Postemergence Herbicide Applications Research Articles

Above Ground Emergence and Floristic Composition of Weeds in Relation to Tillage and Weed Management Practices in Maize and Cowpea

Background: Weeds are one of the most important elements influencing crop productivity. Tillage practices have a significant effect on the weed seed bank and the appearance of weeds, both of which have a direct impact on farm productivity. Different tillage strategies based on ploughing depth, as well as weed control practices, change the dynamics of weed seeds in the soil. This research will aid in the development of integrated weed control methods by investigating the interaction between tillage and weed management practices. Methods: Field trials were carried out in two seasons, Summer and Kharif 2022, using a split-plot design with three tillage methods and four weed management practices. The treatments were replicated three times. Result: Among the different tillage treatments Mouldboard plough fb Cultivator fb Rotovator recorded the lowest weed density. With respect to weed management methods, pre- and post-emergence herbicide application and hand weeding at 20 and 40 DAS recorded the lower weed density. Interaction effects of tillage and weed management practices resulted in lower weed density in Mouldboard plough fb Cultivator fb Rotovator with herbicide application and Mouldboard plough fb Cultivator fb Rotovator with hand weeding. Highest weed density was recorded under Cultivator fb Rotovator in unweeded control. With respect to relative density, among the broad-leaved weeds (BLW) Trianthema portulacastrum and Dactyloctenium aegyptium in grasses dominated among the weed species in 30 and 60 DAS respectively. From the present study it was concluded that the Mouldboard plough fb Cultivator fb Rotovator with hand weeding twice or herbicide application reduces the weed emergence from the soil weed seed bank.

Herbicide response and germination behavior of two goosegrass (Eleusine indica) populations in the Australian environment

AbstractGoosegrass [Eleusine indica (L.) Gaertn.] is one of the most problematic grassy weeds in the world. It is considered to be an important weed in summer fallows and crops grown in the eastern region of Australia. To examine the seed germination ecology of two populations (Gatton and Ingham) of E. indica and their response to postemergence herbicides in Australian conditions, experiments were carried out in the laboratory and screenhouse. Seedling survival, spike production, and plant biomass of both E. indica populations declined markedly with the application of postemergence herbicides such as butroxydim, clethodim, glufosinate, haloxyfop, and propaquizafop, whereas the application of paraquat failed to control the Ingham population. A dose–response study verified the presence of paraquat resistance in the Ingham population. In this regard, it was observed that the paraquat doses required to achieve a 50% reduction in survival and plant biomass were 27 and 21 times greater in the Ingham population compared to the Gatton population, respectively. Higher alternating temperatures (35/25 and 30/20 C) resulted in greater germination of both populations than lower alternating temperatures (20/10 and 25/15 C). At 20/10 C, the Ingham population failed to germinate; however, about 15% germination in the Gatton population was observed. At the lowest alternate temperature range (15/5 C), neither population germinated. The germination of both populations of E. indica was severely reduced under completely dark conditions compared with the alternating light/dark period. Germination was more tolerant of salt and water stress in the Ingham population compared with the Gatton population. Eleusine indica seedling emergence was comparable among populations, and the greatest emergence (83%) was observed for seeds buried at a depth of 2 cm but then declined dramatically, and no seedlings emerged from an 8-cm burial depth. The information acquired from this study could be used in developing effective management strategies for E. indica.

Effect of tillage and weed control practices on weed density, cassava growth and yield at Mkuranga district, Tanzania

Poor and improper weeding in cassava production has been reported to cause cassava yield losses ranging from 40% to 90%. A study was carried out in 2019/2020 planting season at Kiimbwanindi village, Mkuranga, Tanzania to identify common weeds available in the selected cassava field and then the effect of different integrated weed control options was studied. Till only and till + Ridge, pre-emergence herbicides (Primagram Gold a.i 290 g/L S-metolachlor + 370 g/L atrazine and Oxfen a.i Oxyfluorfen 24% EC), post emergence herbicides (Force up a.i 480 g/L of Glyphosate-Isopropylamine salt) and back pack weeder with modified tines were tested on Cassava variety Kiroba in a factorial experiment arranged in a randomized complete block design (RCBD) replicated three times. Data on weed species, weed density, cassava height, girth and fresh root yield and soil were collected. By using Thomas methodology, perennial weeds Cyperus rotundus, Reissantia sp, Mucuna pruriens and Commelina benghalensis found to be the mostly and abundantly occurred weed species. The combination of tillage practices and pre-emergence herbicides application increased number of days’ weeds took to reemerge. The integrated weed control options significantly affected cassava fresh root weight and biomass, p = 0.019 and p = 0.026, respectively. The correlation analysis showed a non-significant positive relationship between cassava stem height and cassava fresh root weight (r = 0.389, p > 0.05), and cassava stem girth and cassava fresh root weight (r = 0.055, p > 0.05). The study concluded that, the combination of till + ridges, application of pre-emergence herbicide (S-metolachlor + atrazine) and post emergence herbicides (glyphosate) can effectively control weeds and provided favorable environment for cassava growth and root formation as compared to other treatment options.

