides, including both glyphosate and the older, more toxic herbicide dicamba, as a way to provide farmers with more options for weed management, although increased spraying of dicamba has introduced further concerns about exposure to toxic chemicals. ...
Article
The growing use of chemical herbicides for weed control has become a dominant feature of modern industrial agriculture and a major environmental and health concern in agricultural systems worldwide. This paper seeks to explain how and why glyphosate-based agricultural herbicides have become so entrenched in modern agriculture. It shows that a complex interplay among technological, market, and regulatory developments have encouraged a lock-in of glyphosate linked technologies in agricultural systems. These are: (1) the repurposing of glyphosate for use with genetically modified crops; (2) the rise of the generic glyphosate market, which globalized the chemical’s use and encouraged new agricultural uses; (3) new technologies such as digital agriculture and genome editing that interface with glyphosate use; and (4) growing corporate market power and declining public investment in agricultural research programs that constrained innovation in non-herbicide weed control technologies.
... Several studies have documented the financial burden herbicide resistance places on growers; for instance, in Georgia and Arkansas, the presence of glyphosate-resistant Palmer amaranth was found to increase management costs in cotton by $48/ha [2]. Economics are an important consideration in growers' choice of weed management strategies [1][2][3]. ...
... the proportion of farmland a grower tills? 3 Can community management provide an avenue for maintaining-or even promotingconservation tillage systems while simultaneously dealing with the threat of herbicideresistant weeds? ...
Article
Full-text available
The use of glyphosate as a replacement for tillage has been credited with spurring the adoption of conservation tillage in the United States. With herbicide-resistant weeds becoming a significant agronomic problem, however, it is unclear whether conservation tillage gains are in danger of being reversed as farmers turn to tillage to manage weeds that herbicides can no longer kill. Using 2015 focus groups, a 2016 national survey, and an ongoing Community Herbicide Resistance Management Initiative in four communities of the Pacific Northwest we assess the following questions: (1) How do U.S. farmers view tillage as an option for controlling herbicide-resistant weeds, (2) Do attitudes towards and experience with herbicide-resistant increase farmers’ usage of tillage, and (3) Can community management provide an avenue for maintaining conservation tillage while also increasing effective management of herbicide-resistant weeds? We find that many farmers consider tillage to be an emergency fail-safe in managing weeds, that there is a complex relationship between herbicide resistance awareness, concern, and tillage use that can be partly explained by experience and dedication to conservation tillage, and finally that community management has the potential to provide the support and resources necessary to prevent a large-scale increase in tillage related to herbicide resistance management.
... Evolution is a natural scenario where plant have tendency to adapt environmental changes by altering its gene and developing a better traits suitable for existing environment. Hence, not only herbicide resistance variety is product of evolutionary pattern changes (Bonny, 2016) but development of non-GM plants from the hybridization of GM plants also. Frequent use of GM crop is ultimately affecting the evolutionary pattern. ...
Chapter
Agri-biotechnological approaches have introduced an expansion of genetically modified crops (GM) which has immense potential for betterment of agricultural practices. There are several possible benefits of GM crops includes high yield thereby solving food and nutritional security, producing herbicide tolerance, insecticide resistance varieties, reducing dependency on agrochemical thus reducing formers exposure to chemicals. However, potential risk and biosafety concerns are associated directly and indirectly with it. Flow of genetic information, generation of super-weed, adverse effects on beneficial species, development of resistance verities, and adverse effects on existing biodiversity reveal its unintentional adverse impacts on environment. Several health implications such as allergenicity, genetic hazards, and toxicity to different organs are associated with it. Moreover, studies revealed its negative impacts not only in existing biodiversity but in evolutionary patterns also. However, controversial data and ill-conducted investigations are few solid limitations. A matter of high significance is to deliver existing information available along with various concerns, that is, socioeconomic, political, and ethical concerns in GM crop adaptation.
... The third advantage is that the change in the plant at the time of genetic modification enables the addition of new genes into the vegetative breeding crops like cassava (Manihot esculenta), potato (Solanum tuberosum), and banana (Musa sp.) (Dong and Ronald, 2019). It also can be used to produce higher-yielding crops under both biotic and abiotic stresses (Kissoudis et al., 2016), unaffected by pathogens and insects (Dong and Ronald, 2019), reducing the unfavorable surroundings for crop production, improves human nutrition (Zhu et al., 2013)and increased tolerance towards herbicides (Bonny, 2016). ...
Chapter
Due to the increasing human population and changing global climate, there is a need for generating high yielding and climate resilient crops using genetically engineering. Genetic engineering is one of the important processes in current day agriculture which can make sure of food safety and energy security. It can help in delivery of new enhanced characters into the crops. Conventional gene delivery systems have challenges such as low efficiency, non-specificity, limited delivery type, and limited species range. So, there is need for efficient methods producing better results by just not improving the current system but also by using new innovative methods. Nanotechnology provides a solution to the problems associated with the conventional system genetic material delivery in plants for achieving the crop improvement for sustainable agriculture. This chapter provides the current and future perspective in research for improving our understanding of genetic engineering in plants using nanotechnology. The development of novel tools as nanocarriers for the delivery of genetic materials in plants for the improvement of crop production are also anticipated here.
... Third, there could be an indirect, bottom-up effect through changes in weed abundance and composition, because weeds provide resources and habitats for a wide range of arthropods (Andow 1991;Norris & Kogan 2000). Agricultural management based on broad-spectrum herbicides as well as on herbicide-tolerant crops could decrease both the diversity and abundance of plants and impact arthropod fauna and other farmland animals (Bonny 2016;Schütte et al. 2017). In addition, arthropod communities can be altered because different herbicide treatments and tillage practices can cause weed shifts and herbicide resistance (Owen 2008). ...
... Farmers frequently mix pesticides in order to overcome weed resistance to a single herbicide. Glyphosate is increasingly applied in combination with other active ingredients such as dicamba, mesotrione, metolachlor or 2,4-D in order to mitigate herbicide-resistance in large-scale monocultures of herbicide-tolerant GM crops (Bonny 2016;Vink et al. 2012). An increasing number of studies have found that pesticides can exert effects as mixtures at concentrations, which they do not show negative health outcomes in isolation (Martin et al. 2021). ...
Preprint
Whether glyphosate-based herbicides (GBHs) are more potent than glyphosate alone at activating cellular mechanisms, which drive carcinogenesis remains controversial. As GBHs are more cytotoxic that glyphosate, we reasoned they may also be more capable of activating carcinogenic pathways. We tested this hypothesis by comparing the effects of glyphosate with Roundup GBHs both in vitro and in vivo . First, glyphosate was compared with representative GBHs namely MON 52276 (EU), MON 76473 (UK) and MON 76207 (USA) using the mammalian stem cell-based ToxTracker system. Here, MON 52276 and MON 76473, but not glyphosate and MON 76207, activated oxidative stress and unfolded protein responses. Second, molecular profiling of liver was performed in female Sprague-Dawley rats exposed to glyphosate or MON 52276 (both at 0.5, 50, 175 mg/kg bw/day glyphosate) for 90 days. MON 52276 but not glyphosate increased hepatic steatosis and necrosis. MON 52276 and glyphosate altered the expression of genes in liver reflecting TP53 activation by DNA damage and circadian rhythm regulation. Genes most affected in liver were similarly altered in kidneys. Small RNA profiling in liver showed decreased amounts of miR-22 and miR-17 from MON 52276 ingestion. Glyphosate decreased mir-30 while miR-10 levels were increased. DNA methylation profiling of liver revealed 5,727 and 4,496 differentially methylated CpG sites between the control and glyphosate and MON 52276 exposed animals respectively. Apurinic/apyrimidinic DNA damage formation in liver was increased with glyphosate exposure. Altogether, our results show that Roundup formulations cause more biological changes linked with carcinogenesis than glyphosate.
... One of them is the competition that weeds exert and the control of them, in the great majority of cases, is achieved with the timely application of herbicides, which is an extended practice (Sannino and Gianfreda, 2001;Petcu et al., 2015). The use of transgenic varieties of this glyphosate tolerant crop has helped certain regions in which this herbicide is transformed into the compound used mainly to control the growth of weeds during the crop cycle (Bonny, 2016). It is one of the most mobile herbicides through the phloem and is especially effective against perennial weeds, as it accumulates in the tissues of stems, roots and storage organs. ...
Article
The aim of this study was to estimate the correlation coefficients and slicing the phenotypic correlations into direct and indirect effects by path analysis between morphoagronomic and bromatological traits in corn hybrids for silage. Nineteen topcross hybrids and five controls were assessed in a randomized block design with four replications in two environments (Campos dos Goytacazes and Itaocara, RJ), in the 2013/2014 agricultural year. Phenotypic correlations and path analysis were estimated between morphoagronomic (average plant height; average first ear height; average stem diameter; ear yield with husk at silage point; grain yield at silage point; green mass yield) and bromatological (dry matter; crude protein; neutral detergent fiber; lignin; crude fat and mineral matter) traits. The highest correlation estimates were obtained between dry matter and crude protein and between dry matter and neutral detergent fiber, with magnitudes of 0.97 and 0.98, respectively. The coefficient of determination was high, indicating that the assessed components explain much of the variation in the dry matter content. Path analysis showed that traits with highest direct effect on dry matter content were the yield of green mass, crude protein, neutral detergent fiber, crude fat, and mineral matter associated to high correlations of 0.96, 0.97, 0.98, 0.90, and 0.96, respectively. The results showed the possibility of obtaining significant gains through indirect selection
... In contrast to traditional methods, IWM integrates several agro-ecological aspects such as the role of conservation tillage and crop rotation on weeds seed bank dynamics [10], the ability to forecast the critical period of weed interference and their competition with crops [45,46], and the specific critical levels of crops/ weeds interaction [47]. Therefore, an effective IWM must rely on a thorough knowledge of crop-weeds competition dynamics, which currently represents one of the most active research areas in weed science [48,49]. ...
Article
Full-text available
Weeds are amongst the most impacting abiotic factors in agriculture, causing important yield loss worldwide. Integrated Weed Management coupled with the use of Unmanned Aerial Vehicles (drones), allows for Site-Specific Weed Management, which is a highly efficient methodology as well as beneficial to the environment. The identification of weed patches in a cultivated field can be achieved by combining image acquisition by drones and further processing by machine learning techniques. Specific algorithms can be trained to manage weeds removal by Autonomous Weeding Robot systems via herbicide spray or mechanical procedures. However, scientific and technical understanding of the specific goals and available technology is necessary to rapidly advance in this field. In this review, we provide an overview of precision weed control with a focus on the potential and practical use of the most advanced sensors available in the market. Much effort is needed to fully understand weed population dynamics and their competition with crops so as to implement this approach in real agricultural contexts.
... One of the steps to obtain a bioherbicide from fungal metabolites is by optimizing cultivation conditions, as the quantitative and qualitative production of these molecules varies significantly according to the conditions in which the fungus is cultivated [8,13]. Another crucial step to obtain a bioherbicide is knowing its environmental toxicity. ...
Article
Full-text available
Research and commercial production of bioherbicides occur to a lesser extent compared to bioinsecticides and biofungicides. In order to contribute to developing new bioherbicides with low environmental impact, this study aimed to increase the phytotoxicity of metabolites of the fungus Mycoleptodiscus indicus UFSM 54 by optimizing solid and submerged fermentation and evaluate the ecotoxicological effects on earthworms (Eisenia andrei). The Plackett–Burman and central composite rotatable designs were used to optimize metabolite phytotoxicity. The variables optimized in the fermentation were temperature, agitation, pH, water volume in the culture medium, glucose concentration, and yeast extract. The fungus was grown on sugarcane bagasse substrate, and its metabolites were applied to detached Cucumis sativus, Conyza sp., and Sorghum bicolor leaves and used in an avoidance test and acute exposure to earthworms. Metabolite phytotoxicity in submerged fermentation was optimized at 35 °C, 50 rpm, and 1.5 g l⁻¹ of glucose and in solid fermentation at 30–37 °C and in 14–32 ml of water. The metabolites severely damaged germination, initial growth, and leaves of the three plants, and at the doses tested (maximum of 113.92 ml kg⁻¹), the metabolites of M. indicus UFSM 54 were not toxic to earthworms.
