Efficacy Of Herbicides Research Articles

Design, Synthesis of Novel Pyrimidine Derivatives Containing Alkenyl Moieties With Herbicidal Activities

ABSTRACTTo identify lead compounds with potent herbicidal activity, a range of pyrimidine derivatives containing alkenyl groups were designed, synthesized, and characterized using nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry (HRMS). The synthetic pathways for producing these compounds involved substitution reactions, cyclization, hydrolysis, and other processes. The starting materials for each reaction step were readily accessible, facilitating synthesis. The purification of the final product was straightforward, yielding approximately 80%, under mild reaction conditions. Moreover, a pot culture experiment was employed to assess the herbicidal efficacy of the aforementioned compounds. Compounds 6a, 6b, 6h, and 6j demonstrated a significant inhibition against Amaranthus retroflexus, comparable to fomesafen at 150 g a.i./hm2. This suggests that these compounds hold promise as potential lead structures for herbicidal agents. The docking results indicated that the binding energies of compound 6a with protoporphyrinogen oxidase (PPO) were both negative and spontaneous, with numerous interaction active sites. Thus, it is speculated that compound 6a is a PPO inhibitor.

Investigation of acetyl-CoA carboxylase-inhibiting herbicides that exhibit soybean crop selectivity.

The sustainable control of weed populations, particularly resistant species, is a significant challenge in agriculture around the world. The α-aryl-keto-enol (aryl-KTE) class of acetyl-CoA carboxylase (ACCase)-inhibiting herbicides represent a possible solution for the control of resistant grasses even though achieving crop selectivity remains a challenge. Herein, we present some of our investigations into identifying the most promising structural features within the aryl-KTE class that give the highest chance of achieving soybean crop selectivity, whilst also maintaining strong and broad efficacy against problematic weed species. We further examined our results by preparing new aryl-KTE molecules which were evaluated in glasshouse screening assays for their herbicidal efficacy as well as their soybean selectivity. We consider that uniting this approach with other optimization criteria, such as toxicological and environmental safety profiles, will enable the streamlining of crop protection optimizations programmes, ultimately delivering safer and more sustainable solutions to farmers and consumers. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Selectivity and efficacy of herbicides used on wheat to control ryegrass

Selectivity and efficacy of herbicides used on wheat to control ryegrass

Efficacy of various herbicides for weed management in irrigated chickpea (Cicer arietinum)

Chickpea is a short-stature crop with slow initial growth and limited leaf area development due to which it is heavily infested with a wide spectrum of weeds. The menace of weeds has increased to such an extent that an ef- fective weed management schedule has become a necessity. A research study was conducted during the rabi season of 2021–22 at the Agronomy Research Farm, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana. Thirteen weed control treatments viz., pre-plant incorporation (PPI) and pre-emergence (PRE) pendimethalin at 1,000 g/ha, PPI imazethapyr at 75 g/ha and 100 g/ha, PRE imazethapyr at 75 g/ha and 100 g/ha, post-emergence (PoE) imazethapyr at 75 g/ha and 100 g/ha, PPI and PRE pendimethalin + imazethapyr Ready mix (RM) at 1,000 g/h and two hand hoeings at 30 and 50 DAS were compared with weedy check and weed free in a randomized block design and replicated thrice. Among the herbicides, lowest weed dry weight was observed un- der PPI and PRE pendimethalin + imazethapyr (RM) at 1,000 g/ha respectively. PoE application of imazethapyr displayed phytotoxicity symptoms like stunting, leaf crinkling, and chlorosis as indicated by phytotoxicity scale ranging from 1-5. Significantly higher seed yield was obtained by pendimethalin + imazethapyr (1,827 kg/ha) over other combinations. Therefore, the PRE-application of pendimethalin + imazethapyr (RM) at 1,000 g/ha was the most suitable herbicide for efficient weed management in chickpea as it not only controlled the diverse weed flora but also improved seed yield.

