Weed Populations Research Articles

Herbicidal and Nitrogen Efficacy on Weed Management in Wheat Fields of Eastern Uttar Pradesh, India

Weeds can significantly affect crop yield and nutrient uptake, making effective management crucial in wheat fields. This study, conducted during the winter (Rabi) season of 2018-19 at the Agricultural Research Farm of Banaras Hindu University in Varanasi, aimed to assess the combined impact of different nitrogen levels and herbicide treatments on weed control and wheat production. The objective was to determine the best practices for reducing weed competition and improving crop performance. The experiment was set up using a split plot design with three replications. The treatments comprised of 3 nitrogen levels and 5 weed control methods. The study identified nine prevalent weed species in wheat fields, including Phalaris minor, Anagallis arvensis, Cynodon dactylon, Chenopodium album, Melilotus indicus, Vicia sativa, Medicago denticulata, Solanum nigrum, and Cyperus rotundus, with Anagallis arvensis, Chenopodium album and Vicia sativa being the most dominant. The application of Sulfosulfuron (25 g ha-1) combined with 2, 4-D (750 ml ha-1) resulted in the lowest weed density and biomass and the highest weed control efficiency. Additionally, performing hand weeding twice (30 and 60 days after sowing) in conjunction with 180 kg N ha-1, followed by the application of Sulfosulfuron (25 g ha-1) + 2, 4-D (750 ml ha-1), significantly reduced Anagallis arvensis, Chenopodium album and Vicia sativa population and biomass and improved weed control effectiveness. Higher weed dry weight and population results in lower plant nutrient uptake and lower dry matter of crop plant and yield.

Weed smothering efficiency of mulching types on groundnut (Arachis hypogea L.) productivity in the dry savanna region of Nigeria

In order to increase groundnut productivity, a field experiment was carried out in the dry season of 2020 to assess the effectiveness of various mulching materials at suppressing weeds. The experimental treatments comprised of five mulching types; Control (no mulch), transparent polythene mulch, black polythene mulch, rice straw mulch and saw dust mulch) and three groundnut varieties (SAMNUT 23, SAMNUT 24 and SAMNUT 26). These were factorially combined and laid out in a Randomized complete block design with three replications. Findings revealed that mulching had a significant (p < 0.05) impact on crop qualities including canopy cover, chlorophyll content, pod yield, 100 kernel weight, and groundnut kernel yield as well as weed attributes like weed cover scores, weed density, weed dry weight, and weed control efficiency in both BUK and Wasai, respectively. The weed compositions were further grouped into various families comprising Poaceae (11), Euphorbiaceae (3), Amaranthaceae (4), Asteraceae (3), Cyperaceae (2), Cucurbitaceae, and Aizoaceae, each having one species with a different level of occurrence across the two locations. On the other hand, SAMNUT 26 significantly produced higher pod (2798 & 2119) and kernel yields (1198 & 1191), although SAMNUT 23 produced a heavier 100 kernel weight (55.51 & 54.52) at BUK and Wasai, respectively. In comparison to the other mulching types, applying black polythene mulch or transparent mulch lowered weed density and dry weight by limiting the amount of sunlight that the weeds got, preventing them from growing. Therefore, for dry season production of groundnut in the Sudan savannah ecology of Nigeria, mulching with black or transparent polythene film using the SAMNUT 26 variety was found to be effective in conserving soil moisture for optimum crop growth and development, while on the other hand, weed populations were suppressed.

Effect of Pre- and Post-Emergence Herbicides on Weed Control and Yield in Sunflower (Helianthus annuus L.)