... Furthermore, glyphosate, which was once just one of many non-selective herbicides in the 1970s, rose to become the world's most widely used herbicide due to the fact that most genetically modified seeds were altered to be resistant to it 35 . As we are becoming more aware of the potential risks associated with widespread glyphosate use, including growing weed resistance to the chemical, its environmental effects, and still-debated health-related concerns, some firms are engineering seeds to be resistant to older, more toxic chemicals that bring their own risks 36 . ...
Article
What are the potential consequences when a relatively small number of large firms come to dominate markets within the global food system? This Perspective examines the implications of corporate concentration and power in the global seed and agrochemical industry, a sector that has become more consolidated in recent years. It outlines the pathways via which concentrated firms in this sector have the potential to exert power in food systems more broadly—both directly and indirectly—in ways that matter for food system outcomes. Specifically, concentrated firms can shape markets, shape technology and innovation agendas, and shape policy and governance frameworks. This Perspective makes the case that a range of measures are needed to ensure that corporate concentration and power do not undermine key goals for food systems, such as equitable livelihoods, sustainability and broad-based participation in food system governance. These include measures to strengthen competition policies, to bolster public sector support for diverse food systems, and to curb corporate influence in the policy process. Corporate concentration and power can shape markets, technology and innovation agendas, and policy and governance frameworks. Issues, implications and mitigating measures to take in food systems are discussed here using the agricultural inputs industry as an example. View here for free: https://rdcu.be/clSoo
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
This chapter examines the ethical significance of gene technology on the health and well-being of livestock, poultry and any other animal species kept for agricultural purposes. Agricultural biotechnologies include drugs and feeds developed for use on livestock, as well as genetic transformations and cloning. Key applications are reviewed and examples are given. Bernard Rollin’s early work on this topic is summarized and used as a basis for further analysis. Philosophical alternatives to Rollin’s approach to understanding the basis of human obligations to other animals are discussed, including the welfarist approach of Peter Singer and the rights approach of Tom Regan. Though not a welfarist in general, Rollin argues that impact on the welfare of the transformed animal is the sole criterion for evaluating the ethics of genetically engineered animals. Additional literature on the ethics of using genetic engineering tools on animals is reviewed, with emphasis on views laying stress on the inherent wrongness of transforming an animal’s nature, irrespective of the impact on pain, suffering or disease. Although many arguments against any and all applications of animal biotechnology are philosophically flawed, they cannot simply be dismissed. Only a more extensive philosophical debate can clarify when a genetic change in an agricultural animal’s nature is inappropriate.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Book
This 3rd edition of Food and Agricultural Biotechnology in Ethical Perspective updates Thompson’s analysis to reflect the next generation of biotechnology, including synthetic biology, gene editing and gene drives. The first two editions of this book, published as Food Biotechnology in Ethical Perspective in 1997 and 2007, were the first comprehensive philosophical studies of genetic engineering applied to food systems. The book is structured with chapter length treatments of risk in four categories: food safety, to animals, to the environment and socio-economic risks. These chapters are preceded by two chapters providing orientation to the uses of gene technology in food and agriculture, and to the goals, methods and background assumptions of technological ethics. There is also a chapter covering all four types of risk as applied to the first US technology, recombinant bovine somatotropin. The last four chapters take up 1) intellectual property debates, 2) religious, metaphysical and “intrinsic” objections to biotechnology, 3) issues in risk and trust and 4) a review of ethical issues in synthetic biology, gene editing and gene drives, the three key technologies that have emerged since the book was last revised.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
The chapter provides an analytic framework for applying classic philosophical theories of property and the distribution of property rights in the context of emerging technology. Instrumental theories of property view property as a convention that should be evaluated according to the purposes it serves. Ontological theories of property claim that holding and exchanging items of property is a natural or intrinsic feature of the human condition. The early debate over so-called Terminator seeds is used to link key philosophical questions to real disputes in policy and practice. The Terminator case illustrates distinctions between property in tangible goods (such as seeds) and intellectual property, as well as the relationship between these forms of property and the risk-based approach that is the focus of earlier chapters. The chapter reviews a sample of the literature on contested property claims in products of gene technology, and discusses how authors draw selectively on concepts from different philosophical traditions. The chapter also identifies logical flaws in many arguments, both for and against the application of intellectual property rights to GMOs and other products of gene technology. In the end, I argue that philosophical theories of property can be enlisted both to support and to criticize current practices. The chapter does not provide a conclusive standard for deciding the legitimacy of property claims in genes, sequences and gene products.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
This concluding chapter from previous editions makes recommendations that follow from the previous eleven chapters analyzing food safety, animal health, environmental and socioeconomic risks associated with agricultural and food biotechnology, as well as discussions of intellectual property rights and religious objections. Scientists and the biotechnology industry have failed to meet reasonable and justifiable expectations for an explanation and defense of their objectives in developing gene technologies for crops, livestock and food processing. Although a rationale for these applications of biotechnology exists, it has not been put forward in a manner that promotes a democratic and respectful dialog. Articulated in 1997, the chapter was a set of ethical recommendations for agricultural insiders. In retrospect, it serves as an indictment that may explain why the technology was resisted and early hopes for agrifood biotechnology remain unrealized. Looking forward, it is a contribution to the literature on public engagement with science.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
Hans Jonas’ principle of responsibility establishes a basic framework for evaluating novel technology in ethical terms. Risk assessment provides a further development of Jonas’s framework as it is applied to agrifood biotechnology. A risk-based approach consists in distinguishing four tasks for implementing technological ethics: hazard identification, exposure quantification, management and communication. The risk-based approach is effective when it operates against the background assumption that technologies passing risk-based tests are at least prima facie acceptable on ethical grounds. However, a complex of social institutions must be in place for this assumption to be valid. These institutions, combined with a risk-based assessment of the potential for unwanted consequences, constitute the presumptive case for agricultural and food biotechnology. This implies that innovators are not ethically required to demonstrate the case for their technology, and that the primary task of ethics is to focus on arguments against the technology. The chapter also discusses some logically and ethically problematic adaptations of the presumptive case.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
This chapter addresses a series of philosophical questions that arise in a general consideration of food safety risks, with specific attention to products of gene transfer. The first topic is to demonstrate the sense in which modern technology has converted what were once norms of prudence and self-interest into ethical responsibilities. The next topic is a summary review of the way that food safety experts view food safety risk, followed by a discussion of how this way of thinking is applied to products of gene transfer. From this point, the chapter summarizes a different conceptual framework that shows how the history of food science has created alternative rationalities for thinking about the risks we bear in consuming food. This alternative helps to explain why communication of risks from gene transfer have been so difficult to communicate, and explains why labeling is a component of food safety policy. The chapter concludes with a discussion of how labeling could address some of the ethical tensions created by the tension between expert and lay perspectives on the risks of consuming food.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
The chapter provides synoptic overviews on key developments in gene technology since publication of the 2nd edition in 2007. Synthetic biology is discussed briefly, and more attention is given to CRISPrCas9, and gene editing. Both techniques can increase the speed at which a new product would move through the R&D process, and both have the potential to increase systemic linkages between gene technologies for food and agriculture, and gene technology for biomedical purposes. Beyond this, lessons learned from the experience with GMOs continue to be relevant. The framework of novel and normal risk will be a useful amendment to the technological ethics framework developed in earlier editions of this book. Three case studies are discussed: alternative proteins, horizontal environmental genetic alteration agents and gene drives for agricultural pest control. Only the last of these involves truly novel risks.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
This chapter completes coverage of environmental risks begun in Chap. 6, which emphasized both the philosophical rationale for expected-value risk analysis, along with weaknesses in the way that approach has been applied to agrifood gene technology. This chapter discusses ethical objections to expected value analysis and takes up classical questions in environmental ethics. These include the basis for associating moral value with non-sentient entities such as plants, collectivities such as species or ecosystems and also for nature or the environment itself. The chapter proposes a novel approach to these problems based on the standpoint or attitude of the valuing subject. Classic approaches that stress intrinsic or instrumental valuation presume that valuation proceeds from the perspective of a spectator standing aloof from nature. Although classic approaches have not presumed that this spectator is a human being, the good of any entity derives from the spectator’s gaze. This is consistent with the notion of value as a consumption activity. In contrast, a more engaged, involved or truly environed approach can be elicited by taking the perspective of a producer. This is an especially fortuitous approach for developing an environmental ethics for agriculture and food.
... That has not been the record for GMOs, however. Bt crops, in particular, appear to have lowered risk profiles in crop production (Yaqoob et al. 2016), while even herbicide tolerant crops may have done so, though the record here is much less clear (Bonny 2016). In turning specifically to animals, however, this principle of not adding risk has more force. ...
Chapter
Metaphysical claims assert categories and categorical systems for the broadest and most general characterizations of reality and experience. The chapter discusses the nature of metaphysical claims and the role of religious or theological doctrines in lending support to them. Early debates over gene technology emphasized metaphysical and religious topics and questioned whether established doctrines in mainstream religious traditions were compatible with applications of genetic engineering. The chapter surveys those debates, with emphasis to their significance for agrifood biotechnologies, and situates them within the context of other technologies that have been alleged to pose religious or metaphysical challenges. Those who write in favor of gene technology from a religious perspective have not based their arguments on metaphysical claims. Hence, religiously metaphysical arguments tend to take a critical stance toward gene technology. However, metaphysical arguments appear to have decreased in frequency and significance since earlier editions of this book.
... Modern crop production is heavily reliant on the use of herbicides for weed management. Glyphosate is currently the most widely used herbicide in many countries around the world including South Africa (Gouse 2014;Bonny 2016;Myers et al. 2016). Initially, the use of glyphosate in agriculture was limited to clearing crop areas prior to planting or application between rows of crops for weed management (Benbrook 2016). ...
Article
Glyphosate is the most widely used herbicide in the world. In South Africa, glyphosate is predominantly used in the production of herbicide-tolerant (HT) maize and soybean. Considering that maize is a staple food and soybean an important source of protein, this study aimed to determine whether glyphosate is present in food products consumed by the general population in South Africa. Food products (81) were purchased from local supermarkets and screened for the presence of glyphosate and HT events using ELISA and real-time PCR, respectively. The majority of products contained glyphosate (66.7%) but at a level below the maximum residue limit. Glyphosate HT event(s) were detected in 70.4% of products but not associated with the presence of glyphosate in all products. This study has confirmed that South African consumers are exposed to low levels of glyphosate reported to cause genotoxic effects at the cellular level.
... El uso intensivo de glifosato en la agricultura, particularmente en el cultivo de maíz se debe a su bajo costo como consecuencia de la expiración de la patente de la formula comercial en el año 2000 (Bonny, 2016). En nuestro país surge paralelamente con la implementación de un paradigma tecnológico mundial de modernización de la agricultura bajo el enfoque de la "Revolución Verde" (Bejarano, 2017). ...
... Herbicide use, especially glyphosate, increased in soybean [Glycine max (L.) Merr.] after the introduction of glyphosatetolerant crops in 1996 (Livingston et al., 2015). Glyphosate reliance is expected to continue with the introduction of new crops with multiple herbicide-resistance genes and as solutions will continue to increase herbicide use and result in more herbicide-resistant weeds (Bonny, 2016;Heap, 2014;Mortensen et al., 2012). Researchers have been looking for more effective and efficient ways to reduce herbicide use. ...
