Postemergence Research Articles

Volunteer rapeseed infestation and management in corn

AbstractThe study was conducted to evaluate the effect of different termination timings for rapeseed (Brassica napus L.) cover crop on biomass production, termination efficiency, and volunteer infestation in the successive cash crop (corn, Zea mays), and control of volunteer rapeseed with herbicides. Delaying termination from 28 days before planting corn (DBP) to 14, 5, or 1 DBP, increased rapeseed biomass by 85%, 148%, and 158%, respectively. Rapeseed termination efficiency was greatest 28 DBP (99%) followed by 14 DBP (92%) and 5 DBP (89%) with the combined use of a roller‐crimper and 2,4‐D [2,4‐dichlorophenoxy acetic acid] + glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl) butanoic acid]. The sole use of roller‐crimper 1 DBP provided only 56% termination efficiency. Zero volunteer plants were observed in successive cash crops with the 28 DBP termination treatment; however, at 14, 5, and 1 DBP termination, the number of volunteer rapeseed plants m−2 were 5, 12, and 22, respectively. Regression analysis showed that variation in volunteer rapeseed density can be explained better by termination efficiency (R2 = 0.80) as compared to rapeseed biomass at termination (R2 = 0.46). Among pre‐emergence (PRE) herbicides, mesotrione [2‐(4‐mesyl‐2‐nitrobenzoyl)‐3‐hydroxycylohex‐2‐enone], rimsulfuron [N‐[[(4,6‐dimethoxy‐2‐pyrimidinyl)amino]carbonyl]‐3‐(ethylsulfonyl)‐2‐pyridinesulfonamide], and flumioxazin {2‐[7‐fluoro‐3,4‐dihydro‐3‐oxo‐4‐(2‐propynyl)‐2H‐1,4‐benzoxazin‐6‐yl]‐4,5,6,7‐tetrahydro‐1H‐isoindole‐1,3(2H)‐dione} provided more than 95% volunteer rapeseed control, and 92%–94% control with PRE‐application of atrazine [6‐chloro‐N‐ethyl‐N9‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], isoxaflutole [(5‐cyclopropyl‐4‐isoxazolyl)[2‐(methylsulfonyl)‐4‐(trifluoromethyl)‐phenyl]methanone], metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one], and pyroxasulfone [3‐[[[5‐(difluoromethoxy)‐1‐methyl‐3‐(trifluoromethyl)‐1H‐pyrazol‐4‐yl]methyl]sulfonyl]‐4,5‐dihydro‐5,5‐dimethylisoxazole]. Among post‐emergence (POST) herbicides, atrazine and glyphosate [N‐(phosphonomethyl) glycine] provided 99% control of rapeseed followed by glufosinate (89%). Results indicate that ineffective or delayed termination of rapeseed can result in volunteer infestation in successive crops, which can be controlled by tested PRE and POST herbicides at an early stage.

Efficacy of New Herbicide Formulation on the Growth and Yield of Maize (Zea mays L.)

A field experiment was carried out at a farmer’s field in the Perambalur District of Tamil Nadu, India, during the kharif season of 2021 to ascertain the effects of various weed management methods on the growth and yield of maize. The study comprised ten treatments (Pre application of Atrazine was fb post emergence application were 2,4-D, Halosulfuron methyl, Tembotrine, Tembotrine+ Atrazine, Mesotrione + Atrazine) and was set up in a Randomized Block Design. Hand weeding on 15 and 30 DAS ranked first and resulted in the lowest weed count on 45 DAS (Grasses – 2.73, Sedges – 3.12, BLW’s – 6.34), weed biomass on 30 and 45 DAS (10.89, 6.09 g), weed index (0 %) and highest weed control efficiency (93.71 %) among all the treatments examined. Among the herbicides sprayed, pre-emergence herbicide atrazine followed by post-emergence herbicide tembotrine had the lowest weed count on 45 DAS (Grasses – 2.90, Sedges – 3.44, BLW’s – 6.68), weed biomass (12.10, 12.55, 6.77 g m2), weed index (0.29%) and highest weed control efficiency (93.28%) and resulted in tallest height (204.12 cm), leaf area index (6.04), dry matter production (8.92 t ha-1), cob length (22.4 cm), grain yield (4.47 t ha-1) and stover production (5.71 t ha-1).

