Effective Weed Management Research Articles

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.

Germination characteristics associated with nicosulfuron resistance in Amaranthus retroflexus L.

Nicosulfuron-resistant biotype (R) and -sensitive biotype (S) Amaranthus retroflexus L. seeds were subjected to different temperature, light, salt, osmotic potential, pH value and burial depth treatments. The difference in germination response of two populations to the above abiotic environmental factors was used to study the fitness cost of nicosulfuron-resistance evolution in A. retroflexus. The aim is to find a powerful tool for weed control in the presence of evolutionary resistance selection. The results of this experiment showed that the germination rate and germination index in S population were generally higher than that in R population. When the salt stress was 80 mM, the water potential was -0.1 Mpa ~ -0.4 Mpa, and under strong acid and alkali conditions, the germination index in S population was prominently higher than that in R population (p<0.05). The delayed seed germination in R population indicated that its nicosulfuron resistance may be linked to seed biochemical compositions that altered seed germination dynamics. The resistant and sensitive biotype of A. retroflexus had differently favourable adaptability in diverse environments. Salt, osmotic potential and pH value are not the major constraints for A. retroflexus germination, however, A. retroflexus are strongly responsive to temperature, light and burial depth. Considering that seeds of A. retroflexus are unable to reach the soil surface beyond the depth of 6 cm, deep inversion tillage before sowing may be an effective and economical weed management tool for the control of nicosulfuron resistant A. retroflexus.

Strategies for effective weed management in black gram (Phaseolus mungo L. Hepper) cultivation

Strategies for effective weed management in black gram (Phaseolus mungo L. Hepper) cultivation

Germination Ecology and Ecology-based Management of Fimbristylis miliacea (L.) in Lowland Rice: A Review

Fimbristylis miliacea (L.) Vahl, commonly referred to as globe fringerush, member of the Cyperaceae family, is a significant and widespread sedge weed in rice cultivation. This C4 plant is characterized by its tall, annual or perennial growth, featuring a fibrous root system and smooth stems, often producing vigorous tillers reaching heights of 80-90 cm. Seedlings of F. miliacea typically emerge shortly after rice is planted, with flowering occurring within about a month, capable of producing a second generation within the same growing season. Found extensively throughout tropical regions, especially in lowlands, F. miliacea thrives in environments such as rice fields, shallow water along ditches, and streams, notably prevalent across South and Southeast Asia, as well as Australia. This weed presents enduring challenges across diverse agro-ecosystems due to its various ecotypes, prolific seed production, rapid germination, vigorous growth, strong competitive abilities and allelopathic interactions. Temperature is a critical factor significantly influencing seed germination of F. miliacea which exhibits non-deep physiological dormancy. Light is essential for the germination of this weed showing positive photoblastic behaviour. F. miliacea thrives in saturated soils but fails to emerge from depths greater than one cm, emphasizing the importance of shallow tillage to manage weed emergence effectively. Effective weed management hinges on a deep understanding of the factors that favour its emergence and establishment. Adopting the germination ecology-based practices such as tillage, stale seed bed preparation, optimal planting density, water management and nutrient management can significantly improve the management of F. miliacea.

