Postemergence Herbicide Treatments Research Articles

Hygienic assessment of occupational risk for workers during pre- and post-emergence herbicide treatments of sunflower crops

Modern agriculture extensively uses pesticide formulations at various stages of crop growth. Sunflower cultivation accounts for 31% of the global production. Assessing the occupational risk associated with pesticide application in sunflower farming is of paramount importance. Improper handling and application of pesticide formulations can have immediate adverse effects on workers, leading to acute poisoning, long-term health consequences, and the potential for chronic illnesses, including neurotoxic effects. The aim of this study was to conduct a hygienic assessment of the professional risk faced by workers during pre- and post-emergence herbicide applications in sunflower cultivation. This assessment was carried out to establish the regulations for their safe usage. Research samples after the application of the herbicides AGAT, GARPUN, KORVUS, and PARUS (patches from overalls, gloves, skin swabs from exposed areas (face-neck, hands), air samples (atmospheric air, working zone and drift zone). The assessment of professional risk was conducted in accordance with the methodological recommendations provided by experts from the L.I. Medved's Research Center of Preventive Toxicology, Food and Chemical Safety, Ministry of Health, Ukraine (State Enterprise). Statistical analysis of the results was carried out using the licensed statistical software packages MedStat v.5.2 (Copyright© 2003-2019) and Microsoft® Excel® for Microsoft 365 MSO (Version 2305, Build 16.0.16501.20074). It has been determined that under real conditions, during pre- and post-emergence herbicide applications in sunflower cultivation using AGAT, GARPUN, KORVUS, PARUS preparations, while adhering to recommended agrotechnical and hygiene safety regulations, the inhalation, dermal, complex, and combined (AGAT and PARUS) risks for applicators are 0.0409±0.0179, 0.0429±0.0193, 0.0838±0.0224, and 0.1557±0.1322 a.u., respectively, and for tractor operators – 0.0818±0.0358, 0.0425±0.0192, 0.1243±0.0356, and 0.2347±0.1567 a.u., respectively. There is no observed increase in hygiene standards in the workplace atmosphere and in the air of the potential drift zone. It has been proven that the professional risk of their use does not exceed permissible limits (<1). It has been determined that during the performance of techno­logical operations, the mentioned risks in applicators and tractor operators did not differ significantly (p>0.05). However, a significant difference was found in the proportion of percutaneous risk (42.7±17.4% in applicators compared to 34.8±17.0% in tractor operators; p=0.034). The regulations for the safe use of the investigated pesticide formulations have been substantiated. Statistical analysis of the obtained results revealed that the values of inhalation, dermal, and combined risks during the application of these pesticides did not significantly differ during the various technological operations (applicators and tractor operators) (p>0.05). The values of the combined comprehensive risk associated with the use of the studied preparations also did not show significant differences (p>0.05). The proportion of dermal risk was significantly higher in applicators compared to this parameter determined in tractor operators (p=0.034).

Johnson Grass (Sorghum halepense) Interference, its Effect on Crops Yield and Soil attributes under Different Cropping Systems and Management Practices

Johnson grass (Sorghum halepense) is one of the most detrimental and toxic weeds among the weed species. Its environment is expanding unceasingly due to deeply expanding of its rhizomes in the soil, self-pollinating reproduction strategy, accelerated growth and poor management which results in production losses of major agronomic crops. Mungbean and sorghum are important crops grown on significant acreage around the world, and a major constraint for their production losses is weeds interference. Thus, field studies were conducted to examine Johnson grass interference, control, and recovery under different management practices and cropping system and its effects on crops production and soil health. Our results indicated that the Johnson grass density was minimized by the application of plastic sheet mulch treatment under wheat-mungbean cropping system. Johnson grass competition had a significant impact on growth and grain yield of both mungbean and sorghum. The crop yield parameters; 100 grain weight and grain yield were lowest in the non-treated treatment (control), while the greatest values of these parameters were recorded in the plastic sheet mulch and post emergence herbicide treatments with wheat-mungbean cropping system. Similarly, soil building attributes; available nitrogen, available phosphorus, available potassium and organic matter content were positively affected by the interaction of plastic sheet mulch + wheat-mungbean cropping system. Besides this, benefit-cost ratio of the research shows that wheat-mungbean cropping system with application of plastic sheet mulch and post emergence herbicide also proved to be economically feasible. Overall, we have concluded that wheat-mungbean and wheat-sorghum are most resilient cropping system with the implementation of plastic sheet mulch and Post Emergence Herbicide to suppress the spread of Johnson grass under changing climatic scenarios.

