Wild radish (Raphanus raphanistrum L.) is a highly competitive annual broadleaf weed that significantly constrains wheat (Triticum aestivum L.) production, particularly under increasing herbicide resistance and limited chemical control options. Optimizing sowing geometry offers a practical, non-chemical approach to enhance crop competitiveness and suppress weed growth. A field study was conducted during 2022 and 2023 to evaluate the impact of different sowing geometries on R. raphanistrum suppression and wheat productivity. The experiment was arranged in a randomized complete block design with seven treatments, including broadcast sowing; line sowing at 11, 22, and 33 cm; ridge sowing (30 cm); bed sowing (60 cm); and cross sowing (22 cm). Sowing geometry significantly influenced R. raphanistrum density and biomass at all growth stages (15–45 days after sowing). Narrow spacing (11 cm) consistently resulted in the lowest weed density and biomass, while the wider 33 cm spacing resulted in the highest weed pressure. Crop growth and yield responses were consistent across years, with 11 cm line sowing producing the highest number of productive tillers (393.7 m-2), grains per spike (42.9), biological yield (15.4 t ha-1) and grain yield (6.0 t ha-1) averaged across two years. This treatment was closely followed by cross sowing (22 cm). In contrast, wider spacing (33 cm) reduced grain yield by approximately 25–30% due to increased weed competition and reduced crop competitiveness. Correlation and principal component analyses revealed a strong negative association between late-season weed biomass and wheat productivity, emphasizing the importance of sustained weed suppression during critical growth stages. Overall, narrow row spacing, particularly 11 cm line sowing, enhanced crop competitiveness, effectively suppressed R. raphanistrum, and maximized wheat yield, demonstrating its potential as an eco-friendly strategy for integrated weed management.

Seed germination responses to light influence the timing of weed emergence and management outcomes. We evaluated (1) variation in light-dependent germination among germplasm sources, (2) the relationship between primary dormancy and far-red light-enforced germination inhibition, and (3) the role of seed size in light-dependent dormancy. Between 2022 and 2025, germination of 70 kochia (Bassia scoparia [L.] A. J. Scott) populations and 49 common lambsquarters (Chenopodium album L.) accessions was evaluated under three light environments—dark, red, and far-red—for both freshly harvested and stored seed.

Bassia scoparia germination did not differ among light environments (ANOVA, P = 0.67), indicating weak photoblastic regulation at the species level. In contrast, C. album exhibited pronounced differences in light-dependent germination among accessions (P < 0.0001). Accessions with greater primary dormancy, defined as the difference between germination of freshly harvested and stored seed, exhibited stronger far-red-enforced germination inhibition, indicating coordinated regulation of dormancy depth and light sensitivity. Seed weight was not strongly associated with primary dormancy (Spearman ρ = 0.057, P = 0.11) or far-red suppression (ρ = 0.50, P = 0.06). These results indicate that variation in light-dependent dormancy and germination in C. album is governed primarily by genetic and physiological regulation of light perception rather than by seed size.

High quality bermudagrass (Cynodon dactylon [L.] Pers.) forage production is a vital component of Southeastern U.S. agriculture. Previous research indicates that environmental stresses like elevated CO2 may significantly affect crop productivity and weed competitiveness and ecological shifts. Although the effects of elevated CO2 on C4 plants like bermudagrass could be marginal, the growth, vigor, and herbicide tolerance of C3 weeds can be affected profoundly. In the final two years of a seven-year study investigating the effects of management practices and elevated CO2 levels on bermudagrass forage production, we aimed to evaluate how these treatments impacted weed competition and diversity. From 2018 to 2025, bermudagrass was grown in a coarse-textured soil bin at the USDA-ARS National Soil Dynamics Laboratory in Auburn, AL. Open-top chambers delivered either ambient or elevated CO2 (+ 200 mg kg-1), and plots were either managed annually with fertilizer and herbicide or left unmanaged. In the final two years, elevated CO2 had no significant effect on total biomass production (bermudagrass + weeds), but in unmanaged plots, elevated CO2 resulted in a significantly greater proportion of weeds. While some C4 grasses and sedges were observed in this experiment, most weed species were C3. Consequently, C3 species dominance was generally high, especially in managed plots exposed to elevated CO2. Weeds were observed and identified in all plots, but those managed with fertilizer and herbicide had a greater proportion of bermudagrass plants to weeds, as well as lower weed densities. Species diversity indices yielded significantly greater species richness under elevated CO2 conditions. Moreover, we observed greater weed diversity with elevated CO2, which was exacerbated without proper nutrient and weed management. This provides compelling evidence that substantial shifts in weed diversity could occur due to environmental change factors like elevated CO2 and the lack of a proper crop management program.