Weeds are a major cause of yield and quality loss in sunflower (Helianthus annuus L.) crops. Therefore, weed control is important in sunflower production. In this context, the study was conducted in 2023 to determine the effectiveness of pre-emergence and post-emergence herbicides with different modes of action on weed population, dry weight of weeds and sunflower yield and yield components in sunflower. Four herbicides with different modes of action, three pre-emergence (aclonifen (A), pendimethalin (P), linuron (L) and one post-emergence (quizalofop-p-ethyl) (Q) and combinations of these herbicides were used in the study. To determine the effects of herbicides on weed populations and species, four different assessments were conducted at regular intervals. As a result of the study, a total of 10 weed species belonging to 5 families were detected in the trial area. The weed species with the highest density were Sorghum halepense (L.) Pers., Xanthium strumarium L., Convolvulus arvensis L. and Chenopodium album L. The study found that the effects of herbicides on weed populations and species varied. In the study, the highest rates of weed control were achieved in plots where both pre-emergence and post-emergence herbicides were used together. The highest weed control rate was observed in plots P+Q (96.66%). The highest effect on weed dry weight was obtained in plot L+Q with a rate of 89.63%. The highest weed dry weight was recorded in the weedy control plots. In the study, the highest yield (287.53 kg da-1) was obtained in the weed-free (hoe) control plot. Yield increases of 18% to 45% can be achieved by controlling weeds in sunflowers. As a result, herbicide efficacy on weed population and dry weight of weeds increased when herbicides were used in combination. Some herbicides have been shown to increase yields when used alone. However, it is important to use herbicides in combination to control more weed populations and prevent a potential resistance problem.

Assessing Herbicide-Resistance and Yield Optimization in Boro Rice (cv. BRRI dhan29) through Post-emergence Herbicides Applications

Effective weed management is crucial for achieving optimal crop performance and yield in rice cultivation. While post-emergence herbicides are commonly used to control weed population (WP), their effectiveness can vary based on the dosage and combinations applied. In this respect, an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from December 2019 to May 2020 to predict herbicide-resistant weeds and assess the yield of boro (dry season irrigated) rice (cv. BRRI dhan29) in response to post-emergence herbicides. The experiment consisted of five post-emergence herbicides: Fenoxaprop-p-ethyl, Triafamone, Penoxsulam, Bispyribac-sodium, and Carfentrazone-ethyl, and four doses of herbicide: control, half of the recommended dose (RD), RD, and double the RD. Weed dry weight (DW), WP, and inhibition were significantly affected by different doses of herbicides. Ten weed species (WS) belonging to four families infested the experimental plots, with the most dominant being Echinochloa crus-galli, Scirpus mucronatus, and Scirpus articulatus. The lowest WP and DW, as well as the highest weed control efficiency (WCE), were achieved with double the RD of Penoxsulam and Triafamone, showing 91.09% and 90.13% efficiency, respectively, at 30 DAT. The tallest plants, highest number of effective tillers hill-1, highest grain yield, straw yield, biological yield, and harvest index were found with double the RD of Penoxsulam. In contrast double the RD of Triafamone produced the second-highest grain yield. Although double doses of herbicides increased yield, the variation was not significantly greater than the RD. Some weeds, particularly E. crus-galli, S. articulatus, Leersia hexandra, and Digitaria sanguinalis, survived even with double the RD of herbicides. This indicates a potential for herbicide-resistant weeds.

Combined Application of Herbicide and Aqueous Extract of Sorghum and Mustard Crop Residue Enhance Weed Management and Yield of Wheat

The rising costs in agriculture and growing public concern over herbicide use have emphasized the need for non-chemical weed control methods. To evaluate the impact of aqueous extracts from sorghum and mustard crop residues on weed control and wheat crop performance, an experiment was conducted at the Agronomy Field Laboratory (AFL) of Bangladesh Agricultural University (BAU), Mymensingh, from November, 2021, to March 2022. The study involved three wheat varieties (BARI Gom-32, BARI Gom-33, and BWMRI Gom-1) and six treatment levels: no weeding, the recommended dose of herbicide (RDH), 80% RDH + aqueous extract of mustard + sorghum (AEMS) (1:20 ratio w/v), 70% RDH + AEMS (1:20), 60% RDH + AEMS (1:20), and 50% RDH + AEMS (1:20). The experiment was designed using a randomized complete block design with three replications. Results demonstrated that the aqueous extracts significantly reduced weed population (WP) and dry weight (DW) of weeds. Among the wheat varieties, BARI Gom-32 achieved the highest grain yield (GY) (3.62 t ha-1) and other yield-contributing traits. The highest numbers of effective tillers (NET) per hill (4.56), numbers of grains per spike (NGS) (34.57), 1000 grain weight (TGW) (57.81 g), GY (4.09 t ha-1), straw yield (SY) (6.05 t ha-1), and biological yield (BY) (10.14 t ha-1) were observed in the RDH treatment, followed by the combined application of 80% RDH and AEMS crop residue (1:20). These findings suggest that AEMS crop residue extracts could be an effective source for suppressing weed population and enhancing yield.