Integrating cover crops and herbicides for weed control in soybean

Abstract In mid-southern, southeastern, and northeastern U.S. soybean production regions, the evolution of herbicide-resistant weeds has become a significant management challenge for growers. The rising herbicide costs for managing herbicide-resistant weeds are also a growing concern, leading to the utilization of cover crops as an integrated weed management strategy for addressing these challenges. Field experiments were conducted at two locations in Alabama in 2022 to evaluate winter cereal cover crops, including a mixture and herbicide system integration in soybean. Treatments included five cover crops: oats, cereal rye, crimson clover, radish, and a cover crop mixture. Cover crops were evaluated for their weed-suppressive characteristics compared to a winter fallow treatment. Additionally, four herbicide treatments were applied: a preemergence (PRE) herbicide, a postemergence (POST) herbicide, PRE plus POST herbicides, and a nontreated (NT) check. The PRE herbicide was S-metolachlor; the POST treatment contained a mixture of dicamba and glyphosate. The PRE plus POST system contained the PRE application followed by POST application. Results show that cereal rye and the cover crop mixture provided weed biomass reduction compared to all cover crop treatments across both locations. Furthermore, we observed greater soybean yield following the cereal rye cover crop than following the winter fallow treatment at one location. POST and PRE plus POST herbicide treatment resulted in greater weed biomass reduction and improved soybean yield than the PRE herbicide treatment alone and the NT check at both locations.

The Manual, Chemical, Cultural, and Integrated Weed Management in Soybean Production

A field experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka, from December 2021 to April 2022 to study the effect of weed management practices in soybean (Glycine max L.). The experiment was laid out in a Randomized three-Complete Block Design (RCBD) with twelve weed management treatments- no weeding (Control), two hand weeding (at 15 and 30 DAS), pre-emergence herbicide (Herbilin 33% EC @ 400 ml ha-1), post-emergence herbicide Irish EC @ 1200 ml ha-1, pre + post-emergence herbicide, pre-emergence + 1 hand weeding {40 days after sowing (DAS)}, post-emergence herbicide + 1 hand weeding (40 DAS), pre + post-emergence herbicide + 1 hand weeding(40 DAS), straw mulching, intercrop with Amaranthus dubius, and Zea mays, and weed-free. The experimental result showed among seven different weed species found, Cyperus rotundus was the most prevalent weed, with the highest weed density (123 and 128.67 m-2) and relative weed emergence (43.16 and 38.79 %) in the control plot at 30 and 60 DAS. The treatment pre + post-emergence herbicide + 1 hand weeding (40 DAS) showed the longest pod length (4.16 cm) and number of seeds pod-1 (3.89). The weed-free treatment resulted in the highest 1000-seed weight (111.00 g), seed yield (1.86 t ha-1), stover yield (2.16 t ha-1), biological yield (4.03t ha-1), and harvest index (46.35 %). However, the highest benefit-cost ratio (2.85) was obtained under post-emergence herbicide (Irish EC) treatment. Therefore, applying Irish EC was the best broad-spectrum effective herbicide to manage the various weed floras in soybeans for profit. SAARC J. Agric., 21(2): 195-206 (2023)

Growth and yield of rice (<i>Oryza sativa</i>) under different establishment methods and weed management practices in Uttarakhand

