Mitigating crop yield losses through weed diversity

International audienc

An ecological future for weed science to sustain crop production and the environment. A review

Sustainable strategies for managing weeds are critical to meeting agriculture's potential to feed the world's population while conserving the ecosystems and biodiversity on which we depend. The dominant paradigm of weed management in developed countries is currently founded on the two principal tools of herbicides and tillage to remove weeds. However, evidence of negative environmental impacts from both tools is growing, and herbicide resistance is increasingly prevalent. These challenges emerge from a lack of attention to how weeds interact with and are regulated by the agroecosystem as a whole. Novel technological tools proposed for weed control, such as new herbicides, gene editing, and seed destructors, do not address these systemic challenges and thus are unlikely to provide truly sustainable solutions. Combining multiple tools and techniques in an Integrated Weed Management strategy is a step forward, but many integrated strategies still remain overly reliant on too few tools. In contrast, advances in weed ecology are revealing a wealth of options to manage weedsat the agroecosystem levelthat, rather than aiming to eradicate weeds, act to regulate populations to limit their negative impacts while conserving diversity. Here, we review the current state of knowledge in weed ecology and identify how this can be translated into practical weed management. The major points are the following: (1) the diversity and type of crops, management actions and limiting resources can be manipulated to limit weed competitiveness while promoting weed diversity; (2) in contrast to technological tools, ecological approaches to weed management tend to be synergistic with other agroecosystem functions; and (3) there are many existing practices compatible with this approach that could be integrated into current systems, alongside new options to explore. Overall, this review demonstrates that integrating systems-level ecological thinking into agronomic decision-making offers the best route to achieving sustainable weed management

Les plantes adventices son-telles (bio)indicatrices

National audienc

Diversified grain-based cropping systems provide long term weed control while limiting herbicide use and yield losses

International audienceAbstractIntegrated weed management encourages long-term planning and targeted use of cultural strategies coherently combined at the cropping system scale. The transition towards such systems is challenged by a belief of lower productivity and higher weed pressure. Here, we hypothesize that diversifying the crop sequence and its associated weed management tools allow long-term agronomic sustainability (low herbicide use, efficient weed control, and high productivity). Four 6-year rotations with different constraints (S2: transition from reduced tillage to no-till, chemical weeding; S3: chemical weeding; S4: typical integrated weed management system; S5: mechanical weeding) were compared to a reference (S1: 3-year rotation, systematic ploughing, chemical weeding) in terms of herbicide use, weed management, and productivity over the 2000–2017 period. Weed density was measured before and after weeding. Crop and weed biomass were sampled at crop flowering. Compared to S1, herbicide use was reduced by 46, 65, and 99% in S3, S4, and S5 respectively. Herbicide use in S2 was maintained at the same level as S1 (− 9%), due to increased weed pressure and dependence to glyphosate for weed control during the fallow period of the no-till phase. Weed biomass was low across all cropping systems (0 to 5 g of dry matter m−2) but weed dynamics were stable over the 17 years in S1 and S4 only. Compared to S1, productivity at the cropping system scale was reduced by 22% in S2 and by 33% in S3. These differences were mainly attributed to a higher proportion of crops with low intrinsic productivity in S2 and S3. Through S4’s multiperformance, we show for the first time that low herbicide use, long-term weed management, and high crop productivity can be reconciled in grain-based cropping systems provided that a diversified crop rotation integrating a diverse suite of tactics (herbicides included) is implemented

Data from: Cereal rye mulch biomass and crop density affect weed suppression and community assembly in no-till planted soybean: A species and trait-based analysis

These files contain data that Menalled et al. (2022) used to test the effects of crop density and mulch biomass on weed suppression and community assembly. The data was generated through a field experiment replicated for four site-years. In each site-year, soybean was planted at five rates from 0 to 74 seeds m-2, and five cereal rye mulch levels were established from 0 to 2 times the ambient cereal rye biomass within each site-year for 25 unique treatments. All treatments were replicated in four blocks for 100 plots per site-year. Approximately 15 weeks after soybean planting, weed biomass, soybean density, and mulch biomass were sampled in each plot. Changes in weed biomass and species abundance were used to assess weed suppression and community composition. We assessed treatment effects on weed life cycle, emergence timing, seed weight, height, and specific leaf area using trait data for each species. Results show that multi-tactic weed management can enhance weed suppression and promote the management of diverse weed functional groups. All analyses and results are reported and discussed in Menalled et al. (2022): “Cereal rye mulch biomass and crop density affect weed suppression and community assembly in no-till planted soybean.”This data is based upon research supported by the Chateaubriand Fellowship of the Office for Science & Technology of the Embassy of France in the United States. This research was also supported by the USDA National Institute of Food and Agriculture, Organic Agriculture Research and Extension Initiative project 2020-51300-32183; the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) project 1023863; and the New York State Environmental Protection Fund for the New York Soil Health Initiative, administered through the New York State Department of Agriculture and Markets Contract No. C00178GS-3000000