THE PRE-em USE OF SOME HERBICIDES IN THE CONTROL OF WEEDS IN POTATOES AND THEIR INFLUENCE ON THE YIELD

In order to mitigate the problem with weeds in the potato crop in the 2017 growing season in the towns Bogovinje-Tetovo (Polog region), a field experiment was established according to the randomized block system with three replications with experimental plot sizes of 21 m2. In the experiment, we investigated the structure of weeds, the degree of appearance, the efficacy of herbicides and the eventual phytotoxicity of the herbicides used. The potato planted was the cultivar "Silvana" and the following treatment variants were included: pendimetalin 5 l/ha, linuron 2.5 l/ha, metobromuron 3 l/ha, metobromuron 4 l/ha, metribuzin 0.75 kg/ha PRE-em, metribuzin 1 kg/h PRE-em, mechanical controls and absolute controls. From the obtained results, it was found that the structure of weeds consists of 9 types of weeds, of which 3 species from the group of monocotyledonous weeds and 6 species from the group of dicotyledonous weeds. The number of weeds was 126 plants/m2. The dominant weeds were Echinochloa crus-galli with 93.7 plants/m2, Polygonum lapathifolium with 10.0 plants/m2, and Polygonum aviculare with 9.3 plants/m2. The efficiency of herbicides in the fight against dicotyledonous weeds has been from 97.7-100%, monocotyledonous weeds from 95.8-98.2%, while the overall efficiency without geophytes has been from 96.8-98.4%. Regarding phytotoxicity in the potato culture, no signs of phytotoxicity were observed in any variant of the treatment.

Bio efficacy of pre and post-emergence herbicides on yield and economics of maize crop (Zea mays)

Bio efficacy of pre and post-emergence herbicides on yield and economics of maize crop (Zea mays)

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

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

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

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

Chemical Desiccation in the Preharvest of Cowpea: A Study of How the Time of Application Interferes in the Enzymatic and Physiological Aspects of Seedlings from Desiccated Plants.

Chemical desiccation in the preharvest of grains and seeds is commonly used in production fields. Using herbicides for this purpose is a viable alternative to reduce beans' exposure to adverse crop conditions. Our objectives were to evaluate (1) the efficacy of herbicides for accelerated defoliation of cowpea, (2) the impact of herbicide application on antioxidant enzyme activity and protein and amino acid contents in seeds, and (3) the effects of different herbicide application schedules on the physiological aspects of seeds. In the first experiment, in addition to the control treatment (without herbicides), seven herbicides and two mixtures were applied at night: diquat, flumioxazin, diquat + flumioxazin, glufosinate ammonium, saflufenacil, carfentrazone, diquat + carfentrazone, atrazine, and glyphosate. Diquat and its mixtures showed greater efficacy in anticipating the harvest. Flumioxazin and diquat alone reduced amino acid content by 61.72 and 51.44%, respectively. The same trend was observed for total soluble proteins. The activity of antioxidant enzymes (CAT, POD, PPO) increased, indicating oxidative stress caused by diquat and flumioxazin. In the second experiment, we tested three application times (6 a.m., 12 p.m., 6 p.m.) with diquat, diquat + flumioxazin, and diquat + carfentrazone. The lowest damage to chlorophyll a was at 6 a.m.; other times reduced photosynthetic pigments and increased carotenoid content. Total soluble sugars decreased by 27.74% with nocturnal application of diquat + flumioxazin. Our data indicate that herbicide use for desiccation affects seed quality. These findings highlight the need for selecting appropriate herbicides and application times. Future research should explore long-term impacts on crop yield and quality.

Efficacy of pre and post emergence herbicides on yield and economics of linseed (Linum usitatissimum L.)

Efficacy of pre and post emergence herbicides on yield and economics of linseed (Linum usitatissimum L.)

Germination Biology of Three Cyperaceae Weeds and Their Response to Pre- and Post-Emergence Herbicides in Paddy Fields

(1) Background: Cyperaceae weeds have become a major type of weed in local paddy fields in China. (2) Methods: We assessed the impact of environmental factors, including temperature, light, salinity, water stress and soil depth, on the germination and emergence of three dominant Cyperaceae weeds: Cyperus difformis L., C. iria L. and Fimbristylis littoralis Gaudich. Using the dish dipping method, the performances of the pre- and post-emergence herbicides commonly used in paddy fields on three Cyperaceae weeds were evaluated using the pot method. (3) Results: The seeds optimally germinated at 35 °C in constant conditions and 25 °C/40 °C in alternating conditions. The seeds of the three Cyperaceae weeds were sensitive to light and could not germinate under dark conditions. The germination rate of the three weeds decreased with the increase in the NaCl concentration and water potential; the three weeds could not germinate at a 320 mmol·L−1 NaCl concentration and −0.1 MPa water potential. When the pH levels were 4 to 9, the germination rates of the three weeds were all greater than 80%. The burial depths to inhibit 50% of the emergence of C. difformis, C. iria and F. littoralis were 0.27, 1.06 and 0.42 cm, respectively. The control efficacy of the pre-emergence herbicides of pretilachlor, butachlor and oxyfluorfen on the three weeds were all above 90% at the recommended dose in the field. Halosulfuron-methyl, florpyrauxifen-benzyl and bentazone could effectively control the three Cyperaceae weeds; their performances on the three weeds at the 3- to 4-leaf stage were all above 82%. (4) Conclusions: The three Cyperaceae weed seeds have a strong adaptability to temperature, water potential, salinity and soil depth, and these weeds are sensitive to most pre- and post-emergence herbicides. Therefore, taking Cyperaceae weed seeds into the deep soil layer by tillage or selecting appropriate herbicides according to their growth stages can effectively control Cyperaceae weeds in rice fields.