An experiment was conducted during the rainy (kharif) seasons of 2021 and 2022 at the Norman E. Borlaug (NEB) Crop Research Centre at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand to study the effect of different establishment methods and weed management practices on growth and yield of rice (Oryza sativa L.). The study was carried in a split plot design with 3 replications. In main plot 4 rice establishment methods and in sub plot 4 weed management practices were included. The results revealed that significantly higher grain yield was recorded in mechanical line sowing (S2) over rest of the treatment. According to the pooled data analysis of grain yield the per cent increase in mechanical line sowing (S2) over broadcasting (S1), raised bed system (S3) and semi-dry system (S4) was 23.1%, 17.6% and 8.1%, respectively. Among the different weed management practices grain yield was recorded maximum in W3 (pre emergence herbicide followed by two manual weeding) treatment which showed at par results with W2 (pre emergence followed by post emergence herbicide) treatment. The per cent grain yield increase in pre emergence herbicide followed by two manual weeding (W3) over manual weeding (W1), pre emergence followed by post emergence herbicide (W2) and mechanical weeding (W4) was 19.3%, 0.75% and 31.7%, respectively. Weed density was recorded minimum in mechanical line sowing (S2) and raised bed system (S3). At panicle initiation stage significantly lower weed density was recorded in mechanical line sowing (S2). However, among the weed management practices manual weeding (W1) and pre emergence herbicide followed by two manual weeding (W3) treatments recorded at par. Weed dry weight remain non-significant under different rice establishment methods during active tillering as well as panicle initiation stage.

Estratégias de manejo para Anredera cordifolia na cultura do café

ABSTRACT Coffee plantations installed at high altitudes and near forested areas have been highly infested with Anredera cordifolia. The objective of this work was to evaluate the effectiveness of different pre- and post-emergence herbicide treatments on A. cordifolia after mechanical mowing. A field experiment was carried out in a coffee plantation with natural infestation of A. cordifolia in a completely randomized design with a split-plot scheme and four replicates, in which the main plot an herbicides application and the subplot was the days after the initial application (DAI). The treatments were as follows: saflufenacil + glyphosate (70 + 960 g a.i. ha-1); chlorimuron + glyphosate (80 + 960 g a.i. ha-1); metsulfuron + glyphosate (6 + 960 g a.i. ha-1); flumioxazin + glyphosate (25 + 960 g a.i. ha-1), and glyphosate (960 g a.i. ha-1); with sequential application of glyphosate (960 g a.i. ha-1); glyphosate + indaziflam (960 + 75 g a.i. ha-1); indaziflam (75 g a.i. ha-1); and a control without herbicide application. Mechanical control, followed by the application of the treatments flumioxazin + glyphosate and metsulfuron + glyphosate in the first application and sequential application of indaziflam, proved to be effective. Control of this weed should be based on the removal of its plant residues from the field to reduce the regrowth and germination of aerial tubers.

Yield and Economics of Onion as Influenced by Pre and Post Emergence Herbicdes

Onion (Allium cepa L.) weed interference lowers bulb yield and financial return for onion growers who pay for labour. During the Rabi seasons of 2011–12 and 2012–13, a field experiment was worked out at the Horticultural College and Research Institute, Dr.Y.S.R Horticultural University, Venkataramanagudem, Tadepalligudem, West Godavari District, A.P to examine the effects of pre and post emergence herbicides on the economics of onion cv.N–53. Ten pre- and post-emergence herbicide treatments (Pendimethalin, Oxyflourfen, Imazethapyr, and Quizalofopethyle) and their combinations, reproduced in a random block design, made up the experiment. Significantly, T9 (weed free-hand weeding at 30, 60, and 90 DAT) outperformed the other treatments in terms of gross and net returns, which was followed by T8 (Oxyfluorfen 0.125 kg a.i as PE + Quizalofopethyl @ 75g a.i per hectareas POE) and T6 (Pendimethalin 0.75 kg a.i as PE + Quizalofop ethyl @ 75 a.iper hectare). When compared to T6 (Pendimethalin @ 0.75 kg a.iper hectare as PE + Quizalofop ethyl @ 75 g a.iper hectare as POE), T8 (Oxyfluorfen @ 0.125 kg a.iper hectareas PE + Quizalofop ethyl @ 75 g a.iper hectare as POE) had a considerably greater B:C ratio. Hand weeding made farming more expensive. This suggested that chemical weed treatment was used to obtain the most profit per acre.

Response of Weed Management Practices on Yield Loss, Soil Enzyme Activity and Microbial Populations in Maize (Zea mays L.)