Impact of cereal rye cover crop on the fate of preemergence herbicides flumioxazin and pyroxasulfone and control of Amaranthus spp. in soybean

AbstractPreemergence herbicides associated with cereal rye (Secale cereale L.) cover crop (hereafter “cereal rye”) can be an effective waterhemp [Amaranthus tuberculatus (Moq.) Sauer.] and Palmer amaranth (Amaranthus palmeri S. Watson) management strategy in soybean [Glycine max (L.) Merr.] production. Delaying cereal rye termination until soybean planting (planting green) optimizes biomass production and weed suppression but might further impact the fate of preemergence herbicides. Limited research is available on the fate of preemergence herbicides applied over living cereal rye in the planting green system. Field experiments were conducted in Illinois, Kansas, Pennsylvania, and Wisconsin to evaluate the fate of flumioxazin and pyroxasulfone and Amaranthus spp. residual control under different cover crop management practices in soybean in 2021 and 2022 (8 site-years). A flumioxazin + pyroxasulfone herbicide premix was applied preemergence at soybean planting under no-till without cereal rye, cereal rye early terminated before soybean planting, and cereal rye terminated at soybean planting. Flumioxazin and pyroxasulfone concentrations in the soil were quantified at 0, 7, and 21 d after treatment (DAT), and Amaranthus spp. density was determined at postemergence herbicide application. The presence of cereal rye biomass intercepted flumioxazin and pyroxasulfone at preemergence application and reduced concentration in the soil when compared with no-till, mainly at 0 DAT. Main differences in herbicide concentration were observed between no-till and cereal rye treatments rather than cereal rye termination times. Despite reducing herbicide concentration in the soil, the presence of the cereal rye biomass did not affect early-season residual Amaranthus spp. control. The adoption of effective preemergence herbicides associated with a properly managed cereal rye cover crop is an effective option for integrated Amaranthus spp. management programs in soybean production systems.

Determination of quizalofop-p-ethyl in onion: residual dissipation pattern, weed control efficiency, and food safety assessment under field conditions.

Monitoring pesticide residue levels becomes crucial to maintain quality and guarantee food safety as the consumption of onion green leaves and immature and mature bulbs (either raw or processed) rises. A field experiment was conducted for two consecutive seasons with quizalofop-p-ethyl (5% EC) at 50 and 100 g a.i. ha-1 to evaluate weed control efficiency and to determine terminal residues. Post-emergence application of fop herbicide at 100 g a.i. ha-1 kept the weed density and dry weight reasonably at a lower level and enhanced the productivity of onion with higher economic returns. A rapid, sensitive, and analytical method was developed using high-performance liquid chromatography (HPLC) with excellent linearity (r2 > 0.99). The limit of quantification for quizalofop-p-ethyl was established at 0.04 mg kg-1 with signal to noise (S/N) ratio ≥ 10. The method was successfully applied and initial quantified residues were in the range of 2.5-4.4 mg kg-1 irrespective of seasons and doses. Finally, the presence of targeted herbicide residues in harvested samples was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS) under optimized operating conditions. Dietary risk assessment assured harvested onions were safe for consumption at the recommended dose. It also can be concluded that quizalofop ethyl did not adversely influence soil micro-organisms at standard rates of application.

Performance of herbicides for managing weed flora in transplanted aman paddy (Oryza sativa L.)

