Weed Suppression Research Articles

Weed suppression and productivity influenced under conservation agriculture and organic weed management practices in rice-maize rotation

Weed suppression and productivity influenced under conservation agriculture and organic weed management practices in rice-maize rotation

Cover crop management strategies affect weeds and profitability of organic no-till soybean

Abstract Cover crop residue retention on the soil surface can suppress weeds and improve organic no-till soybean (Glycine max) yield and profitability compared to a tilled system. Appropriate cereal rye (Secale cereale) fall planting date and termination methods in the spring are critical to achieve these benefits. A plot-scale agronomic experiment was carried out from September 2018 to October 2021 in Kutztown, PA, USA to demonstrate the influence of cereal rye planting date (September or October) and mechanical termination method [no-till (I & J roller-crimper, Dawn ZRX roller, and mow-ted) and tilled (plow-cultivate)] on cover crop regrowth density, weed biomass, soybean yield, and economic returns. In one out of three years, the September rye planting accumulated more cover crop biomass than the October planting, but the regrowth of the rye after roller-crimping was greater with this planting date. Cover crop planting date had no effect on total weed biomass and demonstrated varying effects on soybean grain yield and economic returns. The Dawn ZRX roller outperformed the I & J roller-crimper in effectively terminating cover crops, while the I & J roller-crimper demonstrated more uniform weed suppression and led to greater soybean yields over a span of three years. Organic no-till strategies eliminated the need for tillage and reduced variable costs by 14% over plow-cultivated plots, and generated ~19% greater net revenue across the study period (no-till vs tillage = US $845 vs US $711 ha−1). Terminating cereal rye with roller-crimping technology can be a positive investment in an organic soybean production system.

Dynamic changes in weed abundance and biodiversity following different green manure establishment

Weeds have a negative impact on agricultural production by competing with cultivated crops for resources and fostering conditions conducive to disease and insect pest dissemination. Hence, optimal weed management is of paramount importance for sustainable agricultural. In this study, the ability of four distinct green manure species to suppress weeds was determined in a field experiment conducted in Chongqing, Southwest China. After cultivating the green manure species, the weed density and diversity were monitored over the following year. The findings highlight a notable trend in the suppressive ability of green manures, with increased suppression observed from November to March, an optimal level observed from March to May, and a gradual decline observed thereafter. Poaceae (Lolium perenne L.) demonstrated the highest efficacy in suppressing weeds. The meta-analysis underscore the exceptional suppressive effects of poaceous green manures on weed as well and prove sustained planting for three or more consecutive years yielded superior weed suppression outcomes. Green manure had the most prominent inhibitory effect on poaceae weeds, followed by Polygonaceae and Caryophyllaceae. The field experiment also investigated the effect of green manures on weed community composition, they increased in the proportion of perennial weeds within these communities. This study offers valuable insights that can guide policymakers, agricultural experts, and farmers in devising effective weed management strategies. By highlighting the potential benefits of green manures and unraveling their nuanced impact, this study contributes to the arsenal of sustainable agricultural practices.

Nutritional and Functional Composition of Barley Varieties From Legambo District, Ethiopia.

In agriculture, barley holds significant importance as a vital crop with multiple uses. It provides a variety of advantages, including weed suppression, erosion management, nutrient recycling, and improved soil structure. The nutritional and functional composition of barley varieties' samples were analyzed using AOAC methods. The moisture content of the samples ranged from 7.3% to 12.8%, while the ash content varied from 0.5% to 13%. The crude fiber content ranged from 0.5% to 1.5%, and the crude protein content ranged from 0.73% to 3.4%. Furthermore, the crude fat content ranged from 0.11% to 0.8%. The carbohydrate content of the samples were found to be between 69.5% and 82.5%, with an energy value ranging from 338.2 to 382.02 kcal/100 g. In terms of mineral content, the samples exhibited varying levels of calcium (310-670 mg/100 g), iron (34.9-65 mg/100 g), zinc (8.9-16 mg/100 g), and magnesium (Mg) (520-1122 mg/100 g). In addition, the range of the total phenolic content was 1.2 to 3.1 mg/100 g, while the range of the total flavonoid content was 0.41 to 0.55 mg/100 g. Therefore, barley, a selenium-rich food, acts as an antioxidant, protecting cells from free radical damage, reducing inflammation, and reducing the risk of chronic illnesses. The highest content of stearic acid (3.4 g/100 g) followed by myristic acid (2.6 g/100 g) were found in barley varieties. Barley amino acids are essential nutrients for various biological processes, muscle repair, immunological system function, neurotransmitter generation, and detoxification.