Background: Maize popularly known as “Queen of cereals”. Weeds resulted in the highest crop loss (33%), followed by pathogens (26%), insects (20%), storage pests (7%), rodents (6%) and others (8%) in India. Application of herbicides will affect various soil microbial processes and enzymatic activities in the soil, whose activity is very important for maintaining the soil fertility. Methods: The present field experiment was conducted during Rabi, 2017-18 and 2018-19 under irrigated conditions at wetland farm of S.V. Agricultural College, Tirupati Andhra Pradesh, with ten treatments and three replications in a randomized block design. Result: Higher kernel and stover yield of maize was recorded with hand weeding twice at 15 and 30 DAS and the yield loss was comparatively lower with atrazine 1.0 kg ha-1as PE fb topramezone 30 g ha-1or tembotrione 120 g ha-1 as PoE or atrazine 1.0 kg ha-1as PE fb HW at 30 DAS, while these were lowest with weedy check. Soil microbial count and enzyme activity was statistically comparable in all the pre followed by post emergence herbicide treatments.

Efficacy of pre- and post-emergence herbicide combinations on weed control in no-till mechanically transplanted rice

No-till mechanized-transplanted rice was evaluated for different combinations of pre- and post-emergence herbicides to determine feasible, economically viable weed management options to control complex weed flora in rice fields. All pre-emergence herbicides significantly reduced the population of grassy weeds; of these, pendimethalin resulted in the greatest reductions (83%) at 15 days after transplanting (DAT). Among five post-emergence herbicide treatments, the combination of bispyribac-sodium (10%SP) + pyrazosulfuron (10%WP) was found to be the most effective in controlling all weed flora at both 35 and 55 DAT. The sequential application of pendimethalin (pre-emergence) followed bispyribac-sodium + pyrazosulfuron (post-emergence) resulted in significantly higher rice grain yield (4.4 t-ha−1) and relative gross-margin (417 USD-ha−1) than all other treatments. A strong negative correlation was observed between rice grain yield and weed biomass, and a strong positive correlation between rice grain yield and weed control efficiency. Our findings demonstrate the potential to combine pre- and post-emergence herbicides in no-till mechanized-transplanted rice; these findings have applications globally in regions where rice is established by no-till or mechanized transplanting.

Control of Multiple-Herbicide-Resistant Green Pigweed (Amaranthus powellii) With Preemergence and Postemergence Herbicides in Ontario Corn Production

Green pigweed [Amaranthus powellii S.Wats.] is a prolific annual dicot weed that is a prominent weed of crop production in northeastern North America. Green pigweed interference has been documented to reduce corn yields up to 54% in the absence of control strategies. In 2021, a green pigweed biotype from a field near Dresden, Ontario, Canada was determined to be resistant to MCPA, mecoprop, dichlorprop-p, aminocyclopyrachlor (synthetic auxins), and imazethapyr (acetolactate synthase-(ALS)-inhibitor), further impacting control of this weed biotype. Two field studies, with herbicides applied preemergence (PRE) or postemergence (POST), were conducted in 2020 and repeated in 2021. The objective of the research was to determine the most effective PRE and POST herbicides for the control of multiple-herbicide-resistant (MHR) green pigweed in Ontario corn production. 18 PRE and 18 POST herbicide treatments were evaluated in separate studies. Visible crop injury, visible green pigweed control at specified timepoints after herbicide application, green pigweed density, green pigweed biomass, and corn yield at harvest maturity were collected. In the PRE study, rimsulfuron + mesotrione was identified as the most efficacious treatment providing 88% control at 8 WAA. In the POST study, atrazine was identified as the most efficacious treatment providing 94% control at 8 WAA. Control with all PRE herbicide treatments was impacted by rainfall following application. MCPA ester applied POST controlled green pigweed 30% at 8 WAA; reduced control is attributed to herbicide resistance in this biotype. When compared to similar studies, control of green pigweed was reduced with some of the POST herbicides tested. While MHR green pigweed represents an additional challenge for growers, there are efficacious herbicide treatments that would allow it to be managed in corn production.

