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.

Planting-green (PG), the practice of planting the cash crop into a living cover crop (CC), offers opportunities to maximize CC biomass and weed suppression. The objectives of this study were to evaluate the effects of cereal rye (Secale cerale L.) termination timing and herbicide programs under PG management on cereal rye biomass, Palmer amaranth (Amaranthus palmeri S. Watson) suppression and seed production, corn (Zea mays L.) yield, and economic returns. Field experiments were conducted during 2023–2025 under irrigated conditions in south central Nebraska. The study used a split-plot design, a no cover crop (NCC) and five cereal rye CC termination timings (at planting, emergence, V1, V2, and V3 corn growth stages) as the main plot factor and four herbicide programs [nontreated, pre-emergence (PRE) only (PRE-only), post-emergence only (POST-only), and preemergence followed by postemergence (PP)] herbicide as sub-plot factors. Delaying cereal rye termination from corn planting up to V3 corn growth stage increased cereal rye biomass from 5,992 to 10,888 kg ha–1 in 2024 and from 2,941 to 7,007 kg ha–1 in 2025. Cereal rye terminated at V2 or V3 corn growth stage reduced A. palmeri density, biomass, and seed production by >99% compared with the NCC. Following high biomass conditions, cereal rye provided comparable A. palmeri suppression to herbicide-based programs, and the additional herbicide use offered limited benefit. In contrast, following low-cereal rye biomass conditions (<6,000 kg ha–1), herbicide inclusion remained essential to achieve effective A. palmeri control and minimizing seed production. Corn yield was not affected by delayed cereal rye termination (ranging from 13,110–15,660 kg ha–1). Economic analysis indicated that integrating cereal rye CC with reduced herbicide programs (preemergence-only or POST-only) maintained profitability ($2,064–$2,364 ha–1) comparable to the NCC system with PP herbicide program ($2,353–$2,401 ha–1).

Corn poppy (Papaver rhoeas L.) is a problematic weed in cereal farms in Ireland, necessitating continuous herbicide use to protect crop yields. In 2022, poor control with acetolactate synthase (ALS) inhibitors and auxin-mimic herbicides was reported by growers/advisors in two resistance-suspect populations, namely PAPRH-R1 and PAPRH-R2. In this study, we quantified their resistance to both herbicide modes of action and investigated the underlying mechanisms. ALS inhibitor dose-response experiments revealed that both populations had ED50 and GR50 resistance indices (RI) above 120 to thifensulfuron + tribenuron, mesosulfuron + iodosulfuron + amidosulfuron and metsulfuron, and values of 4-13 to florasulam + pyroxsulam. Results of 2,4-D dose-response assays revealed higher resistance in PAPRH-R2 (ED50 and GR50 RI >9.1) than PAPRH-R1 (ED50 and GR50 RI >3.4). ALS gene sequencing detected Pro-197 mutations in all sequenced plants from both resistant populations. Pre-treatment with piperonyl butoxide (PBO, a cytochrome P450 inhibitor) reversed 2,4-D resistance with GR50, the more sensitive response parameter, decreasing from 680.8 to 84.9 g ha-1 in PAPRH-R1, and from 2508.9 to 456.8 g ha-1 in PAPRH-R2, both well below the recommended label rate of 1000 g ha-1. 14C-2,4-D assays ruled out reduced absorption or translocation as resistance mechanisms. Sensitivity screening further revealed incomplete control with other post-emergence foliar herbicides tested at half and full recommended label rates, except for fluroxypyr + halauxifen, which provided complete control of PAPRH-R1 at the full rate, and glyphosate, which provided complete control of PAPRH-R1 and PAPRH-R2 at both rates. This is the first report of multiple resistance in P. rhoeas in Ireland, involving ALS target-site mutations and likely P450-mediated 2,4-D metabolism. As cultural/non-chemical control of broad-leaved species is difficult, the continued availability of pre-emergence or autumn residual herbicides, together with effective auxin-mimics and stewardship practices, will remain essential for managing these species, including P. rhoeas, in cereal crops.