Article
Full-text available
With over 65% of agronomic crops under no‐till in Pennsylvania, herbicides are relied on for weed management. To lessen the environmental impact and selection pressure for herbicide resistance, we conducted a nine‐year experiment to test herbicide reduction practices in a dairy crop rotation at Rock Springs, PA. The rotation included soybean (Glycine max L.) – corn (Zea mays L.) ‐ 3‐year alfalfa (Medicago sativa L.) ‐ canola (Brassica napus L.). The following practices were used to reduce herbicide inputs: i. banding residual herbicides over corn and soybean rows and using high‐residue inter‐row cultivation; ii. seeding a small grain companion crop with alfalfa; iii. plowing once in six years to terminate the perennial forage. These practices were compared with standard herbicide‐based weed management (SH) in continuous no‐till. We hypothesized: i. There would be more weed biomass in the reduced herbicide treatment (RH), ii. leading to more weeds in RH over time, but iii. the added weed pressure would not affect yield iv. or differences in net return. We sampled weed biomass in soybean, corn, and the first two forage years. In corn and soybean, weed biomass was often greater in RH than SH and increased over the years in the RH treatments. In the forage, weed biomass did not always differ between treatments. Yield and differences in net return were similar in most crops and years. Results suggest that weed management with reduced herbicide inputs supplemented with an integrated approach can be effective but may lead to more weeds over time. This article is protected by copyright. All rights reserved Weed control with banded herbicide and cultivation was less effective than broadcast herbicides. With banded herbicide plus cultivation, weed biomass increased in row crops across years. Even with more weeds, crop yield and net difference in economic returns were similar between systems. In the perennial forage, weed biomass and crop yield were similar between systems. Weeds were consistently low in the second‐year forage regardless of management.
... Of all the traits so far studied, only imazethapyr herbicide tolerance has been taken to the stage of utilization in practical breeding by introgressing this trait in a number of major varieties pertaining to the country's different rice ecosystems (Shoba et al., 2017). As development of dual herbicide-tolerant varieties is now recommended in almost all crop species to delay development of herbicide-resistant super weeds, we are in the process of testing the resources with other herbicides (Bonny, 2016;Fartyal et al., 2018). ...
Chapter
Full-text available
This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.
... Of all the traits so far studied, only imazethapyr herbicide tolerance has been taken to the stage of utilization in practical breeding by introgressing this trait in a number of major varieties pertaining to the country's different rice ecosystems (Shoba et al., 2017). As development of dual herbicide-tolerant varieties is now recommended in almost all crop species to delay development of herbicide-resistant super weeds, we are in the process of testing the resources with other herbicides (Bonny, 2016;Fartyal et al., 2018). ...
... Zira son yıllarda özellikle herbisit toleranslı kültür bitkilerinin kullanımının pestisit kullanımı üzerindeki etkileri önemli bir tartışma konusu olmuştur. Bazıları bu çeşitlerin herbisit kullanımında azalma sağladığını iddia ederken, bazıları ise tam tersini iddia etmektedir (Bonny, 2016). ...
Article
Full-text available
Weeds cause damage by competing with crops for resources such as water, nutrients, light and space. In its control, chemical control methods are preferred due to its advantages such as short-term results and ease of use. However, the problem of resistance, which arises as a result of intensive use of herbicides, has increased with the development of selective herbicides. In particular, the problem of resistance to ALS (Acetolactate synthase) inhibitor herbicides is in the first place. Imidazolinones, one of the active substances in the sulfonylurea class from the ALS inhibitor herbicide group, are widely used against narrow and broad-leaved weeds. Imidazolinones have a very broad weed spectrum that is effective even at low doses, and are herbicides with a relatively environmental profile, with low toxicity to animals, birds, fish and invertebrates. These features have enabled the development of imidazolinone-tolerant (IMI-tolerant) crops with traditional production (non-transgenic) techniques. IMI-tolerant crops mean that are tolerant to imidazolinone group herbicides. While controlling weeds in the production areas where these crops are used, it is aimed to prevent the product from being damaged. It has advantages such as low cost, better and more effective control of weeds, increasing the yield in agricultural production. However, there may be some disadvantages such as negative environmental effects due to intensive use of herbicides in the areas where IMI-tolerant plants are cultivated, gene escape to weed species related to the cultivated plant and the emergence of resistant weeds accordingly. In this review, the advantages and disadvantages of using IMI-tolerant plants in weed control are discussed.
... The application of glyphosate-based herbicides (GBHs) worldwide increased 100-fold from the late 1970s to 2016 around the world (Bonny, 2016;Myers et al., 2016). Glyphosate (Gly) is one of the most extensively used organophosphorus compounds in the world with the characteristics of non-selective and post-emergent for agricultural and non-agricultural applications (Agostini et al., 2020). ...
Article
As the two most commonly used organophosphorus herbicides, glyphosate (Gly) and glufosinate-ammonium (Glu) have unique properties for weed control and algae removal in aquaculture. However, the occurrences and health risks of Gly and Glu in aquaculture ponds are rare known. This study aimed to investigate the occurrences of Gly, AMPA (primary metabolity of Gly) and Glu in surface water, sediment and aquatic products from the grass carp (ctenopharyngodon idella), crayfish (procambarus clarkii) and crab (eriocheir sinensis) ponds around Lake Honghu, the largest freshwater lake in Hubei province, China where aquaculture has become the local pillar industry. Three age groups (children, young adults, middle-aged and elderly) exposure to these compounds through edible aquatic products (muscle) consumption were also assessed by target hazard quotient (THQ) method. The results indicated that Gly, AMPA and Glu were widely occurred in surface water, sediment and organisms in the fish, crayfish and crab ponds. AMPA was more likely to accumulate in the intestine of aquatic products than Gly and Glu. According to the total THQ value (1.04>1), muscle consumption of grass carp may pose potential risk to children.
... The appearance of superweeds involved weeds' biological traits for adaptation. It was also accompanied by governmental agricultural technicians and retailers of agrochemical products who downplayed herbicide resistance issues and were reluctant to recommend alternative methods (Bonny, 2016;Mortensen et al., 2012). The phenomenon is tightly connected to both the widespread adoption of glyphosate-dependent notillage as a promise for sustainability (Mortensen et al., 2012;Soane et al., 2012) and to policies and regulatory systems prone to favour chemical use despite knowledge of associated risks, and which continuously under-enforces pesticides' codes (Galt, 2008;Jansen, 2017;Tosun et al., 2019;Guthman, 2019). ...
Article
Full-text available
This paper presents a vegetal political ecology of weeds. Weeds have barely been analysed in the burgeoning field of ‘more-than-human’ scholarship, this despite their ubiquity and considerable impact on human social life. We review how geographical scholarship has represented weeds’ material and political status: mostly as invasive plants, annoying species in private gardens and spontaneous vegetation in urbanized landscapes. Then, bringing together weed science, agronomic science and the critical geography of agriculture, we show how weeds ecology, weeds management and the environmental problems which weeds are entangled have critically shaped the industrial agriculture paradigm. Three main arguments emerging from our analysis open up new research avenues: weeds’ disruptive character might shape our understanding of human-plant relationships; human-weeds relation in agriculture have non-trivial socio-economic and political implications; and more-than-human approaches, such as vegetal political ecology, might challenge dominant modes of considering and practicing agriculture.
... Farmers frequently mix pesticides in order to overcome weed resistance to a single herbicide. Glyphosate is increasingly applied in combination with other active ingredients such as dicamba, mesotrione, metolachlor, or 2,4-D in order to mitigate herbicide resistance in large-scale monocultures of herbicidetolerant GM crops (Bonny, 2016;Vink et al., 2012). An increasing number of studies have found that pesticides can exert effects as mixtures at concentrations, which they do not show negative health outcomes in isolation (Martin et al., 2021). ...
Article
Whether glyphosate-based herbicides (GBHs) are more potent than glyphosate alone at activating cellular mechanisms, which drive carcinogenesis remains controversial. As GBHs are more cytotoxic that glyphosate, we reasoned they may also be more capable of activating carcinogenic pathways. We tested this hypothesis by comparing the effects of glyphosate with Roundup GBHs both in vitro and in vivo. First, glyphosate was compared with representative GBHs namely MON 52276 (EU), MON 76473 (UK) and MON 76207 (USA) using the mammalian stem cell-based ToxTracker system. Here, MON 52276 and MON 76473, but not glyphosate and MON 76207, activated oxidative stress and unfolded protein responses. Second, molecular profiling of liver was performed in female Sprague-Dawley rats exposed to glyphosate or MON 52276 (both at 0.5, 50, 175 mg/kg bw/day glyphosate) for 90 days. MON 52276 but not glyphosate increased hepatic steatosis and necrosis. MON 52276 and glyphosate altered the expression of genes in liver reflecting TP53 activation by DNA damage and circadian rhythm regulation. Genes most affected in liver were similarly altered in kidneys. Small RNA profiling in liver showed decreased amounts of miR-22 and miR-17 from MON 52276 ingestion. Glyphosate decreased mir-30 while miR-10 levels were increased. DNA methylation profiling of liver revealed 5,727 and 4,496 differentially methylated CpG sites between the control and glyphosate and MON 52276 exposed animals respectively. Apurinic/apyrimidinic DNA damage formation in liver was increased with glyphosate exposure. Altogether, our results show that Roundup formulations cause more biological changes linked with carcinogenesis than glyphosate.
... Of all the traits so far studied, only imazethapyr herbicide tolerance has been taken to the stage of utilization in practical breeding by introgressing this trait in a number of major varieties pertaining to the country's different rice ecosystems (Shoba et al., 2017). As development of dual herbicide-tolerant varieties is now recommended in almost all crop species to delay development of herbicide-resistant super weeds, we are in the process of testing the resources with other herbicides (Bonny, 2016;Fartyal et al., 2018). ...
Conference Paper
Full-text available
The main goals of this study were to evaluate the agronomic performance of wheat mutant lines; to detect the effect of genotype, location and different fertilizer levels on analysed traits; to assess seed and feed quality; and to select best performing mutant lines for dual-purpose growing. Ten wheat mutant lines were sown on two loca�tions in Macedonia, for evaluation of their agronomic performance. At both locations, grain yield, straw mass, harvest index, nitrogen use efficiency, nitrogen and protein content in seed and straw, neutral detergent fibre and acid detergent fibre in the straw were determined. In order to classify the genotypes based on all analysed traits, two-way cluster analysis was applied. According to their overall performance, at both locations and with the three different fertilization treatments, the mutant lines were classified in two main groups. The first cluster con�sisted of mutants 5/1-8, 2/2-21, 4/2-56 and 2/1-51, characterized by very high values for seed yield, straw yield and harvest index, and high to moderate values for all other traits. Only 4/2-56 had very low values for N and protein content in the seed. One mutant line, 6/2-2, did not belong to any of the groups and differed from all other genotypes based on its very low seed and straw yield and very high values for nitrogen and protein content in the straw and neutral detergent fibre. All other mutants belonged to the second group, with low to moderate yield and moderate to high values for the other traits. Mutant lines with the highest seed and straw yield, as well as the best quality of seed and straw under different management systems, were identified and after additional evalu�ation will be submitted for official variety registration.
... IWM involves more complex cultivation practices and requires frequent monitoring, as is performed in organic cultivation. It requires more knowledge development of farmers and still has a higher risk of crop failure [28]. Cultivation of HT crops within an IWM system approach could have formed a good case to prevent or delay the development of herbicide resistance in weeds, but the perceived difficulty of implementation due to the inherent complexities and risks of failure for growers may have been reasons to not demand this. ...
