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1. Are Glyphosate‐Resistant Weeds a Threat to Conservation Agriculture? Evidence from Tillage Practices in Soybeans

   https://doi.org/10.1111/ajae.12243  

   Van Deynze, Braeden ; Swinton, Scott M. ; Hennessy, David A. ( June 2021 , American Journal of Agricultural Economics)

   null (Ed.)

   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. 

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2. PROTAC for agriculture: learning from human medicine to generate new biotechnological weed control solutions

   https://doi.org/10.1002/ps.7741  

   Leon, Ramon G. ; Bassham, Diane C. ( September 2023 , Pest Management Science)

   Weed control has relied on the use of organic and inorganic molecules that interfere with druggable targets, especially enzymes, for almost a century. This approach, although effective, has resulted in multiple cases of herbicide resistance. Furthermore, the rate of discovery of new druggable targets that are selective and with favorable environmental profiles has slowed down, highlighting the need for innovative control tools. The arrival of the biotechnology and genomics era gave hope to many that all sorts of new control tools would be developed. However, the reality is that most efforts have been limited to the development of transgenic crops with resistance to a few existing herbicides, which in fact is just another form of selectivity. Proteolysis‐targeting chimera (PROTAC) is a new technology developed to treat human diseases but that has potential for multiple applications in agriculture. This technology uses a small bait molecule linked to an E3 ligand. The 3‐dimensional structure of the bait favors physical interaction with a binding site in the target protein in a manner that allows E3 recruitment, ubiquitination and then proteasome‐mediated degradation. This system makes it possible to circumvent the need to find druggable targets because it can degrade structural proteins, transporters, transcription factors, and enzymes without the need to interact with the active site. PROTAC can help control herbicide‐resistant weeds as well as expand the number of biochemical targets that can be used for weed control. In the present article, we provide an overview of how PROTAC works and describe the possible applications for weed control as well as the challenges that this technology might face during development and implementation for field uses. © 2023 The Authors.Pest Management Sciencepublished by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

    

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3. Integrated weed management with reduced herbicides in a no‐till dairy rotation

   https://doi.org/10.1002/agj2.20757  

   Summers, Haleigh ; Karsten, Heather D. ; Curran, William ; Malcolm, Glenna M. ( June 2021 , Agronomy Journal)

   null (Ed.)

   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. 

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4. Perceived inclusivity and trust in protected area management decisions among stakeholders in Alaska

   https://doi.org/10.1002/pan3.10312  

   Goodson, Devin J. ; Riper, Carena J. ; Andrade, Riley ; Cebrián‐Piqueras, Miguel A. ; Hauber, Mark E. ( April 2022 , People and Nature)

   1. The success of conservation initiatives often depends on the inclusion of diverse stakeholder interests in the decision-making process. Yet, there is a paucity of empirical knowledge concerning the factors that explain why stakeholders do—or do not—believe that they are meaningfully represented by government agencies. 2. Our study provides insight into the relationship between trust and stakeholder perceptions of inclusivity in public land management decisions. Here, we focus on the U.S. state of Alaska, where almost two-thirds of the land area are managed by the federal government. 3. We used structural equation modelling to test whether an individual's trust and the information sources used to learn about land management positively influenced perceived inclusivity. We conceptualized trust in terms of four dimensions that reflected an individual's disposition to trust, trust in the federal government, trust in shared values and trust that agencies adhere to a moral code. 4. We found that survey respondents across the U.S. state of Alaska had a limited disposition to trust others, did not trust federal land management agencies, did not believe agencies shared their values pertaining to protected area management and did not believe that agencies adhered to a moral code. 5. Beliefs about the morality of agencies were the primary driver of perceived inclusivity in land management decisions, indicating that agencies should focus on solving problems through deliberation and discussion about moral principles rather than by force. 6. Information acquired from professional, community-based or environmental advocacy exchanges also positively influenced perceived levels of involvement among stakeholders in resource management decisions. 7. These results provide a roadmap for how land management agencies can improve public relations and work towards a model of inclusive conservation around protected areas. 

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5. Call of the wild rice: Oryza rufipogon shapes weedy rice evolution in Southeast Asia

   https://doi.org/10.1111/eva.12581  

   Vigueira, Cynthia C. ; Qi, Xinshuai ; Song, Beng‐Kah ; Li, Lin‐Feng ; Caicedo, Ana L. ; Jia, Yulin ; Olsen, Kenneth M. ( January 2018 , Evolutionary Applications)

   Agricultural weeds serve as productive models for studying the genetic basis of rapid adaptation, with weed‐adaptive traits potentially evolving multiple times independently in geographically distinct but environmentally similar agroecosystems. Weedy relatives of domesticated crops can be especially interesting systems because of the potential for weed‐adaptive alleles to originate through multiple mechanisms, including introgression from cultivated and/or wild relatives, standing genetic variation, and de novo mutations. Weedy rice populations have evolved multiple times through dedomestication from cultivated rice. Much of the genomic work to date in weedy rice has focused on populations that exist outside the range of the wild crop progenitor. In this study, we use genome‐wide SNPs generated through genotyping‐by‐sequencing to compare the evolution of weedy rice in regions outside the range of wild rice (North America, South Korea) and populations in Southeast Asia, where wild rice populations are present. We find evidence for adaptive introgression of wild rice alleles into weedy rice populations in Southeast Asia, with the relative contributions of wild and cultivated rice alleles varying across the genome. In addition, gene regions underlying several weed‐adaptive traits are dominated by genomic contributions from wild rice. Genome‐wide nucleotide diversity is also much higher in Southeast Asian weeds than in North American and South Korean weeds. Besides reflecting introgression from wild rice, this difference in diversity likely reflects genetic contributions from diverse cultivated landraces that may have served as the progenitors of these weedy populations. These important differences in weedy rice evolution in regions with and without wild rice could inform region‐specific management strategies for weed control.

    

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