Bibliography Tag: resistant weeds

Delcour et al., 2015

Delcour, Ilse, Spanoghe, Pieter, & Uyttendaele, Mieke; “Literature review: Impact of climate change on pesticide use;” Food Research International, 2015, 68, 7-15; DOI: 10.1016/j.foodres.2014.09.030.


Agricultural yields strongly depend on crop protection measures. The main purpose of pesticide use is to increase food security, with a secondary goal being increased standard of living. In view of a changing climate, not only crop yields but also pesticide use is expected to be affected. Therefore, an analysis of the detailed effect of changing climatic variables on pesticide use is conducted. Not only effects on cultivated crops, occurring pests and pesticide efficiency are considered but also implications for technological development, regulations and the economic situation are included as all of these aspects can influence pesticide use. The objective of this review is to gain insights into the specific effect of climate change on the consumer exposure caused by pesticide residues on crops. In terms of climate change, temperature increase and changes in precipitation patterns are the main pest and pathogen infection determinants. An increased pesticide use is expected in form of higher amounts, doses, frequencies and different varieties or types of products applied. Climate change will reduce environmental concentrations of pesticides due to a combination of increased volatilization and accelerated degradation, both strongly affected by a high moisture content, elevated temperatures and direct exposure to sunlight. Pesticide dissipation seems also to be benefitted by higher amounts of precipitation. To overcome this, pesticide use might be changed. An adapted pesticide use will finally impact consumer exposure at the end of the food chain. FULL TEXT

Chodhury & Saha, 2021

Choudhury, P. P., & Saha, S.; “Dynamics of pesticides under changing climatic scenario;” Environmental Monitoring and Assessment, 2021, 192(Suppl 1), 814; DOI: 10.1007/s10661-020-08719-y.


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Ziska, 2020

Ziska, Lewis H.; “Climate Change and the Herbicide Paradigm: Visiting the Future;” Agronomy, 2020, 10(12); DOI: 10.3390/agronomy10121953.


Weeds are recognized globally as a major constraint to crop production and food security. In recent decades, that constraint has been minimized through the extensive use of herbicides in conjunction with genetically modified resistant crops. However, as is becoming evident, such a stratagem is resulting in evolutionary selection for widespread herbicide resistance and the need for a reformation of current practices regarding weed management. Whereas such a need is recognized within the traditional auspices of weed science, it is also imperative to include emerging evidence that rising levels of carbon dioxide (CO2) and climatic shifts will impose additional selection pressures that will, in turn, affect herbicide efficacy. The goal of the current perspective is to provide historical context of herbicide use, outline the biological basis for CO2/climate impacts on weed biology, and address the need to integrate this information to provide a long-term sustainable paradigm for weed management. FULL TEXT

Vilà et al., 2021

Vilà, Montserrat, Beaury, Evelyn M., Blumenthal, Dana M., Bradley, Bethany A., Early, Regan, Laginhas, Brittany B., Trillo, Alejandro, Dukes, Jeffrey S., Sorte, Cascade J. B., & Ibáñez, Inés; “Understanding the combined impacts of weeds and climate change on crops;” Environmental Research Letters, 2021, 16(3); DOI: 10.1088/1748-9326/abe14b.


Crops worldwide are simultaneously affected by weeds, which reduce yield, and by climate change, which can negatively or positively affect both crop and weed species. While the individual effects of environmental change and of weeds on crop yield have been assessed, the combined effects have not been broadly characterized. To explore the simultaneous impacts of weeds with changes in climate-related environmental conditions on future food production, we conducted a meta-analysis of 171 observations measuring the individual and combined effects of weeds and elevated CO2, drought or warming on 23 crop species. The combined effect of weeds and environmental change tended to be additive. On average, weeds reduced crop yield by 28%, a value that was not significantly different from the simultaneous effect of weeds and environmental change (27%), due to increased variability when acting together. The negative effect of weeds on crop yield was mitigated by elevated CO2 and warming, but added to the negative effect of drought. The impact of weeds with environmental change was also dependent on the photosynthetic pathway of the weed/crop pair and on crop identity. Native and non-native weeds had similarly negative effects on yield, with or without environmental change. Weed impact with environmental change was also independent of whether the crop was infested with a single or multiple weed species. Since weed impacts remain negative under environmental change, our results highlight the need to evaluate the efficacy of different weed management practices under climate change. Understanding that the effects of environmental change and weeds are, on average, additive brings us closer to developing useful forecasts of future crop performance. FULL TEXT

Qu et al., 2021

Qu, R. Y., He, B., Yang, J. F., Lin, H. Y., Yang, W. C., Wu, Q. Y., Li, Q. X., & Yang, G. F.; “Where are the New Herbicides?;” Pest Management Science, 2021; DOI: 10.1002/ps.6285.