Climate Change impact on Weeds and Herbicide Efficacy

Climate change is the change in statistical distribution of weather pattern that lasts for an extended period of time. There are several components of these climate changes occurring globally that includes uneven rainfall, droughts, floods, warming of atmosphere etc. These are the most important challenges influencing natural ecosystems, agricultural productivity and food security. Climate change is not only influencing crop plants and forests directly but can also impact the pests of these crops. Weeds respond to climate change by changing the duration of their life cycles, population dynamics and shift to new habitats and become a potential competitor to crop plants thereby reducing the production and productivity of crops. Elevated temperature and elevated CO2 level in the environment interfere with herbicide activity, which affects the herbicide absorption, translocation and thereby reduces the efficacy of the applied herbicide. Weeds’ resistance to herbicides may probably increase due to further aggressive growth of weeds in future climate conditions, which can cause a decline in the efficacy of routinely used herbicides.

The synergistic effect and mechanism of different adjuvants on pinoxaden efficacy against Lolium multiflorum Lam

Adjuvants play a crucial role in optimizing and improving the efficacy of herbicides. Therefore, adding appropriate adjuvants to herbicides is an important part of weed control. The aim of this study was to investigate the synergistic effect and underlying mechanism of action of three commercial adjuvants (Hasuteng, Penwubao, and Zhenxiao IV) in conjunction with pinoxaden for controlling Lolium multiflorum Lam. The results of synergic effect, which were determined by dose‒response assay showed that the addition of Hasuteng and Penwubao could significantly enhance the efficacy of pinoxaden and decrease the ED50 (the herbicide dose resulting in 50% weed control) on L. multiforum while being safe to wheat. Hasuteng and Penwubao were further selected to investigate the underlying mechanisms by which adjuvants enhanced the efficacy of pinoxaden. The results indicated that the addition of Hasuteng and Penwubao significantly reduced the surface tension and shortened the drying time of the pinoxaden solution; moreover, it significantly increased both expanded diameter and maximum retention. Additionally, ultra high performance liquid chromatography-tandem mass spectrometry (UPLC‒MS/MS) analysis was used to evaluate the recovery rate, absorption level, and rainfastness. These two adjuvants could improve the absorption and metabolism levels of L. multiforum to pinoxaden. However, Hasuteng and Penwubao did not improve the rainfastness of pinoxaden. In summary, Hasuteng and Penwubao enhance the efficacy of pinoxaden by improving its physical properties and absorption level. The studies present a novel approach for enhancing the utilization rate of pinoxaden and provide theoretical guidance toward effectively reducing herbicide application in wheat fields.

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.

Biosynthesis of Iron Oxide Nanoparticles and Combination with Glyphosate Herbicide and Effect Against Cogon Grass Control

For enhancing herbicide efficacy a total of 42 soil samples, five species of bacteria that grew the most were selected for regarding other isolates: (Enterobacter cloacae, Serratia fonticola, Aeromonas hydrophila, Pantoea spp., Pseudomonas mendocina). Extracellular extracts of these bacteria were made and then used to manufacture iron oxide nanoparticles biologically. It was observed after measuring the average diameter by AFM (Atomic Force Microscopy) for each NPs prepared were 65.14, 29.21, 63.87, 57.89 and 36.59 nm, respectively. The synthesis conditions were a pH of 7 and 50°C. Based on the AFM values, Serratia fonticola was selected as having the smallest average diameter of 29.21 nm to complete the rest of the techniques (UV-VIS, AFM, FTIR and FE-SEM). The wavelength of Fe2O3NPs by using UV-VIS is 359 nm, Image FE-SEM displays spherical Fe2O3NPs in Nano-cluster form and the average volume is 29.21 nm by AFM. Utilizing the Randomized Complete Block Design methodology with 6 treatments, two factors: Glyphosate herbicide at the recommended dose and three concentrations of the prepared (Fe2O3NPs) from Serratia fonticola were 0.5, 1 and 1.5 g/ml. Halfa plant was controlled using these treatments, and after 30 days, the efficiency of the treatments was measured on a set of characteristics. It was found the lowest number of plants and the highest percentage of control was in the treatment 5 glyphosate and Fe2O3 NPs con. (1.5g/ml) was 1.26, 5.33 and 90%, respectively. The study effectively shows the potential of employing Fe2O3NPs generated from S. fonticola to improve the efficacy of Glyphosate for Cogon management.