Simulated herbicide mixtures delay both specialist monogenic and generalist polygenic resistance evolution in weeds.

Evolution of herbicide-resistant weed populations is a major challenge to world food production. Using different herbicides in rotation and/or using different herbicides together as mixtures are strategies that may delay the selection of resistance. This study used simulation modelling to investigate whether mixtures and rotations can delay the selection of both generalist polygenic and specialist monogenic herbicide resistance, and whether these strategies are more likely to lead to the selection of generalist resistance in weed types with varying biological characteristics. Our simulations suggest that well-designed effective herbicide mixtures should delay evolution of both polygenic and monogenic resistance better than rotations and single herbicides across all weed types. Both mixture and rotation strategies increased the likelihood of polygenic resistance compared to single-herbicide use, and the likelihood of polygenic resistance increased as the fecundity and competitiveness of the weed increased. Whether monogenic or polygenic resistance occurred in each case depended most on the relative initial allele frequencies. We did not find that herbicide mixtures were more likely than rotations to lead to the selection of generalist polygenic resistance. The simulated efficacy of mixtures over rotations decreased if components were used at reduced rates or when individual components had already been used solo. Herbicide rotations and particularly well-designed mixtures should delay evolution of both polygenic and monogenic resistance, especially if used as part of an effective integrated weed management programme. However, herbicide mixtures and rotations may also increase the risk that resistance will be generalist polygenic rather than specialist monogenic. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Compatibility Analysis of Metolachlor and Pendimethalin for Weed Control in Arabica Coffee Plants

Losses caused by the presence of weeds in an agricultural business are often associated with the ability of weeds as strong competitors for plants to obtain water, nutrients, sunlight, and growing space. A mixture of metolachlor and pendimethalin herbicides is expected to control important weeds of various classes in coffee plants. The purpose of the research was to determine the effect of two herbicide mixtures at different doses on weeds in coffee plantations. This research used a 4 X 4 factorial randomized block design with 2 repetitions, resulting in 32 experimental plots. The first factor was metolachlor herbicide and the second was pendimethalin herbicide, each factor consisting of 4 levels with 0.00, 0.75, 1.75 and 2.25 kg ha-1 doses. The observed parameters consisted of (1) dominance count value, (2) percentage of controlled weeds, (3) weed coverage, (4) weed population, and (5) weed dry weight. The results showed that there was a very significant effect on the combined interaction of metolachlor and pendimethalin herbicide mixtures on the percentage of controlled weeds, percentage of weed closure at 21 and 28 DAA, and weed dry weight at 28 and 42 DAA with the best dose combination at b.a. 1.50 kg ha-1 which could increase the efficiency of weed control. Meanwhile, the percentage of controlled weeds, percentage of weed cover at 14 DAA, and weed population at 28 and 42 DAA showed very significant results independently with a dose of b.a. 2.25 kg ha-1

A 4-year field study monitoring the evolution of Trp574Leu-resistant plants in an Echinochloa crus-galli population under different crop rotation and herbicide programs in maize.

A 4-year experiment evaluated the effects of different integrated weed management (IWM) programs on the evolution of a Echinochloa crus-galli population resistant to acetolactate synthase (ALS) inhibitors in a maize cropping system. The programs included the continued use of ALS inhibitors, mixing them with alternative herbicides, or without ALS-inhibitors, in all cases under maize monocrop or a biennial crop rotation. IWM programs that relied solely on non-ALS-inhibitors usually achieved high control levels across years (> 90%). Additionally, Trp574Leu-resistant plants became prevalent (> 90%) in programs only using ALS inhibitors, while in the rest the frequency of susceptible plants did not substantially decrease below 40%. Regarding the other monitored grass weeds, Digitaria sanguinalis and Panicum dichotomiflorum were effectively controlled in programs using ALS-inhibitors without soybean rotation or in programs without ALS-inhibitors altogether, excepting the program relying on an 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor under maize monocrop for the latter species (0%). At the end of the experiment, the only IWM programs that reduced infestation levels were the one without ALS-inhibitors under soybean rotation, and the one with standard pre-emergence treatments. These findings highlight the effectiveness of crop rotation and alternative herbicides both pre- or post-emergence in controlling E. crus-galli. ALS-inhibitors, while challenged by resistance in E. crus-galli, remain valuable tools for managing other grass weed species in maize. It is crucial to adapt IWM strategies for herbicide-resistant E. crus-galli and other grass weed populations to mitigate the further evolution of resistance. © 2024 Corteva Agriscience. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimizing molecular assays for glyphosate and ALS-inhibitor resistance diagnostics in four weed species