Herbicide resistance has become one of the foremost problems in crop production worldwide. New herbicides are required to manage weeds that have evolved resistance to the existing herbicides. However, relatively few herbicides with new modes of action (MOAs) have been discovered in the past two decades. Therefore, the discovery of new herbicides (i.e., new chemical classes or MOAs) remains a primary but ongoing strategy to overcome herbicide resistance and ensure crop production. In this mini-review, starting with the inherent characteristics of the target proteins and the inhibitor structures, we propose two strategies for the rational design of new herbicides and one computational method for the risk evaluation of target mutation-conferred herbicide resistance. The information presented here may improve the utilization of known targets and inspire the discovery of herbicides with new targets. We believe that these strategies may trigger the sustainable development of herbicides in the future.

Vencill et al., 2017

Vencill, William K., Nichols, Robert L., Webster, Theodore M., Soteres, John K., Mallory-Smith, Carol, Burgos, Nilda R., Johnson, William G., & McClelland, Marilyn R.; “Herbicide Resistance: Toward an Understanding of Resistance Development and the Impact of Herbicide-Resistant Crops;” Weed Science, 2017, 60(SP1), 2-30; DOI: 10.1614/ws-d-11-00206.1.


Development of herbicide-resistant crops has resulted in significant changes to agronomic practices, one of which is the adoption of effective, simple, low-risk, crop-production systems with less dependency on tillage and lower energy requirements. Overall, the changes have had a positive environmental effect by reducing soil erosion, the fuel use for tillage, and the number of herbicides with groundwater advisories as well as a slight reduction in the overall environmental impact quotient of herbicide use. However, herbicides exert a high selection pressure on weed populations, and density and diversity of weed communities change over time in response to herbicides and other control practices imposed on them. Repeated and intensive use of herbicides with the same mechanisms of action (MOA; the mechanism in the plant that the herbicide detrimentally affects so that the plant succumbs to the herbicide; e.g., inhibition of an enzyme that is vital to plant growth or the inability of a plant to metabolize the herbicide before it has done damage) can rapidly select for shifts to tolerant, difficult-to-control weeds and the evolution of herbicide-resistant weeds, especially in the absence of the concurrent use of herbicides with different mechanisms of action or the use of mechanical or cultural practices or both. The purpose of this paper is to introduce the basic tenets of weed management, to define herbicide resistance and tolerance and how they affect crop production and are affected by management practices, and to present the environmental impacts of herbicide-resistant crops. This paper will summarize aspects of herbicide resistance in five different sections: (1) a description of basic weed science management practices and concepts, (2) definitions of resistance and tolerance in weed science, (3) environmental impacts of herbicide-resistant crops, (4) strategies for management of weed species shifts and herbicide-resistant weeds and adoption by the agricultural community, and (5) gene-flow potential from herbicide-resistant crops. FULL TEXT

Powles and Gaines, 2017

Powles, Stephen B., & Gaines, Todd A.; “Exploring the Potential for a Regulatory Change to Encourage Diversity in Herbicide Use;” Weed Science, 2017, 64(SP1), 649-654; DOI: 10.1614/ws-d-15-00070.1.


An overreliance on herbicides in several important grain- and cotton-producing regions of the world has led to the widespread evolution of herbicide-resistant weed populations. Of particular concern are weed populations that exhibit simultaneous resistance to multiple herbicides (MHR). Too often, herbicides are the only tool used for weed control. We use the term herbicide-only syndrome (HOS) for this quasi-addiction to herbicides. Growers and their advisers focus on herbicide technology, unaware of or ignoring basic evolutionary principles or the necessary diversity provided by other methods of weed control. Diversity in weed control practices disrupts resistance evolution. Significant challenges exist to implementing diversity, including how to address information so that producers choose to alter existing behaviors (HOS) and take calculated risks by attempting new and more complex strategies. Herbicide resistance management in the long term will require creativity in many sectors, including roles for growers, industry, researchers, consultants, retailers, and regulators. There can be creativity in herbicide registration and regulation, as exemplified by the recent U.S. Environmental Protection Agency program that encourages herbicide registrants to register products in minor crops. We propose one idea for a regulatory incentive to enable herbicide registrants in jurisdictions such as the United States to receive an extended data exclusivity period in exchange for not developing one new herbicide in multiple crops used together in rotation, or for implementing stewardship practices such as robust mixtures or limitations on application frequency. This incentive would provide a mechanism to register herbicides in ways that help to ensure herbicide longevity. Approaches based only on market or financial incentives have contributed to the current situation of widespread MHR. Our suggestion for regulatory creativity is one way to provide both financial and biological benefits to the registering company and to the overall stakeholder community by incentivizing good resistance management. FULL TEXT

