Postemergence Research Articles

Yield and Growth Attributes of Chia (Salvia hispanica L.) as Influenced by Weed Management Practices

Among all agronomical practices of crop cultivation, weed management is a necessary practice for any crop specially the chia being a newly introduced crop, it becomes necessary to study weed dynamics in the crop and find suitable weed management practice to obtain high seed yield and quality of the chia seed. A field experiment was conducted at research farm of Agricultural Research Station, Mandor, Agriculture University, Jodhpur during Rabi season of 2021-22 to find out efficacy of different herbicides on chia (Salvia hispanica L.) under western Rajasthan. The treatments comprised of herbicides namely bentazon 48% SL 500 g ha-1 and 750 g ha-1 (30 DAS as post emergence (PoE), fluazifop-p-butyl 11.1% SL 100 g ha-1 and 200 g ha-1 (30 DAS PoE), sulfentrazone 39.6% SC 50 g ha-1 and 75 g ha-1 as pre emergence (PE), pendimethalin 38.7% CS 200 g ha-1 and 400 g ha-1 (PE), weed free and weedy check were laid out in randomized block design with three replications. It was found that application of bentazon 48% SL 750 g ha-1 recorded significantly higher plant height (75.18 cm), total no. of branches plant-1 (18.16) and dry matter accumulation (82.23 g m-2), seed yield (495 kg ha-1), straw yield (197 kg ha-1), biomass yield (755 kg ha-1) and harvest index (65.56). Among pre-emergence herbicides, sulfentrazone 39.6% SC 75 g ha-1 and pendimethalin 38.7% CS 400 g ha-1 were found statistically equally effective in controlling weeds in chia.

Impact of Weed Management Strategies on Growth and Yield under Direct-Seeded Rice (Oryza sativa L.) in Eastern Uttar Pradesh, India

A field experiment was conducted during the Kharif 2022 at farm, Department of agronomy, Tilak Dhari Mahavidyalaya Jaunpur, Uttar Pradesh to evaluate the weed management in direct seeded rice. The experiment was laid out in randomized block design (RBD) with ten treatments including viz. three levels of Bispyribac sodium post-emergence (PoE), Butachlor pre-emergence (PE), Pendimethalin (PE), Pendimethalin (PE) followed by (fb)one hand weeding, Pretilachlor (PoE), two hand weeding, weed free and weedy and three replications for efficient weed management in direct seeded rice. Results of the experiment showed that growth attributes viz, (plant height, leaf area per plant, number of tillers m-1 and dry matter accumulation g plant-1) and yield of rice found maximum in treatment T9 i.e., weed free, over the rest of treatments. Whereas treatment T8-two hand weeding at 20 and 40 DAS, T7-pendimethalin1000 g a.i. ha-1 as PE fb one hand weeding at 40 DAS, T3- Bispyribac Sodium (10 SC) @ 30 g a.i. ha-1 as PoE 20 DAS were statistically at par to the treatment T9. Similarly, the highest number of tillers was found in T9 i.e., weed free, which was at par with two-hand weeding at 20 and 40 DAS, pendimethalin 1000 g a.i. ha-1 (PE), one-hand weeding at 40 DAS, and Bispyribac Sodium (10 SC) @ 30 g a.i. ha-1 as PoE 20 DAS. The study concludes that pendimethalin (1000 g a.i. ha⁻¹) followed by one hand weeding at 40 DAS, along with bispyribac sodium (30 g a.i. ha⁻¹), can be viable alternatives to manual weeding, ensuring effective weed control and higher rice yields in direct-seeded systems.

Flusulfinam, a novel amide herbicide to control weed in rice fields, targets 4-hydroxyphenylpyruvate dioxygenase.

Flusulfinam, a novel amide herbicide to control weed in rice fields, targets 4-hydroxyphenylpyruvate dioxygenase.

Effect of early and late post emergence herbicides on weed suppression, crop injury, and biomass yield of industrial hemp in semiarid conditions

Effect of early and late post emergence herbicides on weed suppression, crop injury, and biomass yield of industrial hemp in semiarid conditions

Impact of weed management practices on weed control efficiency and fibre quality in cotton under the high-density planting system

