Weed Management Practices Research Articles

How Does Herbicide Resistance Change Farmer’s Weed Management Decisions? Evidence from the Roundup Ready Experiment

Adoption of diverse weed management practices is viewed as essential for slowing the spread of herbicide-resistant (HR) weeds. Yet, adoption of diverse tactics has remained low, while there has been explosive growth of resistant weeds. This study analyzes U.S.-farm-level data to identify factors affecting adoption of diverse weed management practices. This study uses directed acyclic graphs (DAGs) to consider how practice adoption is influenced by different causal pathways between farmer and farm characteristics and farmer awareness of and concern over HR weeds. This study then uses multiple regression analysis to estimate the direct and indirect pathways that influence practice adoption. Respondents relied more heavily on herbicide-based weed control methods than on mechanical or cultural methods. Concern over herbicide resistance increased the number of practices farmers adopted and the percentage of acres where farmers implemented these practices. Practice adoption was negatively associated with increasing levels of farmer risk aversion. Technological optimism—belief that new herbicides would soon be developed to counter HR weeds—discouraged diverse herbicide use practices that combat resistance, but encouraged use of some non-chemical weed control methods. Perceived weed dispersal externalities (from weed mobility) led to more diverse weed management, running counter to hypotheses that greater mobility reduces incentives for individual resistance management.

Assessing Weed Canopy Cover in No-Till and Conventional Tillage Plots in Winter Wheat Production Using Drone Data

Weed canopy cover assessment, particularly using drone-acquired data, plays a vital role in precision agriculture by providing accurate, timely, and spatially detailed information, enhancing weed management decision-making in response to environmental and management variables. Despite the significance of this approach, few studies have investigated weed canopy cover through drone-based imagery. This study aimed to fill this gap by evaluating the effects of conventional tillage (CT) and no-till (NT) practices on weed canopy cover in a winter wheat field over two growing seasons. Results indicated that in the 2022–2023 season, weed populations were similar between tillage systems, with a high mean weed cover of 1.448 cm2 ± 0.241 in CT plots. In contrast, during the 2023–2024 season, NT plots exhibited a substantially higher mean weed cover (1.784 cm2 ± 0.167), with a significant overall variation (p < 0.05) in weed distribution between CT and NT plots. These differences suggest that, while CT practices initially mask weed emergence by burying seeds and disrupting root systems, NT practices encourage greater weed establishment over time by leaving seeds near the soil surface. These findings provide valuable insights for optimizing weed management practices, emphasizing the importance of comprehensive approaches to improve weed control and overall crop productivity.

Maximizing Productivity and Profitability of Rice through Crop Establishment Methods and Weed Management Practices in Winter Rice-Garden Pea Relay Cropping System

A field experiment was conducted at the farmer’s field at Pirakata Brahmin Gaon under the jurisdiction of Krishi Vigyan Kendra, Jorhat to study resource conservation through crop establishment methods and weed management practices in winter rice (Oryza sativa. L.) - garden pea (Pisum sativum var. hortense) relay cropping system during 2019-20 & 2020-21. The treatment consisted of four crop establishment methods of winter rice (T) viz., T1: WDSR (Broadcasting), T2: WDSR (Modified Drum Seeder with furrow opener), T3: PTR (Farmers’ Practice), T4: PTR (Mechanized Transplanting by paddy transplanter) where WDSR: Wet Direct Seeded Rice, PTR: Puddled Transplanted Rice along with three weed management practices of rice (W) viz., W0: Weedy check, W1: Pretilachlor 0.75 kg/ha as pre-emergence fb bispyribac-sodium 0.025 kg/ha (20 DAS/DAT) as post-emergence, W2: Pretilachlor 0.75 kg/ha as pre-emergence fb manual weeding (30 DAS/DAT). The experiment was laid out in a factorial randomized block design with three replications. The soil of the experimental site was sandy clay loam in texture, medium acidic in reaction, medium in organic carbon and available N and low in available P2O5 and K2O. The study revealed that the establishment method that T2, T3 and T4 had higher growth and yield parameters of the crop as compared to T1: WDSR (B) which resulted in higher grain and straw yield of winter rice as well as uptake of nutrients. The highest grain yield of 49.79 and 50.13 q/ha of winter rice was recorded under T4: PTR (MTR) followed by 46.62 and 47.8 q/ha in T2: WDSR (Drum seeder) during 2019 and 2020, respectively. The percent increase in grain yield of winter rice in W1 and W2 as compared to W0 (control) was 82.97, 84.52 in 2019 and 81.62, 81.58, respectively in 2020. The treatment combination T4W2 recorded the highest grain and straw yield of winter rice which was statistically at par with T4W1, T2W1 and T2W2. The higher B:C of 2.27 and 2.14 was recorded in T2W1 with higher gross return and net return followed by T2W2 (2.18 and 2.08 during 2019 and 2020, respectively).