Article
Full-text available
Breeding innovations are relevant for sustainable agricultural development and food security, as new, resilient production systems require crop varieties optimally suited for these systems. In the societal debate around genetic engineering and other plant breeding innovations, ownership of patents on the technology used in the hands of large companies is often seen as a reason that small breeding companies are denied opportunities for further improving varieties or that farmers are restricted in using such varieties. However, intellectual property (IP) systems may also be used as tools to ensure the use of good agricultural practices when cultivating the resulting varieties. This paper explores documented cases in which IP systems (plant variety rights, patents and brand names) are used to promote that innovative varieties are grown according to good agricultural practices (GAP). These include effective disease resistance management regimes in innovative crop varieties of potato in order to prevent or delay pathogens from overcoming disease resistance genes, management regimes for transgenic insect-resistant Bt or herbicide-tolerant crops to prevent the development of resistant pests or weeds, respectively. The results are discussed with respect to the influence of breeders on GAP measures through various forms of IP and the contribution and role of other stakeholders, authorities and society at large in stimulating and ensuring the use of GAP.
... In the large field of agriculture, there are many evolutionary events that could simultaneously interplay for the emergence of herbicide-resistance gene [36]. In tolerance development, various mechanisms could help the plant, such as target site overproduction, modification in intracellular herbicide compartmentation, minimal herbicide absorbance and translocation, herbicide detoxification, and insensitivity to target site [37]. ...
... Of all the traits so far studied, only imazethapyr herbicide tolerance has been taken to the stage of utilization in practical breeding by introgressing this trait in a number of major varieties pertaining to the country's different rice ecosystems (Shoba et al., 2017). As development of dual herbicide-tolerant varieties is now recommended in almost all crop species to delay development of herbicide-resistant super weeds, we are in the process of testing the resources with other herbicides (Bonny, 2016;Fartyal et al., 2018). ...
Chapter
Full-text available
This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.
... The commercialization of genetically modified crops resistant to the highly effective, non-selective herbicide glyphosate has greatly impacted weed management. Although chemical control has been the main weed control method prior to the release of herbicideresistant crops, the glyphosate-resistant technology allowed farmers to rely primarily on a single herbicide to control weeds, which reduced the diversity of weed management practices and chemistries used in a crop season [1][2][3]. Weed resistance to herbicides is the inevitable consequence of herbicide selection pressure. Relying on a single herbicide exerted tremendous selection pressure on weed populations, resulting in the evolution of many glyphosate-resistant weed species, including Amaranthus spp. ...
Article
Full-text available
In Arkansas, resistance to protoporphyrinogen IX oxidase (PPO)-inhibiting herbicides in Amaranthus palmeri S. Wats. is mainly due to target site mutations. Although A. palmeri PPO-mutations are well investigated, the cross-resistance that each ppo mutant endows to weed populations is not yet well understood. We aimed to evaluate the response of PPO-resistant A. palmeri accessions, harboring the ppo2 mutations ΔG210 and G399A, to multiple PPO-inhibiting herbicides. Six resistant and one susceptible field accessions were subjected to a dose–response assay with fomesafen, and selected survivors from different fomesafen doses were genotyped to characterize the mutation profile. The level of resistance to fomesafen was determined and a cross-resistance assay was conducted with 1 and 2 times the labeled doses of selected PPO herbicides. The accession with higher predicted dose to control 50% of the population (ED50) had a higher frequency of ΔG210-homozygous survivors. Survivors harboring both mutations, and those that were ΔG210-homozygous, incurred less injury at the highest fomesafen rate tested (1120 g ai ha−1). The populations with a high frequency of ΔG210-homozygous survivors, and those with individuals harboring ΔG210 + G399A mutations, exhibited high potential for cross-resistance to other PPO herbicides. The new PPO–herbicide chemistries (saflufenacil, trifludimoxazin) generally controlled the PPO-resistant populations.
... Similar processes have occurred in many cropping systems worldwide, including also genetically modified organisms (GMO) cropping systems where the evolution of glyphosate and glufosinate resistance has made the first herbicide-tolerant varieties less effective against all weeds, necessitating that farmers use other herbicide MOAs in addition to glyphosate and glufosinate (Beckie, 2011). This has led to the introduction of novel GMO varieties with stacked herbicide-tolerant traits able to tolerate a broader spectrum of MOAs, such as dicamba and carotenoid biosynthesis resistant crop varieties which have prompted herbicide use changes again but also promoted the further evolution of resistance against these additional MOAs (Beckie and Hall, 2014;Bonny, 2016), constituting a new process of intensification, the 'transgenic or transgene-facilitated treadmill' (Binimelis et al., 2009;Mortensen et al., 2012). Weeds will adapt to any anthropogenic activity, including herbicides (McElroy, 2014), once they are subjected to repeated and constant disturbances provoking selection pressure. ...
Article
Full-text available
Despite the wide use of herbicides in the past century, their use is decreasing due to rising resistance phenomena, absence of discovery of new modes of actions and more regulatory restrictions. On the other hand, several tactics and technologies have developed recently providing alternatives from mechanical, cultural, robotic and natural products use perspectives, that could profitably enhance weed management within the agroecosystem and usher in a new paradigm of weed management that integrates chemical and non-chemical weed management practices. In the next future, herbicide will remain an important tool for weed management and will be increasingly complemented by other innovative tactics and tools in a IWM perspective. This integrated approach would thus preserve the chemical and transgenic technology for future generations.
... On the other hand, evidence has shown long half-lives depending on soil properties and environmental conditions, and harmful effect on human, animal and ecosystem health (16). This scenario is further aggravated whether one take into account the indiscriminate and negligent use of GBHs, which promoted the emergence of glyphosate resistant weeds, and consequently, the rise in the use of these herbicides and others to control them (17,18). In this context, alarming levels of contamination exist, which is evidence by the detection of glyphosate and AMPA in different environmental matrixes such as surface waters (19), groundwaters and open-reservoir tank waters (20), rainwaters and soil (21), dust (22) and air (23). ...
Article
Full-text available
Glyphosate base herbicides (GBHs) are the most widely applied pesticides in the world and are mainly used in association with GBH-tolerant crop varieties. Indiscriminate and negligent use of GBHs has promoted the emergence of glyphosate resistant weeds, and consequently the rise in the use of these herbicides. Glyphosate, the active ingredient of all GBHs, is combined with other chemicals known as co-formulants that enhance the herbicide action. Nowadays, the safety of glyphosate and its formulations remain to be a controversial issue, as evidence is not conclusive whether the adverse effects are caused by GBH or glyphosate, and little is known about the contribution of co-formulants to the toxicity of herbicides. Currently, alarmingly increased levels of glyphosate have been detected in different environmental matrixes and in foodstuff, becoming an issue of social concern. Some in vitro and in vivo studies have shown that glyphosate and its formulations exhibit estrogen-like properties, and growing evidence has indicated they may disrupt normal endocrine function, with adverse consequences for reproductive health. Moreover, multigenerational effects have been reported and epigenetic mechanisms have been proved to be involved in the alterations induced by the herbicide. In this review, we provide an overview of: i) the routes and levels of human exposure to GBHs, ii) the potential estrogenic effects of glyphosate and GBHs in cell culture and animal models, iii) their long-term effects on female fertility and mechanisms of action, and iv) the consequences on health of successive generations.
... The spread of commercial cultivation of transgenic varieties has led to a huge increase in herbicide use worldwide, and stimulated the emergence of new herbicide-tolerant weeds, a costly challenge for farmers (Heap, 2014;Bonny, 2016;Perry et al., 2016). The widespread use of insect-resistant GM crop varieties has also stimulated the emergence of insect pest populations resistant to toxins expressed by GM varieties (Tabashnik et al., 2013;Tabashnik and Carrière, 2017). ...
Technical Report
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This synthesis summarises the results of studies on agricultural innovation that were commissioned under the DFID--ESRC Growth Research Programme in 2011 and 2015, situates these studies within the wider literature on agricultural innovation in sub-Saharan Africa, and discusses implications for policy.
Chapter
The toxicity of major herbicides on mammalian physiology is reviewed, with a focus on herbicides associated with agricultural systems employing genetically modified crops: glyphosate, 2,4-D, dicamba, glufosinate, quizalofop, sulfonylurea, imidazolinones, mesotrione, and isoxaflutole. Other products used in intensive agriculture worldwide are discussed: paraquat, atrazine, metolachlor, acetochlor, and alachlor. The frequent withdrawal of toxic ingredients creates the impression that herbicides are increasingly safe, but also implies that their initial assessment was insufficient. We highlight knowledge and technical gaps in the determination of safety thresholds: long-term effects of herbicides and their combinations at environmental levels (i.e., real-life exposure scenarios), epigenetics effects, and impacts on the gut microbiome are insufficiently tested. Most of the studies are focused on a few usual suspects (glyphosate, 2,4-D, atrazine), and the toxicology of some major herbicides remains underexplored. This amplifies the inescapable gap between the introduction of a new herbicide and the detection of its health effects.
Article
Background Glyphosate is a widely used herbicide in global agriculture. Glyphosate and its primary environmental degradate, aminomethyl phosphonic acid (AMPA), have been shown to disrupt endocrine function and induce oxidative stress in in vitro and animal studies. To our knowledge, these relationships have not been previously characterized in epidemiological settings. Elevated urinary levels of glyphosate and AMPA may be indicative of health effects caused by previous exposure via multiple mechanisms including oxidative stress. Methods Glyphosate and AMPA were measured in 347 urine samples collected between 16 and 20 weeks gestation and 24–28 weeks gestation from pregnant women in the PROTECT birth cohort. Urinary biomarkers of oxidative stress, comprising 8-isoprostane-prostaglandin-F2α (8-iso-PGF2α), its metabolite 2,3-dinor-5,6-dihydro-15-F2 t-isoprostane (8-isoprostane metabolite) and prostaglandin-F2α (PGF2α), were also measured. Linear mixed effect models assessed the association between exposures and oxidative stress adjusting for maternal age, smoking status, alcohol consumption, household income and specific gravity. Potential nonlinear trends were also assessed using tertiles of glyphosate and AMPA exposure levels. Results No significant differences in exposure or oxidative stress biomarker concentrations were observed between study visits. An interquartile range (IQR) increase in AMPA was associated with 9.5% (95% CI: 0.5–19.3%) higher 8-iso-PGF2α metabolite concentrations. Significant linear trends were also identified when examining tertiles of exposure variables. Compared to the lowest exposure group, the second and third tertiles of AMPA were significantly associated with 12.8% (0.6–26.5%) and 15.2% (1.8–30.3%) higher 8-isoprostane metabolite, respectively. An IQR increase in glyphosate was suggestively associated with 4.7% (−0.9 to 10.7%) higher 8-iso-PGF2α. Conclusions Urinary concentrations of the main environmental degradate of glyphosate, AMPA, were associated with higher levels of certain oxidative stress biomarkers. Associations with glyphosate reflected similar trends, although findings were not as strong. Additional research is required to better characterize the association between glyphosate exposure and biomarkers of oxidative stress, as well as potential downstream health consequences.
Article
Scholars with an interest in agricultural social change have a long history of studying farmer decision-making. While much of the early research was focused on identifying the individual characteristics of progressive farmers, research has evolved into examinations of the many factors that may influence different types of farm decision-making, including the use of so-called Best Management Practices. We utilize an approach for analyzing farmer decision-making that includes some possible internal and external factors for understanding how farmers are responding to the emerging crisis of herbicide-resistant weeds. Based on survey data collected onfarm managers, we contrast farmers that are using an herbicide-centric approach with those who are adopting practices associated with integrated weed management. Our findings indicate that farm decision-making is a complex process that is influenced by a variety of factors.
