Integrated Weed Management Strategies Research Articles

Utilization of the Neighborhood Design to Evaluate Suitable Pasture Crops and Their Density for Navua Sedge (Cyperus aromaticus) Management

Navua sedge (Cyperus aromaticus), a perennial plant native to Africa, poses a significant weed concern due to its capacity for seed and rhizome fragment dissemination. Infestations can diminish pasture carrying capacity, displacing desirable species. Despite the burgeoning interest in integrated weed management strategies, information regarding the efficacy of competitive interactions with other pasture species for Navua sedge management remains limited. A pot trial investigated the competitive abilities of 14 diverse broadleaf and grass pasture species. The results indicated a range of the reduction in Navua sedge dry biomass from 6% to 98% across these species. Subsequently, three broadleaf species—burgundy bean (Macroptilium bracteatum), cowpea (Vigna unguiculata), and lablab (Lablab purpureus), and three grass species—Gatton panic (Megathyrsus maximus), Rhodes grass (Chloris gayana), and signal grass (Urochloa decumbens) were chosen for a follow-up pot trial based on their superior dry biomass performance. These six species were planted at three varying densities (44, 88, and 176 plants/m2) surrounding a Navua sedge plant. Among the grass pasture species, Gatton panic and Rhodes grass exhibited high competitiveness, resulting in a minimum decrease of 86% and 99%, respectively, in Navua sedge dry biomass. Regarding the broadleaf species, lablab displayed the highest competitiveness, causing a minimum decrease of 99% in Navua sedge dry biomass. This study highlights the increasing efficacy of crop competition in suppressing weed growth and seed production, with the most significant suppression observed at a density of 176 plants/m2.

Enhancing Wheat Yield and Economic Viability in Subtropical Rainfed Agriculture through Combined Herbicide Application

The management of weeds remains a critical aspect of agricultural production, particularly in rainfed subtropical regions where weed pressure can significantly impact crop yield and economic returns. This study aimed to evaluate the effects of combined herbicide applications on both the yield and economic viability of wheat (Triticum aestivum L.) in subtropical rainfed agricultural systems. Field trials were conducted over two consecutive growing seasons, employing a randomized complete block design with four treatments: (1) pre-emergence application of herbicide A, (2) pre-emergence application of herbicide B, (3) combined pre-emergence application of herbicides A and B, and (4) control (no herbicide application). The study assessed various parameters including weed density, wheat yield, and economic returns. Results indicated that the combined pre-emergence application of herbicides A and B significantly reduced weed density compared to individual herbicide applications and the control, consequently enhancing wheat yield. Furthermore, economic analysis revealed that the combined herbicide treatment resulted in the highest economic returns compared to individual herbicide applications and the control, indicating its economic viability in rainfed wheat cultivation in subtropical regions. These findings underscore the importance of integrated weed management strategies, particularly the judicious use of combined herbicide applications, for optimizing wheat yield and economic sustainability in subtropical rainfed agriculture.

Weed Management Methods for Herbaceous Field Crops: A Review

Weeds compete with crops for water and nutrients and can adversely affect crop growth and yield, so it is important to research effective weed control methods. This paper provides an overview of the impact of weeds on crop yield and describes the current state of research on weed management in field herbaceous crops. Physical weed control mainly refers to thermal technologies represented by flame weed control and laser weed control, which can efficiently and accurately remove weeds. Mechanical weed control requires a combination of sensor technologies, machine vision technology, and high-precision navigation to improve weed control accuracy. Biological weed control relies heavily on plant extracts and pathogens to create herbicides, but it is costly, and some can be toxic to mammals. Chemical weed control is a common method, resulting in environmental pollution and weed resistance. To reduce the use of chemical herbicides, scholars have proposed integrated weed management strategies, which combine biological control, control of the seed bank, and improve crop competitiveness. Integrated weed management strategies are considered to be the future direction of weed management. In conclusion, physical, mechanical, biological, and chemical weed control methods are commonly used in weed management. Each method has its applicable scenarios, and the implementation of integrated weed management strategies can lead to better weed control, improving crop yield and quality. The main objective of this review is to organize the research progress on weed management methods for herbaceous crops in the field and to provide a reference for the agricultural sector to develop weed control strategies. Specifically, this paper categorizes weed management methods into four groups, discusses and presents the advantages and disadvantages of the aforementioned weed control methods, and discusses future research directions.