Yield stability of winter wheat in intercrop makes better adaptation to climate conditions

Global climate change is a main issue today. Negative effects, such as gradual warming, annual precipitation decrease and frequences of extreme meteorological events have also felt in Hungary. These effects significally tested the adaptive capacity of our cultivated plants. In our country two-thirds of the arable land is occupied by cereals. In most cases there is no crop rotation, pre-crop effect remains unused. Intercrop is a special kind of plant association, where two or more crops growing simultaneously on the same field. It can be increases resilience against pest and pesticides, provides better utilization of growth resources, and weed suppression. In mixture mitigate the effects of climate. Our experiments were made in 2020/2021 with 3 winter wheat varieties (GK Szilárd, Celulle, GK Csillag) and a winter pea variety (Aviron) in 4 repeats, on 10 square meter random layout plots in Szeged-Öthalom. We set 3 different seed density in every variety in every combination. Higher seed density of wheat makes higher yield regardless of pea, except of GK Csillag at 75% seed density of wheat and pea. Increasing pea ratio in mixture, wheat yield decreased. In contrast GK Szilárd and Cellule, their 75% and 100% mixture with 75% Aviron achieved higher wheat yield. Pure stands have shown better values than the combined ones, vice versa for GK Csillag: every seed density with 50% of Aviron gaves the highest wheat yield. Wheat and pea yield together gives the yield advantage what intercrop provides.

Potato (Solanum tuberosum L.) soil covering with organic matter: Results and knowledge gap

AbstractPotato mulching practices and their effects often differ, and the results are sometimes contradictory in the literature, as they vary depending on climatic conditions and growing practices. In this study, we analysed 68 peer-reviewed publications to reveal which problems of potato cultivation were intended to be solved by mulching with organic materials. We have found that the main goals of mulching are the preservation of soil moisture, the reduction of soil temperature, and the suppression of weeds, in which mulching provides effective help. In different parts of the world, different organic mulches increased the yield of potatoes in 78% of the studies. Although the occurrence and damage of pests, pathogens and weeds are extremely understudied (16, 18, 29% of the studies), we can conclude that organic mulches effectively reduced their damage.

Optimizing ecosystem function multifunctionality with cover crops for improved agronomic and environmental outcomes in dryland cropping systems