Herbicide-resistant weeds pose a threat to food production in modern agriculture, causing US$32 billion in crop production losses worldwide. In Michigan, highly troublesome and widespread weeds include waterhemp, Palmer amaranth, common ragweed, and horseweed, with accessions that are resistant to glyphosate (Group 9) and ALS-inhibitors (Group 2), major herbicide sites of action utilized in soybean and corn cropping systems. Molecular assays for rapid resistance diagnostics to confirm the in-field status of herbicide resistance can assist with more effective, timely, and proactive management. In this research, we developed and tested PCR-based assays to identify target site resistance mechanisms to both herbicide groups through Sanger sequencing and EPSPS copy number variation. Nine different SNPs were identified in five ALS positions known to confer herbicide resistance among all species surveyed. Pro197Ser was the most frequent in horseweed and common ragweed accessions, whereas Trp574Leu was the predominant mutation in Palmer amaranth and waterhemp. Four horseweed accessions contained the Pro106Ser mutation in the EPSPS gene, which confers resistance to glyphosate. Additionally, waterhemp and Palmer amaranth had 2–7 and 20–160 copies of EPSPS, respectively. The assays were validated by comparing genotyping of several field-collected accessions of unknown resistance status with known resistant and susceptible accessions. The efficacy of genotyping assays was >98% and required only two days, confirming that molecular assays are a robust tool for rapid resistance diagnostics. These assays can help growers evaluate herbicide resistance status in weed populations within the same growing season, allowing them to adopt effective management practices.

Evolution of "invasion syndrome" in invasive goldenrod is not constrained by genetic trade-offs.

A suite of plant traits is thought to make weed populations highly invasive, including vigorous growth and reproduction, superior competitive ability, and high dispersal ability. Using a breeding design and a common garden experiment, we tested whether such an "invasion syndrome" has evolved in an invasive range of Solidago altissima, and whether the evolution is likely to be genetically constrained. We found an overall shift in invasive phenotypes between native North American and invasive Japanese populations. The invasive populations were taller and produced more leaves, suggesting a superior ability to exploit limited resources. The populations also produced more allelopathic compounds that can suppress competitor growth. Finally, invasive populations produced more seeds, which are smaller and are released from a greater height, indicating a potential for superior dispersal ability than the native populations. Quantitative genetics analyses found a large amount of additive genetic variation in most focal traits across native and invasive populations, with no systematic differences in its magnitude between the ranges. Genetic covariances among three traits representing invasion strategies (leaf mass, polyacetylene concentration and seed size) were small. The R metric, which measures the effect of genetic covariances on the rate of adaptation, indicated that the covariance neither constrains nor accelerates concerted evolution of these traits. The results suggest that the invasion syndrome in S. altissima has evolved in the novel range due to ample additive genetic variation, and relatively free from genetic trade-offs.

Application of a Standardized Impact Monitoring Protocol (SIMP) to assess biological weed control projects in the State of Idaho, USA