Two-Pass Weed Management Programs for White Bean

It is essential to implement effective weed management programs to minimize white bean yield loss from weed interference. Four field experiments were conducted during 2022 and 2023 to determine the efficacy of one-pass compared to two-pass weed control programs. This study evaluated trifluralin + S-metolachlor + imazethapyr or trifluralin + S-metolachlor + halosulfuron applied preplant incorporated (PPI), bentazon + fomesafen + quizalofop-p-ethyl applied postemergence (POST), and trifluralin + S-metolachlor + imazethapyr or trifluralin + S-metolachlor + halosulfuron applied PPI followed by (fb) bentazon + fomesafen + quizalofop-p-ethyl applied POST in white bean. There was minimal white bean injury (&amp;le; 5%) with the herbicide programs evaluated. Weed interference decreased white bean yield 44%. Weed interference with bentazon + fomesafen + quizalofop-p-ethyl applied POST resulted in a 24% decrease in white bean seed yield compared to the weed-free control; however, all other PPI and PPI fb POST herbicide programs resulted in white bean seed yield that was similar to the weed-free control. Weed interference with the one-pass herbicide programs (PPI or POST) resulted in 17% lower white bean seed yield compared to the two-pass herbicide programs (PPI fb POST). Trifluralin + S-metolachlor + imazethapyr, applied PPI, controlled velvetleaf 85%, common ragweed 35%, common lambsquarters 96%, and green foxtail 80% at 8 weeks after the POST application (WAT). Trifluralin + S-metolachlor + halosulfuron, applied PPI, controlled velvetleaf 68%, common ragweed 87%, common lambsquarters 94% and green foxtail 56% at 8 WAT. Bentazon + fomesafen + quizalofop-p-ethyl, applied POST, controlled velvetleaf 86%, common ragweed 97%, common lambsquarters 34%, and green foxtail 29% at 8 WAT. Trifluralin + S-metolachlor + imazethapyr, applied PPI, followed by bentazon + fomesafen + quizalofop-p-ethyl, applied POST, controlled velvetleaf, common ragweed, common lambsquarters, and green foxtail 98, 97, 96, and 94%, respectively at 8 WAT. Trifluralin + S-metolachlor + halosulfuron, applied PPI, followed by bentazon + fomesafen + quizalofop-p-ethyl, applied POST, controlled velvetleaf, common ragweed, common lambsquarters, and green foxtail 97, 99, 97 and 93%, respectively at 8 WAT. Based on orthogonal contrast, the two-pass herbicide programs provided 17, 21, 20, and 38% greater control of velvetleaf, common ragweed, common lambsquarters, and green foxtail in comparison to the one-pass herbicide programs, respectively at 8 WAT. This study concludes that the two-pass herbicide programs of trifluralin + S-metolachlor + imazethapyr or trifluralin + S-metolachlor + halosulfuron applied PPI followed by bentazon + fomesafen + quizalofop-p-ethyl applied POST provides the most consistent weed control in white bean in Ontario.

New segmentation approach for effective weed management in agriculture

Accurate weed detection in agricultural images is a crucial challenge for improving crop management practices and reducing chemical usage. In this study, we propose an innovative segmentation model called DWUNet, inspired by popular architectures and incorporating the latest advances in the state of the art. Our model delivers remarkable accuracy, with a Jaccard index reaching 0.825, while ensuring fast inference speed of only 8 ms per image, thus providing an optimal solution for real-time applications. By comparing DWUNet to several state-of-the-art models, we demonstrate its superiority in terms of accuracy and efficiency. Furthermore, a qualitative analysis of the visual results confirms DWUNet's ability to accurately detect weeds and generalize results beyond the training data. This study represents a significant advancement in the field of precision agriculture, providing a powerful tool for sustainable crop management and reducing environmental impact.

Effect of different weed control techniques on the leaf yield and nutritional qualities of Ocimum sanctum

AbstractOcimum sanctum is a leaf‐vegetable and spice crop with several nutritional, therapeutic, and curative properties. Economic losses due to weeds have posed a major challenge to farmers, who have adopted different techniques to manage weeds without regard to its effect on the crop's nutritional qualities. The objective of this study was to investigate the effect of weed control techniques on weed eradication, leaf yield, and nutritional qualities of O. sanctum. Nine weed control techniques comprising black, red, and transparent polyethylene mulches, rice husk and sawdust mulches, daily removal of weed (DROW), hoe‐weeded, application of Haloxyfop post‐emergence herbicide spray (PEHS), and un‐weeded were investigated in a randomized complete block design with three replications. Significant variations in leaf‐yield and nutritional qualities among the different weed control techniques were recorded. Leaf yield was higher in plots treated with rice husk and black polyethylene mulches. Haloxyfop PEHS and transparent polyethylene mulch were superior in enhancing the proximate and vitamin contents of O. sanctum while black polyethylene and DROW were more efficient in weed control compared with the other weed control techniques. The use of polyethylene mulch as an effective weed management option offers numerous benefits for agriculture and gardening. Its ability to conserve moisture, suppress weed growth, and improve the crop microclimate, makes it a sustainable and cost‐effective option for farmers globally. Additionally, the use of herbicide to exploit plant biosynthetic pathways could lead to the unearthing of chemical innovations that could in addition to eradicating weed, also improve the nutritional qualities of crop.