Italian ryegrass [Lolium perenne ssp. multiflorum (Lam.)] Husnot]; referred as L. multiflorum throughout the manuscript hereafter) is one of the most problematic grass weeds infesting agronomic and specialty crops across the United States. In 2023–2025, inadequate control of L. multiflorum populations (NY_R1, NY_R2, and NY_R3) with glyphosate was reported in Livingston, Ontario, and Genesee Counties, New York (NY). This research aimed to (1) confirm and quantify glyphosate resistance in these suspected glyphosate-resistant (GR) populations, (2) evaluate the efficacy of alternative postemergence herbicides, and (3) determine whether EPSPS gene amplification confers glyphosate resistance. A known glyphosate-susceptible (GS) population (AR_S) from Arkansas was included for comparison. Glyphosate dose–response assays indicated that NY_R1, NY_R2, and NY_R3 populations were 13-, 4-, and 5-fold resistant, respectively, relative to the AR_S population. Alternative postemergence herbicides, including clethodim, glufosinate, paraquat, and pinoxaden, provided 96 to 97% control and reduced shoot dry weight by 91 to 97% at 21 days after treatment (DAT). In contrast, nicosulfuron provided reduced control (63 to 74%) and limited biomass reduction (51 to 56%), suggesting possible resistance to acetolactate synthase (ALS)-inhibiting herbicides in three tested populations. Quantitative PCR analysis revealed that NY_R1 and NY_R3 had approximately 30-fold higher EPSPS gene copy numbers than AR_S, indicating gene amplification as a mechanism of glyphosate resistance. This study confirms the first case of GR L. multiflorum associated with EPSPS gene amplification in NY, underscoring the need for integrated, diversified weed management strategies to mitigate its further spread.

Effective weed management is critical to the long-term productivity of organic grain cropping systems. The Cornell Organic Cropping Systems Experiment was initiated in 2005 at the Musgrave Research Farm in Aurora, NY to compare four organic cropping systems that differed primarily in intensity of mechanical weed management and soil nutrient inputs. A three-year rotation of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and spelt (Triticum spelta L.)/red clover (Trifolium pratense L.) was grown in all systems. The four systems were characterized by High Fertility (red clover green manure, composted poultry manure, and commercial organic fertilizer to reach recommended fertility levels), Low Fertility (no fertility inputs other than the red clover and starter fertilizer for corn), Enhanced Weed Management (fertility management as in Low Fertility with additional tillage and cultivation and a higher spelt seeding density), and Reduced Tillage (primarily ridge tillage with different green manure crops). The experiment included two crop rotation entry points, enabling two of the three crops in the rotation to be grown every year. Results from the first two rotation cycles show that, in most cases, weed abundance and diversity increased during the transition to organic production, especially in the Reduced Tillage system. Perennial weeds increased in corn and soybean in the Reduced Tillage system in the second rotation cycle, which contributed to its poor performance relative to the three other systems. Our results suggest that increased soil disturbance, including tillage and cultivation in corn and soybean, plays an important role in reducing weed populations, whereas high fertility levels may exacerbate weed problems. These findings underscore the importance of balancing weed and nutrient management in enabling sustainable organic grain crop production.

Khasi nightshade (Solanum khasianum C.B. Clarke) is a perennial poisonous weed in tropical and subtropical regions that seriously threatens the development of grasslands. For a high-risk invasive weed, a comprehensive understanding of its seed germination characteristics is important for predicting its spread and developing effective management strategies. However, the impact of various abiotic factors on the germination of S. khasianum is not clear. The study first explored the effect of temperature, light, pH, osmotic stress, salt stress, high-temperature pretreatment and burial depth on the germination of S. khasianum. Seeds germinated at constant temperature of 30, 33, 35, and 38 C, and the germination rate (GR) ranged from 10% to 94%. The optimum germination temperature was 35 C, while germination was completely inhibited at 25 C or 40 C. The germination of S. khasianum was greatly promoted by alternating light and darkness (16/8, 12/12, 8/16 h), but was not sensitive to the time change of photoperiod. The GRs were more than 70% in the pH range of 4 to 10, and strongly acidic environment was more suitable for the germination. The GR gradually decreased with the osmotic potential from 0 to -0.2 MPa, and no germination occurred at -0.4 MPa. Accordingly, germination was also low in sodium chloride (NaCl) solution with concentration higher than 60 mM. Seeds of S. khasianum were not tolerant to high temperature, GR decreased significantly after exposure to 40 C for five minutes, and it decreased to 3% at 120 C. The emergence rate was the highest (93%) when the seeds were buried on the soil surface, while seedlings hardly appeared when the burial depth was more than 2 cm. This study revealed the possible adaptive mechanism of invasive S. khasianum, and will contribute to the effective prediction and management in grasslands.

Rice (Oryza sativa L.) agriculture of the southern United States is plagued by strong biotic competition with several species in the Echinochloa genus. Despite clear genomic differences between barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.] and junglerice (Echinochloa colona (L.) Link], the two major Echinochloa agricultural weeds are nearly indistinguishable phenotypically. This inability to reliably differentiate the species has led farmers to treat the group as a single species, often resulting in ineffective weed control efforts. In this study, we first develop a simple chloroplast-anchored PCR-based restriction enzyme assay to differentiate between E. colona and the other Echinochloa species of agricultural concern. Applying this assay, we identify a strong bias towards E. colona in 2024 rice field collections from eastern Arkansas. Finally, we evaluate anecdotal reports of interspecific hybridization between species and find no evidence. Despite the drawbacks of the maternally inherited nature of the chloroplast, the availability of this species determinant assay will help USDA and academia extension agents and stakeholders to make educated, species-specific decisions about precision chemical weed control and field management.