In the USA, the lack of systematic post-release assessments of weed biological control projects demonstrating quantitative effects of biological control agents on target weed densities, population biology, and/or vegetation responses remain a concern. While there are numerous quantitative assessments, overall conclusions are limited in scope by the spatial scale covered, duration of study, potentially confounding factors, or weed parameters measured. The United States Department of Agriculture’s Animal Plant Health Inspection Service is the regulatory agency responsible for biological control agent releases. USDA APHIS requires post-release impact monitoring of target weed populations as part of release permits issued for new biological control agents. However, large scale, long-term impact assessments are rarely conducted for a variety of reasons. To address this problem, biocontrol practitioners developed a standardized impact monitoring protocol (SIMP) for the State of Idaho in 2007. The intent was to collect ecological data which are sufficiently robust for quantitative analysis, while minimizing time spent in the field to make data collection appealing to citizen scientists and land managers. SIMP has since been implemented for ten weed biocontrol systems, with more than fifteen years of monitoring data for some systems. SIMP data are collected along permanent transects and include weed density and size parameters, categorical vegetation community and biocontrol agent abundance data. Data are repeated measures, which are well suited for dynamic population modeling and can be coupled with environmental factors (e.g., climate or soil data) to analyze how processes like climate (and climate change) can drive variation in weed biocontrol agent interactions. SIMP data can be combined with detailed weed, nontarget plant and/or biocontrol agent surveys to add analytical data. Finally, SIMP has also been implemented for two weeds for which biological control agents have not yet been introduced to provide weed and community vegetation data prior to releases.

Biodiversity and Vegetation Succession in Vineyards, Moravia (Czech Republic)

Maintaining biodiversity in agricultural landscapes is a major challenge for environmental protection in Europe. Vineyards rely heavily on agrotechnical interventions such as herbicide use and tillage for weed control, which affect biodiversity and can lead to soil erosion and resistant weed populations. The fragmentation of agricultural landscapes affects biodiversity by altering community composition and often reducing plant population sizes and genetic diversity. However, it can also increase the abundance of certain species and enhance population resilience to environmental change. Vineyards can support high levels of biodiversity and provide ecosystem services due to their semi-natural habitat structure. This research evaluates vegetation biodiversity using phytosociological relevés in different vineyards. Our results show that species richness and biodiversity are significantly influenced by vineyard age and management type. This study highlights differences in the representation of plant functional groups, with perennial taxa in grassy inter-row contributing to anti-erosion functions and serving as food sources for pollinators. The root zone around vine trunks shows an increase in invasive species with vineyard age, posing a risk to the agroecosystem. Vineyards predominantly follow a ruderal ecological strategy, using nutrients and light efficiently, while tolerating management disturbances. Understanding these dynamics is critical for developing sustainable vineyard management practices that support biodiversity and ecological resilience, counteract the homogenization of agricultural landscapes, and promote the coexistence of viticulture and species-rich ecosystems.

Bio-Efficacy of Pre-and Post-Emergence Herbicides on Growth, Productivity, Nodulation of Black Gram (Vigna mungo L.) under Coastal Plain of Odisha

Background: Weeds compete with plants for resources during cultivation and the control of weeds during the critical period of crop-weed competition is crucial to avoid yield loss ranging from 50%-90% in black gram. The first 4-5 weeks are critical for black gram crop-weed competition. The composition of weed flora, the duration of crop-weed competition and its intensity significantly impact yield losses in black gram cultivation. Therefore, the current study aims to evaluate weed management practices in rabi black gram, with a focus on identifying herbicides that enhance weed control, increase productivity and profitability. Methods: A field experiment was conducted during the rabi season of 2021-2022 and 2022-2023 consecutively at Odisha University of Agriculture and Technology, Bhubaneswar. The field experiment comprised of eight treatments on different herbicide applications as T1- Fenoxaprop-p-ethyl @ 65 g a.i. ha-1, T2- Quizalofop-p-ethyl @ 50 g a.i. ha-1, T3-Cyhalofop-butyl @ 75 g a.i. ha-1, T4-Pendimethalin @ 750 g a.i. ha-1, T5- Oxyflourfen @ 50 g a.i. ha-1, T6- Tembotrione @ 120 g a.i. ha-1, T7- Weed check (control) and T8- Weed free, which was laid under randomised block design. Collected samples were analyzed in the field and laboratory for crop-weed competition, herbicide phytotoxicity and yield attributes. Result: The results revealed that weed-free treatment recorded the lowest weed population (5.27-5.45), weed dry weight (1.35g-2.20 g) and lowest weed index (0.00%) at all growth stages followed by pendimethalin (PE) application. Among yield attributes, weed-free treatment recorded the highest plant height (cm) which was at par with pendimethalin (PE) followed by cyhalofop-butyl (PoE) application. The magnitude of seed yield was increased under weed-free (1035.46 kg ha-1) and pendimethalin (PE) and cyhalofop-butyl (PoE) applications by 53.62% and 48.40%, respectively over the weedy check. Application of tembotrione recorded the highest herbicide phytotoxicity (5.3-7.6) over the rest of the treatments. It can be concluded that the application of pendimethalin 30 EC 750 g ha-1 as PE at 2 DAS followed by cyhalofop-butyl 10 EC 75 g ha-1 can be advisable for better weed control, lower herbicide phytotoxicity and higher yield.