Sulfentrazone crop safety and efficacy in cabbage and broccoli

AbstractIn 2021 and 2022, research was initiated at two locations to evaluate the efficacy and safety of sulfentrazone in transplanted cabbage and broccoli. Treatments included oxyfluorfen at 560 g ha−1 applied pretransplant (PRE-T), sulfentrazone applied at 116 or 233 g ha−1 PRE-T, and S-metolachlor applied at 715 g ha−1 immediately after transplanting (POST-T) followed by (fb) oxyfluorfen applied at 210 g ha−1 postemergence (POST) 14 d after planting (DAP). The weedy cover of nontreated plots averaged between 6% (14 DAP) and 72% (42 DAP); all herbicide-treated plots averaged less than 30% cover at 42 DAP. At 14 and 28 DAP, oxyfluorfen, S–metolachlor fb oxyfluorfen, and the high rate of sulfentrazone reduced total monocotyledonous and dicotyledonous weed densities by 62% and 100%, respectively, relative to the nontreated control. The density of hairy galinsoga (in New Jersey) and combined ladysthumb and prostrate knotweed (in New York) were reduced by 71% to 99%. Except for the low rate of sulfentrazone, all herbicide treatments reduced weed biomass at harvest by ≥88%. Crop injury varied in response to herbicide treatments or weed competition but was also affected by crop and location. Between 14 and 28 DAP, the greatest amount of stunting (22%) was noted in the S-metolachlor fb oxyfluorfen treatments at both locations. Averaged over treatments, greater stunting was observed in broccoli than in cabbage in New York, whereas stunting estimates were higher for cabbage in New Jersey. All treatments in New Jersey resulted in significantly increased cabbage yield and broccoli and cabbage head sizes relative to the nontreated controls. No yield difference was noted between herbicide treatments and the nontreated check in New York. Data derived from these studies will be used to enhance crop safety recommendations in northeastern U.S. production environments for sulfentrazone used PRE in transplanted cabbage and support a potential label for broccoli.

Interaction of quizalofop-p-ethyl with 2,4-D choline and/or glufosinate for control of volunteer corn in corn resistant to aryloxyphenoxypropionates

AbstractCorn that is resistant to aryloxyphenoxypropionate, known commercially as Enlist™ corn, enables the use of quizalofop-p-ethyl (QPE) as a selective postemergence (POST) herbicide for control of glufosinate/glyphosate-resistant corn volunteers. Growers usually mix QPE with 2,4-D choline or glufosinate or both to achieve broad-spectrum weed control in Enlist corn. The objectives of this study were 1) to evaluate the efficacy of QPE applied alone or mixed with 2,4-D choline and/or glufosinate to control glufosinate/glyphosate-resistant corn volunteers in Enlist corn and 2) to determine the effect of application time (V3 or V6 growth stage of volunteer corn) of QPE-based treatments on volunteer corn control and Enlist corn injury and yield. Field experiments were conducted in Clay Center, NE, in 2021 and 2022. Quizalofop-p-ethyl (46 or 93 g ai ha−1) applied at the V3 or V6 growth stage controlled volunteer corn by ≥88% and ≥95% at 14 and 28 d after treatment (DAT), respectively. QPE (46 g ai ha−1) mixed with 2,4-D choline (800 g ae ha−1) produced 33% less than expected control of V3 volunteer corn in 2021, and 8% less than expected control of V6 volunteer corn in 2022 at 14 DAT. Volunteer corn control was improved by 7% to 9% using the higher rate of QPE (93 g ai ha−1) in a mixture with 2,4-D choline (1,060 g ae ha−1). QPE mixed with glufosinate had an additive effect and interactions in any combinations were additive beyond 28 DAT. Mixing 2,4-D choline can reduce QPE efficacy on glufosinate/glyphosate-resistant corn volunteers up to 14 DAT when applied at the V3 or V6 growth stage; however, the antagonistic interaction did not translate into corn yield loss. Increasing the rate of QPE (93 g ai ha−1) while mixing with 2,4-D choline can reduce antagonism.