Enhancing productivity and profitability of spring maize (Zea mays) in Uttarakhand's Tarai region through effective weed management practices and irrigation scheduling

A field experiment was conducted during the spring seasons of 2022 and 2023 at Norman E Borlaug Crop Research Centre, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand to enhance maize yield and profitability. The experiment was conducted a split-plot design (SPD) with two irrigation scheduling treatments, viz. irrigation applied at an IW/CPE ratio of 0.8 (I1); and 1.2 (I2) in main plot and 8 weed management treatments, viz. W1, atrazine 1000 g/ha; W2, tembotrione 120 g/ha; W3, topramezone 25.2 g/ha; W4, atrazine 1000 g/ ha followed by hand-weeding at 35 DAS (days after sowing); W5, atrazine 1000 g/ha followed by tembotrione 120 g/ha; W6, atrazine 1000 g/ha followed by topramezone 25.2 g/ha; W7, weed-free; and W8, weedy check in sub-plots. Irrigation applied at IW/CPE ratio of 1.2 significantly improved the maize productivity and profitability, yielding higher net returns (₹66,206.9/ha) and grain yield (6.1 t/ha). Among the herbicidal treatments, atrazine 1000 g/ha followed by topramezone 25.2 g/ha recorded the highest weed control efficiency (80%) and maize grain yield (6.3 t/ ha). The percentage net monetary return was in the following sequence: W6 (100%) > W7 (92.4%) > W5 (91.8%) > W4 (89.6%) > W3 (81.5%) > W2 (78.2%) > W1 (67.6%) > W8 (46.4%). The percentage gain in grain yield was recorded in the following sequence: W7 (100%) > W6 (91.4%) > W5 (87.4%) > W4 (86.4%) > W3 (84.1%) > W2 (81.1%) > W1 (71.5%) > W8 (52.5%). In conclusion, optimizing irrigation to IW/CPE ratio of 1.2 and employing weed management practice atrazine (1000 g/ha) followed by topramezone (25.2 g/ha) application, can significantly enhance spring maize yield, weed control efficiency and economic returns in Uttarakhand's Tarai region.

Effect of weed management practices on weed dynamics in sweet cherry cv. Regina

Effect of weed management practices on weed dynamics in sweet cherry cv. Regina

Baseline survey reveals glyphosate and dicamba resistance in broadleaf weeds before sugar beet trait introduction

Abstract A pre-launch survey of broadleaf weeds was conducted to predict the weed management efficacy of a novel genetically engineered sugar beet with resistance traits for glyphosate, dicamba, and glufosinate. We targeted problematic broadleaf weed species prevalent in the sugar beet system, including kochia, common lambsquarters, Palmer amaranth, and redroot pigweed across sugar beet areas in Colorado, Nebraska, and Wyoming. The results revealed that a significant percentage of kochia populations in Colorado, Nebraska, and Wyoming exhibited resistance to glyphosate (94%, 98%, and 75%, respectively) and dicamba (30%, 42%, and 17%, respectively). Palmer amaranth populations had resistance frequencies for glyphosate and dicamba of 80% and 20% in Colorado and 20% and 3% in Nebraska, respectively. No resistance to the tested herbicides was identified in common lambsquarters or redroot pigweed. Glufosinate resistance was not identified for any species. Kochia and Palmer amaranth populations from Colorado and Nebraska exhibited glyphosate resistance primarily through 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) gene amplification. However, one glyphosate-resistant kochia population from Wyoming lacked EPSPS gene amplification, indicating the presence of an alternative resistance mechanism. We identified the previously characterized IAA16 G73N substitution in a dicamba-resistant kochia population from Nebraska. However, dicamba-resistant kochia populations from Colorado did not possess this substitution, suggesting an alternative, yet-to-be-determined resistance mechanism. The widespread prevalence of glyphosate and dicamba resistance, coupled with the emergence of novel resistance mechanisms, poses a significant challenge to the long-term efficacy of this novel genetically engineered sugar beet technology. These findings underscore the urgent need for integrated weed management (IWM) strategies that diversify effective herbicide sites-of-action and incorporate alternative weed management practices within cropping systems.