Sequential herbicide application coupled with mulch enhances the productivity and quality of winter onion (Allium cepa L.) while effectively controlling the mixed weed flora

Weed control poses substantial difficulties for winter season onion (Allium cepa L.) cultivation in the north-western Indo-Gangetic Plains, primarily due to the constrained efficacy of the existing herbicides. To address this issue, a 2-year field study was conducted to assess the efficacy of pre- and post-emergence herbicides (pendimethalin, ethoxysulfuron, imazethapyr, and quizalofop-p-ethyl) individually and in combination with crop residue mulch for weed control in winter onion. The results revealed that using herbicides or mulches in isolation did not provide satisfactory weed control. However, the integration of natural mulch with pendimethalin followed by quizalofop-p-ethyl application proved to be the most effective weed control strategy, resulting in the least reduction in bulb yield (10.3%) compared to other treatments. On the contrary, combinations of pendimethalin with ethoxysulfuron or imazethapyr showed adverse effects on the onion crop and inflicted the highest yield losses among all treatments (78.6 and 83.4%, respectively). However, the combination of pendimethalin with quizalofop-p-ethyl coupled with crop mulch resulted in season-long weed control and over 80% bulb yield (36.58 t/ha) gains compared to the weed-free condition. These findings emphasize the efficacy of combining herbicides and mulches as an integrated weed management strategy for onions. By adopting such integrated approaches, farmers could improve weed control while maintaining bulb yield and quality, reducing the risks associated with herbicide resistance, and promoting sustainable onion production in the north-western Indo-Gangetic Plains.

Management of Herbicide resistant Phalaris minor: A Review

Littleseed canarygrass (Phalaris minor Retz), an annual species of the family Poaceae, is a major weed problem in many wheat-producing countries. The excessive dependence on herbicides for its control led to the evolution of multiple herbicides resistance and yield losses. The first case of resistant P. minor in India was to the Photosystem-II inhibitor isoproturon in the early 1990’s. P. minor has been found resistant to Acetolactate Synthase (ALS) inhibitors, Acetyl-CoA Carboxylase (ACCase) inhibitors, Photosystem II inhibitors. It is highly competitive and in severe cases can cause complete crop failure, forcing farmers to harvest their crop as fodder or ploughing the standing crop along with weeds. For management of these multiple herbicide resistant P. minor, pyroxasulfone, pendimethalin, flumioxazin, trifluralin and flufenacet can be used as alternative herbicides. Moreover, in-depth biological and ecological studies on P. minor should be carried out for devising integrated weed management strategies. The long-term strategies of efficient weed management and sustainability of wheat production should include the use of alternative herbicides, herbicide mixture, crop rotation along with other non-chemical methods like manual removal of weeds, mulching, Summer ploughing etc providing the competitive advantages to the wheat crop over P. minor, at the same time increasing the profitability of the farmer by controlling the weed effectively and reducing the selection pressure on the weeds which will inturn reduce the resistance development in weeds

Using integrated weed management systems to manage herbicide-resistant weeds in the Canadian Prairies

Although herbicides have been a dominant and effective weed control strategy for decades in Western Canada, herbicide resistance and the lack of new modes of action have resulted in weed management challenges. Integrated weed management strategies have been shown to be successful in controlling certain weed species that are problematic in cropping systems. The objective of this study was to investigate integrated weed management strategies that have been successful on individual species to determine their applicability to a multiple weed species that may coexist in a field. In addition, harvest weed seed control was incorporated into these integrated weed management strategies to determine its impact in western Canadian cropping systems. A 5-year rotational study was conducted from 2016 to 2020 at Beaverlodge, Lacombe, and Lethbridge, AB; Scott and Saskatoon, SK; and Carman, MB, that incorporated integrated weed management strategies such as rotational crop diversity (including winter annuals and perennials), increased seeding rates, crop silaging, chaff collection, and with or without in-crop herbicides. This research confirmed success in managing some species of weeds such as wild oat when increased seeding rates, 2 years of early cut silage barley, and competitive winter cereals were incorporated into a cropping system, even when no in-crop herbicides were applied. However, some weed growth morphologies (e.g., twining weeds) or life cycles (e.g., facultative winter annuals) were not managed successfully with this combination of strategies. Chaff collection provided incremental weed control benefits but did not serve as a replacement for herbicidal weed control. Weed densities had an apparent impact on the success of these integrated weed management strategies, suggesting that the sooner they are adopted, the more likely they are to be successful at maintaining or reducing weed densities. This study not only showed the ability to reduce reliance on herbicides with strategies that can be effective in Western Canada but also highlighted the need for further understanding of different weed species and their responses to integrated weed management strategies, as well as the complexity of managing a weed community with integrated weed management.