Amenity weed control remains a contentious issue, requiring a balance between maintaining plant growth below acceptable thresholds while simultaneously reducing the use of synthetic herbicides such as glyphosate. The environmental impact of three weed control methods: (1) herbicide only (glyphosate), (2) integrated weed management – IWM (maximum 50% total glyphosate active ingredient applied to (1) + mechanical and/or thermal), and (3) zero-herbicide (mechanical and/or thermal alone) were evaluated. The herbicide only method consumed the least amount of fuel, had the lowest fossil resource depletion and emitted the fewest greenhouse gases of the three methods. Aquatic ecotoxicity was potentially higher, mainly due to the secondary metabolite of glyphosate, aminomethylphosphonic acid. The weighted aquatic ecotoxicity of IWM was 28% of that of the herbicide only method. Fossil resource depletion was 24% of the zero-herbicide method but increased by a factor of 1.5 relative to the herbicide only method although the zero-herbicide method increased by a factor of 6.2 compared to the herbicide only regime. Of the zero-herbicide methods evaluated, brushing and hot foam consumed the smallest quantities of fuel. Future weed control strategies should ideally focus on combined control methods that spatially target weeds for optimum control and low environmental impact depending on location. Weed control methods for amenity and environmental impacts in urban areas as part of an IWM strategy are discussed.

Understanding how crop species or communities influence weed seed mortality could effectively build ecological weed management systems. Therefore, we examined whether perennial forage monocultures or mixtures can accelerate weed seed mortality and affect the microbial composition of seeds. We buried mesh bags containing weed seeds of either Powell amaranth (Amaranthus powellii S. Watson) or velvetleaf (Abutilon theophrasti Medick.) in perennial forage treatments consisting of monocultures and mixtures of alfalfa (Medicago sativa L.), forage chicory (Cichorium intybus L.), and orchardgrass (Dactylis glomerata L.). Throughout a 2.5-year duration, we evaluated seed mortality of both weed species and used 16S rRNA and ITS amplicon sequencing to characterize A. powellii seed bacterial and fungal composition, respectively. We found limited effects of perennial forage treatment on A. theophrasti seed mortality, as the alfalfa-chicory biculture resulted in greater seed mortality compared to the orchardgrass monoculture. However, we found no other effects of perennial forage treatment on A. theophrasti or A. powellii seed mortality, nor did forage treatment affect the composition of bacteria or fungi associated with A. powellii seeds. We also found no effect of perennial forage richness on seed mortality of either weed species. Interestingly, soil cations (Ca, Mg, and K) tended to be negatively associated with weed seed mortality. Our research provided limited evidence that perennial forage communities can vary in their ability to accelerate weed seed mortality in the soil. However, we did uncover insights into microbial communities associated with weed seeds that could be promising for further research.