CONTEXTIntegrating cover crop mixtures into dryland crop-fallow rotations may foster ecological intensification by enhancing ecosystem function multifunctionality compared with conventional fallows and monoculture cover crops. However, the expression of functional traits in cover crop mixtures is influenced by arrays of agronomic and environmental filters that differently influence cover crop performance. OBJECTIVETo (1) determine the identity and diversity effects of different cover crop functional types on ecosystem functions and trade-offs, and (2) determine the optimal cover crop mixture that maximizes ecosystem function multifunctionality in a subtropical dryland environment. METHODSUsing three-site-year field experiments, we assessed if cover crop mixtures enhanced ecosystem function multifunctionality (MF) above that of monoculture cover crops and conventional fallow. We measured a range of ecosystem functions as indicators of three major ecosystem service categories: 1) provisioning services (biomass production, cash crop yield, and profitability); 2) supporting services (weed suppression, soil active carbon accrual, soil aggregate distribution, nitrogen (N) mineralization, N supply, and N retention); and 3) regulating services (parasitic nematode suppression, promotion of free-living nematodes, soil respiration, and soil water conservation). RESULTS AND CONCLUSIONSWe found greater suite of ecosystem functions following mixture cover crops compared to monocultures, likely due to synergistic trait combinations that increased ecosystem function multifunctionality. The legume and forage brassica monocultures had consistently low multifunctionality (MF < 0.5). The oat:legume mixture resulted in the highest multifunctionality (MF > 0.5), driven by moderate water use and aboveground biomass production, and high groundcover residency, thus favouring higher cash crop yields and system profitability. They also generated overall improvements in soil health by providing additional carbon inputs, increasing the proportion of larger soil aggregates, and improving soil food web structure. We predicted the optimum cover crop mixture to maximize ecosystem function multifunctionality was 64% oat, 36% legume and 0% forage brassica. SIGNIFICANCEThis study offers novel insight into the agronomic and environmental impacts of replacing fallow with cover crops in a subtropical dryland. It shows that integrating mixture of oat:legume cover crops can increase multifunctionality. Further research is required on the extent of ecosystem trade-offs between competing ecosystem functions. The predicted optimum cover crop mixture composition will likely vary when different ecosystem functions are considered or if long-term experiment data are used. Hence, the recommended optimum cover crop mixture must be interpreted with caution and cover crop selection should be based on practical recommendations according to target management goals.

Suppression of weed and insect populations by living and straw mulches in sesame (Sesamum indicum L.)

In order to evaluate the effect of different weed management treatments on weeds, pest and natural enemies populations in sesame (Sesamum indicum L.), a 2-year study was conducted in East Azarbaijan, Iran in 2020–2021. The study was conducted based on randomized complete block design with four replications. The weed management treatments consisted of trifluralin use (960 g ai ha−1), wheat straw mulch (WSM), living mulches of fenugreek (Trigonella foenum-graecum L.) (FLM), bitter vetch (Vicia ervilia L.) (VLM), calendula (Calendula officinalis L.) (CLM) and one-time hand weeding (OHW). The effect of weed management treatment was significant on densities of insect pests, natural enemies and weed and also weed biomass and sesame seed yield. The lowest densities of insect pests including Myzus persicae, Brevicoryne brassicae, Helicoverpa armigera and Spodoptera exigua were observed in CLM treatment. Also, the highest densities of natural enemies Coccinella septompunctata, Coccinella undecimpunctata and Orius niger were observed in CLM treatment. The highest reductions in grass (51.0%), broadleaf (72.0%), and total (62.6%) weed biomasses and highest seed yield (1456 kg ha−1) were obtained in OHW. The seed yields in CLM and WSM treatments were not significantly different with trifluralin treatment and could be recommended in sustainable production of sesame.

Nontarget Effects of Preemergence Herbicide Diuron in Hamlin and Valencia Sweet Orange (Citrus sinensis L. Osbek) in Florida

The prevalence of Huanglongbing (HLB) disease, also known as citrus greening, has compelled the citrus industry to change management practices to increase production. However, these changes, such as enhanced nutrition and irrigation programs, have caused weed proliferation, subsequently leading to increased use of herbicides. Thus, our study evaluated a popular preemergence herbicide active ingredient, diuron, for nontarget impacts on young Hamlin and Valencia sweet orange (Citrus sinensis L. Osbek) trees in two commercial orchards in southwest Florida. The treatments included the preemergence application of diuron at three rates (1.8, 3.6, and 7.3 kg a.i./ha), a weed-checked control (using postemergence herbicides: glufosinate ammonium + saflufenacil), and a nontreated control. The treatments were applied twice (in Fall 2021 and Spring 2022) in a randomized complete block with four replicates. Results indicate that over a 5-month period, the application of diuron generally had no significant impact on citrus root growth. Further, over a 2-month observation period for Hamlin and a 4-month observation period for Valencia, it was found that diuron application had no notable effect on fruit detachment force. Valencia trees treated with diuron high showed higher HLB disease severity at location 1. In addition, Hamlin trees treated with diuron low and medium showed higher fruit drop (∼19% more) than the untreated control at location 1. However, this trend was inconsistent across the locations and cultivars. This result suggests that increased disease severity and fruit drop were not associated with diuron treatment. Thus, our study finds diuron as a tree-safe option for preemergence weed suppression in citrus production, as long as it is used in accordance with the recommended dosage and restrictions stated on the herbicide label.