Monitoring the effects of weed management strategies on tree canopy structure and growth using UAV-LiDAR in a young almond orchard

The primary objective of this study was to assess the potential effect of integrated weed management (IWM) on canopy structure and growth in a young almond orchard using unmanned aerial vehicle (UAV) LiDAR point cloud data. The experiment took place in the Neve Ya’ar Model Farm, with four IWM strategies tested: (1) standard herbicide, (2) physical-mechanical, (3) cover crops, and (4) integrated management combining herbicide and mowing. One pre-treatment sessions in 2019 and two experiment sessions in 2020–2021 were conducted. During these three experimental sessions, manual measurements, including trunk diameter (TD), were taken for all trees in the orchard. Six canopy growth parameters (e.g., tree height and volume), and functionality parameters (e.g., leaf density, gap fraction profile (GFP) and entropy) were calculated for individual trees using UAV-LiDAR data and were compared to manual measurement (i.e., TD). The results indicated that the herbicide treatment enabled effectively maintained weed coverage at approximately 5–10 % throughout the experiment, demonstrating successful control over weed growth. In contrast, the integrated weed management strategy yielded the highest weed cover (∼50 %). With the view of replacing ground manual measurements with UAV-LiDAR-derived measurements, we explored the relationships between TD and UAV-LiDAR-derived volume and GFP. The relationships between TD and GFP were with R2 values of 0.43 and 0.57 for 2021, respectively. The relationship between GFP and volume showed an R2 value of 0.65 for both years. We observed significant differences between IWM for TD, volume, and GFP in both years, indicating on higher tree development in the herbicide and integrated management treatments. The standard herbicide-based management yielded the highest crop yield, while the cover crop strategy yielded the lowest per plot. Finally, random forest (RF) model was used to identify key factors that significantly influence tree volume, TD, and GFP. The RF results showed that IWM explained about 30 % of tree structural changes, while the rest were attributed to environmental factors (i.e., topographical and climatic). The RF model R2 values ranged between 0.79 and 0.86, representing the topographical and climatic effects on tree structural parameters and growth, reflecting the natural field variability. Our study designed and successfully implemented a framework for estimating canopy characterization in young almond orchards subjected to varied IWM treatments. Ensuring the precise calibration of the LiDAR system and validating data, especially in complex canopy structures, can be challenging since the accuracy of ground-truth data has its errors. For future study, the fusion of LiDAR data with multispectral imagery or terrestrial LiDAR data can be considered, as well as more frequent UAV-LiDAR re-visits, offering insights into phenological states and higher resolution of canopy characteristics in orchards. This research enhances our understanding of the advantages and challenges of using UAV-LiDAR point cloud data analysis to assess the impact of IWM on young almond tree growth.

Demographics of Palmer amaranth (Amaranthus palmeri) in annual and perennial cover crops