Chiral Herbicide 2,4-D Ethylhexyl Ester: Absolute Configuration, Stereoselective Herbicidal Activity, Crop Safety, and Metabolic Behavior on Maize and Flixweed.

This study represents the initial examination of the herbicidal efficacy, crop safety, and degradation patterns of 2,4-D ethylhexyl ester (2,4-D EHE) at the enantiomeric level. Baseline separation of 2,4-D EHE enantiomers was achieved using a superchiral R-AD column, with their absolute configurations determined through chemical reaction techniques. Evaluation of weed control efficacy against sensitive species such as sun spurge and flixweed demonstrated significantly higher inhibition rates for S-2,4-D EHE compared to R-2,4-D EHE. Conversely, no stereoselectivity was observed in the fresh-weight inhibition rates of both enantiomers on crops or nonsensitive weeds. A sensitive HPLC-MS/MS method was developed to simultaneously detect two enantiomers and the metabolite 2,4-D in plants. Investigation into degradation kinetics revealed no substantial difference in the half-lives of R- and S-2,4-D EHE in maize and flixweed. Notably, the metabolite 2,4-D exhibited prolonged persistence at elevated levels on flixweed, while it degraded rapidly on maize.

First case of evolved herbicide resistance in the holoparasite sunflower broomrape, Orobanche cumana Wallr.

The development and commercialisation of sunflower varieties tolerant to acetolactate synthase (ALS)-inhibiting herbicides some 20 years ago provided farmers with an alternative method for the cost-effective control of Orobanche cumana. In 2020, however, two independent sunflower broomrape populations from Drama (GR-DRA) and Orestiada (GR-ORE), Greece, were reported to be heavily infested with O. cumana after application of the ALS-inhibiting herbicide imazamox. Here we have investigated the race of GR-DRA and GR-ORE and determined the basis of resistance to imazamox in the two Greek O. cumana samples. Using a set of five diagnostic sunflower varieties characterised by different resistant genes with respect to O. cumana infestation, we have clearly established that the GR-ORE and GR-DRA populations belong to the invasive broomrape races G and G+, respectively. Live underground tubercles and emerged shoots were identified at the recommended field rate of imazamox for GR-DRA and GR-ORE but not for two other standard sensitive populations in a whole plant dose response test using two different herbicide-tolerant sunflower hybrids as hosts. Sequencing of the ALS gene identified an alanine 205 to aspartate mutation in all GR-ORE samples. Most GR-DRA tubercles were characterised by a second serine 653 to asparagine ALS mutation whilst a few GR-DRA individuals contained the A205D mutation. Mutations at ALS codons 205 and 653 are known to impact on the binding and efficacy of imazamox and other imidazolinone herbicides. The knowledge generated here will be important for tracking and managing broomrape resistance to ALS-inhibiting herbicides in sunflower growing regions.

Effectiveness of integrating mowing and systemic herbicides applied with a weed wiper for Sporobolus indicus var. pyramidalis management in Florida