Chapter
Biopesticides are derived from living organisms and naturally occurring materials. These compounds are classified as biochemical, microbial and genetically derived pesticides in the form of the active ingredients. Currently, biopesticides share only about 5% i.e. $3 billion worldwide in terms of the crop protection market. Chemical pesticides are heavily deployed in commercial agriculture for the management of pests and pathogens. However, they come with unaccountable threats and poses risk to the environment as well as all the living creatures including humans. An alternative approach to limit the use of chemical pesticides would be the use of biopesticides, which have proven to be eco-friendly, comparatively safer and sustainable from several research studies. Nevertheless, with the advancements in genetics, genomics and molecular biology in the present era, the international research community has been intensively focused to determine the genetic aspects of microbial pesticides and their pragmatic use for the management of pests and pathogens. This paper reviews current technological applications on the use of biopesticides from genetics, genomics and molecular biology perspective along with future directions for the safe and sustainable management of the agricultural pests and pathogens.
Chapter
Genetically modified (GM) crops have provided plant biotechnologists with a strong option to meet the global food demand of mounting world population. However, cultivation of these crops in agrosystems and incorporation of their products into the food chain has raised several debates within the scientific community, consumers, farmers, and policymakers. Majority of these debates stem from the uncertainty about risk assessment of GM crops on human health and environment. Although these modified crops render a strong alternative against major agricultural problems of weeds, pests, and stressed environmental conditions, several independent studies have indicated that there may be new risks related to the environment and human health, for example, food allergies, antibiotic resistance, emergence of superbugs, and decline in biodiversity. Benefits of GM crops have been recognized on the global scale, however, realization of the gross abilities of this technology can only be achieved after a comprehensive risk assessment and trust-building among all the stakeholders. This chapter identifies various sectors of human health and environment that need major vigilance during assessment studies of GM crops thereby contributing toward strengthening the scientific guidelines of GM crop bio-safety.
Article
With the continuous increase in the population and the industrial sector, it has been observed that there has been a subjugation of the sources of energy along with the reduction in the repositories of fuel. Lignin is one such potential candidate to curb the issues associated with the environment along with the replacement of reservoirs of fuel based on petroleum. Lignin is extremely resistant to degradation processes which usually pass via unmodified ruminants. All together with cellulose and hemicelluloses, lignin is an important component in the arrangements of the cell wall at a minute scale and hence the formation of structures made up of lignin–carbohydrate network. Certain problems such as complex molecular structures of lignin result in difficultly during the isolation and identification approaches and hence significant issues while developing bio-refineries based on the biomass.
Article
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The shikimate pathway enzyme 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) catalyzes the reaction involved in the production of amino acids essential for plant growth and survival. Thus, EPSPS is the main target of various herbicides, including glyphosate, a broad-spectrum herbicide that acts as a competitive inhibitor of phosphoenolpyruvate (PEP), which is the natural substrate of EPSPS. However, punctual mutations in the EPSPS gene have led to glyphosate resistance in some plants. Here, we investigated the mechanism of EPSPS resistance to glyphosate in mutants of two weed species, Conyza sumatrensis (mutant, P106T) and Eleusine indica (mutant, T102I/P106S), both of which have an economic impact on industrial crops. Molecular dynamics (MD) simulations and binding free energy calculations revealed the influence of the mutations on the affinity of glyphosate in the PEP-binding site. The amino acid residues of the EPSPS protein in both species involved in glyphosate resistance were elucidated as well as other residues that could be useful for protein engineering. In addition, during MD simulations, we identified conformational changes in glyphosate when complexed with resistant EPSPS, related to loss of herbicide activity and binding affinity. Our computational findings are consistent with previous experimental results and clarify the inhibitory activity of glyphosate as well as the structural target-site resistance of EPSPS against glyphosate.
Article
This study describes the use of spray drying technology to obtain biomolecules containing powder from Diaporthe schini with herbicidal activity produced by submerged fermentation. The efficiency of the bioherbicide was tested for the post-emergence control of Bidens pilosa L., Amaranthus viridis L., Echinochloa crusgalli (L.) Beauv., and Lolium multiflorum Lam. In the first step, different additives were used and lactose was the most suitable one because it resulted in high herbicidal activity and weed suppression. In the second step, process variables were investigated, including inlet air temperature, drying air flow rate, and feed flow rate. The highest herbicidal activity was obtained with an inlet air temperature of 100 °C, and air and feed flow rates of 1.4 m³/min and 0.22 L/h, respectively. Maximum herbicidal activities were 38, 45, 21 and 18%, while weed heights reduction were 69.0, 74.3, 20.4 and 24.8% for B. pilosa, A. viridis, E. crusgalli and L. multiflorum, respectively. The bioherbicide was effective to suppress weed growth and spray drying is a promising technology for the production of solid formulations of bioherbicides.
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Agriculture is now more dependent on pesticides than ever. The value of global pesticide imports increased 3x faster in the 2000s than in the 1990s. Structural transformations in the industry – including reduced innovation, increased regulatory costs, consolidation, and a dramatic shift to generic pesticides largely produced in China – have shifted prices, supply chains and formulations. The ‘supermarket revolution’, migration, and rising labor costs are driving an increase in demand. The result is a pesticide complex that is multipolar, where commodity chains and environmental impacts are less legible, requiring a hard look at the chemical nature of agrarian capitalism.
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This paper analyses the use of metaphor in discourses around the “superweed” Palmer amaranth. Most weed scientists associated with the US public agricultural extension system dismiss the term superweed. However, together with the media, they indirectly encourage aggressive control practices by actively diffusing the framing of herbicide resistant Palmer amaranth as an existential threat that should be eradicated at any cost. We use argumentative discourse analysis to better understand this process. We analyze a corpus consisting of reports, policy briefs, and press releases produced by state extension services, as well as articles from professional and popular magazines and newspapers quoting extension specialists and/or public sector weed scientists or agronomists. We show how the superweed discourse is powered by negative metaphors, and legitimizes aggressive steps to eradicate the weed. This discourse reinforces the farmers’ techno-optimism master frame, contributes to deskilling of farmers and sidelines ethical concerns.
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The concept of genetically modified foods is becoming increasingly popular. Consumer attitude towards GMOs is influenced by various factors, including food safety, quality, and taste. This shows the dire need to understand current consumer attitudes towards GMO (genetically modified organism) products, especially since there are growing concerns locally and globally related to their health, finance, and environmental safety. Hence, the study's objective is to determine the extent to which government information influences and changes current consumer attitude of GMOs. Once consumers were “forced” to read a trusted scientific statement on the safety of GMOs, their concerns about whether it is bad for your health or caused cancer decreased significantly.
Chapter
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Genetic engineering is a molecular technique of altering the existing genome by inserting a novel gene from external. Genetically Modified Organisms (GMOs) are at the center stage of international debate because it causes many social, economic, and ecological problems. The commercialization of GMOs created more and more ethical dilemmas related to horizontal gene transfer and biodiversity. A critical analysis of genetic engineering (GE) and transgenic crops is indispensable in this situation. The science of biotechnology is essential for the advancement of human life. But the fundamental questions concerning biosafety and environment are still lingering unanswered. For example, the relationship between different genes and its traits is not so collinear as it was considered earlier. The more we know about genes the more the complexities of the gene expression. The role of regulatory genes in the expression, the combined outcome of many genetic factors, the pleiotropic effect of genes, the stable inheritance of DNA segment, the chances of escaping of genes from GMOs are questions still not responded. The influence of other epigenetic factors is also not appropriately investigated in recombinant DNA technology. The present article attempts to analyze these essential questions. The future of biotechnology lies in the development of GMOs with less environmental hazards. This is crucial as this is having a direct influence on human beings. A treatise of the debate taken place in the past 20 years concerning socio-economic, environmental, and ethical issues of genetic engineering is scrutinized in this review. The consequences of transgenics on biodiversity such as the evolution of pest and herbicide resistance and outcrossing of genes, impacts of GM crops on soil, controversies associated with the seed industry and IPR are the important arenas of discourse. The latest techniques like genome editing by altering the nucleotides and the benefits and threats of GM crops has also conversed. More advanced transgenic technologies would be required to develop successful GM plants on large scale to meet, food demands in the future. Public education about biotechnology is most important in this milieu. A new relationship between public and academics is necessary to develop research plans in plant biotechnology.
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Most of the genetically modified (GM) plants currently commercialized encompass a handful of crop species (soybean, corn, cotton and canola) with agronomic characters (traits) directed against some biotic stresses (pest resistance, herbicide tolerance or both) and created by multinational companies. The same crops with agronomic traits already on the market today will continue to be commercialized, but there will be also a wider range of species with combined traits. The timeframe anticipated for market release of the next biotech plants will not only depend on science progress in research and development (R&D) in laboratories and fields, but also primarily on how demanding regulatory requirements are in countries where marketing approvals are pending. Regulatory constraints, including environmental and health impact assessments, have increased significantly in the past decades, delaying approvals and increasing their costs. This has sometimes discouraged public research entities and small and medium size plant breeding companies from using biotechnology and given preference to other technologies, not as stringently regulated. Nevertheless, R&D programs are flourishing in developing countries, boosted by the necessity to meet the global challenges that are food security of a booming world population while mitigating climate change impacts. Biotechnology is an instrument at the service of these imperatives and a wide variety of plants are currently tested for their high yield despite biotic and abiotic stresses. Many plants with higher water or nitrogen use efficiency, tolerant to cold, salinity or water submergence are being developed. Food security is not only a question of quantity but also of quality of agricultural and food products, to be available and accessible for the ones who need it the most. Many biotech plants (especially staple food) are therefore being developed with nutritional traits, such as biofortification in vitamins and metals. The main international seed companies continue to be the largest investors in plant biotechnology R&D, and often collaborate in the developing world with public institutions, private entities and philanthropic organizations. These partnerships are particularly present in Africa. In developed countries, plant biotechnology is also used for non-food purposes, such as the pharmaceutical, biofuel, starch, paper and textile industries. For example, plants are modified to specifically produce molecules with therapeutic uses, or with an improved biomass conversion efficiency, or producing larger volumes of feedstocks for biofuels. Various plant breeding technologies are now used in the entire spectrum of plant biotechnology: transgenesis producing proteins or RNAi. Cisgenesis (transgenes isolated from a crossable donor plant) and intragenesis (transgenes originate from the same species or a crossable species), null segregants are also used. To date, the next generation precision gene editing tools are developed in basic research. They include: clustered regularly interspaced short palindromic repeats (CRISPR), oligonucleotide-directed mutagenesis (ODM), transcription activator-like effects nucleases (TALENs) and zinc-finger nuclease (ZFN).
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For more than a decade, the U.S. government has promoted integrated pest management (IPM) to advance sustainable agriculture. However, the usefulness of this practice has been questioned because of lagging implementation. There are at least two plausible rationales for the slow implementation: (1) growers are not adopting IPM—for whatever reason—and (2) current assessment methods are inadequate at assessing IPM implementation. Our research addresses the second plausibility. We suggest that the traditional approach to measuring IPM implementation on its own fails to assess the distinct, biologically hierarchical components of IPM, and instead aggregates growers' management practices into an overall adoption score. Knowledge of these distinct components and the extent to which they are implemented can inform government officials as to how they should develop targeted assistance programs to encourage broader IPM use. We address these concerns by assessing the components of IPM adoption and comparing our method to the traditional approach alone. Our results indicate that there are four distinct components of adoption—weed, insect, general, and ecosystem management—and that growers implement the first two components significantly more often than the latter two. These findings suggest that using a more nuanced measure to assess IPM adoption that expands on the traditional approach, allows for a better understanding of the degree of IPM implementation.