Effect of different herbicide spray volumes on weed control efficiency of a battery-operated Unmanned aerial vehicle sprayer in transplanted rice (Oryza sativa L.)

The effect of spray volume on weed control in transplanted rice ecosystems using the Unmanned aerial vehicle (UAV) needs to be better understood for management in the advancements of UAV-based spraying technology. The present study aimed to find out the influence of varied spray volumes of 15 L/ha, 20 L/ha and 25 L/ha using the UAV and 500 L/ha using a Knapsack sprayer (KS) to compare the weed density, weed dry matter and weed control efficiency and yield in transplanted rice (Oryza sativa L.). Pre-emergence (PE) application of Pyrazosulfuron-ethyl at 25 g a.i./ha at three days after transplanting (DAT) and post-emergence (PoE) application of Bis-pyribac sodium at 25 g a.i./ha at 25 DAT were used as herbicide treatments. The results revealed that varied spray volumes significantly influenced the weed density, dry matter, and weed control efficiency of the UAV and KS. Application of herbicides using KS (500 L/ha) and UAV (25 L/ha) had better control on the weeds by reducing weed density and dry matter at 20, 40, and 60 DAT, with no significant difference. Higher grain yield and straw yield were recorded in KS (500 L/ha) and UAV (25 L/ha), with no significant difference. However, applying 25 L/ha had better weed control efficiency and higher yield, possibly due to optimum deposition. Considering the low volume application of UAV (25 L/ha) as compared with KS (500 L/ha), it is better to go for the optimal application of 25 L/ha, which is an energy-efficient and cost-effective, labour-saving approach compared to KS.

Assessment of Post Emergence Herbicide Efficacy for Drone Spraying in Transplanted Rice (Oryza sativa L.)

A field experiment was conducted at Rice Research Centre, Agriculture Research Institute, Rajendranagar, Hyderabad during kharif, (2022) to assess the post emergence herbicide efficacy for drone spraying in transplanted rice (Oryza sativa L.). The experiment was laid out in randomized block design with 7 treatments and replicated thrice. Results revealed that among different doses of herbicidal treatments, post emergence application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 180 g a.i ha-1using drone recorded highest number of tillers at harvest, plant height at harvest, number of panicles at harvest, grain yield and low weed dry matter at 60 DAT. It was statistically on par with application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using knapsack sprayer, application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 150 g a.i ha-1 using drone, and application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using drone followed by application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 90 g a.i ha-1 using drone followed by unweeded control.

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.

Studies on Sesbania, rice residue mulching and post emergence herbicides on weed growth and yield in unpuddled transplanted hybrid rice

AbstractWeeds are a major threat in unpuddled transplanted rice during rainy seasons. To manage weeds by using Sesbania residue green mulch, rice straw mulch and post emergence herbicides in an integrated way, an experiment was conducted in a split plot at Varanasi during the rainy season of 2017 and 2018. The experiment was taken with three mulching treatments in main plots, namely, no mulching (NM), cover crop of Sesbania aculeatea followed by its green residue mulch (SRGM) and rice straw mulch (RRM) in inter rows and five weed management treatments, namely, weedy, hand weeding twice (HWT), post emergence application of bispyribac 25 g a.i ha−1 (BP), penoxsulam 30 g a.i ha−1 (PX), bispyribac 25 g a.i ha−1 + pyrazosulfuron 20 g a.i ha−1 (BP + PS) in subplots replicated thrice. SRGM and RRM were noted to be successful in reducing density and biomass of grasses including Echinochloa colona and sedges and total weed (59% and 49%) biomass compared to NM under weedy conditions. Mulching, integrated with post emergence herbicides proved its potency in not only weed reduction but is also in yield enhancement.