Breeding allelopathy in cereal rye for weed suppression

AbstractRapid increase in the hectarage and agricultural systems that use cover cropping for soil conservation and improvement, soil moisture retention, and weed management has highlighted the need to develop formal breeding programs for cover crop species. Cereal rye (Secale cereale L.) is preferred by many growers due to high biomass production and weed-suppression potential, which is believed to be partially due to allelopathy. Rye germplasm exhibits large variability in allelopathic activity, which could be used to breed rye with enhanced weed suppression. Here, we provide an overview of rye history and breeding and describe a strategy to develop rye lines with increased allelopathic activity. The discussion focuses on ways to deal with important challenges to achieving this goal, including obligate cross-pollination and its consequent high segregation levels and the need to quantify allelopathic activity under field conditions. This review seeks to encourage weed scientists to collaborate with plant breeders and promote the development of cover crop cultivars better suited to reduce weed populations.

Performance and Degradation of Nonwoven Mulches Made of Natural Fibres and PLA Polymer-Open Field Study.

The need for sustainable alternatives to conventional plastic mulches in agriculture has led to the development of various types of biodegradable mulches made from natural fibres and biopolymers to reduce environmental pollution and mitigate soil pollution caused by conventional plastic mulch usage. Degradation, impact on soil temperature and humidity, and weed suppression properties of needle-punched nonwoven mulches of different mass per unit area, made of jute, hemp, viscose, and PLA biopolymer, are investigated. Their biodegradation is determined by changes in the mulch properties (mass per unit area, thickness, air permeability, tensile properties, microscopic images, and FTIR analyses) during 300 days of exposure to the environmental conditions in the period from May 2022 to February 2023. The change in mass per unit area, thickness, air permeability, and tensile properties of nonwoven mulches did not show a tendency to degrade during exposure to environmental conditions. The microscopic and FTIR analysis showed the degradation of the fibres from the mulches during the exposure time to a certain extent. The environmental conditions influence the change in the dimensions of the mulches (shrinkage and expansion)-which impact periodically tested mass results per unit area-as well as their thickness and air permeability. The nonwoven mulches provide higher temperatures compared to bare soil, though not as high as those observed beneath traditional agricultural foil. When comparing the humidity in bare soil and soil covered by mulches during the plant growth period (June to October), it was found that soil humidity was higher beneath all mulches. The nonwoven mulches provide superior soil moisture retention compared to conventionally used agrofoil. Almost all nonwoven mulches effectively suppressed weed growth, except hemp mulches. The newly produced mulches have the potential to replace traditional agrofoil, offering improved conditions for plant growth, effective weed control, and faster degradation without causing harm to the environment.

Impact of planting green on soil properties under irrigated no‐till soybean

AbstractPlanting green refers to the practice of planting a row crop into an actively growing cover crop (CC) and terminating it at or after row crop planting. Planting green could have more beneficial impacts on soil properties, erosion control, nutrient cycling, weed suppression, and other soil ecosystem services because it allows greater CC biomass accumulation than early‐terminated CC. The objectives of this 2‐year study were to evaluate the impact of planting green on soil properties (bulk density, wet aggregate stability, sorptivity, particulate organic matter, organic matter, nutrients, and others) and soybean (Glycine max L.) yield in an irrigated no‐till soybean system in south‐central Nebraska. Treatments were cereal rye (Secale cereale L.) CC terminated 2 weeks before planting (2WBP), CC terminated 2 weeks after planting (2WAP) soybean, and no CC. On average, CC produced 2.35 Mg ha−1 of biomass for 2WBP and 12.03 Mg ha−1 for 2WAP. Both 2WBP and 2WAP reduced N concentration by 48% (31.10 vs. 59.70 mg kg−1) but had no effect on other soil properties compared with no CC. Despite the abundant CC biomass production, terminating 2WAP had little to no effect on most soil properties in the short term (2 years). Wet aggregate stability increased as CC biomass production increased, while soil sorptivity (initial water infiltration) increased as wet aggregate stability increased. CC termination timing had inconsistent effects on soybean yield. In general, after 2 years, planting green had no effect on most soil properties or soybean yield, warranting long‐term studies on this topic.