A field investigation was performed during the rainy seasons of 2018 and 2019 at the Instructional Farm, Bidhan Chandra Krishi Viswavidyalaya, Jaguli, Nadia, West Bengal, India (22056'N and 86048'E, 9.75m above mean sea level) with the aim of determining the comparative effectiveness of different herbicides in controlling various kinds of weeds (grass, sedge and broad-leaf) in the transplanted aman paddy. The experiment was laid out in Randomized Block Design having sixteen treatments with three replication, that includes application of either pre-emergence [butachlor, pretilachlor, pyrazosulfuron ethyl and ready mix (RM) of bensulfuron methyl + pretilachlor at 2 days after transplanting (DAT)] or post-emergence [bispyribac sodium and bispyribac sodium + penoxsulum at 20 DAT] herbicides followed by hand weeding at 40 DAT; application of both pre-emergence and post-emergence herbicides; hand weeding at 20 and 40 DAT and weedy check. Hand weeding at 20 and 40 DAT registered significantly lower weed density, weed dry matter and the highest weed control efficiency. Among the herbicidal treatments, ready-mix formulation of bensulfuron methyl 0.6% + pretilachlor 6% (Londax power 6.6%) performed better in controlling weeds of all categories and recorded higher paddy (3.96 t/ha) and straw yield (4.92 t/ha ) with the maximum weed index which were statistically at par with the hand weeded treatment. Hence, to fetch the effective suppression of weed, application of Londax power 6.6% @ 0.66 kg a.i./ha as pre-emergence (at 2 DAT) with hand weeding at 40 DAT can easily replace additional one hand weeding at 20 DAT.

Drone-based herbicide application for energy saving, higher weed control and economics in direct-seeded rice (Oryza sativa)

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore during kharif (rainy) and rabi (winter) seasons of 2022 and 2023 to evaluate the efficiency, energy and economics of drone-based herbicide application in direct-seeded rice (Oryza sativa L.). The study was carried out with application of pre-emergence, early post-emergence and post-emergence herbicides using drone and knapsack sprayer to assess the weed control efficiency. Treatments included pretilachlor followed by (fb) application of post-emergence herbicides, such as bispyribacsodium (Na), fenoxyprop ethyl + carfentrazone ethyl and early post-emergence herbicides, such as bispyribac-Na, fenoxyprop ethyl + carfentrazone ethyl, bispyribac-Na fb post-emergence of fenoxyprop ethyl + carfentrazone ethyl, weed-free check and unweeded check. Application of pretilachlor fb bispyribac-Na using knapsack sprayer reduced weed density from 83 to 87% and weed dry weight from 81 to 83% over unweeded plot. Moreover, it was found on par with drone application of same herbicides in both seasons. Pretilachlor fb bispyribac-Na application through knapsack sprayer and drone produced higher grain yield and it was comparable with weed-free plot. Higher net return, benefit: cost ratio (2.27 and 2.09), energy-use efficiency (10.86 and 9.55 MJ) and energy productivity (0.81 and 0.71 kg/MJ) were noticed with drone application of pretilachlor fb bispyribac-Na in both the seasons. From the experiment, drone application of pretilachlor fb bispyribac-Na is found as an effective strategy to manage weeds in direct-seeded rice and more advantageous in terms of energy-use and profitability.

Evaluation of smart spray technology for postemergence herbicide application in row middles of plasticulture production

AbstractPostemergence herbicides used to control weeds in the space between raised, plastic-covered beds in plasticulture production systems are typically banded, and herbicides are applied to weeds and to where weeds do not occur. To reduce the incidence of off-targeted applications, the University of Florida developed a smart-spray technology for row middles in plasticulture systems. The technology detects weed according to categories and applies herbicides only where the weeds occur. Field experiments were conducted at the Gulf Coast Research and Education Center in Balm, FL, in fall 2021 and spring 2022. The objective was to evaluate the efficacy of postemergence applications of diquat and glyphosate in row middles in jalapeno pepper fields when banded or applied with smart-spray technology. The overall precision of the weed detection model was 0.92 and 0.89 for fall and spring, respectively. The actuation precision achieved was 0.86 and 1 for fall and spring, respectively. No significant differences were observed between banded and targeted applications either with glyphosate or diquat in terms of broadleaf, grass, and nutsedge weed density. No significant pepper damage was observed with either herbicide or application technique. The smart-spray technology reduced herbicide application volume by 26% and 42% in fall and spring, respectively, with no reduction in weed control or pepper yield compared to a banded application. Overall, the smart-spray technology reduced the herbicide volume applied with no reductions in weed control and no significant effects on crop yield.