Control of Multiple-Herbicide-Resistant Green Pigweed (Amaranthus powellii) with Preemergence and Postemergence Herbicides in Ontario Soybean Production

Green pigweed [Amaranthus powellii S. Wats.] is a competitive, annual, broadleaf weed that can significantly reduce soybean yield due to rapid early growth and biomass production. As a consequence of green pigweed’s high competitiveness with crops, the weed species is generally managed with the use of herbicides; this may, however, lead to the selection of resistance. A green pigweed biotype with resistance to MCPA, mecoprop, dichlorprop-p, aminocyclopyrachlor (synthetic auxins), and imazethapyr (acetolactate synthase-(ALS)-inhibitor) was recently confirmed in Ontario, Canada. Research was conducted to identify alternative effective preemergence (PRE) and postemergence (POST) herbicides for the control of multiple-herbicide-resistant (MHR) green pigweed in Ontario soybean production. Four field trials, two with PRE and two with POST herbicides were conducted near Dresden, Ontario in 2019 and 2020. Visible soybean injury, green pigweed control, density, aboveground biomass, and soybean yield were evaluated following application with 19 PRE herbicide treatments and 12 POST herbicide treatments in separate studies. At 8 wk after application (WAA), pyroxasulfone/flumioxazin applied PRE controlled green pigweed 95% and was the most effective soil-applied herbicide. In the POST study, glyphosate was the most effective herbicide, controlling green pigweed 94% at 8 WAA. Imazethapyr, applied PRE or POST did not control this green pigweed biotype as it is also resistant to ALS-inhibitors. Control with other ALS-inhibiting herbicides as well as with PPO-inhibiting herbicides was variable, and further research is needed to determine the reason for variable control with these herbicides.

Evaluating Sensor-Based Mechanical Weeding Combined with Pre- and Post-Emergence Herbicides for Integrated Weed Management in Cereals

Due to the increasing number of herbicide-resistant weed populations and the resulting yield losses, weed control must be given high priority to ensure food security. Integrated weed management (IWM) strategies, including reduced herbicide application, sensor-guided mechanical weed control and combinations thereof are indispensable to achieve this goal. Therefore, this study examined combinations of pre- and post-emergence herbicide applications with sensor-based harrowing and hoeing in cereals by conducting five field experiments at two locations in Southwestern Germany from 2019 to 2021. Each experiment contained an untreated control and a single post-emergence herbicide treatment as a comparison to these IWM treatments. The effects of the different IWM approaches on weed control efficacy (WCE), crop density, and grain yield were recorded. All experiments were set up in a randomized complete block design with four repetitions. Pre-emergence herbicide application combined with one-time harrowing and subsequent hoeing (Pre-Herb + Harr + Hoe) achieved the highest WCE (100%), followed by an approach of WCE (95%) for two-times hoeing. In contrast, a single pre-emergence herbicide application achieved the worst result with an average WCE of 25%. Grain yield was equal between all treatments in between 6 t ha−1 and 10 t ha−1, except for a single pre-emergence herbicide application, which achieved a 2.5 t ha−1 higher grain yield in winter wheat in 2021 that averaged 11 t ha−1, compared to the combination of Pre-Herb + Harr + Hoe that averaged 8.5 t ha−1. The results showed that it is possible to reduce and replace herbicides while achieving equivalent yield and WCE.

System productivity, energetics and economics of soybean (Glycine max)-wheat (Triticum aestivum) cropping system as influenced by weed management practices

A field experiment was conducted during 2015–16 and 2016–17 to assess the system productivity, energetics and economics of weed management practices in soybean (Glycine max L.)-wheat (Triticum aestivum L.) cropping system at ICAR-Directorate of Weed Research, Jabalpur, Madhya Pradesh. The experiment comprised 10 treatments having combinations of sole and sequential application of pre-emergence and post-emergence herbicides in both the crops, and their integration with hand weeding undertaken in randomized block design replicated thrice. The highest system productivity (8.04 t/ha) was obtained by employing two hand weedings, sequential application of pendimethalin followed by (fb) imazethapyr in soybean and pendimethalin fb mesosulfuron + iodosulfuron in wheat as well as by integrating either pre or post-emergence herbicides with one hand weeding. Among weed management practices, energy requirement was lowest in sole post-emergence herbicide treatment, however, integration of manual weeding required maximum energy. The energy input for hand weeding was a major share of integrated weed management practices, and it varied from 54–83% of the total treatment energy. Due to requirement of less energy for sole post-emergence herbicides, energy output, net energy return and energy ratio were the maximum. Total output energy was higher (258×103 MJ/ ha) in post-emergence herbicide fb hand weeding treatment because of higher system productivity (7.29 t/ha), and this treatment was more energy efficient and gave the highest economic returns among the weed management practices. The highest benefit: cost ratio (3.10) was obtained by the application of post-emergence herbicides in both the crops.