Cotton enjoyed the synonyms ‘White Gold,’ ‘King of Fibre Crops,’ and ‘Friendly Fibre’, playing a vital role as both a cash and fibre crop in India. However, weeds pose a major challenge, causing an approximate 45% yield reduction in cotton nationwide. Effective weed management is crucial for optimizing cotton yield and fibre quality. This study evaluated the impact of various weed management practices on productivity and fibre quality. Field trials were conducted using multiple treatments, including pre-and post-emergence herbicides, hand weeding, and power weeding. Fibre quality parameters, such as fibre length, strength, fineness, micronaire, and elongation percentage, were measured across treatments. While results showed no significant differences in fibre quality among the treatments, the combination of preemergence (PE) application of Pendimethalin at the rate of 1.0 kg active ingredient ha-1 + Metolachlor at the rate of 1.0 kg active ingredient ha-1 followed by post-emergence (POE) application of Pyrithiobac sodium at the rate of 0.075 kg active ingredient ha-1 + quizalofop ethyl at the rate of 0.075 kg active ingredient ha-1 emerged as the most effective weed control strategy.This treatment provided effective weed suppression, reduced competition for resources, and resulted in a higher seed cotton yield than other treatments. The study concluded that, although fibre quality did not vary significantly, the integrated use of Pendimethalin and Metolachlor as preemergence herbicides and Pyrithiobac sodium and quizalofop ethyl as post-emergence herbicides offers an optimal solution for cotton growers.

Effect of New Generation Herbicides on Weed Dynamics and Yield of Chickpea (Cicer arietinum L.)

The present research was conducted to study the differential doses and time applications of topramezone on weed dynamics and yield of chickpea (Cicer arietinum L.) at agronomical research farm of Trihut College of Agriculture, Dholi, Muzaffarpur (Bihar), during the rabi 2022-23. The experiment was carried out in an RBD design with three replications and twelve treatments: Pre-emergence (PE) application of oxyfluorfen (150 & 250 g/ha), post-emergence (PoE) application quizalofop-p-ethyl, propaquizafop (each 100 g/ha at 20 DAS), topramezone 20.6 g/ha (14 & 21 DAS) and 25.7 g/ha (21 DAS) applied. Among pre + post emergence applications oxyfluorfen (150 g/ha) fb quizalofop-p-ethyl (100 g/ha at 15-20 DAS), oxyfluorfen followed by propaquizafop (100 g/ha at 20 DAS) and oxyfluorfen fb topramezone (20.6 g/ha at 21 DAS) applied, along with the weed-free control (WFC) and weedy check. Among all the herbicidal treatments, the combination of oxyfluorfen at 150 g/ha followed by topramezone at 20.6 g/ha at 21 DAS (pre + post-emergence) recorded lowest weed dry matter and highest weed control efficiency (WCE) and crop yield.

Growth and Productivity Improvement of Chickpea (Cicer arietinum L.) through Weed Management by Topramezone

Background: Chickpea (Cicer arietinum L.) is the most important pulse crop widely cultivated for its nutritional and economic value. However, weed infestation poses a significant challenge to chickpea production, leading to reduced growth and productivity. Effective weed management strategies are therefore essential to mitigate the losses due to weeds and improve crop productivity. Selective herbicides with low or no phytotoxicity to the crop offer a promising solution for controlling weeds in order to boost up crop productivity. Currently available post emergence herbicides such as imazethapyr, can cause phytotoxic effects on chickpea. Therefore, it is essential to identify new post-emergence herbicides that can effectively control weeds without harming plant health. This study investigates the impact of topramezone, a selective post-emergence herbicide, on weeds as well as growth and productivity of chickpea. Methods: A field experiment was conducted at Agricultural Farm of Palli Siksha Bhavana, Visva-Bharati, Sriniketan during rabi season of 2021-22 and 2022-23. The experiment was laid out in randomized block design with nine treatments and three replications. The treatments were - T1 - topramezone 15 g ha-1 as POE, T2 - topramezone 17.5 g ha-1 as POE, T3 - topramezone 20 g ha-1 as POE, T4 - topramezone 22.5 g ha-1 as POE, T5 - topramezone 25 g ha-1 as POE, T6 - imazethapyr 60 g ha-1 as POE, T7 - pendimethalin 750 g ha-1 as PE, T8 - weed free and T9 - unweeded control. The study assessed the density and dry weight of weeds, weed control efficiency, growth and yield parameters as well as yield of chickpea under various application doses of topramezone in comparison with imazethapyr and pendimethalin. Result: Among all the herbicides, post-emergence application of topramezone 25 g ha-1 at 25 days after sowing resulted the lowest density and dry weight of weeds, the highest growth (plant height, LAI) and yield parameters (number of pods plant-1, number of seeds pod-1), seed yield and harvest index. Therefore, post-emergence application of topramezone 25 g ha-1 at 25 days after sowing proved to be an effective herbicide for weed control in chickpea in the lateritic belt of West Bengal.