Integrating mechanical and cultural methods for weed control in organic chickpea

Abstract The Northern Great Plains of the United States is a major production region for organic pulse crops that are prone to yield losses due to weeds. Weed management in organic systems relies on the integration of several tactics to stack additive effects and for redundancy to deal with variable efficacy of individual weed management practices. To address the need for effective, integrated weed management, we conducted a 2-yr trial that evaluated the effects of planting date, seeding rate, and preemergent weed control practices (shallow tillage and flame weeding) on weed biomass, crop density, and yield in organically managed chickpea (Cicer arietinum L.) in Montana. Stacking weed management practices increased yields. Early planting had the largest effects on yields, increasing them by 1.8- to 3.6-fold compared with planting 10 to 14 d later. Increasing the seeding rate from the standard rate (43 viable seeds m−2) by 50% increased yields by 47% from 889 to 1,304 kg ha−1. Both preemergent weed control practices increased yields by 40% to 50 % relative to the non-weeded controls. By integrating all three practices, yields of organic chickpea increased greater than 6-fold from 318 kg ha−1 in the controls to 2,006 kg ha−1. The effects of weed control treatments on midseason weed biomass were complex and variable. Although efficacy of the cultural (seeding rate and planting date) and physical (preemergent) treatments on weed biomass varied between years and when combined with other treatments, their full integration, that is, early planted, at higher seeding rate, and preemergent weed control, produced consistently lower weed biomass (84% reduction on average) compared with the standard grower practice (later planting, standard seeding rate, no preemergent weed control). The results lend support to the concept of integrating multiple weed management practices to achieve weed control and high yields in organically managed crops.

Effects of weed management on soil metagenomic composition in cultivated chickpea fields

Abstract Non-chemical methods, including mechanical and manual weed management are important for improving crop yields and preserving soil microbial diversity. In Tunisia, chickpea cultivation uses a combination of these methods to suppress weeds. This study aimed to evaluate the impact of weeding practices on chickpea (Cicer arietinum L. cultivar REBHA) yield and soil microbial diversity. Field experiments were conducted at the Technical Center for Biological Agriculture in Essaida, Tunisia, using six plots with manual and no weeding treatments. Chickpea yield was measured, and soil samples were collected for metagenomic analysis. Floristic surveys identified 13 weed species, with Chenopodium album L., Rumex acetosa L., and Urtica dioica L. being the most dominant. Seed yield ranged from 23.2 to 26.2 qls/ha in non-weeded plots and from 25.1 to 30.1 qls/ha in weeded plots, showing an increase in yield (11.75%) with manual weeding.
Soil metagenomics revealed changes in bacterial community composition between the two treatments. The dominant phylum was Pseudomonadota, whose relative abundance increased from 24.88% in non-weeded plots to 34.76% in weeded plots. Alpha diversity indices showed lower species richness and diversity in weeded soils, with 62000 OTUs in weeded plots compared to 43202 OTUs in non-weeded plots. Betaproteobacteria and Alphaproteobacteria exhibited higher OTU counts in weeded soils. The Simpson diversity index was lower in non-weeded soils (0.025) than in weeded soils (0.075), indicating a more irregular microbial distribution in non-weeded plots. Thus, manual weeding improved chickpea yield and altered the soil bacterial community, increasing diversity in key microbial taxa. This study highlights the complex interaction between weed management practices and soil microbial ecosystems, which may influence crop productivity.