Impact of different establishment methods for summer-sown cover crops in Southwestern Germany on their weed suppression properties

Early establishment of cover crops (CCs) is essential for attaining successful weed suppression in the autumn-to-spring period. Due to reduced precipitation and extended periods of drought in the summer within temperate zones, the establishment of CCs poses challenges. Three methods of cover crop (CC) establishment were tested: 1) preharvest sowing 10 days before harvest of cash crop (PreHa); 2) no-till sowing directly after harvest of cash crop (NoTi) and 3) sowing with reduced tillage 10 days after harvest of cash crop (ReTi). The five CC species black oat (Avena strigosa Schreb.); common buckwheat (Fagopyrum esculentum Moench), phacelia (Phacelia tanacetifolia Benth.), fodder radish (Raphanus sativus var. oleiformis L.) and common vetch (Vicia sativa L.), along with a mixture comprising 20% of all five species, were included as second factor in a three-year field experiment (2020–2022) conducted in South West Germany. One treatment per establishment method was maintained without CCs as a control. Measurements of CC, volunteer cereal and weed density, soil coverage, and dry matter were carried out throughout the autumn-to-late autumn timeframe. On average across all years and CCs, the PreHa and NoTi establishment demonstrated the highest CC dry matter contents of 99 g m−2 and 119 g m−2, respectively, despite lower CC densities. This had a particularly notable impact on weed density in the ReTi variant, which, over the three-year average across all CC treatments, was 5 times higher than in NoTi and PreHa but exhibited a 18–27% smaller volunteer cereal density by comparison, thereby influencing the respective volunteer cereal and weed coverages. Meanwhile, weed and volunteer cereal dry matters were consistent across all establishment methods. The CC mixture exhibited enhanced resilience to fluctuating weather conditions, leading to an overall superior performance across the three-year experimental period and showing highest measured CC dry matters up to 272 g m−2 in 2022. However, the observed effects in the treatments varied considerably depending on the CC species, sowing date, and weather conditions. In summary, this study demonstrates that early CC sowing, whether directly after the cash crop harvest or 10 days before the cash crop is harvested, has a positive impact on CC biomass formation, especially leading to a reduced weed emergence. Additionally, under variable weather conditions, a diverse CC mixture can exhibit a more stable overall performance compared to CC monocultures.

Solarized IPM Module for Biocontrol of Root-knot Nematode on Tomato at Nursery Level in District G.B Nagar, Uttar Pradesh