Resistance Profile of Glufosinate-Resistant Palmer amaranth Accessions and Herbicide Options

Abstract Glufosinate resistance was previously confirmed in three Palmer amaranth accessions from Arkansas (MSR1, MSR2, and CCR). Greenhouse screening results suggested the presence of multiple herbicide resistance. Therefore, this study aimed to determine the postemergence resistance profile of three glufosinate-resistant Palmer amaranth accessions from Arkansas. Field experiments were also conducted to assess preemergence (PRE) and postemergence (POST) herbicide options to control the accession with the highest glufosinate resistance level (MSR2). A dose-response assay with the three resistant accessions and two susceptible standards was conducted with the herbicides 2,4-D, atrazine, dicamba, diuron, fomesafen, glyphosate, imazethapyr, and mesotrione. The PRE and POST field experiments with MSR2 evaluated fifteen and sixteen single active ingredients, respectively. The previously described Palmer amaranth accessions carrying glufosinate resistance were also confirmed resistant to six other POST herbicides: 2,4-D, diuron, fomesafen, glyphosate, imazethapyr, and mesotrione. CCR is also resistant to dicamba. Therefore, accessions MSR1, MSR2, and CCR have evolved resistance to POST herbicides pertaining to seven sites of action. A shift towards increased tolerance to atrazine has been observed among all resistant accessions as well. Overall, field PRE treatments with atrazine, pyroxasulfone, or trifludimoxazin obtained the highest MSR2 control levels at all evaluation times and the lowest number of seedlings emerging at 3 and 6 weeks after treatment. In the POST experiment, only paraquat obtained MSR2 control levels above 90% at all ratings. The lowest number of alive MSR2 plants was obtained in POST treatments with paraquat or trifludimoxazin. Fields near where glufosinate resistance has been confirmed in Palmer amaranth will likely demand a more diverse and proactive management strategy relying on combinations of chemical, cultural, and mechanical control tactics. Future efforts should focus on sequential applications and mixture, the elucidation of all resistance mechanisms in the evaluated accessions, and soil applied dose-response.

Management of weeds in summer maize (Zea mays L.) by pre and post emergence herbicides

Maize (Zea mays L.) is highly sensitive to weed infestation and management of weeds is the most difficult aspect of summer maize cultivation, leading to significant yield losses of maize fields. The lack of weed management in critical period of growth results in major losses. To address these issues, reducing actively growing weeds at various stages and improving the bio efficacy of herbicides is beneficial. In addition, due to the scarcity of farm labour and rising labour costs during crop growth, this study aims to investigate the impact of chemical weed management, specifically pre and post emergence herbicides, on maize. In this context, a study was conducted with 8 treatments viz., with 2 pre-emergence and 4 post emergence herbicides, as well as hand weeding and a weedy check (control), with each treatment replicated 3 times in randomized block design. The results revealed that weed density and weed dry matter were considerably lower and weed control efficiency was higher, with the application of Atrazine at 1 kg a.i. ha-1 as Pre-emergence (PEA). The highest treatment remained on par with Tembotrione + Atrazine (1:10) at 750 g a.i. ha-1 during 20 and 40 DAS as Post emergence (PoETA) compared to other treatments except for manual weeding (MW). The higher growth, yield attributes and grain yield were obtained with application of Atrazine at 1 kg a.i. ha-1 as Pre-emergence (PEA) application and the highest treatment was comparable with Tembotrione + Atrazine (1:10) at 750 g a.i. ha-1 during 20 and 40 DAS as Post emergence (PoETA) over other treatments. This paper relates to the SDG of UN 1, 2, 4 and 15.

P-1033. Post-transplant Outcomes in Kidney Transplant Recipients with Invasive Fungal Infections Prior vs. After the Emergence of SARS-CoV2