Sole and sequential application of herbicides and botanicals for weed management in summer sesame

Weed infestation poses a significant challenge in sesame cultivation, leading to yield losses and decreased economic returns for farmers. The present study comprehensively analyses various weed control approaches, including allelopathic interaction with integrating herbicides and hand-weeding practices. The experiment was conducted at the Agriculture Farm, SOA, Odisha, during the summer of 2023 with 10 weed management treatments in RBD with 3 replications. The objective was to study different weed management practices, including the sole and sequential application of herbicides and botanicals, to control diverse weeds and enhance summer sesame growth, yield and profitability. The dominance of Digitaria sanguinalis (L.) Scop., Echinochloa colona (L.) Link. and Poa annua L. among grassy weeds and Melochia corchorifolia L., Cleome viscosa L. and Cassia tora L. among the broadleaved weeds were evident in summer sesame. The execution of different treatments showed that integrated use of aqueous leaf extract of Parthenium hysterophorus at 5 % concentration, followed by quizalofop-p-ethyl at 50 g/ha, was found on par with hand-weeding and brought down the weed count and biomass, which in turn increased the growth of summer sesame. The maximum yield of (793 kg seed/ha and 3035 kg stalk/ha) was registered under twice hand weeding. It was comparable with the spraying of aqueous leaf extract of Parthenium hysterophorus at 5 % concentration followed by (fb) quizalofop-p-ethyl at 50 g/ha (772 kg seed/ ha and 2968 kg stalk/ha). Economic analysis of sesame revealed that the maximum return (Rs. 37454/- per ha) and return/rupee (2.28) were recorded with aqueous leaf extract of P. hysterophorus at 5 % concentration fb quizalofop-p-ethyl at 50 g/ha treatment.

Climate and management changes over 40 years drove more stress‐tolerant and less ruderal weed communities in vineyards

AbstractSpontaneous plant communities have undergone considerable constraints due to human‐mediated changes. Understanding how plant communities are shifting in response to land management and climate changes is necessary to predict future ecosystem functioning and improve the resilience of managed ecosystems, such as agroecosystems. Using Mediterranean weed communities as models of managed plant communities in a climate change hotspot, we quantified the extent to which they have shifted from the 1980s to the 2020s in response to climate and management changes in vineyards. The weed communities of the same 40 vineyards in the Montpellier region were surveyed using the same protocol in spring, summer, and autumn, for two years, with a 40‐year interval (1978–1979 vs. 2020–2021). In four decades, the annual range of temperatures (i.e., the difference between the warmest month's and the coldest month's mean temperatures) increased by 1.2°C and the summer temperatures by 2°C. Weed management diversified over time with the adoption of mowing that replaced the chemical weeding of interrows. Chemical weeding is now mostly limited to the area under the row. Current weed communities were 41% more abundant, 24% more diverse, and with a less even distribution of abundance across species than the 1980s communities at the vineyard level. Modern communities were composed of more annual species (57% of annual species in the 1980s vs. 80% in the 2020s) with lower community‐weighted seed mass and were composed of fewer C4 species. They had higher community‐weighted specific leaf area, higher leaf dry matter content, and lower leaf area than the 1980s weed communities. At the community level, the onset of flowering was earlier and the duration of flowering was longer in the 2020s. Climate change induced more stress‐tolerant communities in the 2020s while the diversification of weed management practices favored less ruderal communities. This study shows that plant communities are shifting in response to climate change and that land management is a strong lever for action to model more diverse and eventually more desirable weed communities in the future.

Interactive effect of nutrient and weed management in transplanted rice (Oryza sativa L.) for enhancing the productivity in Eastern India

A field experiment comprising three nutrient and six weed management practices was conducted in strip plot design with three replications during 2019 and 2020 at Odisha University of Agriculture & Technology (OUAT), Bhubaneswar, India to assess the effect of the treatments on weed dynamics, productivity and nutrient uptake by crop and weed. Averaged over both years, among nutrient management practices, the soil test based dose (STD: 100-40-40 N-P2O5-K2O kg ha-1) + green manuring (GM) of dhaincha recorded the minimum weed density of 45.3 and 64.2 number m-2 and weed biomass of 19.2 and 37.6 g m-2 at 30 and 60 days after transplanting (DAT), respectively and the minimum N, P and K uptake of 6.4, 2.0 and 6.8 kg ha-1 by weed and the maximum N, P and K uptake of 113.6, 23.2 and 122.6 kg ha-1 by the crop, respectively. Among weed management practices, bensulfuronmethyl + pretilachlor (PE) fb HW on 35 DAT produced the minimum weed density of 25.15 and 20.66 number m-2, the minimum weed biomass of 7.70 and 8.08 g m-2 at 30 and 60 DAT, respectively and the minimum N, P and K uptake of 2.4, 0.5 and 2.6 kg ha-1 by weed and the maximum N, P and K of 117.9, 25.3 and 263.7 kg ha-1 by crop, respectively. Among nutrient management practices, the STD + GM proved to be the best with the maximum grain yield of 5562 kg ha-1. whereas the application of bensulfuronmethyl + pretilachlor (PE) fb HW on 35 DAT excelled over other weed management practices with the maximum grain yield of 5907 kg ha-1 registering 17.71 and 47.64% higher grain yield compared to the STD and the weedy check, respectively.