Glyphosate-resistant Italian ryegrass (Lolium perenne ssp. multiflorum) control with preemergence and postemergence herbicide programs

AbstractA field study was conducted twice in Elizabeth, MS, at on-farm sites in 2010–11 and 2011–12, and twice in 2012–13 at Mississippi State University’s Delta Research and Extension Center in Stoneville, MS, to evaluate glyphosate-resistant (GR) Italian ryegrass control and crop response to fall treatments followed by postemergence herbicide treatments in winter and/or spring. Italian ryegrass was controlled ≥92% and 61% following S-metolachlor and tillage 77 d after fall treatments (DA-FT), respectively. S-metolachlor fall treatment provided 33% greater control than clethodim winter treatment at 21 d after winter treatments (DA-WT). Tillage fall treatment followed by (fb) clethodim winter treatment fb paraquat spring treatment provided similar control (93%) to treatments containing S-metolachlor fall treatment fb a winter or spring herbicide treatment (≥93%) 24 d after spring treatments (DA-ST). Greatest soybean and corn density and yield were also observed following programs containing S-metolachlor fall treatment. Sequential postemergence herbicide treatments were not required to increase corn and soybean density and yield when S-metolachlor was used as a fall treatment. Growers have the best opportunity to maximize GR Italian ryegrass control when S-metolachlor fb a winter or spring herbicide treatment is used.

Production strategies management to minimize root rot disease in field pea grown on infected southwestern Saskatchewan soils

Multilocational field studies were conducted near North Battleford, Wilkie and Cando in Saskatchewan (SK), Canada during the 2015 (year 1) and 2016 (year 2) summer crop growing seasons to evaluate Aphanomyces euteiches Drechs and Fusarium root rot response to different seed place fertility, preemergence herbicide combination, and foliar fertility. Seven seed place fertility treatments (F1 to F7) were Nitrogen and phosphorus inoculant, liquid Optimize inoculant (LCO), LCO /5.5-25-0-0 (N-P-K-S), LCO /15-25-0-0, LCO /15-25-0-15, LCO/liquid orthophosphate (2-8-1) at 33.7 L/ha/15-0-0-15 and LCO/15-40-40-15 respectively. The four preemergence herbicide (P RE1 to P RE4) were: Glyphosate/Saflufenacil; Glyphosate/Sulfentrazone/Carfentrazone; Glyphosate/Sulfentrazone/Pyroxasulfone and Glyphosate/Sulfentrazone/Trifluralin. Pea was treated with five postemergence (POST 1-5) herbicide with/without adjuvants/foliar fertility at 4-5 node stage as Imazamox/bentazon (Viper) plus 28% v/v Urea Ammonium Nitrate (UAN) – POST 1; Viper plus 2X 28% UAN – POST 2; Viper plus 1X 28% UAN plus foliar fertility – POST 3; Viper plus 2X 28% UAN plus foliar fertility – POST 4 and Quizalofop-p-ethyl at 494.23 mL/ha – POST 5. Growth response, root rot disease severity and yield (kg/ha) were analyzed using SAS statistical software. Significant means were at F < 0.05 were separated by the Fisher’s Protected LSD test at the 5% level. Root rot was significantly lower in P RE4 compared to other treatments. Postemergence herbicide treatments and seed-place fertility recorded significant interaction on root rot incidence and yield. There was over 30% yield improvement between 2016 and 2015 trials due to soil moisture. The trial minimized pea root rot from infested soils and increased yield.