Background: The role of soil solarization in suppression of soil borne pathogens and weeds has been established by several researchers around the globe It involves capturing solar radiations when the soil receives the maximum sunlight in May-June using a polythene mulch. Its effectiveness depends on ambient temperature, duration of the treatments and soil moisture. This not only acts as a soil disinfectant but also as soil decontamination. It includes various changes in the soil like physical, chemical and biological properties. Methods: The field to lab and vice-versal based investigations were carried during 2021-2022 at Amity Centre for Biocontrol and Plant Disease Management, Amity University, Uttar Pradesh, Noida and identified tomato nurseries of district G B Nagar where heavy infestation (10-12 J2/cc soil) of root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood was recorded. The treatments comprised of sustainable components viz. deoiled seed cake of neem, a Arbuscular Mycorrhizal fungus Glomus intraradices and indigenous fungal strain of Trichoderma harzianum, (Th7) alone and together applied for evolving IPM module at solarized and unsolarized sets. Under microplot trials, the entire solarized treatments were carried out measuring 3 × 1 sq. meter each in which one set of all the treatments including control covered with clear transparent polythene sheet (400 ì gauge) for solarization. The treatments were replicated thrice in randomized block design. Result: The observations of solarized and unsolarized treatments clearly revealed that the soil solarization in treatments where the sun radiant energy was trapped by 400 µ transparent polysheets significantly reduced the root knot nematode Meloidogyne incognita population both in root and soil in comparison to unsolarized treatments where no solar energy trapping was done. The combined application of locally isolated Trichoderma harzianum (Th7) and VA mycorrhiza, Glomus intraredices enhanced germination and plant growth in nurseries. In the present investigation, the solarized IPM module- 4 comprising of other sustainable components viz. neem oil-seed cake, T. harzianum (Th-7) and Arbuscular Mycorrhizal (AM) fungus G. intraredices is proved to be an ideal one in root-knot nematode pest management in tomato nurseries.

Compatibility between Conservation Agriculture and the System of Rice Intensification

Conservation Agriculture (CA) and the System of Rice Intensification (SRI) are both agroecologically-oriented production systems that support more productive, sustainable, and resource-conserving farming, with synergies arising from their respective assemblages of reinforcing agronomic methods. This review article examines the compatibility between CA and SRI, considering examples of their being utilized in complementary ways. The application of CA principles enhances the growth, yield, and performance of the crops grown under the cropping system as well as the health and resilience of the whole ecosystem. SRI practices create more favorable conditions for the development of crop plants below- and above-ground, including conditions that can be enhanced by CA management. SRI practices such as reduced plant density m−2 can elicit a better phenotypic expression of the genetic potentials of crops grown with CA. For these two agronomic systems to converge at the field level, some of their respective practices for plant, soil, water, and nutrient management need to be modified or aligned. One such adaptation is to practice SRI in CA systems on permanent, no-till, mulch-covered raised beds, with rainfall or irrigation water in the furrows between the beds furnishing and controlling water and providing weed suppression and improved nutrient recycling. SRI rice cropping can benefit from the CA practices of no-tillage, mulch soil cover, and diversified cropping, both in paddies and on raised beds. Several examples have shown that this convergence of cropping systems is feasible for smallholding farmers as well as for larger-scale producers and also that SRI practices within a CA system are amenable to considerable mechanization. Further research and experimentation are needed to identify and assess appropriate practices for capitalizing upon their synergies.

Phylogenetic relatedness can influence cover crop-based weed suppression

Cover crops are plants grown to provide regulating, supporting, and cultural ecosystem services in managed environments. In agricultural systems, weed suppression services from cover crops can be an important tool to promote sustainability as reliance on herbicides and tillage for weed management has caused pollution, biodiversity loss, and human health issues. However, to effectively use weed suppression services from cover crops, farmers must carefully select species that fit within their rotations and suppress their problematic weeds. Understanding how the relatedness between cover crops and weeds affects their interactions will help farmers select cover crops for targeted weed management. The phylogenetic distance between species reflects their relatedness and was studied through a series of field experiments that compared weed suppression in winter and summer cover crops with tilled controls. This study demonstrates that cover crops can reduce up to 99% of weed biomass and alter weed community structure by suppressing phylogenetically related weed species. Results also suggest that cover crop planting season can influence weed community structure since only overwintering treatments affected the phylogenetic distance of weed communities. In an applied context, these results help develop cover crop-based weed management systems, demonstrating that problematic weeds can be managed by selecting phylogenetically related cover crop species. More broadly, this study provides a framework for evaluating weed communities through a phylogenetic perspective, which provides new insight into plant interactions in agriculture.