Abstract Background Invasive fungal infections (IFIs) are a serious complication in kidney transplant recipients (KTRs), leading to increased mortality and graft failure. Given changes in care associated with pandemic conditions and potential compounding effects of COVID-19 infection, we sought to determine whether the emergence of SARS-CoV2 contributed to a rise in adverse transplant outcomes associated with IFIs. Methods We performed a retrospective study of adult KTRs transplanted at Johns Hopkins from 2012-2018 with follow up through 5/2023. IFI diagnoses were based on EORTC/MSGERC criteria. If a patient had more than one IFI, the date of first IFI served as the index exposure. KTRs with and without IFIs were matched 1:1 on time-post-KT. We followed patients until all-cause graft loss (ACGL), a composite outcome of graft failure and mortality, and estimated cumulative incidence of ACGL prior vs. after emergence of SARS-CoV2 in 2/2020. We then determined whether the association between IFI and ACGL varied before vs during SARS-CoV2 pandemic using Cox regression with an interaction term and adjusting for age, transplant risk, and cardiovascular disease.Table 2.First post-transplant invasive fungal infection among kidney transplant recipients prior vs. post emergence of SARS-CoV2 Results Among 1453 KTRs, 79 (5.4%) had proven/probable IFIs of which 12 occurred after emergence of SARS-CoV2 (Table 1). Yeast caused the majority of IFIs (50/79) over the study period, but mold (5/12) and yeast (6/12) were equally represented among IFIs occurring after the emergence of SARS-CoV2 (Table 2). Prior to the pandemic, ACGL occurred in 66% (44/67) of KTRs with IFIs compared to 31% (414/1338) of KTRs without IFIs (log-rank p < 0.001). During the pandemic, ACGL occurred in 75% (9/12) of KTRs with IFIs compared to 31% of KTRs without IFIs (log-rank p < 0.001) (Fig 1). KTRs with IFIs had a 2-fold greater risk of ACGL (aHR 2.05, 95% CI 1.17-3.57, p = 0.012) prior to the pandemic and a 5.5-fold greater risk of ACGL (aHR 5.54, 95% CI 1.17-26.24, p < 0.01) during the pandemic. The risk of ACGL associated with IFIs was significantly different after the emergence of SARS-CoV2 (p-interaction term < 0.001; Fig 2).Figure 1.ACGL-free survival of KTR with IFIs vs. without IFIs Conclusion KTRs with IFIs had higher rates of ACGL during the pandemic, and molds constituted a greater proportion of the IFIs during the pandemic. The emergence of SARS-CoV2 seems to have shifted the epidemiology of IFIs among KTRs, leading to increased ACGL.Figure 2.ACGL-free survival of KTR with IFIs prior vs. after emergence of SARS-CoV2 Disclosures Nitipong Permpalung, MD, MPH, CareDx: Grant/Research Support|Cidara Therapeutics: Grant/Research Support|ClearView: Advisor/Consultant|IMMY Diagnostics: Grant/Research Support|Merck: Grant/Research Support|Pearl Diagnostics: Grant/Research Support|Pulmicide: Advisor/Consultant|Scynexis: Grant/Research Support

Morphological and DNA analysis of pollen grains on butterfly individuals reveal their flower visitation history.

Many butterfly species are conspicuous flower visitors. However, understanding their flower visitation patterns in natural habitats remains challenging due to the difficulty of tracking individual butterflies. Therefore, we aimed at establishing a protocol to solve the problem using the Common five-ring butterfly, Ypthima argus (Nymphalidae: Satyrinae). Focusing on the pollen grains attached the butterfly's body surface, we examined validities of two pollen analyses based on pollen morphology and DNA markers (ITS1 and ITS2), in addition to the classical route census method. We captured thirty-nine butterflies from mid-April to early July and collected pollen grains from each individual. Morphological and DNA analyses of collected pollens identified eighteen and thirty-four taxa of insect pollinated plants respectively, including woody plants such as Castanopsis. The DNA analysis detected as many as thirteen plant taxa from a single butterfly, indicating its high sensitivity for detecting flower visitation. We detected more plant taxa in May when many individuals were flying. This is assumingly related to the post emergence days of the butterflies with more foraging experience. We also found that fluctuations of pollen grain numbers of Leucanthemum vulgare and Erigeron philadelphicus on individual butterflies depend on their flowering periods overlapping partly. Consequently, we conclude that pollen morphology and DNA barcoding analysis, and field observations are mutually complementary techniques, providing an integrated pollen analysis method to study the pollination ecology of butterflies.

Postemergence giant ragweed management as affected by soil and cover crop management, soybean planting time, and preemergence herbicide application