Weed control and response of yellow and white popcorn hybrids to herbicides

AbstractPopcorn (Zea mays L. var. everta) is an important crop to Midwestern US producers. While there is considerable research on field corn and sweet corn sensitivity to herbicides, there is a lack of information on popcorn sensitivity to herbicides. Field experiments were conducted in 2017 and 2018 to evaluate herbicides labeled for yellow popcorn in commercially available popcorn hybrids for weed control and crop response in Nebraska. The experiments were arranged in a split‐plot design. The main plot treatments consisted of two white and six yellow popcorn hybrids. Ten sub‐plot treatments consisted of nontreated control, weed‐free control, and four pre‐emergence (PRE) followed by postemergence herbicide treatments applied at labeled rates (1X) and double the labeled rates (2X). Across hybrids, PRE herbicide treatments resulted in 4–8% injury. Across all PRE herbicide treatments, a yellow hybrid, R265, displayed the greatest average plant injury (11%). At labeled rates, broadleaf weed control in both years, and foxtail control in 2017, ranged from 95–99% with all treatments; however, foxtail control was limited (72–86%) for most treatments in 2018. Weed biomass reduction in all herbicide treatments ranged from 90–98% and 68–97% control in 2017 and 2018, respectively. Yield losses ranged from 0–7% in herbicide treatments, with a 42% yield loss in the untreated control. Although slight hybrid differences in herbicide sensitivity were detected, the differences were not linked to popcorn color. Information reported in this research are the first that determined popcorn sensitivity to herbicides.

Effect of weed control technologies on chickpeas (Cicer arietinum L.) and weeds

Purpose. In our experiment, effect of weed technologies on chickpeas (Cicer arietium L.) was set up in 2018 and 2019 at the Szeged-Othalom experimental area.Methods. In the first year we applied mechanical weed control in addition to pre-emergence herbicide (May 19, 2018) and 6–8 leaf chickpeas (June 20, 2018) in addition to post-emergence herbicide treatments. The year 2019 was different in that after the pre-emergence treatment (April 10, 2019), the post-emergence treatment of chickpeas with 6–8 leaf condition (May 15, 2019) was repeated in the budding state (June 18, 2019). The yield components one way analysis of variance was prepared using SPSS 22 software and graphic representation of the development of the plants was carried out Svab's cumulative yield analysis.Results. The effect of the treatments of 2018 and 2019 on the yield elements of chickpeas can be illustrated graphically in Figure 1 and Figure 2. For both years, the data are from plots of the ʻRealeʼ variety, where the 100% level is made up of the yield elements of the weed-free plots, and the yield elements of the other treatments are compared to this. Figure 1 shows that the number of shoots per unit area (1 m2) of weed-free plots that did not control weeds was 15%, the number of pods 45%, the number of seeds 58% and the weight of seeds 49% less than the weed-free control plots the same crop elements. Weeds were also significantly present in the plots treated only with pre-emergence treatment in the second half of the growing season, so the number of shoots per unit area was 3 %, the number of pods 23 %, the number of seeds 34% and the seed weight 35 % lower, as on weed-free plots. In the case of herbicide treatments, the decrease in yield elements was much smaller: the number of plants per unit area by 1%, the number of shoots by 3–10%, the number of pods by 5–12%, the number of seeds by 13–18%, the seed weight was by 1–5% less than on mechanically weed-controlled plots. Conclusions. Our two-year weed survey results show that the later sowing time of chickpeas favored warm-loving weeds. This is in complete agreement with the opinion of Nagy (2017), who found that sowing time determines the predominant weed species in a given area. At the same time, the statement of Kurnik (1970) was not confirmed, since in our experiment we proved in the case of ʻRealeʼ cultivar that the later sowing stock in 2018 gave higher yields than the plots with earlier sowing time in 2019. The changing weather caused by climate change makes the site characteristics of the given period much more unpredictable, so the yield is determined much more by the field factors developed during the growing season than by the calendar period.

Control of ALS- and EPSPS-Resistant Amaranthus palmeri by Alternative Herbicides Applied in PRE- and POST-Emergence

ABSTRACT: The emergence of resistant biotypes of the Amaranthus palmeri species in cotton production areas of the state of Mato Grosso, Brazil, generated the need for correct identification of this species and information on viable herbicidal tools for their management. Thus, greenhouse experiments were conducted to evaluate the efficacy of alternative herbicides applied to A. palmeri in pre and post emergence. A randomized block design with four replications was used. The efficacy of herbicides applied in pre emergence was evaluate in two experiments, one in a clayey and other in a sandy soil; 9 herbicide treatments (8 with herbicide application and a control without application) were applied on each soil. Subsequently, two experiments with different populations of A. palmeri were conducted, using a 13 x 2 factorial arrangement, to evaluate the efficacy of herbicides applied in post emergence. The factors consisted of 13 herbicide treatments (12 with herbicide application and a control without application) and two weed development stages (2-4 and 6-8 leaves). Pre-emergence application of the flumioxazin, S-metolachlor, isoxaflutole, and trifluralin herbicides controlled the weed satisfactorily in both evaluated soils. The sulfentrazone and metribuzin herbicides were effective in the sandy soil, and diuron was effective in the clayey soil. The clomazone herbicide did not successfully controlled the A. palmeri plants in any of the soils. All post-emergence herbicide treatments were effective for the management of A. palmeri plants, when they were applied at the 2-4 leaf stage.