Significance of Mulching on Soil Conservation

The rapidly expanding global population, coupled with limited accessible freshwater resources and recurrent climatic fluctuations, have placed significant stress on humanity. This pressure has necessitated decisive actions to curb water wastage. Concurrently, water conservation initiatives have gained momentum, particularly within the world's largest water-intensive sector, agriculture. One notable advancement in enhancing water use efficiency in agronomy is the widespread adoption of drip irrigation. This method involves the precise delivery of water directly to the root zone of crops, minimizing water losses up to 70% attributed to evaporation and distribution inefficiencies. Furthermore, the synergistic application of mulching in conjunction with drip irrigation in arid crop cultivation has emerged as a robust strategy for alleviating water stress in agriculture. Mulch, comprising natural, synthetic, or blended materials, serves as a protective layer between the soil and the atmosphere. Its multifaceted benefits include efficient soil moisture retention, regulation of soil temperature, prevention of nutrient leaching, improved fertilizer utilization, erosion resistance, weed suppression, and aesthetic enhancement of landscapes. This review paper comprehensively explores various facets of mulching, underscoring its role as a dynamic tool for water and soil management in agriculture while preserving the intrinsic value of cultivated crops.

Alternative ground covers and strip-tilling in CBD hemp production

ObjectiveLittle research has been done on managing soil health for large-scale, outdoor hemp production, contributing to the possible overuse of black plastic for weed suppression. Our experiment aimed to understand the performance of alternative ground covers including forage crops and hay as well as a less disruptive tilling method called strip-tilling compared to black plastic.ResultsYield and soil health data were taken from three experimental plantings from two different outdoor CBD hemp farms in Vermont, USA. We find that hay may be a competitive alternative to black plastic in terms of producing heavier plants. Our research also found that clover seed and hay are both more cost-effective options than black plastic which may sway some farmers to adopt these alternative ground cover options.

Effect of multi‐tactic weed management on weed suppression and yield in the establishment year of intermediate wheatgrass

AbstractIntermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth &amp; Dewey] (IWG) is a new perennial grain crop that can be harvested for multiple years. However, IWG grows slower than annual grain crops and is relatively uncompetitive with weeds during its establishment. Using multiple weed management tactics is a foundational principle of ecological weed management that can lead to synergistic interactions between tactics. Red clover intercropping, cultivation, and mowing—applied in isolation and all possible combinations—were assessed in a field experiment conducted at two sites in the northeastern United States. No single tactic or combination of tactics suppressed weeds relative to an untreated control. Likewise, there were no synergistic interactions between weed management tactics, indicating that the multi‐tactic treatments did not reduce weed biomass more than expected from the performance of each single‐tactic treatment in isolation. The lack of weed suppression across treatments likely contributed to their null to negative effect on IWG yield. Additionally, the competition from intercropping and the crop damage from cultivation and mowing may have reduced weed suppression and yield benefits. Although more research is needed to improve weed management in establishment year IWG, the experimental and analytical approach used here provides a framework that can be applied in other systems for evaluating the effects of multi‐tactic weed management and testing for synergistic interactions.

Uso de glyphosate no manejo de Panicum maximum cv. BRS Zuri consorciado com milho

ABSTRACT The intercropping between maize and forage species is an alternative commonly used within farming systems. Competition among crops may be a limiting factor in intercropping, compromising maize and forage yield. Although necessary, the literature does not provide satisfactory answers on the interaction of forage crops launched in the market recently, such as BRS Zuri, intercropped with maize. Therefore, techniques such as the use of herbicide subdoses come in as an option to suppress forage growth, making simultaneous cultivation feasible. Thus, the present study aimed to evaluate the effects of glyphosate herbicide subdoses on the development of Panicum maximum cv. BRS Zuri intercropped with Roundup Ready® (RR) maize and how this interaction reflects on the weed population, forage yield, and biometric and yield variables of maize. The experimental design was randomized blocks with treatments consisting of six subdoses of glyphosate herbicide (0, 48, 96, 240, 480, and 960 g acid equivalent [a.e.] ha-1) and maize in monoculture with four replications. For the conditions of this study, the dose of 480 g a.e. ha-1 of glyphosate may be an alternative since there was weed suppression and adequate forage development. Maize yield was not affected by the presence of forage.