Herbicide resistance in Palmer amaranth (Amaranthus palmeri S. Watson) continues to threaten the sustainability of cotton (Gossypium hirsutum L.) production in the U.S., partly because management programs often emphasize in-season suppression without sufficiently limiting the number of individuals repeatedly exposed to postemergence herbicide selection. A five-year large-plot field experiment (2019–2023) was conducted to evaluate four integrated weed management (IWM) components, zero tolerance for seedbank replenishment (ZT–SBR), occasional deep inversion tillage (Occ_DIT), cereal rye cover crop (CRCC), and dicamba-inclusive herbicide programs (Dic_inCrop), applied singly, in combination, or absent altogether in a conventional four-pass base program lacking all four components. Preemergence escapes, defined here as emerged A. palmeri surviving the residual herbicide preceding each pass, were quantified at each timing and analyzed as annual trajectories and five-year cumulative exposure (a proxy for accumulated postemergence selection). In 2024, legacy emergence was measured under unmanaged conditions. Occ_DIT strongly structured temporal trajectories, inducing an immediate low-density state (12% of the base program in Year 1) versus gradual decline without Occ_DIT (∼75% in Year 1; steep early slope), yielding markedly lower cumulative preemergence-escape pressure. Across five years, cumulative exposure was most reduced by Occ_DIT, followed by Dic_inCrop, CRCC, and ZT–SBR, with significant interactions indicating non-additive benefits. In the legacy year, main-effect incidence rate ratios (IRRs) showed substantial suppression by Dic_inCrop (IRR = 0.02), ZT–SBR (IRR = 0.02), Occ_DIT (IRR = 0.06), and CRCC (IRR = 0.24), with four-way combinations reducing emergence by >98% relative to the base program. Positive interaction IRRs reflected diminishing marginal returns near the ecological floor, not antagonism. Collectively, these results demonstrate that IWM efficacy at low weed densities is governed less by additive suppression than by how mortality is repartitioned across independent demographic bottlenecks, reinforcing the value of diversified IWM as an evolutionary risk-management strategy.

The global climate is changing, characterized by rising temperatures (projected to increase by 1.5–2 C by the end of the century) and elevated atmospheric CO2 levels (>410 ppm), which are recognized as the primary drivers of climate change. These changes significantly affect multiple aspects of weed biology, including seed germination, seedbank dynamics, photosynthesis, root growth, phenology, and biomass production, often enhancing weed growth and competitive ability by 60–90% under elevated temperature and CO2 conditions. Climate change not only modifies the biological traits of weeds but also influences the effectiveness of current management practices, including herbicide application, potentially increasing herbicide resistance. In this context, smart agriculture and artificial intelligence–based technologies offer promising tools for precise weed identification, monitoring of distribution patterns, and prediction of weed dynamics, thereby optimizing management strategies, reducing herbicide use, and improving control efficiency. Understanding climate-induced biological changes in weeds and integrating advanced technologies into management approaches are crucial for mitigating ecological threats and ensuring the sustainability of agricultural production.

Winning the battle against weeds is crucial for sustainable rice (Oryza sativa L.) production in sub-Saharan Africa (SSA), where weeds remain a leading cause of yield losses and continue to threaten the livelihoods of millions of smallholder farmers, with farms below one hectare. This review evaluates the dynamic landscape of weed control strategies by examining weed ecology, the limitations of traditional hand weeding, and the growing risks associated with overreliance on herbicides including escalating health concerns, environmental impacts, and the rapid rise of herbicide resistance. The central finding advanced in this review is that, despite the proven potential of integrated weed management (IWM) to provide sustainable and resilient weed control, its widespread adoption remains considerably low. Key barriers include weak extension services, low farmer awareness, and insufficient policy support which collectively prevent timely and effective uptake of diversified weed control strategies. While approaches such as biological control, cover cropping, crop rotation, and precision tools old promise, they remain underutilized without strong institutional backing. Drawing from case studies across the region, the review argues that IWM could deliver the most resilient and context appropriate results if embedded within robust advisory systems and supportive incentives. The paper concludes with recommendations to strengthen extension capacity, promote farmer centered innovation, and align policies to accelerate sustainable, scalable adoption of IWM across SSA.