Efficacy of Pre and Post Emergence Herbicides against Complex Weed Flora, Yield and Economics of Blackgram under High Hills Wet Temperate Zone of Himachal Pradesh

Background: Implementing integrated strategies for weed management is essential in maximizing blackgram yield. Unchecked weed proliferation leads to substantial decrease in crop productivity. Methods: The current field experiment was conducted at Salooni, Himachal Pradesh, to evaluate the efficacy of different integrated weed management practices during Kharif 2022 and 2023. Eleven treatments targeting weed control were evaluated both at pre and post - emergence stages. Result: The predominant weeds were Echinochloa colona, Galinsoga parviflora, Cyperus species and other broad leaf weeds were Plantago lanceolata, Trifolium repens, Trianthema species, Ageratum conyzoides. Data on weed dynamics revealed that; after weed-free treatment, the application of Imazethapyr 75 g/ha as PE fb HW at 30 DAS; Pendimethalin 1.0 kg/ha as PE fb HW at 30 DAS and Pendimethalin 1.0 kg/ha + imazethapyr 75 g/ha (PE) recorded a significantly lower total weed count as compared to other treatments. Parameters related to blackgram growth and yield, including plant height, number of branches per plant, pods per plant, grain yield and haulm yield were significantly higher with weed-free treatment followed by application of imazethapyr 75 g/ha as PE fb HW at 30 DAS, remaining at par with application of pendimethalin 1.0 kg/ha + imazethapyr 75 g/ha (PE) and pendimethalin 1.0 kg/ha as PE fb HW at 30 DAS. The most economically efficient weed control method was the combination of pendimethalin 1.0 kg/ha + imazethapyr 75 g/ha (PE), as it resulted in the highest net returns and marginal benefit-cost ratio.

Effect of Different Weed Management Practices on growth and yield in Potato at Khumaltar, Lalitpur, Nepal

Potato (Solanum tuberosum L.) is the fifth most important crops in the world in terms of production with an estimate of 375 million metric tons. In Nepal, potato ranks second in terms of production and sixth in terms of area coverage. Potato production is affected by weed infestation. Weeds compete with crops for nutrients, water and other resources, which eventually reduce the crop yield. The critical period of crop-weed competition for potato is 25-40 days from planting depending on the climatic-zone and planting seasons. The most common method of weed control in Nepal is manual method, while herbicides are uses in less areas. Weeds are considered as the major problem in conventional and organic farming, due to lower yields by weeds and higher costs of labor for weed control. Mulching is one of the best and safest practice for effective weed management in potato due to which micro-climate manipulation is developed. Metribuzin is widely used herbicides in potato that controls a range of broadleaf weed species and suppresses many grassy weeds. To study the performance of different weed management practices in potato ten treatments were set up viz., three herbicides (pendimethalin@ 1.0 kg a.i ha-1, metribuzin@ 0.5 kg a.i ha-1 and atrazine @ 0.25 kg a.i ha-1) constituting seven treatments, one mulching with rice straw, one treatment with two manual hoeing, and another treatment with no any weed management practices as control.The treatments were laid out in RCB design with 4 replications. The potato variety Janak Dev was planted on 12th Feb 2021 and 23rd Jan 2022 with tuber rate of 4.1 t.ha-1 with row spacing of 60 cm and plant to plant 20 cm in a plot size of 4 x 3 meter in flat bed. Growth parameters such as plant height, plant fresh and dry biomass were recorded. Data on weed density, weed dry biomass, and tuber yield were taken.The economics of the different treatments were calculated. Among the treatments metribuzin@ 0.25 kg a.i ha-1 as pre-emergence proved effective in controlling weeds showing highest weed control efficiency (200.7 %) and tuber yield (32.79 t ha-1) . However, the treatment rice straw mulch @ 6 t ha-1 produced the highest tuber yield (38.31 t ha-1), 73.4 % increased yield over control, weed control efficiency(147.1%), economic benefit (NRS 13,40,850), benefit cost ratio (4.93).The treatment rice straw mulch @ 6 t ha-1 showed superiority among the different weeds management practices.