Manalil et al, 2017

Manalil, Sudheesh, Busi, Roberto, Renton, Michael, & Powles, Stephen B.; “Rapid Evolution of Herbicide Resistance by Low Herbicide Dosages;” Weed Science, 2017, 59(2), 210-217; DOI: 10.1614/ws-d-10-00111.1.


Herbicide rate cutting is an example of poor use of agrochemicals that can have potential adverse implications due to rapid herbicide resistance evolution. Recent laboratory-level studies have revealed that herbicides at lower-than-recommended rates can result in rapid herbicide resistance evolution in rigid ryegrass populations. However, crop-field-level studies have until now been lacking. In this study, we examined the impact of low rates of diclofop on the evolution of herbicide resistance in a herbicide-susceptible rigid ryegrass population grown either in a field wheat crop or in potted plants maintained in the field. Subsequent dose–response profiles indicated rapid evolution of diclofop resistance in the selected rigid ryegrass lines from both the crop-field and field pot studies. In addition, there was moderate level of resistance in the selected lines against other tested herbicides to which the population has never been exposed. This resistance evolution was possible because low rates of diclofop allowed substantial rigid ryegrass survivors due to the potential in this crosspollinated species to accumulate all minor herbicide resistance traits present in the population. The practical lesson from this research is that herbicides should be used at the recommended rates that ensure high weed mortality to minimize the likelihood of minor herbicide resistance traits leading to rapid herbicide resistance evolution. FULL TEXT

Bonny, 2011

Bonny, Sylvie; “Herbicide-tolerant Transgenic Soybean over 15 Years of Cultivation: Pesticide Use, Weed Resistance, and Some Economic Issues. The Case of the USA;” Sustainability, 2011, 3(9), 1302-1322; DOI: 10.3390/su3091302.


Genetically modified (GM) herbicide-tolerant (HT) crops have been largely adopted where they have been authorized. Nevertheless, they are fiercely criticized by some, notably because of the herbicide use associated with them. However, how much herbicide is applied to GMHT crops compared to conventional crops, and what impacts does the use of herbicide have? The paper first presents some factors explaining the predominance of GMHT crops. Then, trends in the use of herbicide for GM crops are studied in the case of the most widespread HT crop: HT soybean in the USA. The trends in the toxicity of herbicides applied to HT soybean are also addressed, as well as the appearance of glyphosate-resistant (GR) weeds. Lastly, the paper examines the spread of GR weeds and its impact. How are farmers, weed scientists, and the industry coping with this development, and what are the prospects of glyphosate-tolerant crops given weed resistance? In conclusion, some issues of sustainability and innovation governance raised by genetically modified herbicide-tolerant crops are discussed.  FULL TEXT

Beckie, 2017

Beckie, Hugh J.; “Herbicide-Resistant Weeds: Management Tactics and Practices;” Weed Technology, 2017, 20(3), 793-814; DOI: 10.1614/wt-05-084r1.1.


In input-intensive cropping systems around the world, farmers rarely proactively manage weeds to prevent or delay the selection for herbicide resistance. Farmers usually increase the adoption of integrated weed management practices only after herbicide resistance has evolved, although herbicides continue to be the dominant method of weed control. Intergroup herbicide resistance in various weed species has been the main impetus for changes in management practices and adoption of cropping systems that reduce selection for resistance. The effectiveness and adoption of herbicide and nonherbicide tactics and practices for the proactive and reactive management of herbicide-resistant (HR) weeds are reviewed. Herbicide tactics include sequences and rotations, mixtures, application rates, site-specific application, and use of HR crops. Nonherbicide weed-management practices or nonselective herbicides applied preplant or in crop, integrated with less-frequent selective herbicide use in diversified cropping systems, have mitigated the evolution, spread, and economic impact of HR weeds. FULL TEXT