A series of laboratory experiments was conducted to evaluate the germination ecology of buttongrass [Dactyloctenium radulans (R. Br.) P. Beauv.] for designing weed management practices in eastern Australia. Two populations (BG3 and BG4) were evaluated under varying temperature, light, salinity, water stress, residue cover, and burial depth conditions. Germination was completely inhibited at 15/5 C (alternating day/night temperature regime) but increased at high temperature regimes, reaching 90–92% at 30/20 C and remaining high (72–88%) at 35/25 C, indicating strong adaptation to warm climates. Both populations germinated well in light (12 h)/dark (12 h) conditions (87–93%), while BG3 showed a reduction (80%) in complete darkness (24 h) compared with light/dark conditions, suggesting weak positive photoblastic behaviour. Germination decreased progressively with increasing sodium chloride (NaCl) concentrations, with 50% inhibition at 40 mM NaCl, indicating moderate salt tolerance. Germination was reduced by 50% at osmotic potentials of -0.30 MPa and -0.25 MPa for BG3 and BG4 populations, respectively. Seedling emergence declined with increasing sorghum residue loads, dropping by >80% at >6 Mg ha-1, and was completely inhibited at 8 cm burial depth. These results demonstrate that D. radulans is a thermophilic, light-responsive, shallow-emerging grass capable of germinating under moderate salinity and water stress conditions, enabling persistence in semi-arid and reduced-tillage systems. High residue retention and deep burial of seeds (≥8 cm) could significantly suppress emergence, providing ecologically sustainable management options. Future studies should quantify population-level physiological variations and integrate temperature, moisture, and residue interactions into predictive emergence models to guide region-specific weed management under changing climatic conditions.

Annual bluegrass (Poa annua L.) is an extremely problematic weed in turfgrass, posing a significant challenge for turfgrass management. Injudicious use of herbicides for controlling this weed has led to resistance issues and environmental concerns. Site-specific weed control offers an opportunity to achieve effective weed control with less herbicide use, but it requires the development of a pipeline for weed detection and localization, and a path planning algorithm. To achieve this, unmanned aerial system (UAS) based RGB imagery of P. annua plants in bermudagrass turf was collected at different weed growth stages at two locations in Texas: Deer Park and College Station. A CNN (YOLO11) and a transfer (RTDETRD) model were evaluated for weed detection. The results showed that the YOLO11n model achieved the highest F1-score (0.64) and mAP@0.50 (0.68), while the RTDETRD-x model achieved the lowest F1-score (0.52) and mAP@0.50 (0.51). The geo-transformation function transforms image coordinates into a world coordinate system with centimeter-level accuracy (mean error =1.5 cm). However, the precision of the transformation depends on the quality of the orthophoto georeferencing. Additionally, the path planning algorithm showed a significant reduction (37.7%) in travel distance compared to the original weed-model-derived distance. The research highlighted the potential of UAS-based imagery for weed detection and localization in turfgrass. Further improvements are needed to enhance model performance by modifying the model architecture (e.g., input image size, hyperparameters) and evaluating its robustness across different weed growth stages and turfgrass species.

Palmer amaranth (Amaranthus palmeri S. Watson) is one of the most problematic weeds in U.S. agriculture, capable of rapidly adapting to environmental and management pressures. This study assessed temporal changes in glyphosate response in A. palmeri by comparing ED50 values, shikimic acid accumulation, and 14C-glyphosate absorption and translocation in four biotypes collected from two Georgia fields, Jones (J) and Little Jones (LJ), in 2008 and 2023. Glyphosate ED50 increased 9-fold (J08 vs. J23) and 25-fold (LJ08 vs. LJ23), indicating a marked reduction in glyphosate sensitivity between collection periods. Shikimic acid accumulation increased with glyphosate dose in all biotypes but remained substantially lower in biotypes collected in 2023, indicating reduced EPSPS inhibition. Radiolabeled assays revealed differences in early uptake, with populations collected in 2023 reaching near maximum absorption more rapidly, as reflected by shorter times to 95 percent absorption (A95), although total absorption continued to increase across all biotypes through 48 hours after treatment. Translocation patterns varied only slightly among biotypes, suggesting that changes in glyphosate response are associated more closely with altered uptake kinetics and EPSPS related mechanisms than with major reductions in systemic movement. These results demonstrate a temporal shift in glyphosate response in Georgia A. palmeri populations and highlight the importance of integrating kinetic analyses with traditional resistance metrics.