Optimizing herbicide types and concentrations: Crucial elements for achieving intensive cultivation of common buckwheat

An appropriate herbicide type and concentration is essential for effective weed management and enhancing crop yield. However, the optimal herbicide type and corresponding application concentration for controlling weeds in common buckwheat on the Loess Plateau region of Northwestern China remain unclear. To address this gap, experiments were conducted to investigate the effects of various herbicides on weed control, dry matter accumulation, and grain yield in common buckwheat, and to analyze the variances in weed control efficacy and grain yields of the optimal herbicides at different concentrations. The results showed that both metolachlor and quizalofop-P-ethyl demonstrated effective weed control with lower phytotoxicity. Dry matter accumulation was lower under metolachlor, with no significant differences observed among the post-emergence herbicide treatments. Importantly, metolachlor and quizalofop-P-ethyl promoted the allocation of dry matter to grains. Remarkably, metolachlor and quizalofop-P-ethyl increased the grain yield by 15.59% and 26.97%, respectively, compared to spraying an equivalent amount of water. Additionally, the m2.25, q0.9, and q1.2 treatments exhibited excellent weed control effectiveness. And the higher grainnumber per plant observed under m2.25, q0.9, and q1.2 contributed to the increase in grain yield. Consequently, m2.25, q0.9 and q1.2 increased the grain yield by 34.42%, 38.86% and 33.16%, respectively. These findings demonstrate that applying metolachlor and quizalofop-P-ethyl at 2.25 L ha−1 and 0.9 or 1.2 L ha−1 respectively, is beneficial for efficient weed management and yield enhancement in common buckwheat cultivation on the Loess Plateau region of Northwestern China. These studies provide important guidance for promoting common buckwheat cultivation in this region.

Mapping of flumioxazin tolerance in a snap bean diversity panel leads to the discovery of a master genomic region controlling multiple stress resistance genes.

Effective weed management tools are crucial for maintaining the profitable production of snap bean (Phaseolus vulgaris L.). Preemergence herbicides help the crop to gain a size advantage over the weeds, but the few preemergence herbicides registered in snap bean have poor waterhemp (Amaranthus tuberculatus) control, a major pest in snap bean production. Waterhemp and other difficult-to-control weeds can be managed by flumioxazin, an herbicide that inhibits protoporphyrinogen oxidase (PPO). However, there is limited knowledge about crop tolerance to this herbicide. We aimed to quantify the degree of snap bean tolerance to flumioxazin and explore the underlying mechanisms. We investigated the genetic basis of herbicide tolerance using genome-wide association mapping approach utilizing field-collected data from a snap bean diversity panel, combined with gene expression data of cultivars with contrasting response. The response to a preemergence application of flumioxazin was measured by assessing plant population density and shoot biomass variables. Snap bean tolerance to flumioxazin is associated with a single genomic location in chromosome 02. Tolerance is influenced by several factors, including those that are indirectly affected by seed size/weight and those that directly impact the herbicide's metabolism and protect the cell from reactive oxygen species-induced damage. Transcriptional profiling and co-expression network analysis identified biological pathways likely involved in flumioxazin tolerance, including oxidoreductase processes and programmed cell death. Transcriptional regulation of genes involved in those processes is possibly orchestrated by a transcription factor located in the region identified in the GWAS analysis. Several entries belonging to the Romano class, including Bush Romano 350, Roma II, and Romano Purpiat presented high levels of tolerance in this study. The alleles identified in the diversity panel that condition snap bean tolerance to flumioxazin shed light on a novel mechanism of herbicide tolerance and can be used in crop improvement.

Effect of weed management on growth and yield of green gram (Vigna radiate L) under medium land situation of Manipur

Effect of weed management on growth and yield of green gram (Vigna radiate L) under medium land situation of Manipur

Effect of Planting Methods and Weed Control Treatments on Weed Dynamics, Yield and Economics of Green Gram (Vigna radiata L.)