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More than 15 years after their first successful commercial introduction in the United States, genetically engineered (GE) seeds have been widely adopted by U.S. corn, soybean, and cotton farmers. Still, some questions persist regarding the potential benefits and risks of GE crops. The report finds that, although the pace of research and development (measured by the number of USDA-approved field tests) peaked in 2002, other measures show that biotech firms continue to develop new GE seed varieties at a rapid pace. Also, U.S. farmers continue to adopt GE seeds at a robust rate, and seed varieties with multiple (stacked) traits have increased at a very rapid rate. Insecticide use has decreased with the adoption of insect-resistant crops, and herbicide-tolerant crops have enabled the substitution of glyphosate for more toxic and persistent herbicides. However, overreliance on glyphosate and a reduction in the diversity of weed management practices have contributed to the evolution of glyphosate resistance in some weed species.
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Introduction Mechanisms of Engineering Glyphosate Resistance Development of First-Generation GR Crops Identification of at-Risk Tissues for Glyphosate Injury Development of Second-Generation GR Crops Use of Alternative Herbicides for Weed Resistance Management Engineering Crop Resistance to the Glufosinate Herbicide Engineering Crop Resistance to the Dicamba Herbicide Stacking of Herbicide-Resistant Traits Acknowledgments References
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Various indicators of pesticide environmental risk have been proposed, and one of the most widely known and used is the environmental impact quotient (EIQ). The EIQ has been criticized by others in the past, but it continues to be used regularly in the weed science literature. The EIQ is typically considered an improvement over simply comparing the amount of herbicides applied by weight. Herbicides are treated differently compared to other pesticide groups when calculating the EIQ, and therefore, it is important to understand how different risk factors affect the EIQ for herbicides. The purpose of this work was to evaluate the suitability of the EIQ as an environmental indicator for herbicides. Simulation analysis was conducted to quantify relative sensitivity of the EIQ to changes in risk factors, and actual herbicide EIQ values were used to quantify the impact of herbicide application rate on the EIQ Field Use Rating. Herbicide use rate was highly correlated with the EIQ Field Use Rating (Spearman's rho >0.96, P-value <0.001) for two herbicide datasets. Two important risk factors for herbicides, leaching and surface runoff potential, are included in the EIQ calculation but explain less than 1% of total variation in the EIQ. Plant surface half-life was the risk factor with the greatest relative influence on herbicide EIQ, explaining 26 to 28% of the total variation in EIQ for actual and simulated EIQ values, respectively. For herbicides, the plant surface half-life risk factor is assigned values without any supporting quantitative data, and can result in EIQ estimates that are contrary to quantitative risk estimates for some herbicides. In its current form, the EIQ is a poor measure of herbicide environmental impact.
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In 2005, the existence of glyphosate-resistance in Palmer amaranth was confirmed at a single 250 ha field site in Macon County, Georgia. Currently, all cotton producing counties in Georgia are infested, to some degree, with glyphosate-resistant Palmer amaranth. In 2010 and 2011, surveys were administered to Georgia growers and extension agents to determine how the development of glyphosate-resistance has affected weed management in cotton. According to respondents, the numbers of cotton acres that were treated with paraquat, glufosinate and residual herbicides effective against Palmer amaranth more than doubled between 2000 to 2005 and 2006 to 2010. Glyphosate use declined between 2000 to 2005 and 2006 to 2010 although, on average, the active ingredient was still applied to a majority of cotton acres. Although grower herbicide input costs have more than doubled following the evolution and spread of glyphosate resistance, chemically-based control of Palmer amaranth is still not adequate. As a consequence, Georgia cotton growers hand weeded 52% of the crop at an average cost of $57 per hand-weeded ha; this represents a cost increase of at least 475% as compared to the years prior to resistance. In addition to increased herbicide use and hand weeding, growers in Georgia are also using mechanical, in-crop cultivation (44% of acres), tillage for the incorporation of preplant herbicides (20% of the acres), and post-harvest deep-turning (19% of the acres every three years) for weed control. Current weed management systems are more diverse, complex and expensive than those employed only a decade ago, but are effective at controlling glyphosate-resistant Palmer amaranth in glyphosate-resistant cotton. The success of these programs may be related to producers improved knowledge about herbicide resistance, and the biological attributes that make Palmer amaranth so challenging, as well as their ability to implement their management programs in a timely manner.
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Glyphosate, known by many trade names, including Roundup, is a highly effective herbicide. Widespread glyphosate use for corn and soybean has led to glyphosate resistance, which is now documented in 14 weed species affecting U.S. cropland, and recent surveys suggest that acreage with glyphosate-resistant (GR) weeds is expanding. Data from USDA’s Agricultural Resource Management Survey (ARMS), along with the Benchmark Study (conducted independently by plant scientists), are used to address several issues raised by the spread of GR weeds. Choices made by growers that could help manage glyphosate resistance include using glyphosate during fewer years, combining it with one or more alternative herbicides, and, most importantly, not applying glyphosate during consecutive growing seasons. As a result, managing glyphosate resistance is more cost effective than ignoring it, and after about 2 years, the cumulative impact of the returns received is higher when managing instead of ignoring resistance.
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Most of the genetically modified (GM) plants currently commercialized encompass a handful of crop species (soybean, corn, cotton and canola) with agronomic characters (traits) directed against some biotic stresses (pest resistance, herbicide tolerance or both) and created by multinational companies. The same crops with agronomic traits already on the market today will continue to be commercialized, but there will be also a wider range of species with combined traits. The timeframe anticipated for market release of the next biotech plants will not only depend on science progress in research and development (R&D) in laboratories and fields, but also primarily on how demanding regulatory requirements are in countries where marketing approvals are pending. Regulatory constraints, including environmental and health impact assessments, have increased significantly in the past decades, delaying approvals and increasing their costs. This has sometimes discouraged public research entities and small and medium size plant breeding companies from using biotechnology and given preference to other technologies, not as stringently regulated. Nevertheless, R&D programs are flourishing in developing countries, boosted by the necessity to meet the global challenges that are food security of a booming world population while mitigating climate change impacts. Biotechnology is an instrument at the service of these imperatives and a wide variety of plants are currently tested for their high yield despite biotic and abiotic stresses. Many plants with higher water or nitrogen use efficiency, tolerant to cold, salinity or water submergence are being developed. Food security is not only a question of quantity but also of quality of agricultural and food products, to be available and accessible for the ones who need it the most. Many biotech plants (especially staple food) are therefore being developed with nutritional traits, such as biofortification in vitamins and metals. The main international seed companies continue to be the largest investors in plant biotechnology R&D, and often collaborate in the developing world with public institutions, private entities and philanthropic organizations. These partnerships are particularly present in Africa. In developed countries, plant biotechnology is also used for non-food purposes, such as the pharmaceutical, biofuel, starch, paper and textile industries. For example, plants are modified to specifically produce molecules with therapeutic uses, or with an improved biomass conversion efficiency, or producing larger volumes of feedstocks for biofuels. Various plant breeding technologies are now used in the entire spectrum of plant biotechnology: transgenesis producing proteins or RNAi. Cisgenesis (transgenes isolated from a crossable donor plant) and intragenesis (transgenes originate from the same species or a crossable species), null segregants are also used. To date, the next generation precision gene editing tools are developed in basic research. They include: clustered regularly interspaced short palindromic repeats (CRISPR), oligonucleo- tide-directed mutagenesis (ODM), transcription activator-like effects nucleases (TALENs) and zinc-finger nuclease (ZFN ,
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In response to the recent spread of pesticide resistant weeds and insects in Iowa, the 2013 and 2014 Iowa Farm and Rural Life Poll surveys examined farmers’ perspectives on pesticide resistance and resistance management. Findings showed that many Iowa farmers believe that they have identified pesticide resistance on the land they farm, and most are concerned that herbicide-resistant weeds and Bt-resistant insects will become a problem. They also understand that the way farmers use pest management technologies has a major impact on the rate of resistance evolution. Further, they view resistance management as a community problem involving multiple stakeholders. Overall, the findings suggests that Iowa farmers think that resistance management should be a community effort among stakeholders, and that they would support coordinated, collaborative pest management approaches.
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Background Despite the rapid adoption of genetically modified (GM) crops by farmers in many countries, controversies about this technology continue. Uncertainty about GM crop impacts is one reason for widespread public suspicion. Objective We carry out a meta-analysis of the agronomic and economic impacts of GM crops to consolidate the evidence. Data Sources Original studies for inclusion were identified through keyword searches in ISI Web of Knowledge, Google Scholar, EconLit, and AgEcon Search. Study Eligibility Criteria Studies were included when they build on primary data from farm surveys or field trials anywhere in the world, and when they report impacts of GM soybean, maize, or cotton on crop yields, pesticide use, and/or farmer profits. In total, 147 original studies were included. Synthesis Methods Analysis of mean impacts and meta-regressions to examine factors that influence outcomes. Results On average, GM technology adoption has reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%. Yield gains and pesticide reductions are larger for insect-resistant crops than for herbicide-tolerant crops. Yield and profit gains are higher in developing countries than in developed countries. Limitations Several of the original studies did not report sample sizes and measures of variance. Conclusion The meta-analysis reveals robust evidence of GM crop benefits for farmers in developed and developing countries. Such evidence may help to gradually increase public trust in this technology.
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Background There is interest in more diverse weed management tactics because of evolved herbicide resistances in important weeds in many US and Canada crop systems. While herbicide resistances in weeds is not new, the issue has become critical because of the adoption of simple, convenient and inexpensive crop systems based on genetically engineered glyphosate tolerant crop cultivars. Importantly, genetic engineering has not been a factor in rice and wheat, two globally important food crops.ResultsThere are many tactics that help mitigate herbicide resistance in weeds and should be widely adopted. Evolved herbicide resistance in key weeds has influenced a limited number of growers to include a more diverse suite of tactics to supplement existing herbicidal tactics. Most growers still emphasize herbicides often to the exclusion to alternative tactics.Conclusions Application of integrated pest management for weeds is better characterized as integrated weed management and more typically, integrated herbicide management. However, adoption of diverse weed management tactics is limited. Modifying herbicide use will not solve herbicide resistance in weeds and the relief provided by different herbicide use practices is generally short-lived at best. More diversity of tactics for weed management must be incorporated in crop systems.
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Proposition 37 would have required genetically engineered food in California to be labeled. This paper reports the results of a survey designed to determine Californians' voting intentions prior to the vote, perceptions about the prevalence of genetically engineered foods in the United States, willingness to pay for a mandatory label, and effectiveness of advocacy advertising. Overall, Californians had inaccurate knowledge about the prevalence of genetically engineered foods, and stated they were willing to pay up to 13.8% higher food costs on average for a mandatory label. Findings suggest that the effectiveness of opposition advertising was likely a formative factor in the defeat of Proposition 37.
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ABSTRACT In response to changing market dynamics, herbicide discovery has significantly declined over the past few decades, and only recently begun to modestly increase again. Although new compounds have been commercialized in recent years, none represent new modes of action. Despite the challenges, interesting molecules have been discovered and introduced, even in known and established herbicidal classes. One of the most important changes in the market is the increase in herbicide resistance. It threatens future agricultural productivity and needs to be better understood. HT (herbicide tolerant) or HR (herbicide resistant) crops have allowed new herbicide classes to be introduced into new crops. Despite the increased barriers to the introduction of new herbicides, new screening tools may offer promising leads. Adoption of diversity in crop rotations, herbicides and including non-chemical measures is a must to keep herbicides sustainable. Our industry urgently needs to supply agriculture with new, effective resistance breaking herbicides.