Pre-and post-emergence herbicide sequences for management of multiple herbicide-resistant littleseed canary grass in wheat

Littleseed canary grass (Phalaris minor) is the ubiquitous and pernicious grass weed of wheat in rice-wheat cropping system in north-western Indo- Gangetic plains of India. A field experiment was conducted during Rabi 2014–15 and 201516 in a farmers field infested with P. minor having history of poor control with acetyl-CoA-carboxylase inhibitors in village Nangla, district Fatehabad, Haryana, India with an objective to compare pre-emergence only, postemergence only and pre-emergence followed by post-emergence herbicide treatments for control of P. minor in wheat. The sequential application of preemergence pendimethalin 1.5 kg/ha fb post-emergence pinoxaden + metsulfuron 64 g/ha and pre-emergence pendimethalin 1.5 kg/ha fb post-emergence mesosulfuron + iodosulfuron 14.4 g/ha provided 88–93% control of P. minor compared to alone pre- and post-emergence herbicide treatments. Grain yield of wheat increased significantly by 69–78% with pre-emergence pendimethalin 1.5 kg/ha fb post-emergence pinoxaden + metsulfuron 64 g/ha or pre-emergence pendimethalin 1.5 kg/ha fb post-emergence mesosulfuron + iodosulfuron 14.4 g/ha due to significant increase in yield attributes. Alone pre- or post-emergence herbicides provided ineffective control of P. minor (44–66%) and recorded lower grain yield. It was concluded that herbicide sequences having both pre- and postemergence herbicides would be better option as compared to their alone applications in order to manage resistant populations of P minor in wheat.

INTEGRATING PRE AND POST-EMERGENCE HERBICIDES FOR CONTROLLING WEEDS IN DRILL-SEEDED RICE (ORYZA SATIVA L.)

Two field experiments were carried out at the experimental farm of Sakha Agricultural Research Station, Kafrelsheikh, Egypt during the summer seasons of 2015 and 2016 to find out the optimum pre and post-emergence herbicide treatments from the recommended herbicides to control weeds under drillseeded rice conditions (Giza179 cv). Fourteen weed control treatments included two pre-emergence herbicides i.e. thiobencarb 50% at the rate of 3.57 kg ai ha-1 alone and followed by six weed control treatments included; penoxsulam 2.5% at 0.0238 kg ai ha- 1 , bispyribac-sodium 2% at 0.0381 kg ai ha-1 and fenoxaprop-ethyl 7.5% at 0.0625 kg ai ha-1 alone and mixed with halosulfuron 75% at 0.0357 kg ai ha-1, also pendimethalin 50% at rate of 2.023 kg ai ha-1 alone and followed by the previous six post-emergence weed control treatments as compared to weedy check (untreated). Randomized Complete Block Design (RCBD) with three replications was used. The results revealed that, spraying pendimethalin as pre-emergence herbicides at 4 days after seeding (DAS) recorded the best weed control, highest rice growth characters and grain yields, as compared to thiobencarb. Each of penoxsulam 2.5% or bispyribac-sodium 2% or fenoxaprop-ethyl 7.5% mixed with halosulfuron 75% gave the lowest dry weights of grasses, broadleaves and total weeds in addition to rice dry biomass, grain yield and its studied attributes. Based on obtained results, it can be concluded that pendimethalin as pre-emergence herbicide at 4 DAS followed by spraying any of penoxsulam 2.5% or bispyribac-sodium 2% or fenoxaprop-ethyl 7.5% mixed with halosulfuron 75% at recommended doses applied at 15, 22 and 35 DAS, respectively were the best combinations for controlling weeds and gave the highest grain yield in drill-seeded rice.