An experiment was conducted at the Agronomy Research Farm, College of Agriculture, Gwalior (M.P.), during the 2019 kharif season to investigate the effects of different planting methods and weed control treatments on the weeds, growth, yield, and economics of green gram. The field experiment followed a split-plot design with three planting methods as main plot treatments (broadcasting on a flat bed, line sowing on a flat bed, and ridge and furrow) and five weed management practices as sub-plot treatments (Pendimethalin 1000 g/ha, Diclosulam 26 g/ha, Imazethapyr 75 g/ha, hand weeding at 20 and 40 DAS and weedy check), replicated thrice. The experimental field was primarily infested with narrow-leaved weeds such as Cyperus rotundus, Cynodon dactylon, Echinochloa spp., and Dactyloctenium aegyptium, and broad-leaved weeds like Digera arvensis, Celosia argentea, Commelina benghalensis, and Phyllanthus niruri. Among the herbicidal treatments, Imazethapyr at 75 g/ha effectively controlled both narrow-leaved and broad-leaved weeds, resulting in the lowest weed index. The ridge and furrow planting method recorded the highest values in growth parameters, yield attributes, and seed yield, proving to be more remunerative compared to other methods. These findings indicate that the combination of ridge and furrow planting with effective weed management, particularly using Imazethapyr, optimizes green gram productivity and economic returns.

Enhancing productivity and profitability of quinoa through optimization of plant spacing and weeding regimes

ContextWeeds are a major constraint to quinoa production since no herbicide tolerant variety is available worldwide. This raises the importance of cultural practices for controlling weeds. Optimizing plant spacing and implementing effective weeding practices may help to enhance quinoa productivity and profitability. ObjectiveThe objective of current study was to utilize the plant spacing as an alternate option for ensuring effective weed management and profitable quinoa production for the irrigated plains. MethodsThe effect of planting spacing on weed flora in quinoa was evaluated for two consecutive years (2021–22 and 2022–23). Two weeding regimes (weedy and weed-free) along with three plant spacings viz., 10, 20, and 30 cm were tested using a randomized complete block design in split-plot arrangement with three replications. In the weedy plots, no weeding was done, while in the weed-free plots, manual weeding was performed to keep them weed-free throughout the growing season. Results and conclusionsDifferent plant spacing significantly influenced weed biomass and density in quinoa. Narrow spaced plants (10 cm) gave maximum weed suppression as against widely spaced plants (30 cm) and a concomitant yield increase. Medium plant spacing (20 cm) gave maximum grain yield by attaining the optimum plant population under weed-free conditions during both years. Economic analysis also revealed that medium plant spacing with weed-free conditions was beneficial compared to other treatments regarding gross returns, net returns, and benefit-cost ratio. SignificanceThis study highlights that quinoa spacing primarily determined quinoa-weed competition and can be a tool for weed management in this crop.

How the Management and Environmental Conditions Affect the Weed Vegetation in Canary Grass (Phalaris canariensis L.) Fields

Canary grass (Phalaris canariensis L.) is a versatile crop with global significance; it is primarily cultivated for its small elliptical seeds, which are used as bird feed and for human consumption. This crop is adapted to various climates and soils, so it can be grown successfully in Hungary. However, challenges such as weed control, climate change impacts, and soil factors require strategic management for sustained success in canary grass cultivation. Our study investigated the impact of management and environmental (as seasonal and soil) factors on pre-harvest weed vegetation in canary grass fields in Southeast Hungary between 2017 and 2020. In addition to showing the weed vegetation of the canary grass, the aim of our work was to promote more effective weed management of canary grass by revealing correlations between soil, seasonality, and management variables, influencing weed diversity and coverage. Using the analysis of covariance (ANCOVA) and correlation tests, we tested significant variables, providing insights into the complex interactions affecting weed composition. A redundancy analysis (RDA) further unveiled the relationships between explanatory variables and weed species’ composition. The findings offer valuable information for effective weed management strategies in canary grass cultivation. Our comprehensive study on canary grass fields in Southeast Hungary sheds light on significant factors influencing weed composition and abundance. The average weed coverage was 10.8%, with summer annuals and creeping perennials being the most prevalent life forms. Echinochloa crus-galli, Cirsium arvense, Xanthium italicum, and Setaria viridis were among the dominant species. ANCOVAs revealed the impact of soil, management, and seasonal factors on weed cover, species richness, diversity, and yield levels. Soil properties like texture, pH, and nitrogen content showed varying effects on weed parameters. The vintage effect, tillage systems, and farming practices also played crucial roles. The redundancy analysis highlighted the influence of the year, soil sulfur content, and winter preceding crops on weed composition. In conclusion, the herbaceous vegetation in the studied area is dominated by summer germinating and creeping perennial species. Despite slight differences in average coverage and occurrence, a well-defined set of significant species is evident. Multicollinearity among variables suggests limitations to further increase the number of variables that can be included in the analysis. The ANCOVAs showed that the soil, seasonal, and farming variables significantly influence overall weed vegetation and crop yield, with a lesser impact on species richness and diversity. The reduced RDA model highlights the strong influence of the year on species’ composition, emphasizing the inherent factors during canary grass cultivation that are challenging to modify through farming practices.