Weed management in broadcast sesame (Sesamum indicum L.) through sequential application of herbicides

A field experiment was conducted to study the effect of sequntial application of pre-and post-emergence herbicides on growth, nutrient uptake and yield of broadcast sesame on sandy loam soils. Eleven weed managementpractices consisting of pre-emergence application of pendimethalin @ 750 g/ha, oxyfluorfen @ 75g/ha and oxadiargyl @ 75g/ha alone and sequential application ofthese pre-emergence herbicides followed by post-emergenceapplication of quizalofop @ 50g/ha and propaquizafop @ 60g/ha including two hand weedings at 20 and 40 DAS and unweeded check were compared in randomized block design with three replications. Results revealed that thelowest density and dry weight ofweeds with lesser weed index were recorded in the plots treated with pre-emergence application of oxyfluorfen @ 75g/ha followed by quizalofop @ 50 g/ha applied at 20 DAS. The same weedmanagement practice recorded significantly higher stature of growth parameters and yield attributes. The increase in seed yield of sesame was 38.0 per cent with sequential application of oxyfluorfen @ 75g/ha followed byquizalofop @ 50 g/ha applied at 20 DAS compared to unweeded check. Heavy weed infestation in unweeded check plots resulted in incresed weed nutrient uptake upto 44.6, 5.6 and 34.0 kg of N, P and K/ha, respectively. Oxadiargyland oxyfluorfen @ 75 g/ha each showed phytotoxicity score of '4' and '3' respectively in 0 to 10 scale. Pre-emergence application of oxyfluorfen @ 75 g/ha followed by propaquizafop @ 60g/ha applied at 20 DAS recorded the highest benefit-cost ratio.

Using soybean chaff lining to manage waterhemp (Amaranthus tuberculatus) in a soybean–corn rotation

AbstractWaterhemp (Amaranthus tuberculatus[Moq.] Sauer) escapes are common in midwestern U.S. soybean [Glycine max(L.) Merr.] fields due to the continued rise in herbicide-resistant (HR) populations. In a conventional harvesting system, weed seeds are harvested with the crop grain and spread back on to the field. Harvest weed seed control methods such as chaff lining concentrate weed seed-bearing crop and weed chaff into a narrow row (chaff line). These chaff lines (30- to 50-cm wide) are undisturbed the following growing seasons, under the assumption that the chaff line creates an environment less favorable for weed seed germination and survival. Field experiments were conducted in a soybean–corn (Zea maysL.) rotation in 2020 and 2021 in Ames, IA, and Roland, IA, to quantify the effectiveness of chaff lining for managingA. tuberculatusseeds. About 70% of theA. tuberculatusseeds were retained on the mother plant at soybean harvest in 2020. The chaff lining system concentrated more than 99% of theA. tuberculatusseeds exiting the combine into the chaff line. AlthoughA. tuberculatuspopulation density in 2021 was 76% higher inside the chaff line than outside the chaff line,A. tuberculatusaboveground biomass was 63% lower inside the chaff line than outside the chaff line at 12 wk after corn planting. Similarly,A. tuberculatusinside the chaff line had delayed emergence compared withA. tuberculatusoutside the chaff line. Application of preemergence herbicides in corn inside the chaff line delayedA. tuberculatusemergence by more than 2 wk compared withA. tuberculatusoutside the chaff line. Additionally, a follow-up postemergence herbicide application in corn was needed only inside the chaff line to manageA. tuberculatus, suggesting the possibility of lower overall herbicide use. These results support implementing chaff lining in soybean-based crop systems of the U.S. Midwest to help manage HRA. tuberculatusseedbanks.

Effect of different weed management practices on production of spring maize in Dang, Nepal