A follow‐up survey to assess stakeholders’ perspectives on weed management challenges and current practices in Nebraska, USA

AbstractStakeholders across the state of Nebraska, USA, were surveyed in 2019–2020 to assess problem weeds and weed management practices in agronomic crops. A total of 420 complete responses were obtained across four Nebraska districts (Northeast, Panhandle, Southeast, and West Central). Accumulated across the state, 65.5% of farmed or scouted crop ground in Nebraska was under no‐till production, with the major crops being corn and soybean representing 39.3% and 30.7% of agronomic crop production area, respectively. Palmer amaranth, horseweed, waterhemp, kochia, and giant ragweed were ranked the most problematic weeds. In a 2014–2015 survey, Palmer amaranth was the sixth most problematic weed. The most used preplant herbicides were 2,4‐D, glyphosate, and dicamba in the 2019–2020 survey. Atrazine applied alone or in mixture with acetochlor, bicyclopyrone, clopyralid, mesotrione, or S‐metolachlor were the most applied pre‐emergence (PRE) herbicides in corn, whereas the most applied PRE herbicides in soybean were metribuzin/sulfentrazone, flumioxazin/pyroxasulfone, and chloransulam‐methyl/sulfentrazone. Like the previous survey, glyphosate was the most frequent choice of survey respondents as a post‐emergence (POST) herbicide in glyphosate‐resistant corn and soybean, while 2,4‐D was the most applied POST herbicide in grain sorghum and wheat. Most of the respondents (77%) were aware of the new multiple herbicide‐resistant crops, and 86% listed physical drift and volatility of dicamba/2,4‐D as a primary concern. Twenty‐three percent of survey respondents identified integrated pest management as a primary research and extension priority for profitable agronomic crop production in Nebraska.

Effect of Weed Management Practices on Growth, Yield of Vegetable Cowpea (Vigna unguiculata (L.) Walp.) cv. Kashi Kanchan

The present investigation contains seven different treatments viz., weedy check (control), weed free check (3 hand weeding) (first hand weeding at 25 DAS), pre-emergence application of Pendimethalin @ 6ml/L, pre-emergence application of Pendimethalin @ 6ml/L + one hand weeding, pre- emergence application of Pendimethalin @ 6ml/L + post emergence @ 40-50 g/ha at 25 DAS, post-emergence application of Metribuzin @ 525g/ha at 25DAS and post-emergence spray of Imazethapyr @ 100 g ai/ha at 25 DAS replicated thrice. The cowpea variety ‘Kashi Kanchan’ was used in experiment. Results of the experiment revealed that though, the weed free check (T2) recorded zero weed population and slightly higher values of growth and yield parameters but among tested treatments, pre-emergence application of Pendimethalin @ 6ml/L + one hand weeding (T4) and pre-emergence application of Pendimethalin @ 6ml/L + Quizalofop ethyl @ 40-50 g/ha at 25 DAS(T5) significantly reduced weed number (48.12 and 52.18/m2) and produced significantly highest plant height (47.30 and 45.98 cm), pod length (21.64 and 20.86 cm), number of pods/plant (35.94 and 34.18), average pod weight(11.18 and 11.06 g), green pod weight/plant (367.84 and 348.63g), green pod weight/plot (11.24 and 10.54 kg) and green pod yield per hectare(118.96 and 111.55q). However, these three treatments (T2, T4 and T5) were statistically at par with each other in terms of growth and yield parameters.Hence, these two weed management practices (T4 and T5) may serve as alternative of manual weeding and may be recommended for farmers of the central plain zone of Uttar Pradesh for higher returns from vegetable cowpea crop.

Weed management in sunflower: A review on challenges and opportunities

Weed management is a science-based decision-making process that coordinates the use of macro andmicro-environment information, weed biology and ecology, and all available technologies to control weeds by the most economical and ecologically viable methods. The concept of weed management is not new and many advances have been made in recent years in India. Weeds compete with crop plants for nutrients, soil water, space and sunlight causing poor growth and yield losses. The extent of yield losses caused by weeds depends up weed density and type of weed flora. The age old practice of controlling weeds in sunflower by hand weeding and hoeing is time consuming, more expensive and tedious although it is more effective. However, timely weed management may not be possible manually due to non-availability of labourers and high rate of wages during peak farm operation. Under such condition, use of herbicides is the need of the hour for crop production. Therefore, use of newly introduced pre-emergence and post emergence herbicides along with cultural and mechanical methods is needed for effective weed management and increase the productivity of sunflower.