AbstractPalmer amaranth (Amaranthus palmeri S. Watson) is the most problematic weed of cotton (Gossypium hirsutum L.)-cropping systems in the U.S. Southeast. Heavy reliance on herbicides has selected for resistance to multiple herbicide mechanisms of action. Effective management of this weed may require the integration of cultural practices that limit germination, establishment, and growth. Cover crops have been promoted as a cultural practice that targets these processes. We conducted a 2-yr study in Georgia, USA, to measure the effects of two annual cover crops (cereal rye [Secale cereale L.] and crimson clover [Trifolium incarnatum L.]), a perennial living mulch (‘Durana®’ white clover [Trifolium repens L.]), and a bare ground control on A. palmeri population dynamics. The study was conducted in the absence of herbicides. Growth stages were integrated into a basic demographic model to evaluate differences in population trajectories. Cereal rye and living mulch treatments suppressed weed seedling recruitment (seedlings seed−1) 19.2 and 13 times and 12 and 25 times more than the bare ground control, respectively. Low recruitment was correlated positively with low light transmission (photosynthetic active radiation: above canopy photosynthetically active radiation [PAR]/below cover crop PAR) at the soil surface. Low recruitment rates were also negatively correlated with high survival rates. Greater survival rates and reduced adult plant densities resulted in greater biomass (g plant−1) and fecundity (seeds plant−1) in cereal rye and living mulch treatments in both years. The annual rate of population change (seeds seed−1) was equivalent across all treatments in the first year but was greater in the living mulch treatment in the second year. Our results highlight the potential of annual cover crops and living mulches for suppressing A. palmeri seedling recruitment and would be valuable tools as part of an integrated weed management strategy.

The impact of burial depth on Centaurea diluta emergence and modelling of its growth using a nonlinear regression and artificial neural network.

Centaurea diluta Aiton (North African knapweed) is a major weed concern in Spain as a result of the limited herbicides capable of controlling it, and the limited knowledge of its biology hinders the development of integrated weed management strategies. The current study presents results from two experiments that aimed to: (i) determine the effect of seed burial on seedling emergence; and (ii) model its phenology progression using sigmoidal (SRM) and artificial neural network models (ANN) based on different cohort emergence times. In the first experiment, burial at 2 cm and 5 cm decreased C. diluta emergence by 54% and 90%, respectively, compared to the emergence at 0 cm. In the second experiment, without crop-weed competition conditions, the emergence delay led to reductions in leaf number, rosette diameter, plant height and dry biomass by 63%, 50%, 59% and 93%, respectively. Seed production per plant exceeded 21 469. According to the growth model, leaf number was the most consistent morphological trait and critical for timing weed control actions, so it was used to compare SRMs and ANNs. On average, ANNs increased the precision in 5.72% (± 2.4 leaves) compared to SRMs. This slight performance of ANNs may be valuable for controlling C. diluta because control methods must be applied at the 4-leaf stage to achieve good efficacy. Seed burial at 5 cm depth is an effective method reducing C. diluta emergence. ANNs accurately predicted the leaf number employing environmental variables can help increase the efficiency of C. diluta control actions and reduce the risk of escapes. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Rotational Tillage Practices to Deal with Soil Compaction in Carbon Farming

Conservation tillage practices, such as reduced tillage and no-tillage, have recently garnered significant attention as core elements of the regenerative agriculture and carbon farming concepts. By minimizing mechanical soil disturbance, these practices preserve soil carbon and facilitate CO2 fixation in the soil. Despite the widely acknowledged benefits, many farmers still approach no-tillage with skepticism. Their primary concerns are weed management and soil compaction. While weeds can be effectively controlled with the deployment of integrated weed management strategies, urgent soil compaction problems can be rapidly resolved only with mechanical interventions. That is why many no-till farmers resort to occasional heavy tillage, in a scheme characterized as rotational tillage, inadvertently sacrificing their regenerative assets in soil carbon. This is also a pivotal issue within carbon farming: the fate of soil carbon at the end of a compliant scheme focused on carbon fixation. The present study explores data of soil organic matter (SOM), soil penetration resistance (PR), and dry bulk density (DBD) from the initial, six-year period of a long-term tillage experiment in Greece. During that period, modifications to the experimental design allowed diverse combinations of five tillage methods (conventional tillage, 3 reduced tillage methods, and no-tillage). The findings indeed underscore the farmers’ concerns about soil compaction. High levels of PR and DBD were observed even at the topsoil layer of the no-tillage (NT). Conventional, moldboard plowing (MP) or reduced, chisel plowing (CP) applied after four years of uninterrupted no-tillage ameliorated most of the soil compaction; however, at the same time, this induced unfavorable consequences for SOM. In contrast, NT applied permanently for six years resulted in a substantial enhancement in SOM that reached 2.24%, for a sampling depth 0–0.30 m compared to 1.54% for permanent MP. When no-tillage was rotated with plowing in the fifth year, almost 50% of the sequestered carbon was lost and the SOM dropped to 1.87%. Nevertheless, the amount of SOM observed at the deeper 0.15–0.30 m layer was greater compared to permanent NT. This suggests that while plowing induced some loss of SOM, it also facilitated the uniform distribution into the soil profile, in contrast with the accumulation in the topsoil at prolonged NT. The permanent CP method and the NT/CP rotation provided comparative outcomes in terms of both soil compaction and soil carbon sequestration with the rotational NT/MP scheme, while all the other tillage combinations were inferior.