Effect of Crop Geometry and Weed Management Practices on Yield and Yield Attributes of Spring Maize in Banke, Nepal

The experiment was conducted in Banke, Nepal, from February 2021 to May 2021 to find suitable spacing and weed management practices for spring maize. The experiment was conducted in a split-plot design in which main plots consisting of two spacings (S1:60 cm × 25 cm and S2:60 cm × 30 cm) and subplots consisting of five weed management practices as, W1: weedy check, W2: weed free, W3: atrazine @ 2 kg a.i. ha-1 as pre-emergence herbicide, W4: atrazine as pre-emergence herbicide followed by single-hand weeding at 30 DAS, and W5: straw mulch. Observations were taken for different parameters, that are, cob length, cob circumference, number of grains per cob, number of ears per hectare, thousand-grain weight, and grain yield. Based on spacing non-significant variations were found for all traits except for the number of ears per hectare. The highest number of ears per hectare (61667 ears ha-1) was found in S1 (60 cm × 25 cm). Based on weed management practices all the traits were significantly different, except the number of ears per hectare and thousand grain weight. The highest value of grain yield (6.15 mt ha-1) was found in straw mulch, and the lowest grain yield (3.72 mt ha-1) was found in the weedy check. A positive correlation was observed between yield and different weed management practices (WEM) (r = 0.5**) and other yield-attributing traits, that are, number of ears per hectare (NE) (r = 0.62**), the number of grains per cob (NK) (r = 0.82**), cob length (CL) (r = 0.47**), cob diameter (CD) (r = 0.68**), and total grain weight (TGW) (r = 0.52**). A negative correlation was observed between yield and spacing (S) (r = -0.41*).

Beyond yield: Unveiling farmer perceptions and needs regarding weed management in Bangladesh.

More than 3.5 billion people depend on rice for more than 20% of their daily calories. Globally, Bangladesh is the third largest rice producer. With 171 million people, Bangladesh is also among the top consumers. Local rice production not only affects the country's food security but also influences the global rice trade. A large yield gap has been reported due to weeds. Traditional hand weeding is very costly because of labor shortages resulting from industrialization. Limited data showed a higher yield and profits when using herbicides. However, quantitative data on various aspects of weed management and associated issues representing the country's variable rice ecosystem, which is characterized by 30 agroecological zones, are lacking. We collected data on weed management practices from 865 farmers and 69 agrochemical shops covering all 30 agro-ecological zones (AEZs) through a structured survey. We observed a significant regional variation among various parameters. Approximately 82% of farmers use herbicides, and few rely solely on either manual weeding or herbicides. Pre-emergence herbicides are the predominant. Application procedures are almost the same across the country. Although 40% of farmers had secondary and higher-level education, most depend upon local sellers' suggestions rather than reading the product label regarding the dose. Few farmers consider herbicides hazardous, and respondents rarely perceive any environmental impact. Pyrazosulfuron ethyl (35%) and acetochlor-containing bensulfuron methyl (27%) are the most-used chemical species. Approximately 45% of farmers observed that herbicides suppress early seedling growth. Additional fertilizer is required to compensate for this. Multiple weed species that are difficult to control through presently used herbicides were noted in all AEZs. Around 64% of farmers observed that herbicide application contributes to higher yields as a function of timely weeding. Cost comparisons showed that high labor prices will make rice cropping unprofitable in most parts of the country if herbicides are eliminated. Clear adverse effects of pre-emergence herbicides on early crop growth implied the potential benefits of broad-spectrum herbicide-tolerant genetically engineered (GE) rice to sustain the country's food security. Additionally, such GE rice could incentivize the adoption of alternate wet and dry irrigation methods, leading to water and cost savings.