Weed Ecology: Insights for Successful Management Strategies: A Review

In crop ecosystems, the primary challenge in establishing a long-term weed management strategy arise from a lack of understanding regarding the nature of weediness and the factors that contribute to species dominance. To address this, farmers and researchers often rely on quick and efficient, yet temporary weed control methods, which can lead to long-term issues. To develop a more effective and sustainable weed management approach, it is crucial to gain a comprehensive understanding of both the biological characteristics and ecological behaviours of weeds. This can be achieved by incorporating preventive techniques, scientific knowledge and management skills, with the goal of enhancing crop production and benefiting farmers. While further information is needed in all aspects of weed management, the primary objective of weed science is to increase our knowledge of weed biology and ecology, thus fostering a better understanding of weediness. This understanding will facilitate the adoption of appropriate management strategies instead of relying solely on short-term solutions that may create or exacerbate long-term problems. The successful growth and reproduction of any species depend on a variety of conditions. In a given ecosystem, the species that can thrive more efficiently under the specific set of environmental conditions will produce the most viable offspring and become the most abundant organisms. Weed ecology, which examines the adaptive mechanisms that enable weeds to thrive in highly disturbed soil conditions, provides essential insights into the distribution and abundance of weeds in both natural and managed systems. The occurrence of a weed in a particular area is influenced by multiple factors, with climatic, soil-related (edaphic) and biotic factors being the most significant among them.

Weed species classification with UAV imagery and standard CNN models: Assessing the frontiers of training and inference phases

Accurate weed species identification is crucial for effective site-specific weed management (SSWM), enabling targeted and timely control measures for each weed in crop field. This study advanced the current approach to species-level weed identification during the early growth stage by integrating unmanned aerial vehicles (UAVs) imagery with standard convolutional neural networks (CNNs) models such as VGG16, Resnet152 and Inception-Resnet-v2. For this, a robust dataset was created with 33,467 labels of weeds (Atriplex patula, Chenopodium album, Convolvulus arvensis, Cyperus rotundus, Lolium rigidum, Portulaca oleracea, Salsola kali, Solanum nigrum) and crops (maize, tomato), which was subjected to different training, validation and test scenarios. Model inputs were adjusted in order to align them with the information represented by the UAV images. Initially, models were developed in balanced scenarios, gradually increasing label numbers to assess their performance. Inception-ResNet-v2 achieved over 90% accuracy with 400 labels, while ResNet152 and VGG16 required 600 and 800 labels, respectively, for similar accuracy. In a more complex and realistic scenarios with unbalanced datasets, Inception-ResNet-v2 outperformed, likely due to its deeper architecture and enhanced capability to capture intricate features and patterns within UAV images. The study emphasized the importance of the minority-to-majority species ratio in unbalanced datasets, which affects minority species classification. To prevent misclassification, it is crucial to determine the right number of labels for CNN model training and validation. Weed maps were generated after species classification using the Faster R–CNN algorithm as an object detector. This advancement in methodology facilitates the precise and efficient implementation of SSWM techniques.