Weeds in the cotton growing areas in the Southeastern Anatolia Region

The Southeast Anatolia Region plays an important role, as it accounts for around sixty percent of Türkiye's cotton production. One of the most important factors limiting cotton cultivation is weeds. The aim of this study was to determine the weed species, their frequency and population density in the cotton growing areas of the Southeast Anatolia region. For this purpose, surveys were conducted in 152 cotton growing areas in Diyarbakır, Mardin and Şanlıurfa provinces in 2020 and 2021. The surveys were conducted using the segmented sampling method. As a result of the studies, 43 weed species belonging to 16 families were identified. When the weed species found in cotton are evaluated by family, the Poaceae family ranks first with 7 species, followed by Asteraceae with 6 species, Euphorbiaceae and Amaranthaceae with 5 species. redroot pigweed (Amaranthus retroflexus L.), field bindweed (Convolvulus arvensis L.), purple nutsedge (Cyperus rotundus L.), jungle rice (Echinochloa colonum (L.) Link), ground cherry (Physalis spp.), common purslane (Portulaca oleracea L.), black night shade (Solanum nigrum L.), johnson grass [Sorghum halepense (L.). Pers] and common cocklebur (Xanthium strumarium L.) were identified as the most common weed species. These weeds are widespread in many summer crops, especially in cotton. The development of effective management methods against these weeds in cotton will contribute to higher yields.

Weed Biology and Ecology Studies: Diversity, Dominance, Population and Weed Growth and Land Use Efficiency in Intercropping Corn (Zea mays l.) with Leguminous Crops in Dryland

The aim of the research is to examine the effect of intercropping corn with leguminous crops on weeds and land use efficiency. The experimental research method was designed using a randomized complete block design (RCBD) with three blocks. The treatments tested were monocrop planting patterns and intercropping between corn and leguminous crops. The results of the research showed that 16 weed species were found with high species diversity, evenness, dominance, and abundance, so that there were six dominant species that existed during plant growth. Peanuts and cowpeas are suitable for intercropping with corn because they can suppress the population and growth of weeds. Soybeans, green beans, and red beans are not suitable because they are not effective in suppressing the population and growth of weeds and compete with corn, so that corn yield losses due to competition are 38.20%–40.96% and due to weed competition, they reach 62.37%–63.77%. The best ecological and agronomic land use efficiency was obtained by intercropping corn with peanuts and cowpeas, with NKL values based on dry biomass weights of 1.90 and 1.89 (NKL > 1) and dry seed weights of 1.79 and 1.78 (NKL > 1).

Herbicides in modern sustainable agriculture: environmental fate, ecological implications, and human health concerns

AbstractHerbicides play a crucial role in modern agriculture by controlling weeds and ensuring sustainable crop productivity. However, the use of herbicides has raised concerns regarding their contamination, posing serious threat to the environment, biodiversity, and food safety. Recent trends indicate a decline in the overall volume of herbicides usage, suggesting a shift towards more specific and targeted formulations of herbicides. Also, there has been an increased use of systemic and pre-emergence herbicides. The global agriculture still faces several challenges because of the adverse environmental impacts caused by herbicide contamination, both at the application site and offsite. In view of the growing concern, it is necessary to develop new herbicides with greater selectivity or bio-based herbicide that can degrade after successful control of the intended weed population and minimize or eliminate the environmental hazards. Furthermore, the adoption of integrated weed management practices rather than prolonged and repeated use of herbicide in agriculture can effectively reduce the growth of herbicide-resistant weed populations. The present review is a single valuable resource, providing insights into the recent trends and future challenges associated with herbicide use in modern agriculture, with a focus on human health and food safety. Also, we emphasize the advancements in herbicide technology, emergence of new herbicide-resistant weed species, regulatory considerations, and alternative approaches in herbicide use, all of which are particularly valuable to agroecology, policymakers, and stakeholders. Graphical Abstract