The study was carried out at Lamahi-8, Satbariya, Dang to evaluate the effect of different weed management practices on the production of spring maize. The experiment was carried out in a Randomized Complete Block Design using three replications and seven treatments. Rampur hybrid 10 variety and early post emergence (EPoE) herbicide were used in the experiment. The treatment consisted of single as well as combined weed management methods as T1: Broadcasting-One hand weeding, T2: Broadcasting-Herbicide, T3: Line sown- One hand weeding, T4: Line sown-Herbicide + one hand weeding, T5: Line sown- Mini tiller weeder, T6: Line sown- herbicide + mini tiller and T7: Line sown- One hand weeding + mini tiller. The experiment result showed that the combined application of early post emergence herbicide and mini tiller resulted the highest grain yield (8.62 Mt/ha) with minimum total weed density at 60 DAS (41.33/m2) and at harvest (68/m2) thus resulting minimum weed dry weight at 60 DAS (5.45 g/m2) and at harvest (10.64 g/m2). Sixteen different weed species belonging to 9 different families were identified in the experimental field. The highest benefit: cost (3.37) was obtained in the treatment Line sown-Herbicide + mini tiller weeder which was significantly higher compared to other treatments. Among the treatments applied, one with the application of herbicide in combination with mini tiller weeder was found to be the most effective one that resulted in the minimum weed density and minimum dry weight, higher grain and biological yield with the highest benefit cost ratio thus proving to be the most economical one. At the same time, application of mini tiller weeder as a single method was found to be the next better alternative for weed control in spring maize that could benefit the farmers in comparison to other single weed management practices.

Effectiveness of herbicide application with plant growth regulators and microfertilizer in late crops of winter wheat

Goal. To establish the features of the formation of weed complex, yield and grain quality of winter wheat sown on the late sowing period, depending on the application of post-emergence herbicides, plant growth regulators and microfertilizers.
 Methods. Field, measuring and weighing, statistical, laboratory, analytical.
 results. According to the results of investigations in 2016—18, 30 species of weed plants were found in late crops of winter wheat: late spring grasses (3 species); early and late dicotyledonous (14 species); dicotyledonous wintering, winter and biennial (7 species); dicotyledonous perennials (6 species). In terms of quantity, late spring grasses weeds dominated (40.6%), and in terms of raw mass dicotyledonous perennials dominated (87.6%). Technical efficiency of tank mixture of anti-perennial herbicides Dekabrist 480 SL (0.15 l/ ha) + Gryzny, W.G. (15 g/ha) + Talant, surface-active substance (0.2 l/ha), when applied at the tillering stage (standard) against the total raw mass of dicot annual and perennial weeds was 96.7 and 69.2%, respectively. The low level of control of dicotyledonous perennial species by this tank mixture was associated with the partial regrowth of root-sprouting weeds, especially sow thistles, after the introduction of the specified herbicides, namely during the booting period. The application of plant growth regulators Emistym C, w.-a.s. (10 ml/ha) and Vermiiodis, w.s. (6.0 l/ha) at the booting stage, against the background of application of herbicides at the tillering stage, stimulated the growth of the raw weight of dicotyledonous perennials and the total raw weight of all weeds, compared to their application in a tank mixture with herbicides at the tillering stage. At the same time, these indicators, when applying microfertilizer Nanomix, s. (2.0 l/ha) in a tank mixture with herbicides at the tillering stage, were higher, compared to applying the preparation separately from herbicides at the booting stage. An increase in the level of raw mass of weeds against the background of the use of stimulating preparations led to a decrease in grain yield in most variants with these preparations, compared to the standard. No effect of the studied preparations on the protein content of the grain, as well as the germination energy and laboratory germination of the grown grain was found.
 Conclusions. The application of post-emergence herbicide compositions with plant growth regulators and microfertilizers in late crops of winter wheat stimulates the growth of the raw mass of weeds, which negatively affects the grain yield of the crop.

Growth and Yield Attributes of Groundnut (Arachis hypogaea L.) as Influenced by Tank-mix Application of Early Post Emergence Herbicides

Background: Groundnut or peanut (Arachis hypogaea L.) is known as the ‘king’ of oilseeds. It is one of the most important food and cash crop of India. Among different constraints that limit the productivity of groundnut, weed menace is one of the serious bottlenecks. A field experiment was conducted at Perunthalaivar Kamaraj Krishi Vigyan Kendra, Puducherry during 2019 to 2020 to study the tank mix application of post-emergence herbicides for efficient weed control in Groundnut. Methods: The experiment was laid out in randomized block design with 13 treatments and replicated thrice. The treatments consisted of weed management practices viz., pre emergence herbicide pendimethalin and post emergence herbicide viz., imazethapyr, quizalofop-ethyl and those herbicides used either alone or combined with hand weeding once. In addition, hand weedings twice at 15 and 30 DAS were tested with unweeded check. Result: The experiment results of the two years study revealed that the Pendimethalin @ 1.5 kg ai ha-1 (PE) + tank mix of Imazethpyr (40%) + Quizalofop ethyl (60%) at 20-30 DAS recorded maximum plant height (58.17 cm), DMP (36.81 g plant-1), Significantly higher pod yield (3752 kg ha-1), highest net income (₹ 90,762 ha-1) and B:C ratio (2.80). Correlation and Regression analysis also indicated that the yield attributes had a positive impact on groundnut yield.