Conservation agriculture and weed management effects on weed community and crop productivity of a rice-maize rotation

In recent years, an increase in weed infestation, which is adversely affecting crop growth and productivity has been a major challenge facing the farmers of South Asia. The adoption of a permanent bed in combination with residue retention-based crop management practices may reduce weed abundance and increase crop productivity. In a two-year field study, we evaluated the responses of different organic weed management practices with contrasting tillage and residue (R) management strategies to weed dynamics and crop productivity under rice-maize rotation. The main plot treatments consisted of zero-tillage direct seeded rice and zero-tillage maize (ZTR fb ZTM); ZTDSR and maize both on permanent raised beds with residue (PBDSR + R fb PBDSM + R); PBDSR and PBM without residue (PBDSR-R fb PBDSM-R) and conventional tillage puddled transplanted rice and conventional tillage maize (CTR fb CTM). The subplots comprised unweeded control; vermicompost mulch; P- enriched vermicompost mulch; live mulch with Sesbania spp. in rice and Pisum sativum in maize and weed-free. Total weed density and biomass in rice and maize at 30 days after sowing (DAS) were minimum for PBDSR + R fb PBDSM + R compared to remaining tillage and residue management practices in both years. Apart from weed-free treatment, the highest weed control index was found with live mulch. Yield of rice and maize were found higher in permanent beds along with residue retention-based practices. In rice, the weed-free treatment showed the highest grain yield and live mulch reported 9.8 and 6.8 % higher grain yield than vermicompost mulch and P-enriched vermicompost mulch respectively. Our study shows that conservation agriculture practices under rice-maize rotation is one of the ways to reduce weed density and improve crop productivity in South Asia and other similar agro-ecologies.

Automated classification of saffron and broadleaf weeds of Flixweed and Hoary Cress using deep learning and color images

Today, the use of precision agriculture strategies that lead to effective weed management and minimize damage to crops is of great importance. In this research, color images and deep learning were used to distinguish Saffron from two common broadleaf weeds, namely Hoary Cress and Flixweed. A total of 291 photos of the three classes were taken under completely natural field conditions. The image data were resized to 150 × 150 pixels, normalized to [0,1] range, and then augmented. A total of 24 deep learning models with varying architectures and parameters were evaluated to identify the most optimal structure. The proposed models were established on the Xception network and leveraged initial weights from ImageNet via the transfer learning approach. These models underwent fine-tuning and modification by introducing additional layers to the base model. Ultimately, two models were proposed based on their performance in accuracy and loss on test data. One model demonstrated impeccable performance, attaining 100% accuracy and a loss of 0.41, despite potential network instability. It successfully differentiated all classes with precision, recall, and F1-score all at 100%. The second model proposed exhibited a more stable performance with 95% accuracy and a loss of 3.78. It achieved precision ranging from 91% to 100%, recall from 88% to 100%, and F1-score from 91% to 96% across the three classes, showing promising results. The results of this research can be considered as a basis for the development of weed removal robots for the purpose of automatic weed control using precision agriculture strategy.

Weed and nitrogen management effects on weed flora and productivity of transplanted rice (Oryza sativa) in North-Eastern region of India

A field study was conducted during rainy (kharif) season of 2017 at Barapani, Meghalaya, to find out the effects of weed and nitrogen management on weed flora and yield of transplanted rice (Oryza sativa L.) in North-Eastern region of India. The experiment was taken in split-plot design with 3 replications. In the main plot, 4 weed management practices, viz. unweeded control; oxadiargyl 0.08 kg/ha followed by (fb) bispyribac-Na 0.02 kg/ha; oxadiargyl 0.08 kg/ha fb hand weeding (HW) at 40 days after transplanting (DAT), and 2 HW at 20 and 40 DAT was taken, while 4 N levels, viz. 0, 30, 60 and 90 kg N/ha were taken in sub-plots. At 60 DAT, total weed population and weed density were remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. The grain yield also followed the same trend and remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. However, in terms of net returns, application of oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha recorded the highest followed by oxadiargyl 0.08 kg/ha fb HW at 40 DAT. Application of N at higher level reduced the total weed population at 60 DAT and a reverse trend was found with weed dry weight. Application of 90 kg N/ha recorded higher grain yield, net returns and benefit: cost ratio. It may be concluded that oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha with 90 kg N/ha could be an alternative for HW to enhance the productivity in transplanted rice for North-Eastern region of India.