Early detection and management of herbicide resistant weeds

Small weed patches may be noticed in fields after herbicide application, but they typically do not have a significant impact on the season’s crop yield. As a result, they are usually not treated as a threat to future yields. However, if these patches harbour weed biotypes resistant to one or multiple herbicides, resistance alleles can spread both spatially (via various dispersal pathways, including seed transport by machinery and commodity contamination) and temporally (through seed persistence). This poses a significant threat to herbicide-based weed management. Once these populations spread and cover a large enough area, eradication becomes improbable despite all the resistance management efforts. Therefore, a proactive and collaborative endeavour is needed to detect and manage small and patchy resistant weed populations. In this paper we review the current potential of weed resistance detection using imagery and molecular markers as well as possible weed management approaches. Finally, we advocate for the use of a combination of these techniques to manage herbicide resistant weeds when populations are small. This multifaceted approach is presently not applicable to all resistance mechanisms, and all weed species located in any crop, but could initially focus on biotypes and species that are easy to detect and represent the greatest threat.

Bio-Efficacy Evaluation of Herbicides for Weed Management in Rabi Onion

A field experiment entitled “Bio-efficacy evaluation of herbicides for weed management in rabi onion” was conducted at Weed Control Research Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh (Gujarat) during the rabi season of 2021-22 on medium black calcareous soil. The experiment comprising 14 treatments was laid out in a randomized block design with three replications. The results revealed that next to weed-free treatment, tank-mix pendimethalin 450 g/ha + oxyfluorfen 120 g/ha as pre-planting fb HW at 40 DATP, tank-mix pendimethalin 450 g/ha + oxyfluorfen 120 g/ha as pre-planting fb pre-mix propaquizafop + oxyfluorfen 43.75+105 g/ha at 40 DATP and tank-mix pendimethalin 450 g/ha + oxyfluorfen 120 g/ha as pre-planting fb pre-mix quizalofop + oxyfluorfen 100 g/ha at 40 DATP control of complex weed flora, reduced population and dry matter of weeds and having less reduction in yield due to better control of weeds, less crop-weed competition, higher weed control efficiency.

Current Status of Auxin‐Mimic Herbicides

The challenge of managing pesticide resistance in modern agriculture has become increasingly daunting. Herbicide resistance presents a complex scenario due to the continuous selection pressure from synthetic herbicides in global agricultural systems. Auxin‐mimic herbicides (AMHs) have traditionally served as a dependable tool for managing resistant weed populations in crop systems. However, overreliance on AMHs because of the lower incidence of resistance compared to other herbicide classes has intensified selection pressure on weed populations. Resistance to AMHs primarily arises from generalist mechanisms such as non-target site resistance (NTSR), involving reduced translocation, absorption, and enhanced metabolism. Nevertheless, specific mechanisms like target site resistance have also emerged in certain problematic weed species. These resistance mechanisms are complex to manage because some of them can confer resistance to single, cross, or multiple herbicide groups with diverse chemical and action mechanisms.

Weed Biology and Ecology Studies: Diversity, Dominance and Prediction of Yield Loss of Corn (Zea mays L.) Due to Broadleaf Weeds Competition in Dryland

The aim of the research was to determine the diversity, distribution, dominance, and yield loss of corn due to competition from broadleaf weeds. Descriptive research method with direct survey techniques of research objects. Data were collected using 10 sample plots measuring 1 m2, which were placed using random sampling. Observation parameters include the population and dry biomass weight of weeds and corn. The data was analyzed descriptively and comparatively by calculating density, frequency, and dominance to obtain an important value index and summation diminance ratio (SDR). The results of the research showed that 14 species of broad-leaved weeds were found with high species diversity, distribution, dominance, and abundance indices. The competitiveness and relative weighted dominance of six weed species, namely Amaranthus spinusus, Amaranthus gracilis, Synedrella nodiliflora, Acalypha indica, Ageratum conyzoides, and Alternanthera philoxeroides, are higher than those of other weed species, causing corn yield losses of 5.56%–21.90%. Therefore, these six weed species must be controlled.