Abstract Giant smutgrass [Sporobolus indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldkamp] is an invasive species in grasslands, and herbicide application has been the most efficient management method to suppress this weed. Experiments were conducted in 2017 and 2018 to determine the effects of wiping glyphosate and hexazinone on S. indicus var. pyramidalis. A dose–response experiment using a handheld weed wiper was established with 20 treatments comprising two herbicides (glyphosate and hexazinone), uni- and bidirectional wiping methods, and 5 herbicide concentrations (6.25% v/v, 12.5% v/v, 25.0% v/v, 50.0% v/v, and 100% v/v basis). Data were collected 30 and 60 d after treatment (DAT). An ATV-mounted roto-type weed-wiper experiment was established in a strip-plot arrangement, with mowing as the horizontal strip, the wiping method (unidirectional vs. bidirectional) randomized as the vertical strip with three dosages of each herbicide for a total of 12 wiping treatments. Data were collected at 35 and 90 DAT. The percent plant mortality was calculated using differences in pre- and posttreatment plant counts. ANOVA and log-logistic linear regression were used to analyze the data. The dose–response experiment showed that S. indicus var. pyramidalis mortality increased with herbicide concentration, and mortality was greater with the bidirectional wiping method compared with the unidirectional method. Treatments wiped bidirectionally with glyphosate at 70% v/v, hexazinone at 30% v/v, and hexazinone at 60% v/v resulted in S. indicus var. pyramidalis mortality ranging from 75% to 98% by 90 DAT across all locations. The ATV-mounted weed-wiper experiment showed that mowing before herbicide application with weed wipers decreased the efficacy of both herbicides. Overall, both experiments indicate that S. indicus var. pyramidalis should be wiped bidirectionally using either glyphosate (70% v/v) or hexazinone (at least 30% v/v) to obtain satisfactory control. Further work should be conducted to determine whether seasonality impacts the response of S. indicus var. pyramidalis to mowing and the application of these herbicides.

Unraveling the reasons for failure to control Amaranthus albus: insights into herbicide application at different growth stages, temperature effect, and herbicide resistance on a regional scale.

This study investigates factors contributing Amaranthus albus control failure in processing tomato fields in northern Israel. The study region is characterized by a significant climate gradient from east to west, providing the opportunity to investigate the effect of critical elements of the agricultural environment, e.g., temperature. Eight populations were collected from commercial fields in this region. Post-emergence herbicide efficacy of metribuzin, a photosystem II inhibitor, and rimsulfuron, an acetolactate synthase (ALS) inhibitor, was assessed through dose-response analyses at various growth stages. Temperature effects on control efficacy and resistance mechanisms were also explored. Standard metribuzin dose (X) was ineffective on A. albus plants with more than six true-leaves, whereas 2X dose proved effective. Rimsulfuron at 16X dose was ineffective on plants with more than four true-leaves. We report here the first case of target site resistance to ALS inhibitors in A. albus, due to point mutation in the ALS gene (Pro197 to Leu). Furthermore, our findings suggest potential involvement of CYT P450 enzymes in enhanced metabolizing of rimsulfuron. An overall decrease in dry weight was observed in response to both herbicides at 16/22 °C (P < 0.0001). Rimsulfuron was effective against only one population when applied at 28/34 °C. A possible fitness cost associated with target site-resistant biotypes was observed under low temperature conditions, leading to effective control. This regional-scale study highlights the challenges faced by growers, emphasizes the need for adapting management practices to the local climatic conditions and lays the groundwork for implementing location-specific weed management strategies in commercial fields. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Multifunctional Adjuvants Affect Sulfonylureas with Synthetic Auxin Mixture in Weed and Maize Grain Yield.

A field study in the years 2017-2019 was carried out to evaluate the impact of novel adjuvant formulations on the efficacy of sulfonylurea and synthetic auxin herbicides. Treatments included nicosulfuron + rimsulfuron + dicamba (N+R+D) at full and reduced rates with three multicomponent (TEST-1, TEST-2, TEST-3) as well as standard (MSO, S) adjuvants. In this greenhouse study, Echinochloa crus-galli seeds were planted and treated with N+R+D at 2-3 leaf stages. The water with the desired pH (4, 7, and 9) for the preparation of the spray liquid was prepared by incorporating citric acid or K3PO4 to either lower or raise the pH of the water. Adjuvant TEST-1 added to the spray liquid at pH 4 increased the effectiveness to 68%, TEST-2 to 81%, and TEST-3 to 80%, compared to 73% and 66% with the MSO and S. The efficacy of N+R+D at pH 7 with TEST-1 increased to 83%, TEST-2 to 82%, and TEST-3 to 77%, but with MSO, it increased to 81%, and 71% with S. Adjuvants TEST-1, TEST-2, and TEST-3 in the liquid at pH 9 increased efficacy to 76 and 80%, compared to 79 and 63% with MSO or S adjuvants. N+R+D applied with TEST-1, TEST-2, and TEST-3 provided greater weed control than herbicides with surfactant (S) and similar or even better than with standard methylated seed oil (MSO) adjuvants. Maize grain yield after herbicide-with-tested-adjuvant application was higher than from an untreated check, and comparable to yield from herbicide-with-MSO treatment, but higher than from S treatment.