Comparative Efficacy of Different Herbicidal Combinations on Weed Growth and Yield Attributes of Wheat

Weeds are the main biotic obstacles on wheat production, which can impair wheat productivity by up to 60%, if not handled under critical stages of crop life cycle. Chemical weed control through herbicides has been the most popular and effective method among farmers. The weed management using similar herbicides however has led to herbicide resistance in weeds. This requires the evaluation of newer herbicidal combinations for the control of weeds in wheat. Therefore, an experiment was conducted at Research Farm, Department of Agronomy, JNKVV, Jabalpur, Madhya Pradesh during the Rabi season of 2016-17 to evaluate the effect of post emergence application of herbicides on the weeds and yield of wheat. The experiment was laid out in randomized block design with ten treatments comprising of eight herbicidal combinations along with a hand weeding and a weed check and replicated thrice. Observations on different weed parameters, growth parameters and yield of wheat were recorded. Among the different herbicidal combinations, the post emergence application of halauxifen-methyl ester + florasulam at 10.20 g/ha resulted in greatest suppression of weeds and had highest weed control efficiency (56.73%). It also led to highest growth in wheat which resulted in highest grain yield (5.81 t/ha) and harvest index (44.99%). From this study, it can be concluded that the post emergence application of halauxifen-methyl ester + florasulam at 10.20 g/ha can not only control weeds effectively but also increase the yield of wheat.

Ефективність післясходових гербіцидів залежно від строків застосування в посівах сої в Східному Лісостепу України

Goal. To determine the influence of the timing of application of multi-component postemergence herbicides on crop weediness, yield, and quality of soybean seeds in the conditions of the Eastern Forest Steppe of Ukraine. Methods. Field, weighing, statistical, analytical. Results. According to the results of research in 2017–2019, 15 types of weeds, represented by 4 agrobiological groups — early spring weeds, late spring weeds, biennials, and rhizomes — were found in soybean crops in the conditions of the Eastern Forest Steppe of Ukraine. Cereal annual weeds were dominated by number, and dicotyledonous annual weeds by raw mass. It was established that against the background of the use of anti-dicotyledons drug with the active substance bentazon + acifluorfen (in the phases of primordial leaves, 2 and 4 ternate leaves of soybeans) with a graminicide based on hyzalofop-P-ethyl (in the phase of 5 ternate leaves of soybeans), the technical efficiency of these combinations concerning the total weediness of soybean crops was, respectively: in terms of quantity at the beginning of the growing season — 65.7; 65.0 and 48.8%; by the amount at the end of vegetation — 88.6; 88.0 and 67.5%; by raw mass at the end of the growing season — 86.3; 83.9 and 62.4%. When applying the herbicide with the active substance imazetapir + propakhizafop in the phase of primordial leaves and 2-3 ternate leaves of soybean, the technical effectiveness of the effect on the total weediness of the crops was 81.7 and 58.9%, respectively, at the beginning of the growing season, and 82, 1 and 58.8% — at the end, by raw mass at the end of the growing season — 68.3 and 55.2%. The greatest increase in the yield of soybean seeds was provided by the combination of the herbicide with the active substance bentazon + acifluorfen (primordial soybean leaves) with the drug based on hyzalofop-P-ethyl (5 ternate soybean leaves) — 0.29 t/ha, or 33%, the smallest was provided by the application of the drug with the active substance imazetapir + propakhizafop in the phase of 2–3 ternate soybean leaves (0.12 t/ha, or 13%). In almost all options, with the application of herbicides, the increased collection of protein (by 0.06–0.08 t/ha) and oil (by 0.03–0.04 t/ha) was fixed. Conclusions. The use of anti-dicotyledons herbicide with the active ingredient bentazon + acifluorfen (in the phase of primordial soybean leaves) with a graminicide based on hyzalofop-P-ethyl (in the phase of 5 ternate soybean leaves) is promising for effective control of weeds in crops and ensuring an increase in the yield of soybean seeds in the conditions of the Eastern Forest Steppe of Ukraine.