Impact of varying doses and application methods of metribuzin on productivity and profitability of wheat (Triticum aestivum) under different tillage systems

Addressing the imperative of aligning food production with the escalating global population necessitates the identification of sustainable land management strategies. In the Indo-Gangetic Plains of India, weed infestation causes a significant threat to wheat (Triticum aestivum L.) productivity. To address this concern, a field experiment was conducted during the winter (rabi) seasons of 2021–22 and 2022–23 at the research farm of CCS Haryana Agricultural University, Rice Research Station, Kaul, Haryana. The primary objective of this experiment was to assess the effects of varying doses and application methods of metribuzin on the productivity and profitability of wheat crop under zero and conventional tillage systems. Notably, the application of post-emergence (POE) metribuzin at a dose of 350 g/ha as a urea-mix broadcast at 35 days after sowing (DAS) in combination with pinoxaden (PDN) exhibited notablebenefits in terms of productivity and economic viability of wheat. This treatment yielded significantly higher number of effective tillers/mrl (111 in zero tillage; 112 in conventional tillage) and grain yield (5,573 kg/ha in zero tillage; 5,972 kg/ha in conventional tillage). Moreover, the treatment combination of metribuzin at 350 g/ha as a urea-mix broadcast and pinoxaden applied at 35 DAS resulted in the highest net returns and benefit-cost ratio under both tillage systems.

What Are the Most Efficacious Herbicides Applied Postemergence for Control of Multiple-Herbicide-Resistant Canada Fleabane [Conyza canadensis (L.) Cronq.] in Corn?

Multiple-herbicide-resistant (MHR) Canada fleabane [Conyza canadensis (L.) Cronq.] control has become a major concern for corn producers in Ontario. Postemergence (POST) herbicides are critical for the control of emerged MHR Canada fleabane in corn. A study that consisted of five field experiments was conducted in southwestern Ontario in fields with confirmed MHR Canada fleabane to evaluate various herbicide mixtures applied POST for the control of MHR Canada fleabane in corn. Glyphosate + 2,4-D amine, glyphosate/2,4-D choline, glyphosate + clopyralid, glyphosate + S-metolachlor/mesotrione/bicyclopyrone, glyphosate + tolpyralate + atrazine, glyphosate + dicamba, glyphosate + dicamba/atrazine, glyphosate + S-metolachlor/mesotrione/ atrazine, glyphosate + mesotrione + atrazine, glyphosate + bromoxynil + atrazine, glyphosate + S-metolachlor/ mesotrione/bicyclopyrone/atrazine, glyphosate/S-metolachlor/mesotrione + atrazine, glyphosate/dicamba + tembotrione, glyphosate + tembotrione + bromoxynil, glyphosate/dicamba + tembotrione + atrazine, and glyphosate + tembotrione + atrazine applied POST provided 63-99% control, 77-100% density reduction, and 88-100% shoot biomass reduction of MHR Canada fleabane in corn. MHR Canada fleabane interference reduced corn yield up to 58%; reduced MHR Canada fleabane interference with all herbicide treatments resulted in corn yield similar to the weed-free control. Results of this study indicate that among the herbicide mixtures evaluated glyphosate + mesotrione + atrazine, glyphosate + bromoxynil + atrazine, glyphosate + S-metolachlor/ mesotrione/bicyclopyrone/atrazine, glyphosate/S-metolachlor/mesotrione + atrazine, glyphosate/dicamba + tembotrione, glyphosate + tembotrione + bromoxynil, glyphosate/dicamba + tembotrione + atrazine, and glyphosate + tembotrione + atrazine applied POST provided the most consistent control of MHR Canada fleabane in corn.