Delaying cover crop termination until planting (i.e., planting green) in no-till production systems is likely to mediate the fate of herbicides that provide soil residual activity. In a planting green scenario, there is currently limited knowledge of how the interaction between physiochemical properties of cover crop residues and sorption properties of herbicides influence the washoff potential of residual herbicides from cover crop residues. We conducted field- and laboratory-based experiments using herbicide washoff assay methods to evaluate the interaction between lignin (%) of cereal rye (Secale cereale, L.) and herbicide lipophilicity (Kow) on washoff potential across herbicide application timings. We contrasted herbicides with intermediate lipophilicity (atrazine, pyroxasulfone , and S-metolachlor) to less (mesotrione) and highly lipophilic (pendimethalin) herbicides. When applied into living cereal rye, washoff of atrazine and pyroxasulfone were greater than mesotrione and S-metolachlor. Pendimethalin had the least washoff potential. When applied into fresh- to aged-cereal rye residues (0 to 84 days after termination), pendimethalin washoff was below the detection threshold. Washoff of mesotrione, pyroxasulfone, and atrazine declined as lignin (%) in cereal rye residues increased, whereas a positive relationship between S-metolachlor recovery and lignin (%) was observed. Results of our study partially support the hypotheses that (1) herbicide lipophilicity, measured via log Kow values, can be a useful indicator of washoff potential among residual herbicides used in cover crop systems, and (2) washoff potential declines as cover crop residues age within herbicide application windows.

Every year agriculture uses 2 million metric tons of plastic mulch in the form of polyethylene (i.e., “PE mulch”) to grow the world’s food. Plastic mulch is a key tool for growers to suppress weeds, improve crop microclimates, increase yields, mitigate erosion, and potentially enhance crop quality. However, plastic mulch use comes at a major environmental cost due to poor end-of-life outcomes. Hydromulch (also known as “hydramulch” or “hydro-mulch”) is an alternative, sprayable, soil-biodegradable mulch technology made from biobased feedstocks that can be formulated to be acceptable in certified organic agriculture in the United States and Canada. Paper-based hydromulches are generally made from some combination of recycled cellulose fiber, water, tackifier or other binding agents, and sometimes filler derived from various agricultural residues or waste products. The objective of this review is to provide a historical overview of hydromulch, highlight key findings from previous hydromulch research, and provide recommendations to advance the use of hydromulch as a biobased, soil-biodegradable alternative to plastic mulches in specialty crop agriculture. Feedstock and application costs are still major barriers for commercialization and may be mitigated by further research, including the creation of hydromulch formulations that utilize agricultural residues without compromising the physical properties of the mulch layer. Overall, this literature review indicates that hydromulch is a promising technology, but also one in need of further research to be viable across a broad spectrum of cropping systems and environments.

Object detection models, such as those in the YOLO family, are generally effective identifying individual weeds, but their performance can be limited by occlusion of target structures in high density scenes. These models are typically trained on images with low weed densities, where individual plants are clearly visible and easy to annotate, yet they are used in field conditions where areas of high density and dense vegetation may occur. Greenhouse experiments were conducted at the University of Florida, Wimauma, FL, to evaluate how purple nutsedge (Cyperus rotundus L.) density impacts the performance of a YOLOv8 model. A greenhouse density test dataset was developed by collecting 480 images of twelve densities ranging from 7 to 331 plants m-2, at transplant and at 3, 6, 10, and 17 days after transplanting. An independent dataset of 2,221 field and greenhouse images was used for the training of a YOLOv8 extra-large model to detect C. rotundus. A logistic sigmoidal model was fitted to evaluate the F1 score as a function of increasing C. rotundus density at each data collection time point. The F1 score showed sigmoidal relationships with density at all time points, exceeding 0.9 at low densities but dropping sharply to near 0 at the highest density and later time points. Performance decline was primarily driven by increased false negatives as density and occlusion increased, with minimal contribution from false positives except at the highest densities. Density thresholds for optimal performance (F1 ≥ 0.90) decreased from 157 to 86 plants m-2 as canopy coverage increased, while marginal performance (F1 = 0.50) dropped from 322 to 140 plants m-2. Our findings suggest that object detection models for C. rotundus are strongly influenced by increased occlusion and morphological changes resulting from greater plant proximity and canopy coverage in high density scenes.