Selection and adaptation to weed management methods: implications for non-chemical and integrated weed management approaches.

Herbicide-resistant weeds are a growing global concern, threatening food security. Non-chemical weed management approaches are becoming increasingly important. Furthermore, the adoption of non-conventional agricultural practices is on the rise, with regenerative farming practices aimed at rebuilding soil organic matter, restoring biodiversity, and reducing chemical use gaining traction. Consequently, non-chemical weed management methods are seen as essential solutions. However, excessive reliance on these methods may inadvertently lead to weed selection and adaptation, reducing their effectiveness. Here, we explore the mechanisms driving changes in efficacy due to selectivity and adaptation to non-chemical weed management practices. Additionally, we discuss potential integrated weed management (IWM) strategies that combine chemical and non-chemical methods to mitigate the risks of weed adaptation. This study highlights the role of evolutionary processes in shaping weed adaptation to non-chemical weed management methods and underscores the need to understand these processes to develop IWM approaches that remain effective over time. Monitoring phenological shifts and adaptations in the field should be a key component of decision support systems, tailored to the unique conditions of each site. Furthermore, a deeper understanding of weed adaptation mechanisms can enhance the efficacy of IWM strategies and help delay the inevitable adaptation to these control methods. © 2024 Society of Chemical Industry.

Cover crop and herbicides can control purple nutsedge (Cyperus rotundus L.) and increase crop yields in conservation agriculture-based crop rotations

Adoption of conservation agriculture (CA) practices can lead to the dominance of perennial weeds including purple nutsedge (Cyperus rotundus L.) in different agroecologies over time. Without effective management of this weed, successful adoption of CA in smallholder farming systems is rather unlikely. Therefore, we aimed to develop an integrated strategy for managing C. rotundus in CA-based crop rotations. This study encompassed a two-year (during 2020–21 and 2021–22) field experimentation at Kanpur, India with a split-plot design with three replications. The treatments included purple nutsedge management practices in main plot and crop rotations in sub-plot under CA platform (no-tilled with added crop residues). Six management options were adopted in the summer season (during April to June) as main plots that were super-imposed with two crop rotations such as pigeonpea (Cajanus cajan (L.) Huth) – wheat (Triticum aestivum L.) and pearlmillet (Pennisetum glaucum (L.) R.Br) – chickpea (Cicer arietinum L.) as sub-plot. Growing of cover crop Sesbania (Sesbania aculeata (Willd.) Pers.) during the summer season for 45 days followed by knockdown with 2,4-D 500 g a.i. Ha−1 (cultural management; Sesbania+2,4-D) and/or summer irrigation followed by application of halosulfuron-methyl 70 g a.i. Ha−1 at 20 days after irrigation (chemical management; halosulfuron-methyl) reduced the C. rotundus density by 37–42% and 23–64% over years, respectively, than conventional practice (ploughing during summer followed by irrigation and glyphosate 1.5 kg a.e. Ha−1 application). Besides, these practices could decrease 25–27% total weed density (p < 0.05) than conventional practice (mean of years) in summer season. Importantly, these management practices had a carry-over effect on reduction in density of C. rotundus and total weeds of rainy and winter season crops. For instance, Sesbania +2,4-D and halosulfuron-methyl decreased 35% and 15% density of C. rotundus, respectively, during rainy season than conventional practice. Irrespective of crop rotations, Sesbania +2,4-D and halosulfuron-methyl decreased 30–40% density of C. rotundus (mean of years) in winter season than conventional practice (p < 0.05). A significant reduction in dry weight of C. rotundus was recorded under Sesbania +2,4-D and halosulfuron-methyl in summer season by 13–23%, rainy season by 23–29%, and winter season by 55–72% than conventional practice. Pearlmillet-chickpea rotation had a 10–35% lower infestation of C. rotundus than pigeonpea-wheat (p < 0.05). Management practices such as Sesbania +2,4-D and halosulfuron-methyl had higher system productivity by 15–19% in 2020–21 (p < 0.05), 5–7% in 2021–22 (p > 0.05), and 10–12% in average (p > 0.05) than conventional practice. Summer mungbean cultivation increased 45.2% and 10.1% density of C. rotundus in rainy season over Sesbania +2,4-D and halosulfuron-methyl in CA system, respectively (p < 0.05). Furthermore, the density of this weed was significantly higher under pigeonpea crop during rainy season by 41.4% than under pearlmillet crop (mean of years). Therefore, system-based approaches such as growing of cover crop Sesbania followed by knockdown with 2,4-D (Sesbania +2,4-D) and/or herbicide-based management through halosulfuron-methyl during summer season and subsequently recommended weed management practices in cropping systems (pearlmillet – chickpea and pigeonpea – wheat) can reduce the infestation of C. rotundus and total weeds in CA than conventional practice.