Bio-efficacy of Sulfentrazone 39.6% SC against Weed Flora of Soybean

Inadequate weed control is one of the primary causes of a decrease in soybean production. Weeds compete for resources with crops (water, light and nutrients). This competition is especially important during the early stages of crop development, when production losses of up to 80 per cent are possible, and in extreme cases, harvest operations are hampered. As a result, the current study sought to identify an effective weed control practice in soybean.To assess the bio-efficacy of Sulfentrazone 39.6% SC as a post-emergent (PRE) herbicide for weed control in soybean. The experiment was laid in RCBD (Randomized complete Block Design). A field experiment was conducted at Agricultural Research Station, Bidar, University of Agricultural Sciences, Raichur, Karnataka, India during kharif seasons of 2019 and 2020. The study consisted seven treatments with three levels of Sulfentrazone as PRE (240, 360, and 480 g a.i ha-1), two check herbicides (Authority XL @ 360 g a.i. ha-1 and Pendimethalin @ 1 kg a.i ha-1as PRE), hand weeding twice at 20 and 40 days after sowing, and a weedy check replicated three times. Application of sulfentrazone 39.6%SC premergent herbicide significantly reduced weed density and dry biomass a during the critical period of crop-weed competition. Sulfentrazone 39.6% SC @ 360 g a.i. ha-1 (PRE) application resulted in significantly higher weed control efficiency (WCE), yield, and economics in soybean, which was comparable to Sulfentrazone 39.6% SC @ 480 g a.i. ha-1 (PRE) application. Hence, Application of sulfentrazone 39.6% SC @ 360 g a.i. ha-1 as pre emergent herbicide is advocated to the farmers in effective control of weeds.

Effect of Chemical and Non-Chemical Weed Management Practices in Direct Seeded Rice

A field experiment was conducted at Regional Research Station, Tamil Nadu Agricultural University, Paiyur, Tamil Nadu, India during the Summer of 2022 to study the effect of herbicide combination and non-chemical weed management techniques in puddled direct seeded rice. The experiment was laidout in a randomized block design with ten treatments and three replications. The treatments include Pre emergence (PE) Pyrazosulfuron ethyl 10% WP @ 20 g ha-1, Pyrazosulfuron ethyl 70% WDG @ 21 g ha-1, Post emergence (PoE) Bispyribac sodium 10% SC @ 25 g ha-1, Power weeder, Hand weeding (HW), Weed free and Weedy check. The results revealed that, among different weed control treatments, PE application of Pyrazosulfuron ethyl 10% WP @ 20 g ha-1 on 3 DAS fb (PoE) Bispyribac sodium 10% SC @ 25 g ha-1 on 20 DAS fb Power weeder at 30 DAS fb Hand weeding at 45 DAS (T5) recorded higher grain yield of 5422 kg ha-1 and B: C ratio of 2.35. The higher weed control efficiency of 83.52 % and 55.47 % was recorded at 30 and 60 DAS. Hence,it can be concluded that combination of PE (Pyrazosulfuron ethyl 10% WP @ 20 g ha-1 on 3 DAS) and POE (Bispyribac sodium 10% SC @ 25 g ha-1 on 20 DAS) herbicides along with non-chemical weed management technique (power weeder at 30 DAS and HW at 45 DAS) was found to be effective for weed control in direct seeded puddled lowland rice to deal with the issues of labour shortage and weed infestation faced by farmers.

An Integrated Effect of Weed Management in Blackgram

A field experiment was conducted at Wetlands farm, Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during summer season (March-June) of 2023, to study the effect of different weed management practices on weed flora, weed growth and yield of summer irrigated blackgram (VBN11). The field experiment was laid out in Randomized Block Design with nine treatments and three replications. Treatments comprised of power operated weeder at 15 DAS and 30 DAS with 40 × 7.5 cm and 45 × 7.5 cm plant spacing; pre-emergence application of pendimethalin 30% EC @ 1 kg ha-1 fb (followed by) power operated weeder at 20 DAS with 40 × 7.5 cm and 45 × 7.5 cm plant spacing; pre-emergence application of pendimethalin 30% EC @1 kg ha-1 fb early post emergence application of Imazethapyr @ 100 g ha-1 + Quizalofop-ethyl @ 50 g ha-1 (Tank mix) at 20 DAS with 40 × 7.5 cm plant spacing and 45 × 7.5 cm plant spacing; hand weeding at 20 DAS and 40 DAS with 30 × 10 cm plant spacing. The results revealed that among the various weed management practices, the weeds were effectively controlled by the pre-emergence application of pendimethalin 30 % EC @ 1 kg ha-1fb power weeder at 20 DAS with 40 × 7.5 cm plant spacing with significantly lower weed density, higher Weed Control Efficiency and higher grain yield (881 kg ha-1).