Ethofumesate-resistant annual bluegrass (Poa annua) in grass seed production systems

AbstractThe prolific seed production and polyploidy of annual bluegrass allow for the rapid development of herbicide resistance. Ethofumesate-resistant annual bluegrass plants were identified in the 1990s in grass seed production in Oregon, but their prevalence and distribution are not well documented. Therefore a dose–response experiment was initiated to determine the potential level of ethofumesate resistance in seed production systems. Seeds from 55 annual bluegrass populations were obtained from three sources: seed production fields (31 populations), the seed cleaning process (6 populations), and seed testing lots prior to retail distribution (18 populations). Additionally, two populations, one with known ethofumesate resistance and one with known susceptibility, were identified in preliminary testing and used as controls in this experiment. Seed from each collected population was increased. Individual seedlings were then transplanted into separate cone-tainers, grown to a size of 2 to 3 tillers in the greenhouse, and then sprayed using a compressed air track spray chamber with 10 doses of ethofumesate at 0, 0.56, 1.1, 2.8, 5.6, 8.4, 11.2, 16.8, 22.4, and 44.8 kg ai ha−1, with 0.84 to 2.2 kg ha−1 as the label application rate for perennial ryegrass. The resistant to susceptible ratio of populations across all sources ranged from 0.5 to 5.5. The most resistant populations found in production fields, seed cleaning, and seed testing lots had the effective dose necessary to kill 50% of the population (ED50) of 12.1, 9.4, and 13.1 kg ha−1, respectively. Furthermore, 68% of the populations found in production fields had ED50 higher than 6 kg ha−1, indicating common annual bluegrass resistance in grass seed production. As such, growers should implement integrated weed management strategies, as herbicides alone will likely be ineffective at controlling annual bluegrass.

Integrated Control of Echinochloa oryzoides, Echinochloa crus-galli and Cyperus difformis Based on Pre-Sowing Herbicide and Some Herbicide Combinations in Rice

Cosmopolitan weeds are even constant elements where rice cultivation started just a century ago. There are few but important weed species with high adaptation in rice, which requires monoculture production systems and aquatic environment. Rotation difficulty resulted in the proliferation of highly competitive weed species strongly adapted to the aquatic environment. Constant use of herbicides with the same mechanisms of action leads to an evaluation of herbicide-resistant weed population and an increased number of herbicide-resistant populations in Türkiye. Chemical weed control and alternative integrated weed management strategies in rice production systems have significantly evolved throughout the years as well as rice herbicide traits and weed spectrum. The study was carried out in rice fields with resistance problems in two different locations, in the Black Sea and the Marmara Regions. The clamozone 480 EC, oxadiazon 200 CS, glyphosate potassium 441 g/l, glyphosate IPA 360 g/lt +carfentrazone-ethyl 5 g/l, cyhalofop-butyl 200 EC, penoxsulam 25.2 OD +bentazon-sodium 480 SL active ingredients and combinations’ efficacy were investigated on ALS and ACCase inhibitor herbicides resistant Cyperus difformis, Echinochloa oryzoides and Echinochloa crus-galli populations. At the end of the study, it was determined that including pre-sowing herbicides such as clomazone and oxadiazon in the weed control program would help control the ALS and ACCase-resistant this species. Implementing integrated weed management strategies for managing existing herbicide-resistant weeds and reducing future development of herbicide resistance is one of our most influential and economical long-term strategies.

Effect of Integrated Weed Management Practices on Growth and Yield of Green Chilli (Capsicum annum L.)