Sericea lespedeza control with postemergence and preemergence herbicide applications in fields managed for northern bobwhite

AbstractSericea lespedeza (Lespedeza cuneata) is an invasive nonnative legume that commonly occurs on sites managed for northern bobwhite (Colinus virginianus). Sericea reduces bobwhite habitat availability by outcompeting native plants that provide food and cover. Sericea can be controlled with postemergence herbicides such as glyphosate as well as a mixture of triclopyr with fluroxypyr, but these herbicides do not provide preemergence control. Imazapic has been effective at controlling a limited number of planted sericea seeds, but the efficacy of imazapic at various application rates to control sericea seedbank response following treatment with a postemergence herbicide has not been evaluated. We designed a field experiment to evaluate sericea control and changes in the plant community as related to bobwhite habitat with 2 postemergence herbicides followed by preemergence treatment of imazapic at 3 sites in Tennessee and Alabama, USA, 2018–2022. Specifically, we treated sericea with postemergence broadcast applications of glyphosate or triclopyr with fluroxypyr in 2018 and applied spot treatment with the same herbicides in 2019–2021. We applied imazapic at 4 rates following prescribed fire in 2019 and 2022. We measured coverage of sericea, native forbs, annual grasses, perennial grasses, and bobwhite food plants before treatment in 2018 and after all treatments in 2022. Nearly all postemergence treatments reduced sericea coverage, but imazapic did not increase control compared to postemergence herbicides alone. Perennial grasses used for nesting and bobwhite foraging were maintained following treatments. We recommend managers use either glyphosate or triclopyr with fluroxypyr to control sericea postemergence and consider using a low rate of imazapic to reduce annual grasses if coverage is a problem on the site.

Evaluating sequential application of pre and post emergence herbicides in direct- seeded rice

A field experiment was conducted at Agriculture Research Farm, Bihar Agricultural University, Sabour, Bhagalpur, Bihar during kharif season of 2018-19 to study the effect of different herbicides on weed species, growth attributes and yields of direct seeded rice. The experiment comprised of 11 treatments based on weed management practices. The 11 treatments were lone application of pendimethalin and pyrazosulfuron as pre-emergence herbicides while others were as post-emergence at 20 days after sowing i.e. pyrazosulfuron @ 25 g/ha PE, pendimethalin @1000 g/ha PE, pyrazosulfuron @ 25 g /ha PE fb 2,4-DEE @ 750 g/ha POE, pyrazosulfuron @ 25 g /ha PE fb bispyriba-Na @ 25 g/ha POE, pyrazosulfuron @ 25 g/ha PE fb bispyribac-Na @ 20 g/ha + pyrazosulfuron @ 20 g/ha POE, bispyribac-Na @ 25 g/ha POE, bispyribac-Na @ 20 g/ha + pyrazosulfuron @ 20 g/ha POE, ethoxysulfuron @ 15 g/ha + pyrazosulfuron @ 20 g /ha POE, halosulfuron @ 67.5 g/ha + azimsulfuron @ 30 g/ha POE, hand weeding thrice and weed check. Among all the herbicidal treatments, the minimum weed density (5.13 m-2), dry weight (4.82 g m-2), highest grain yield (5.41 t/ha) and benefit cost ratio (1.9) were recorded with application of pyrazosulfuron @ 25 g/ha PE fb bispyribac-Na @ 20 g/ha + pyrazosulfuron @ 20 g/ha POE.

Selectivity of latifolicides associated with glyphosate applied in post-emergence on soybean cultivars

The genetic improvement of soybean cultivars over the years has focused on increasing the yield capacity and tolerance to some abiotic and biotic factors, such as drought, diseases, and pests. However, during the transfer of genes of interest, some genes responsible for a lower tolerance to herbicides can be integrated into the genome of the new cultivar. Thus, tests designed to assess the tolerance of these new soybean cultivars to herbicides are needed to avoid yield losses caused by poisoning after application. The objective of this study was to evaluate the selectivity of herbicides associations applied in post-emergence of three soybean cultivars. The experimental design used was a randomized complete block, with four replications. The selected cultivars were M7110 IPRO®, Foco IPRO®, and Bônus IPRO®. The herbicides and the respective doses (g a.i. ha-1) used were: glyphosate (960), glyphosate + bentazon (960 + 600), glyphosate + fomesafen (960 + 175), glyphosate + lactofen (960 + 120), glyphosate + imazethapyr (960 + 100), glyphosate + chlorimuron (960 + 10), glyphosate + cloransulam (960 + 39.5), and a control without herbicide application. The components of growth and yield evaluated were: height, stand, the weight of one hundred grains, and yield. A visual note of intoxication was also made for each treatment. The application of post-emergence herbicides does not alter the plant stand of soybean cultivars. Also, these herbicides were not reduced the yield of M7110 IPRO® and Foco IPRO® cultivars. Both glyphosate isolated and mixed with lactofen or imazethapyr reduced yield of Bônus IPRO® cultivar. Highlights Herbicide associations applied post-emergence cause higher levels of injuries on soybean crop. The visualization of injuries resulting from herbicides on soybean does not necessarily imply yield reductions. The genetics of the soybean cultivar is decisive for the response in terms of sensitivity to herbicides.