Norflurazon and metribuzin as components of postemergence tank mixtures with HPPD-inhibiting herbicides for multiple-resistant waterhemp control

Field and greenhouse studies investigated the phytoene desaturase (PDS) and photosystem II (PSII)-inhibiting herbicides, norflurazon and metribuzin, as components of two- and three-way postemergence (POST) tank mixtures for controlling multiple herbicide-resistant (MHR) waterhemp (Amaranthus tuberculatus). Studies were conducted at two locations (Champaign County, Illinois, U.S.A (CHR) and McLean County, Illinois, U.S.A. (MCR)) during 2019 and 2020. One of three commercial HPPD-inhibiting herbicides (mesotrione, tembotrione or topramezone) was added to a tank mixture with norflurazon, a reduced rate of metribuzin, or both to determine if greater MHR waterhemp control with tank mixtures could be achieved compared to individual herbicides and assess the potential benefit of norflurazon. Field results indicated the addition of norflurazon to HPPD-inhibiting herbicides resulted in greater waterhemp control (14% increase on average) compared to individual herbicides applied alone. Additionally, metribuzin in combination with HPPD-inhibiting herbicides consistently increased control of MHR waterhemp populations compared to the herbicides applied alone. However, only the three-way tank mixture containing tembotrione at the MCR site reduced biomass relative to two-way treatments containing tembotrione, metribuzin or norflurazon. Greenhouse experiments characterized mixtures of norflurazon with metribuzin and the HPPD-inhibiting herbicides, mesotrione and topramezone. Waterhemp biomass was significantly reduced when metribuzin and HPPD inhibitors were combined in comparison to individual components. Two-way tank mixtures containing norflurazon with mesotrione or metribuzin also resulted in significant biomass reductions compared to herbicides applied alone in MHR waterhemp. However, lower control levels were noted in MHR waterhemp when norflurazon was mixed with either topramezone or topramezone plus metribuzin compared to topramezone alone. In summary, norflurazon and metribuzin can be effective tank mixture components with HPPD-inhibiting herbicides for MHR waterhemp control. However, more research on these tank mixtures is warranted to optimize weed control and crop selectivity, which includes investigating active ingredient ratios, application timings and droplet spectrum effects on coverage.

Influence of Sowing Time and Weed Management Practices on the Performance and Weed Dynamics of Direct Drum Seeded Rice.

Direct drum seeding has emerged as a viable and alternate substitute to the current transplanted rice to address constraints of labor and water scarcity as well as rising cultivation costs. However, heavy weed infestation is the main biological factor leading to immense yield loss, which requires immediate attention. Therefore, adoption of efficient weed management practice is critical for the success and widespread adoption of direct seeded rice. In this regard, an experiment was laid out at the Faculty of Agriculture, Wadura, SKUAST of Kashmir, India, in Kharif seasons of 2018 and 2019 to assess the efficiency of direct seeded rice (DSR) under two sowing dates (D1: 10th May and D2: 3rd June) and six weed management strategies (W1: weedy check (untreated check), W2: four mechanized conoweedings at 15, 30, 45, and 60 DAS (days after sowing), equivalent to weed free (four conoweedings, equivalent to weed free), W3: bensulfuron-methyl + pretilachlor @ 60 and 600 g a.i. ha-1 as pre-emergence (BSM + pretilachlor, PE), W4: oxyfluorfen @ 750 g a.i. ha-1 as pre-emergence (oxyfluorfen, PE), W5: bensulfuron-methyl + pretilachlor @ 60 and 600 g a.i. ha-1 as pre-emergence followed by 2,4-D @ 0.75 kg a.i. ha-1 as post-emergence (30-35 DAS) (BSM + pretilachlor PE fb 2,4-D PoE), and W6: oxyfluorfen @ 750 g a.i. ha-1 as pre-emergence followed by 2,4-D @ 0.75 kg a.i. ha-1 as post-emergence (30-35 DAS) (oxyfluorfen PE fb 2,4-D PoE) on growth characteristics, productivity, weed infestation, and nutrient dynamics. The pooled results showed that 10th May sowing recorded significantly higher values of growth characteristics viz. plant height, dry matter production, tiller count, and yield characteristics, including panicle weight, panicle length, filled grains per panicle, and test weight, as compared to delayed sowing (3rd June). Earlier sowing (10th May) produced significantly higher grain yield (7.33 t ha-1) and straw yield (8.99 t ha-1) when compared to the delayed sowing (3rd June) which produced a grain yield of 6.08 t ha-1 and straw yield of 7.93 t ha-1. Among weed management strategies, four mechanized conoweeding at 15, 30, 45, and 60 DAS resulted in enhanced growth, yield characteristics, and yield but was statistically similar to bensulfuron-methyl (BSM) + pretilachlor PE fb 2,4-D post-emergence (PoE). Delayed sowing (3rd June; D2) recorded significantly higher weed density and dry-weed biomass as compared to earlier sowing (10th May; D1). Among the herbicides tested, sequential application of BSM + pretilachlor PE fb 2,4-D PoE proved an efficient weed management practice with a significantly reduced population and dry weight of weeds. Therefore, it was concluded that 10th May sowing with four mechanized conoweedings or sequential application of BSM + pretilachlor PE fb 2,4-D PoE is promising for improving productivity and efficient weed control in direct drum seeded rice under temperate Kashmir conditions.