Weed infestation in chilli production, especially during early growth stages, is a major constraint leading to significant yield loss. Effective weed management during this critical phase is crucial for maximizing chilli crop productivity. Keeping this in view a field experiment was conducted at the research farm of Abhilashi University, Mandi (H.P) during the Kharif season of 2022-23. The main objective was to assess the impact of various integrated weed management strategies on the growth and yield of green chilli crops. The experiment consisted of seven treatments with control, laid out in Randomized Block Design with three replications. The treatment details viz., T1[Weedy check (Control)], T2(Weed free), T3[Hand weeding at 30 and 60 days after transplanting (DAT)], T4[organic mulch (paddy straw)], T5 (Oxyfluorfen 1.0 kg/ha, T6 Pendimethalin 1.0 kg/ha) and T7 (Pendimethalin 1.0 kg/ha. + HW after 60 DAT). The results of the study revealed that the "Weed-free" treatment (T4) exhibited the highest plant height (80.35 cm), number of leaves per plant (120), number of fruits per plant (85) with an average weight of fruits per plant (276.74 g), dry weight of fruits per plant (33.21 g) and yield (7.56 kg/plot and 189.05 q/ha). The treatment "Pendimethalin 1.0 kg/ha + Hand weeding after 60 DAT" (T7) followed closely, recording the plant height (75.78 cm), number of leaves per plant (114.66), number of fruits per plant (82.33) with an average weight of fruits per plant (251.56 g), dry weight of fruits per plant (32.7 g) and yield (7.12 kg/plot and 178.08 q/ha). The "Weedy check" treatment (T1) required the longest duration for 50% flowering and the first and final harvest, with 76, 108 and 124 days, respectively. On the other hand, the "Weed-free" treatment (T2) required the shortest period, with 66, 93, and 106 days, respectively. Regarding weed-related parameters, the "Weedy check" treatment (T1) demonstrated the highest weed count (110), fresh weight of weeds (2160.03 g) and dry weight of weeds (388.81 g), while the "Weed-free" treatment (T2) exhibited the minimum weed count (0.00), fresh weight of weeds (0.00 g) and dry weight of weeds (0.00 g). The highest weed control efficiency (WCE) of 100% and the lowest weed index (0.00%) were observed in the "Weed-free" treatment (T2), whereas the lowest WCE (0.00%) and the highest weed index (69.69%) were recorded in the "Weedy check" treatment (T1). Economically, the combined treatment of "Pendimethalin 1.0 kg/ha with hand weeding after 60 DAT" (T7) resulted in the highest net return of 4,39,192.78 ₹/ha, followed by the "Weed-free" treatment (T2) with 4,35,207 ₹/ha. The lowest net return was observed in the "Weedy check" treatment (T1) with 62,117.28 ₹/ha.

Competing with the competitors in an endless competition: a systematic review of nonchemical weed management research in peanut (Arachis hypogea) in the United States

AbstractWeed interference is a major factor that reduces peanut (Arachis hypogaea L.) yield in the United States. Peanut growers rely heavily on herbicides for weed control. Although effective, herbicides are not a complete solution to the complex challenge that weeds present. Therefore, the use of nonchemical weed management options is essential. The literature on weed research in peanut in the past 53 yr in the United States was reviewed to assess the achievements and identify current research gaps and prospects for nonchemical weed management for future research. More than half (79%) of the published studies were from the southeastern United States. Most studies (88%) focused on weed management, while fewer studies (12%) addressed weed distribution, ecology, and competitive mechanisms. Broadleaf weeds were the most frequently studied weed species (60%), whereas only 23% and 19% of the published studies were relevant to grasses and Cyperus spp., respectively. Seventy-two percent of the published studies focused on curative measures using herbicides. Nonchemical methods using mechanical (5%) and preventive (13%) measures that influence crop competition and reduce the buildup of the weed seedbank, seedling recruitment, and weed seed production have received less attention. In most studies, the preventive weed management measures provided weed suppression and reduced weed competition but were not effective enough to reduce the need for herbicides to protect peanut yield. Therefore, future research should focus on developing integrated weed management strategies based on multiple preventive measures rather than one preventive measure combined with one or more curative measures. We recommend that research on mechanical weed management should focus on the role of cultivation when integrated with currently available herbicides. For successful weed management with lasting outcomes, the dominant weed communities of specific target locations should be addressed within the context of climate change and emerging constraints rather than focusing on single problematic species.