This systematic review evaluated studies published between 1980 and 2025 on the chemical control of smut grass [Sporobolus indicus (L.) R. Br.] in the Americas, with a focus on pastures. After screening 446 publications, 13 peer-reviewed articles met the inclusion criteria. Most studies were conducted in the subtropical United States, particularly in Florida, on bahiagrass (Paspalum notatum Fluggé) pastures, with only one study carried out in Brazil. The most frequently reported herbicide was hexazinone, present in over 80% of the studies, applied either alone or in combination with mechanical methods or fertilization. Consistent results indicated control efficacy above 85%, especially at doses ≥ 0.84 kg ha⁻¹ and when applied during summer. Selectivity for use in P. notatum was considered satisfactory, despite temporary phytotoxic symptoms. Integrated strategies, such as herbicide applications combined with nitrogen fertilization, showed potential to restore forage dominance and reduce reinfestation. Other herbicides, such as glyphosate, indaziflam, imazapic, mesotrione, and triazines, were less frequently investigated. Indaziflam, applied pre-emergence, caused a significant reduction in the seedbank, showing promise for preventive management, given the high dormancy and longevity of S. indicus seeds. The integration of chemical and mechanical control produced variable outcomes: in some cases, mowing prior to application reduced efficacy, whereas in others, when associated with strategies to remove growing points and subsequent herbicide application, it enhanced control. The scarcity of studies under Brazilian and other tropical or subtropical conditions limits the understanding of species adaptation and the efficiency of management methods across different edaphoclimatic contexts. Expanding research in these regions is crucial for developing effective and sustainable management strategies.

Understanding weed community structure is essential for designing sustainable integrated weed management (IWM) strategies in perennial fruit systems. This study aimed to characterize the floristic composition, abundance, and spatial structure of weed communities in jackfruit (Artocarpus heterophyllus Lam.) orchards across Vinh Long province, Vietnam. Field surveys were conducted during the main rainy season of 2023 using systematic quadrat sampling across multiple agroecological zones. A total of 35 weed species in 18 families were recorded, with Poaceae being the most dominant family (10 species, 28.6%), followed by Asteraceae and Cyperaceae (4 species each, 11.4%). Quantitative metrics including density, mean field density (MFD), relative MFD, cover, and multiplied dominance ratio (MDR) identified a consistent group of dominant species: Ludwigia octovalvis (Jacq.) P.H.Raven, Ageratum conyzoides L., and Axonopus compressus (Sw.) P.Beauv., while sedges such as Fimbristylis quinquangularis (Vahl) Kunth also contributed significantly. Hygrophilous species such as Peperomia pellucida (L.) Kunth, Centella asiatica (L.) Urb., and Pouzolzia zeylanica (L.) Benn. showed high mean occurrence field density (MOFD), whereas A. conyzoides and L. octovalvis dominated relative MFD, indicating adaptation to high-light environments. Diversity indices (Margalef’s richness, Shannon’s H′, Pielou’s evenness, and Simpson’s dominance) differed modestly among agroecological regions. Ordination analysis grouped species along a gradient primarily associated with density and cover. Similarity indices (Jaccard and Sørensen) were uniformly high (mostly >0.75), suggesting strong species overlap between regions. Notably, community composition shifted with orchard age, with older orchards exhibiting less species mixing. Weedy rice (Oryza sativa f. spontanea) was detected but was relatively infrequent. These findings provide a quantitative baseline for designing integrated weed management strategies in perennial fruit systems. Specifically, the results support a transition away from routine herbicide use toward ecologically based practices such as mowing before flowering and selective suppression of high-importance weeds, tailored by orchard age and site conditions.

To address the complexity and excessive reliance on expert experience in tuning fuzzy Proportional-Integral-Derivative (PID) controller parameters, this study proposes a variable-rate spraying control system that integrates an improved Beetle Antennae Search (IBAS) algorithm with fuzzy PID control. To evaluate the feasibility of the system, a mathematical transfer function of the variable-rate spraying system was constructed, and a flow control simulation platform was established for simulation analysis. To overcome the limitations of conventional BAS, which is prone to premature convergence and limited search precision, the IBAS algorithm was developed. The improvements include a hybrid disturbance strategy to enhance individual search capability and a simulated annealing mechanism to prevent the algorithm from being trapped in local optima. Using the IBAS algorithm, the proportional and quantization factors of the fuzzy PID controller were optimized offline to obtain the optimal parameters. The IBAS-fuzzy PID controller was then compared in simulation with conventional PID, fuzzy PID, and BAS-optimized fuzzy PID controllers. The simulation results demonstrated that the IBAS-fuzzy PID algorithm achieved higher flow control accuracy than existing methods. To further validate the effectiveness of the improved algorithm under practical conditions, field experiments were conducted. The results indicated that the IBAS-optimized fuzzy PID controller outperformed the three other control methods in terms of flow control accuracy. Overall, both simulation and field results confirm that the proposed IBAS algorithm for fuzzy PID parameter optimization significantly enhances response speed, control precision, and overshoot reduction, providing a novel approach and potential application for variable-rate spraying technology.