Multiple-herbicide-resistant waterhemp control in glyphosate/glufosinate/2,4-D-resistant soybean with one- and two-pass weed control programs

AbstractWaterhemp control in Ontario has increased in complexity due to the evolution of biotypes that are resistant to five herbicide modes of action (Groups 2, 5, 9, 14, and 27 as categorized by the Weed Science Society of America). Four field trials were carried out over a 2-yr period in 2021 and 2022 to assess the control of multiple-herbicide-resistant (MHR) waterhemp biotypes in glyphosate/glufosinate/2,4-D-resistant (GG2R) soybean using one- and two-pass herbicide programs. S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, pyroxasulfone/flumioxazin, and pyroxasulfone + metribuzin applied preemergence (PRE) controlled MHR waterhemp similarly by 46%, 63%, 60%, and 69%, respectively, at 8 wk after postemergence (POST) application (WAA-B). A one-pass application of 2,4-D choline/glyphosate DMA POST provided greater control of MHR waterhemp than glufosinate. Two-pass herbicide programs of a PRE herbicide followed by (fb) a POST-applied herbicide resulted in greater MHR waterhemp control compared to a single PRE or POST herbicide application. PRE herbicides fb glufosinate or 2,4-D choline/glyphosate DMA POST controlled MHR waterhemp by 74% to 91% and by 84% to 96%, respectively, at 8 WAA-B. Two-pass herbicide applications of an effective PRE residual herbicide fb 2,4-D choline/glyphosate DMA POST in GG2R soybean can effectively manage waterhemp that is resistant to herbicides in Groups 2, 5, 9, 14, and 27.

Impact of sequential herbicides application on crop productivity, weed and nutrient dynamics in soybean under conservation agriculture in Vertisols of Central India.

Adoption of conservation agriculture (CA) is very slow due to weed infestations. The application of herbicides is the only viable option to deal with problem of weed management to adhere with basic principles of CA. A field experiment was carried out for three years to evaluate the expediency of different herbicides and their sequential applications under CA. In this study, seven treatments comprised of either alone or sequential application of pre-emergence (PE) and post-emergence (PoE) herbicides, hand weeding and weedy check were tested in soybean. Result indicated that sequential application of glyphosate at 1 kg ai ha-1 + pendimethalin at 1 kg ai ha-1as PE followed by PoE application of imazethapyr at 100 g ai ha-1 at 30 days after sowing (DAS) proved to be the best economical option in terms of plant growth parameters, crop biomass, seed yield, weed index and carbon and nutrient recycling. Pearson's correlation coefficients matrix revealed that grain yield was significantly (P<0.0001) related to weed density at harvest (r = -0.84), (WDH) (r = -0.63), weed dry biomass (WDB) (r = -0.52), weed nitrogen (N), phosphorus (P) and potassium (K) uptake (r = -0.56, r = -0.59 and r = -0.66), respectively and weed index (WI) (r = -0.96). The bivariate linear regression study of grain yield on weed control efficiency (WCI) biomass, N, P and K uptake by grain showed a clear significant (P<0.0001) dependence with R2 value of 0.53, 0.99, 0.95 and 0.98, respectively. The fitted stepwise multiple regression model also revealed that N and P uptake in grain, weed density at 20 DAS and K uptake in weed were actual predictor for grain yield. We concluded that, effective and economical weed control under CA in soybean can be achieved through sequential application of glyphosate along with pendimethalin at 1 kg ai ha-1 each PE followed by PoE use of imazethapyr at 100 g ai ha-1 at 30 DAS.