Direct Seeded Rice as Resource Efficient Technology

In Asia, seedlings are typically transplanted into puddled soil to cultivate rice (Oryza sativa L.). Due of the manpower, water, and energy requirements of this manufacturing system, it is becoming less lucrative as these resources become more scarce. Additionally, it impairs the soil's physical qualities, negatively impacts the performance of succeeding upland crops, and increases methane emissions. Different issues, such as a declining water table, a manpower shortage during peak seasons, and worsening soil quality, need the use of alternate establishment techniques to maintain both natural resource and rice yield. Due to its low input requirement, ability to reduce greenhouse gas emissions, and ability to adjust to climatic hazards, the direct seeded rice (DSR) technique has gained a lot of attention and popularity in recent years. Dry seed must be sown into a ready seedbed, while pre-germinated seed must be sown into standing water and puddles of soil. Many farmers have switched from transplanted to DSR culture as a result of the introduction of early maturing cultivars, the application of effective fertiliser management techniques, and increased adoption of integrated weed management strategies. In certain industrialised nations, such the USA, Australia, Japan, China, and Korea, DSR technology is heavily mechanised. By switching from conventional rice to DSR, crop water requirements, soil organic matter turnover, improved nutrient management, carbon sequestration, weed management, greenhouse gas emissions, and crop intensification will all be significantly reduced. The transition from PTR to DSR is hampered by a number of factors, including a high weed infestation, the development of weedy rice, an increase in soil-borne diseases (nematodes), nutritional disorders, poor crop establishment, lodging, the prevalence of blast, brown leaf spot, etc. By addressing these limitations, DSR may show to be a very viable, economically and technically viable substitute for PTR.

Developing and implementing a sustainable, integrated weed management program for herbicide‐resistant Poa annua in turfgrass

AbstractThe ability of Poa annua L. to adapt to most turfgrass environments extends to its ability to develop resistance to commonly used herbicides. Herbicide resistant P. annua is of almost epidemic proportions. The loss of once viable chemical‐based treatments pushes practitioners towards more expensive, and often less effective, control strategies. This management guide focuses on integrated weed management (IWM) practices for P. annua control and herbicide resistance—what it is and how to overcome it. Also discussed are resistance mechanisms and documentation of common occurrences of field‐level resistance within much of the United States. Finally, a summary of some of the social and economic constraints that practitioners face in the implementation of IWM strategies for P. annua is discussed.

Germination ecology and growth phenology of cowvine (Ipomoea lonchophylla) as influenced by environmental parameters

AbstractCowvine (Ipomoea lonchophylla J.M. Black) is a native and widely spread summer broadleaf weed in Australia. It contains glycoresins, which are toxic to livestock. However, limited information is available on seed germination ecology and growth phenology of this species. A series of experiments were conducted to determine the response of I. lonchophylla to different environmental conditions. Results showed that the primary dormancy exhibited by I. lonchophylla is due to the physical impediment of the hard seed coat. The seed germination percentage was the highest at the constant temperature of 27 C and alternating temperatures of 35/25 C. Germination of I. lonchophylla was not stimulated by light, suggesting that this species is non-photoblastic. Ipomoea lonchophylla germination was intolerant of a medium to high level of salt stress, and germination was completely inhibited at 250 mM NaCl. The emergence of I. lonchophylla was not restricted by seeding depth up to 8 cm, but only 5% emergence was recorded when seeds were planted at a 16-cm depth. The germination percentage was also drastically reduced by 90% to 100% after exposure to either 3 mo in silage, 48-h digestion in steers, or silage plus digestion treatments. The growth and reproductive phenology of I. lonchophylla was affected by emergence time. Plants that emerged in late spring (November 15) were able to produce more berries per plant than those that emerged in midsummer (January 15) in southern New South Wales. Information gained in our study concerning high soil salinity, ensiling, and digestion will help to develop more sustainable and effective integrated weed management strategies for controlling and reducing the spread of this weed.