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Controlling herbicide resistance (HR) and its associated environmental risks is impossible without integrating social and economic science with biophysical and technology aspects. Herbicide resistance is a dynamically complex and ill-structured problem involving coupled natural human systems that defy management approaches based on simple scientific and technology applications. The existence of mobile herbicide resistance and/or herbicide tolerance traits add complexity because susceptibility to the herbicide is a resource open to all farmers, impacting the weed population. Weed scientists have extensively researched the biophysical aspects and grower perceptions of HR. They also recognize that the "tragedy of the commons" can appear when herbicide resistance is mobile across farms. However, the human structures and processes, especially private and public institutions that influence individual and group decisions about HR, have received little analysis. To start filling that gap, we discuss an integrative management approach to sustainable weed control, that addresses the social complexity of farm heterogeneity. For example, the need for a private or public collective mechanism becomes apparent to address common-pool resource (CPR) aspects when one farmer's weed control actions influence their neighbors' situations. In such conditions, sole reliance on education, technical assistance, and other incentives aimed at changing individual grower behavior likely will fail to stem the advance of HR. Social science theories can be used to enrich the understanding of human interaction with the biophysical environment and identify key actors and social change processes influencing those interactions in the case of HR. The short-run economic advantages of herbicides such as glyphosate work against social change to address HR, including the development of collective actions when mobile HR conditions exist. We discuss seven design principles that can improve the efficacy and cost of such collective approaches and draw insights from CPR approaches outside of HR.
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Conservation tillage reduces the physical movement of soil to the minimum required for crop establishment and production. When consistently practiced as a soil and crop management system, it greatly reduces soil erosion and is recognized for the potential to improve soil quality and water conservation and plant available water. Adoption of conservation tillage increased dramatically with the advent of transgenic, glyphosate-resistant crops that permitted in-season, over-the-top use of glyphosate (N-[phosphonomethyl] glycine), a broad-spectrum herbicide with very low mammalian toxicity and minimal potential for off-site movement in soil or water. Glyphosate-resistant crops are currently grown on approximately 70 million ha (173 million ac) worldwide. The United States has the most hectares (45 million ha [99 million ac]) of transgenic, glyphosate-resistant cultivars and the greatest number of hectares (46 million ha [114 million ac]) in conservation tillage. The practice of conservation tillage is now threatened by the emergence and rapid spread of glyphosate-resistant Palmer amaranth (Amaranthus palmeri [S.] Wats.), one of several amaranths commonly called pigweeds. First identified in Georgia, it now has been reported in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee. Another closely related dioecious amaranth, or pigweed, common waterhemp (Amaranthus rudis Sauer), has also developed resistance to glyphosate in Illinois, Iowa, Minnesota, and Missouri. Hundreds of thousands of conservation tillage hectares, some currently under USDA Natural Resources Conservation Service conservation program contracts, are at risk of being converted to higher-intensity tillage systems due to the inability to control these glyphosate-resistant Amaranthus species in conservation tillage systems using traditional technologies. The decline of conservation tillage is inevitable without the development and rapid adoption of integrated, effective weed control strategies. Traditional and alternative weed control strategies, such as the utilization of crop and herbicide rotation and integration of high residue cereal cover crops, are necessary in order to sustain conservation tillage practices.
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Evolution of pest resistance to pesticides is an urgent global problem with resistance recorded in at least 954 species of pests, including 546 arthropods, 218 weeds, and 190 plant pathogens. To facilitate understanding and management of resistance, we provide definitions of 50 key terms related to resistance. We confirm the broad, long-standing definition of resistance, which is a genetically based decrease in susceptibility to a pesticide, and the definition of "field-evolved resistance," which is a genetically based decrease in susceptibility to a pesticide in a population caused by exposure to the pesticide in the field. The impact of field-evolved resistance on pest control can vary from none to severe. We define "practical resistance" as field-evolved resistance that reduces pesticide efficacy and has practical consequences for pest control. Recognizing that resistance is not "all or none" and that intermediate levels of resistance can have a continuum of effects on pest control, we describe five categories of field-evolved resistance and use them to classify 13 cases of field-evolved resistance to five Bacillus thuringiensis (Bt) toxins in transgenic corn and cotton based on monitoring data from five continents for nine major pest species. We urge researchers to publish and analyze their resistance monitoring data in conjunction with data on management practices to accelerate progress in determining which actions will be most useful in response to specific data on the magnitude, distribution, and impact of resistance.
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In little over 20 yr, Palmer amaranth has risen from relative obscurity to its current status as one of the most widespread, troublesome, and economically damaging agronomic weeds in the southeastern U.S. Numerous factors have enabled Palmer amaranth to become such a dominant and difficult-to-control weed, including its rapid growth rate, high fecundity, genetic diversity, ability to tolerate adverse conditions, and its facility for evolving herbicide resistance. It is both a serious threat to several U.S. cropping systems and a fascinating model weed. In this paper, we review the growing body of literature on Palmer amaranth to summarize the current state of knowledge on the biology, agricultural impacts, and management of this weed, and we suggest future directions for research. En poco más de 20 años, Amaranthus palmeri ha salido de una relativa oscuridad a su estado actual como una de las malezas agrícolas más ampliamente distribuida, más problemática y económicamente dañina en el sureste de los Estados Unidos. Numerosos factores le han permitido a A. palmeri convertirse en una maleza tan dominante y difícil de controlar, incluyendo su rápida tasa de crecimiento, alta fecundidad, diversidad genética, habilidad para tolerar condiciones adversas, y su facilidad para evolucionar resistencia a herbicidas. Es una amenaza para varios sistemas de cultivos en los Estados Unidos, pero también es una maleza modelo fascinante. En este artículo, revisamos la cantidad creciente de literatura sobre A. palmeri para resumir el estado actual de conocimiento sobre la biología, impactos agrícolas, y manejo de esta maleza, y sugerimos futuras direcciones para su investigación.
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This article describes the nutrient and elemental composition, including residues of herbicides and pesticides, of 31 soybean batches from Iowa, USA. The soy samples were grouped into three different categories: (i) genetically modified, glyphosate-tolerant soy (GM-soy); (ii) unmodified soy cultivated using a conventional “chemical” cultivation regime; and (iii) unmodified soy cultivated using an organic cultivation regime. Organic soybeans showed the healthiest nutritional profile with more sugars, such as glucose, fructose, sucrose and maltose, significantly more total protein, zinc and less fibre than both conventional and GM-soy. Organic soybeans also contained less total saturated fat and total omega-6 fatty acids than both conventional and GM-soy. GM-soy contained high residues of glyphosate and AMPA (mean 3.3 and 5.7 mg/kg, respectively). Conventional and organic soybean batches contained none of these agrochemicals. Using 35 different nutritional and elemental variables to characterise each soy sample, we were able to discriminate GM, conventional and organic soybeans without exception, demonstrating “substantial non-equivalence” in compositional characteristics for ‘ready-to-market’ soybeans.
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Background Genetically engineered, herbicide-resistant and insect-resistant crops have been remarkable commercial successes in the United States. Few independent studies have calculated their impacts on pesticide use per hectare or overall pesticide use, or taken into account the impact of rapidly spreading glyphosate-resistant weeds. A model was developed to quantify by crop and year the impacts of six major transgenic pest-management traits on pesticide use in the U.S. over the 16-year period, 1996–2011: herbicide-resistant corn, soybeans, and cotton; Bacillus thuringiensis (Bt) corn targeting the European corn borer; Bt corn for corn rootworms; and Bt cotton for Lepidopteron insects. Results Herbicide-resistant crop technology has led to a 239 million kilogram (527 million pound) increase in herbicide use in the United States between 1996 and 2011, while Bt crops have reduced insecticide applications by 56 million kilograms (123 million pounds). Overall, pesticide use increased by an estimated 183 million kgs (404 million pounds), or about 7%. Conclusions Contrary to often-repeated claims that today’s genetically-engineered crops have, and are reducing pesticide use, the spread of glyphosate-resistant weeds in herbicide-resistant weed management systems has brought about substantial increases in the number and volume of herbicides applied. If new genetically engineered forms of corn and soybeans tolerant of 2,4-D are approved, the volume of 2,4-D sprayed could drive herbicide usage upward by another approximate 50%. The magnitude of increases in herbicide use on herbicide-resistant hectares has dwarfed the reduction in insecticide use on Bt crops over the past 16 years, and will continue to do so for the foreseeable future.
Book
Product Information. About The Product. New technologies are becoming available for managing glyphosate resistant (GR) weeds and reducing their spread. GR crop technology has revolutionized crop production in the developed world and the benefits are gradually spilling over to the developing world. In order to sustain an effective, environmentally safe herbicide such as glyphosate and the GR crop technology well in to the future, it is imperative that the issue of GR weeds be comprehensively understood. This book provides such an essential, up-to-date source of information on glyphosate resistance for researchers, extension workers, land managers, government personnel, and other decision makers. Provides comprehensive coverage of the intensely studied topic of glyphosate resistant (GR) in crops. Details the development of glyphosate resistance and how to detect and manage the problem in crops. Helps standardize global approaches to glyphosate resistance. Encompasses interdisciplinary approaches in chemistry, weed science, biochemistry, plant physiology, plant biotechnology, genetics, ecology. Includes a chapter on economic analysis of GR impact on crops.
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Despite several decades of modern weed control practices, weeds continue to be a constant threat to agricultural productivity. Herbicide-resistant weeds and weed population shifts continue to generate new challenges for agriculture. Because of weed community complexity, integrated approaches to weed management may help reduce economic effects and improve weed control practices. Integrated weed management emphasizes the combination of management techniques and scientific knowledge in a manner that considers the causes of weed problems rather than reacts to existing weed populations. The goal of weed management is the integration of the best options and tools to make cropping systems unfavorable for weeds and to minimize the effect of weeds that survive. No single practice should be considered as more than a portion of an integrated weed management strategy. The best approach may be to integrate cropping system design and weed control strategies into a comprehensive system that is environmentally and economically viable. Management decisions must also be made on a site- and time-specific basis. Considering weeds in a broader ecological and management context may lead to the use of a wider range of cultural and management practices to regulate weed communities and prevent the buildup of adapted species. This will help producers manage herbicides and other inputs in a manner that preserves their effectiveness and move weed scientists toward the development of more diverse and integrated approaches to weed management.
Article
Glyphosate can now be used for selective, post-emergence weed control ol in glyphosate-tolerant varieties of soybeans, cotton, canola and maize. It is estimated that glyphosate-tolerant soybeans in the US will account for 50-80% of the area planted by 2001. The rapid acceptance of this new technology is due to multiple factors including broad-spectrum weed control, low cost: and simplicity. The use of glyphosate has resulted in a major reduction in the use of other herbicides including the ACCase inhibitors, ALS inhibitors, and Protox inhibitors, In the short term (three to five years) this change in herbicide use patterns will continue, In the long term (five to eight years), the primary reliance on glyphosate for weed control particularly in continuous cropping or in rotations of glyphosate-tolerant crops will result in a shift in the weed spectrum toward more tolerant weed species. As a result of this shift, other herbicides will be needed to fill these weed gaps, Continuous use of glyphosate may also lead to the selection of glyphosate-resistant weed populations, as has already occurred in Australia. However, shies in the weed species' composition from highly susceptible toward more tolerant species will happen more rapidly than selection of resistance, New herbicides developed in the future will have to be extremely cost-effective to compete against glyphosate and may be geared towards controlling weeds tolerant to glyphosate, There will also be further development of new tolerant crops to other broad-spectrum, non-selective herbicides that will be able to compete direct-ly with glyphosate. (C) 2000 Society of Chemical Industry.