Ethofumesate applied at greater than labeled rates postemergence to sugarbeet

AbstractEthofumesate is a broad-spectrum, soil-applied herbicide used to control broadleaf and grass weeds in sugarbeet crops. Ethofumesate is commonly applied preemergence at rates ranging from 1.25 to 4.2 kg ai ha−1, or applied postemergence (POST), up to 0.38 kg ai ha−1. The Generic Crop Science company has developed a new Ethofumesate 4SC label that has increased ethofumesate POST rates up to 4.48 kg ha−1 in sugarbeet with more than two true leaves per plant. Field and greenhouse experiments were conducted in 2018 and 2019 to evaluate sugarbeet tolerance and herbicide efficacy. Field tolerance experiments indicated sugarbeet stature from ethofumesate applied POST at 0.28, 0.56, and 1.12 kg ha−1 was the same as that of the nontreated control, but ethofumesate at 2.24 kg ha−1 reduced sugarbeet stature, although that rate did not affect yield components. Ethofumesate applied POST at 4.48 kg ha−1 reduced sugarbeet stature and affected sugarbeet yield components. Ethofumesate applied alone POST provided weed control of up to 85%, 76%, and 84% on common lambsquarters, redroot pigweed, and waterhemp, respectively, in field efficacy experiments. Mixing ethofumesate at 1.12 kg ha−1 with glyphosate does not provide a second effective herbicide for POST control of common lambsquarters or redroot pigweed, but it does provide residual control of these weeds when at least one-half inch of penetrating rainfall occurs, following application. In greenhouse experiments, ethofumesate alone or ethofumesate plus glyphosate applied to common lambsquarters, redroot pigweed, or waterhemp at heights of less than 2.5 cm provided the best combination of burndown and soil residual control compared with weeds that were 2.5 to 5 cm tall. Ethofumesate applied POST at 1.12 kg ha−1 plus glyphosate provided the best combination of tolerance and efficacy, especially on waterhemp.

Effect of Moisture Regimes and Weed Management Practices on Growth Indices under Drum Seeded Rice (Oryza sativa L.)

Afield experiment was conducted during Kharif season 2021 and 2022 at Agronomy research farm, Acharya Narendra Deva University of Agriculture and Technology Kumarganj, Ayodhya Uttar Pradesh, (India). The experiment was laid out in split plot design with thrice replications taking three moisture regime viz., 6 cm at 1 DADPW (Days after disappearance of ponded water); 6 cm at 4 DADPW (Days after disappearance of ponded water); 6 cm at 7 DADPW (Days after disappearance of ponded water)in main plot, and four weed management practices viz., control; Organic Mulch (Rice Straw @5t ha-1);Herbicide (Bispyribac sodium (10%) @ 200 ml ha-1 post Emergence) and two hand weeding at 25 and 45 DAS in sub plot. Results revealed that significantly higher crop growth rate, relative growth rate, absolute growth rate, net assimilation rate and grain yield was recorded in 6 cm at 4 DADPW (Days after disappearance of ponded water) during both the years of investigation. Among the weed management practices, higher value recorded with sequential two hand weeding at 25 and 45 days after sowing.