Weed control in a pesticide‐free farming system with mineral fertilisers

AbstractNegative impacts of pesticides on the environment and human health, the risk of pesticide residues in the food chain, and the problems with herbicide‐resistant weed biotypes support the need for alternative cropping systems. The objective of this study was to investigate weed populations, weed management and crop yield in a pesticide‐free cropping system with the use of mineral fertilisers. Conventional‐, organic‐ and mineral‐ecological cropping systems (MECS) with 6‐year crop rotations including winter wheat, maize, winter triticale or winter rye, soyabean or spring pea, and spring barley were established in a randomised complete strip plot design with four repetitions. Experiments were conducted at four locations in Germany. Preventive and sensor‐guided mechanical weed management strategies were applied in all crops in the organic system and in MECS. Herbicide were applied in the conventional farming system. Weed densities, weed species composition, weed control efficacy (WCE) and crop yield were analysed over 2 years in 2020 and 2021. Conventional farming had the highest WCE and 1–7 weeds m−2 (2.7% weed coverage) after herbicide application. In the organic cropping system and MECS, up to 27 weeds m−2 were counted after camera‐guided weed hoeing. Weed coverage in MECS (9.7%) was higher than in the organic cropping system with 7.7%. Crop yield in MECS was equal to the conventional farming system and 20% higher yield than in the organic farming system. MECS represents a promising new and productive cropping practice if an effective integrated weed management strategy is applied.

Germination ecology and response to herbicides of Ludwigia prostrata and their implication for weed control in paddy fields

AbstractProstrate water primrose is a troublesome weed in rice paddy fields. A study was conducted to determine the influence of environmental and agronomic factors on its emergence. The efficacy of herbicides on this species was also examined. The germination percentage of mature seeds remained above 90% within 180 d after harvest, indicating a low primary dormancy of this species. Light stimulated seed germination. Seeds buried deeper than 0.5 cm did not form seedlings. These results suggest that stale seedbed practices and deep tillage operations can mitigate the occurrence of this species in paddy fields. The optimum temperature for germination varied from 25/15 C to 35/25 C. The osmotic potential and salt concentration needed to inhibit 50% of maximum germination were −0.4 MPa and 197 mM, respectively. Seeds were tolerant to flooding and did not germinate at pH 8 to 10. The preemergence herbicides oxadiazon, oxadiargyl, and butachlor had excellent control efficacy on prostrate water primrose, with a 95.4% to 100% reduction in seedling number and a 99.2% to 100% reduction in biomass, respectively. The postemergence herbicides MCPA-Na + bentazone, bentazone, MCPA-Na, and fluroxypyr applied at the 2- to 3-leaf stage of prostrate water primrose provided a 90.6% to 100% reduction in seedling number and a 99.3% to 100% reduction in biomass. The results of this study can help in developing sustainable and effective integrated weed management strategies for controlling prostrate water primrose in paddy fields.

Growth analysis and yield evaluation under tillage and weed management practices in maize-wheat cropping system

Integrated weed management strategies combine tillage systems and weed control strategies. Conservation agriculture (CA) and sustainable intensification cropping systems are potential sources of improved growth and overall productivity. This study evaluated tillage and weed management strategies effects on crop growth parameters and biological yields in maize-wheat cropping system in North Western Himalayan region. Different tillage (five) and weed management practices (three) were evaluated from 2018 to 2020 on growth indices and yield with fifteen treatments. Conservation agriculture (CA) based production system (ZT, zero tillage; crop rotation and intensification; residue management i.e. ZTR-ZTR) had higher crop dry matter accumulation (DMA), relative growth rate (RGR), crop growth rate (RGR) and biological yield of maize (28698 kg/ha) and wheat crops (18750 kg/ha). The zero tillage in maize and wheat (ZT-ZT) resulted in lowest maize (24677 kg/ha) and wheat biological yield (14009 kg/ha. Among weed management treatments, application of recommended herbicides in maize and wheat crop (H-H) resulted in higher crop DMA and biological yield of maize (27652 kg/ha) and wheat crop (19540 kg/ha). Therefore, for North Western Himalayan conditions, ZTR+H-ZTR+H (Conservation tillage combined with herbicide application in maize and wheat) is superior to other combinations for growth and yield.