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There is an array of understandings of what integrated weed management (IWM) should look like; thus, it has been defined in many different ways. Some defined it as “a combination of mutually supportive technologies in order to control weeds,” while others described it as “a multi-disciplinary approach to weed control utilizing the application of numerous alternative control measures.” Regardless of the definition, in practical terms, it means developing a weed management program using a combination of preventive, cultural, mechanical, and chemical practices. It does not mean abandoning chemical weed control, but relying on it less. Much has been written about IWM in various journals and books; thus, the objective of this chapter is not necessarily to provide an existing overview of the literature of various aspects of IWM, but rather to synthetize various aspects of IWM into a package that can be utilized by those who work and live in the applied world of weed science (e.g., practitioners). A single weed control measure is not feasible due to the number of different weed species and their highly diverse life cycles and survival strategies. In addition, controlling weeds with one or two methods provides the weeds a chance to adapt to those practices. Therefore, instead of using a particular weed control method, IWM suggests the use of a mixture of control methods that minimize the economic impact of weeds. Applying the principles of IWM can reduce the use of herbicides applied to the environment and at the same time provide optimum economic returns to the producers. In essence, the development of an IWM program is based on a few general principles that can be used at any farm: (1) use agronomic practices that limit the introduction and spread of weeds (preventing weed problems before they start), (2) help the crop compete with weeds (help “choke out” weeds), and (3) use practices that keep weeds “off balance” (do not allow weeds to adapt). Combining agronomic practices based on the above principles will allow designing an IWM program for any farming operation. IWM program is not a “recipe”; it needs to be changed and adjusted to the particular farming operation not just in soybean but in any crop. The goal is to manage, not eradicate, weeds.
Since their introduction in the mid 1990s, growers adopted genetically modified (GM), herbicide resistant (HR) crop varieties quickly in the United States and they now account for most of the hectares planted to corn, soybeans, and cotton. Benefits to growers not captured in standard farm profit calculations appear to account for the popularity of HR varieties. HR crops have been credited with encouraging the adoption of conservation tillage and causing substitution to herbicides with lower toxicity and persistence in the environment. Evidence for the effect on conservation tillage is stronger than evidence for herbicide substitution. The latter has relied more on expert opinion surveys that are sometimes, but not always corroborated by careful farm-level studies. Adoption of HR crop varieties led to a dramatic reduction in the diversity of weed control tactics in U.S. agriculture and the predictable evolution of HR weeds. Grower adoption of resistance management strategies has been limited and insufficient to delay resistance. Development of crop varieties resistant to multiple herbicides is being pursued as one strategy to respond to HR weeds. Debates remain over the potential of this approach relative to a more comprehensive integrated weed management strategy to successfully delay resistance. © Springer Science+Business Media Dordrecht 2014. All rights are reserved.
Article
Glyphosate-resistant (GR) crops represent more than 80% of the 120 million ha of transgenic crops grown annually worldwide. GR crops have been rapidly adopted in soybean, maize, cotton, canola, and sugarbeet in large part because of the economic advantage of the technology, as well as the simple and superior weed control that glyphosate delivers. Furthermore, the GR crop/glyphosate technology is generally more environmentally benign than the weed management technologies that it replaced. In the Americas, except for Canada, adoption has meant continuous and intense selection pressure with glyphosate, resulting in evolution of GR weeds and shifts to weed species that are only partially controlled by glyphosate. This development is jeopardizing the benefits of this valuable technology. New transgenic crops with resistance to other herbicide classes-in some cases coupled with glyphosate resistance-will be introduced soon. If used wisely, these tools can be integrated into resistance management and prevention strategies. Greater diversity in weed management technologies is badly needed to preserve the utility of the GR crop/glyphosate technology.
Article
While crop biotechnologies deployed worldwide with herbicideresistant (HR) or insect-resistant (IR) traits have provided significant economic and environmental benefits, these benefits are threatened by the evolution of insect and weed resistance. This article examines why field-level resistance has not posed a problem for IR crops but has become a growing problem for HR crops. Key factors include compatibility of the technologies with integrated pest and weed management and the regulatory and institutional setting in which they were deployed. Transgenic crops will be more sustainably deployed if they are embedded in integrated pest and weed management with strong, outward extension linkages to farmers and backward linkages to research institutions. Public and private plant breeding can play a critical role in developing stacked traits that reduce overreliance on single chemical compounds or toxins. Extension can serve two important functions along with its traditional role of information provision: (a) facilitating farmer collective action for area-wide resistance management and (b) providing government agencies with information needed to increase the flexibility and cost-effectiveness of resistance management regulations. The article concludes by discussing some implications for resistance management in developing countries.
Article
The lack of evolution of weed resistance to the herbicide glyphosate has been considered from several perspectives. Few plant species are inherently resistant to glyphosate. Furthermore, the long history of extensive use of the herbicide has resulted in no verified instances of weeds evolving resistance under field situations. Unique properties of glyphosate such as its mode of action, metabolism, chemical structure, and lack of residual activity in soil may explain this observation. Selection for glyphosate resistance of crops using intense whole plant and cell/tissue culture techniques, including mutagenesis, has had only limited success and is unlikely to be duplicated under normal field conditions. Information obtained in the development of glyphosate-resistant crops suggests that target-site alterations that decrease the herbicidal activity of glyphosate also may lead to reduced survival of a weed. In addition, the complex manipulations that were required for the development of glyphosate-resistant crops are unlikely to be duplicated in nature to evolve glyphosate-resistant weeds.
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Commercial introduction of cultivars of soybean and cotton genetically modified with resistance to the synthetic auxin herbicides dicamba and 2,4-D will allow these compounds to be used with greater flexibility but may expose susceptible soybean and cotton cultivars to nontarget herbicide drift. From past experience, it is well known that soybean and cotton are both highly sensitive to low-dose exposures of dicamba and 2,4-D. In this study, a meta-analysis approach was used to synthesize data from over seven decades of simulated drift experiments in which investigators treated soybean and cotton with low doses of dicamba and 2,4-D and measured the resulting yields. These data were used to produce global dose–response curves for each crop and herbicide, with crop yield plotted against herbicide dose. The meta-analysis showed that soybean is more susceptible to dicamba in the flowering stage and relatively tolerant to 2,4-D at all growth stages. Conversely, cotton is tolerant to dicamba but extremely sensitive to 2,4-D, especially in the vegetative and preflowering squaring stages. Both crops are highly variable in their responses to synthetic auxin herbicide exposure, with soil moisture and air temperature at the time of exposure identified as key factors. Visual injury symptoms, especially during vegetative stages, are not predictive of final yield loss. Global dose–response curves generated by this meta-analysis can inform guidelines for herbicide applications and provide producers and agricultural professionals with a benchmark of the mean and range of crop yield loss that can be expected from drift or other nontarget exposures to 2,4-D or dicamba. Nomenclature: 2,4-D (2,4-dichlorophenoxyacetic acid); dicamba (3,6-dichloro-2-methoxy benzoic acid); glyphosate; soybean, Glycine max (L.) Merr.; cotton, Gossypium hirsutum L.
Article
For millennia, weeds have slowly evolved in response to ever-changing environments and crop production practices. Weeds are now evolving much more quickly due to consistently repeated cropping systems and intense herbicide selection pressures. Weed resistance to herbicides now threatens cropping system sustainability in several industrialized nations. Integrated weed management (IWM) provides opportunities to reduce selection pressure for weed resistance while maintaining current crop yields. Combining optimal IWM tactics that discourage weeds by minimizing disturbance (no till, direct-seeding), adopting diverse crop rotations, and attempting to preclude resource acquisition by weeds are encouraged. New research knowledge on practical IWM systems is available, but despite current and looming threats of major weed resistance, most crop producers will require greater incentives than those currently available to more-fully adopt IWM systems in the near future.
Article
Increasingly, genetically engineered (GE) crops are promoted as a ‘twenty-first century’ agricultural strategy. From trade negotiations of the Transatlantic Trade and Investment Partnership to international climate negotiations, GE crops are endorsed as a major solution to hunger and malnutrition, as well as for climate change mitigation and adaptation. This article addresses some of the central concerns that many have about GE crops, and proposes more promising, immediate alternatives.
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As US legislatures and voters continue to wrestle with GM labeling, what is at stake? Jim Kling investigates.
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GMHR crops have been cultivated in the Americas for nearly 20 years. Prior to release, regulators asked the question, “will herbicide selection pressure for evolution of HR weeds increase significantly as a result of GMHR crop cultivation?” In hindsight, they could not have imagined the rapid, widespread adoption of glyphosate-resistant (GR) crops and subsequent chain of events: surge in glyphosate usage at the expense of other herbicides, sharp drop in investment in herbicide discovery, unrelenting rise of GR and multiple-HR weed populations, and increasing herbicide use in GMHR cropping systems. In this brief review, we outline grower adoption of GMHR soybean, maize, cotton, and oilseed rape (canola) in the Americas, and their impact on herbicide-use practices for weed management. Cultivars with stacked-HR traits (e.g., glyphosate + glufosinate + dicamba or 2,4-D) will provide a short-term respite from HR weeds, but will perpetuate the chemical treadmill and selection of multiple-HR weeds. The only sustainable solution is for government or end-users of commodities to set herbicide-use reduction targets in our major field crops similar to European Union member states, and include financial incentives or penalties in agricultural programs to support this policy. Concomitantly, industry incentives must expand to improve grower adoption of best management practices for HR weeds. New or emerging technologies will provide additional tools for reactive HR weed management in the future, but their time of arrival is uncertain.
Article
Glyphosate use in the United States increased from less than 5,000 to more than 80,000 metric tons/yr between 1987 and 2007. Glyphosate is popular due to its ease of use on soybean, cotton, and corn crops that are genetically modified to tolerate it, utility in no-till farming practices, utility in urban areas, and the perception that it has low toxicity and little mobility in the environment. This compilation is the largest and most comprehensive assessment of the environmental occurrence of glyphosate and aminomethylphosphonic acid (AMPA) in the United States conducted to date, summarizing the results of 3,732 water and sediment and 1,018 quality assurance samples collected between 2001 and 2010 from 38 states. Results indicate that glyphosate and AMPA are usually detected together, mobile, and occur widely in the environment. Glyphosate was detected without AMPA in only 2.3% of samples, whereas AMPA was detected without glyphosate in 17.9% of samples. Glyphosate and AMPA were detected frequently in soils and sediment, ditches and drains, precipitation, rivers, and streams; and less frequently in lakes, ponds, and wetlands; soil water; and groundwater. Concentrations of glyphosate were below the levels of concern for humans or wildlife; however, pesticides are often detected in mixtures. Ecosystem effects of chronic low-level exposures to pesticide mixtures are uncertain. The environmental health risk of low-level detections of glyphosate, AMPA, and associated adjuvants and mixtures remain to be determined.
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Since the introduction of glyphosate-resistant (GR) crops, growers have often relied on glyphosate-only weed control programs. As a result, multiple weeds have evolved resistance to glyphosate. A 5 year study including 156 growers from Illinois, Iowa, Indiana, Nebraska, North Carolina and Mississippi in the United States was conducted to compare crop yields and net returns between grower standard weed management programs (SPs) and programs containing best management practices (BMPs) recommended by university weed scientists. The BMPs were designed to prevent or mitigate/manage evolved herbicide resistance. Weed management costs were greater for the BMP approach in most situations, but crop yields often increased sufficiently for net returns similar to those of the less expensive SPs. This response was similar across all years, geographical regions, states, crops and tillage systems. Herbicide use strategies that include a diversity of herbicide mechanisms of action will increase the long-term sustainability of glyphosate-based weed management strategies. Growers can adopt herbicide resistance BMPs with confidence that net returns will not be negatively affected in the short term and contribute to resistance management in the long term. © 2014 Society of Chemical Industry.