Herbicide Strategies for Weed Control in Rice Cultivation: Current Practices and Future Directions

Rice, as a staple food for more than half of the world's population, plays a crucial role in global food security. However, weed competition poses a significant challenge to rice cultivation, affecting yield and quality. To address this challenge, rice farmers have increasingly turned to chemical herbicides as a cost-effective alternative to labor-intensive manual weeding. This review paper explores the current practices and future directions in herbicide strategies for weed control in rice cultivation, with a specific focus on diverse approaches adopted in various agro-ecological regions, particularly in Pakistan. The paper begins by highlighting the importance of rice cultivation in global agriculture and the economic significance of the crop, emphasizing the need for effective weed management to ensure sustainable production. It discusses the impact of labor shortages and rising labor costs on weed control practices, driving the adoption of chemical herbicides, especially in direct-seeded rice cultivation. Additionally, the review underscores the importance of integrated weed management systems, which combine cultural practices, targeted herbicide applications, and legislative measures to optimize crop productivity while minimizing environmental impact. Furthermore, the paper evaluates the efficacy of different herbicides and their timing of application in managing weeds and maximizing rice yield. It synthesizes findings from recent studies to provide insights into the effectiveness of pre-emergence and post-emergence herbicides, as well as their impact on weed-crop competition and overall crop health. By analyzing the strengths and limitations of existing herbicide strategies, the review identifies opportunities for innovation and improvement in weed management practices. Overall, this review paper offers a comprehensive overview of herbicide strategies for weed control in rice cultivation, highlighting the need for sustainable and integrated approaches to address weed challenges while ensuring food security and environmental sustainability in rice-producing regions.

Two-Pass Weed Management Programs for Identity-Preserved Soybean

Weed management is a challenge in Identity-Preserved (IP) soybean in Ontario, Canada. Six experiments were established in southwestern Ontario, Canada during 2021 and 2022 to evaluate weed control and soybean yield with preemergence (PRE), early postemergence (EPOST), and PRE followed by (fb) late POST (LPOST) herbicide programs. At 8 weeks after LPOST herbicide applications, S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, and flumioxazin/metribuzin/imazethapyr applied PRE provided 7, 49, and 99% control of velvetleaf; 65, 98, and 100% control of green pigweed; 7, 8, and 82% control of common ragweed; 25, 68, and 98% control of common lambsquarters; 91, 77, and 89% control of barnyardgrass; and 62, 68, and 93% control of green foxtail, respectively. Imazethapyr + bentazon applied EPOST provided 91% control of velvetleaf; 91% control of green pigweed; 78% control of common ragweed; 95% control of common lambsquarters; 76% control of barnyardgrass; and 79% control of green foxtail. S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, and flumioxazin/metribuzin/imazethapyr applied PRE fb bentazon + fomesafen + quizalofop applied LPOST provided 61, 86, and 100% control of velvetleaf; 97, 99, and 100% control of green pigweed; 94, 88, and 99% control of common ragweed; 96, 98, and 100% control of common lambsquarters; 97, 95, and 97% control of barnyardgrass; and 97, 96, and 99% control of green foxtail, respectively. There was minimal and transient soybean injury (6% or less) with all PRE or EPOST herbicide treatments, however, S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, or flumioxazin/metribuzin/imazethapyr applied PRE fb bentazon + fomesafen + quizalofop LPOST caused up to 22% injury in soybean. Weed interference reduced soybean yield 40%. Weed interference with S-metolachlor/metribuzin and pyroxasulfone/sulfentrazone applied PRE reduced soybean yield 25 and 31%, respectively. Reduced weed interference with flumioxazin/metribuzin/imazethapyr applied PRE, imazethapyr + bentazon applied EPOST, and the two-pass programs of a PRE fb LPOST herbicide resulted in soybean yield that was similar to the weed-free control. This study concludes that there are many effective weed management programs in IP soybean; however, the two-pass weed control programs are recommended since they provide good to excellent weed control, minimize soybean yield loss from weed interference, and ensure the use of multiple herbicide modes of action which reduces the selection intensity for the evolution of herbicide-resistant weeds.