Growth, nutrient uptake and yield ofdirect seeded rice as influenced by weed management practices

A field experiment was conducted during the rainy (Kharif) seasons of 2018 and 2019 at the Kerala Agricultural University, Kerala, to evaluate the effect of herbicides and herbicide combinations on the weed management and growth, nutrient uptake and yield of direct seeded rice (DSR). The experiment was laid out in a randomized block design with three replications. Nine weed control treatments were used, including sole application of three herbicides (cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha, fenoxaprop-p-ethyl@ 60 g/ha), five herbicidal combinations (penoxsulam + cyhalofop butyl commercial formulation @ 150 g/ha, cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha, bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and stale seedbed followed by (fb) glyphosate @ 800 g/ha + oxyfluorfen @ 150 g/ha at 15-20 days after land preparation + cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha), and hand weeding twice at 20 and 40 days after sowing. Weeds removed 27.72, 4.61 and 67.95 kg of N, P and K/ha respectively at 45 days after treatment application (DATA) under unweeded conditions in direct seeded rice. Herbicidal treatments enhanced grain yield by 23.89 to 58.84 % and herbicide combinations increased grain yield by 56 to 59 % compared to the unweeded control in direct seeded rice. Tank mix combination of bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha and premix combination of penoxsulam + cyhalofop butyl @ 150 g/ha recorded higher nutrient uptake and grain yields (5.03, 4.76 and 4.79 t/ha, respectively) and were on par to hand weeding twice. Unweeded control recorded the lowest pooled grain yield (2.07 t/ha) and uncontrolled weed competition resulted in 59.95 % reduction in grain yield. Keywords: Crop competition, Herbicide combinations, Herbicide interactions, Nutrient removal, Nutrient uptake, Yield reduction

Effect of chemical weed management on growth, yield and economics of drum seeded rice (Oryza sativa)

Field experiment was conducted at Periyanarkunam, Bhuvanagiri Taluk, Cuddalore District during Kuruvai 2021 and 2022 to study the effect of different herbicidal weed management on growth, yield and economics of drum seeded rice (Oryza sativa L.) variety ‘ASD 16’. The experiment was conducted in randomized block design with four replications. The treatments comprised of six weed management practices and are made up of a combination of herbicides (pre-emergence, early-post and post-emergence herbicides) with hand weeding, which was com- pared with unweeded control and twice hand weeding on 25 and 45 DAS. Application of bensulfuron methyl 0.6% + pretilachlor 6% GR @ 660 g a.i./ha PE fb metsulfuron methyl 10% + chlorimuron ethyl 10% WP @ 4 g a.i./ha PoE on 25 DAS fb hand weeding on 45 DAS recorded the highest weed control efficiency of 77.55 and 74.23% during Kuruvai 2021 and 2022 respectively, growth attributes at 60 DAS viz., plant height (96.82 and 91.79 cm), tillers/m2 (367 and 343) and dry matter production (8.01 and 7.78 t/ha), yield attributes like productive tillers/m2 (319 and 312), filled grains/panicle (100.64 and 98.42), grain yield (6.19 and 6.11 t/ha) and benefit cost ratio (2.78 and 2.49) during Kuruvai 2021 and 2022, respectively over bispyribac sodium 10% SC @ 25 g a.i./ha PoE on 20 DAS fb hand weeding on 45 DAS (farmers practice). Hence, it is an efficient weed management practice and an economically feasible method for achieving the maximum growth, yield and economics of drum seeded rice.

Response of sulphur and weed management practices on cowpea [Vigna unguiculata L.

Response of sulphur and weed management practices on cowpea [Vigna unguiculata L.