Abstract Early soybean planting and cover crop adoption in the US Midwest prompt investigation into the impact of these practices on weed community dynamics and best management practices. While previous research has explored different aspects of giant ragweed control, the specific integration among soil management practices, including cover crop adoption, soybean planting timing, and herbicide use, has not been thoroughly investigated. This study assessed soil management, soybean planting time, and PRE herbicide application on giant ragweed control and soybean yield in Wisconsin and Nebraska in 2022 and 2023. The study included a factorial arrangement of four soil management treatments [conventional tillage, no-till, and fall-planted cereal rye early terminated and terminated at planting (planting green)]; two soybean planting times; and two PRE herbicide treatments (PRE and no PRE). Postemergence (POST) herbicides were applied when ∼50% of giant ragweed plants within each treatment reached ∼10 cm in height. In Nebraska, cereal rye and tillage treatments without a PRE had at least 67% lower giant ragweed density than no-till at POST. In no-till, densities were at least 60% lower with PRE compared to no PRE. In Wisconsin, cereal rye did not reduce giant ragweed density at POST compared to no-till, likely due to relatively low biomass accumulation. In contrast, delayed soybean planting reduced giant ragweed density for most treatments but lowered soybean yield in no-till and planting green treatments. The PRE herbicides had either no or positive effects on reducing giant ragweed density and increasing soybean yield. Overall, this study suggests that soil management and soybean planting timing are crucial for effective giant ragweed management in Wisconsin, where biotypes with a long emergence window during the spring and summer are present, while in Nebraska, soil management and soybean planting timing are less critical due to giant ragweed biotypes with an early and short emergence window in the spring.

Soil Residual Activity of Tetflupyrolimet and the Influence of Soil Moisture and Flood Timeliness on Barnyardgrass Efficacy

ABSTRACT Tetflupyrolimet is the first herbicide with a novel site of action to be commercialized for use in agronomic crops in three decades. Direct-seed rice field experiments were conducted at research facilities near Stuttgart (silt loam), AR, and Keiser (clay), AR, to evaluate tetflupyrolimet as a preemergence herbicide versus commercial standards. Greenhouse experiments determined the influence of soil moisture on pre- and postemergence (POST) barnyardgrass control with tetflupyrolimet and clomazone, and the impact of a delayed flood on efficacy when POST-applied. For the field experiments, clomazone, tetflupyrolimet, and quinclorac were applied individually PRE at 336 and 560, 134 and 224, and 336 and 560 g ai ha-1, respectively, on a silt loam and clay soil, along with clomazone plus tetflupyrolimet and clomazone plus quinclorac at the same rates. The soil moisture experiment included a single PRE and POST application of clomazone at 336 g ai ha-1, tetflupyrolimet at 134 g ai ha-1, and a mixture at the respective rates, on a silt loam soil at 50, 75, and 100% of field capacity. For the flood timing experiment, tetflupyrolimet was applied to 2- to 3-leaf barnyardgrass at 134 g ai ha-1, and a flood was established at 4 hr after treatment (HAT) and 5 and 10 d after treatment (DAT). Barnyardgrass control with a tetflupyrolimet and clomazone mixture was comparable to clomazone plus quinclorac when averaged over all evaluations on silt loam and clay texture soils (≥91%). Soil moisture interacted with herbicide treatments for PRE and POST barnyardgrass efficacy when averaged over DAT, with tetflupyrolimet plus clomazone generally providing the greatest and most consistent control across regimes. Flooding barnyardgrass at 4 HAT provided superior control to later flood timings. Tetflupyrolimet is an effective residual barnyardgrass herbicide, and the addition of clomazone will aid in providing consistent control across varying soil moisture conditions.

Tolerance of Cotton to Herbicide-Coated Fertilizers

Abstract Cotton producers need residual herbicides that can safely and practically be applied postemergence (POST). Herbicide-coated fertilizers could allow for simultaneous application of residual herbicides and a bulk fertilizer blend. Therefore, a study was conducted in 2022 and 2023 in Fayetteville, AR, to evaluate cotton tolerance to 12 herbicide treatments coated onto a fertilizer blend and applied over cotton. Herbicides and rates evaluated included: diuron at 840 g ai ha-1, florpyrauxifen-benzyl at 29 g ai ha-1, flumioxazin at 105 g ai ha-1, flumioxazin plus pyroxasulfone at 70 + 90 g ai ha-1, fluridone at 168 g ai ha-1, fluometuron at 840 g ai ha-1, fomesafen at 280 g ai ha-1, pyroxasulfone at 128 g ai ha-1, saflufenacil at 66 g ai ha-1, saflufenacil plus dimethenamid-P at 25 + 219 g ai ha-1, saflufenacil plus pyroxasulfone at 44 + 91 g ai ha-1, and S-metolachlor at 1388 g ai ha-1. In both years, fluridone, fluometuron, diuron, and S-metolachlor caused less than 10% injury at 7 d after treatment (DAT). Higher injury levels were observed in 2022 (19 to 30%) compared to 2023 (4 to 12%) for flumioxazin, fomesafen, saflufenacil, saflufenacil plus dimethenamid-P, and saflufenacil plus pyroxasulfone. The elevated injury in one of two years was attributed to the presence of dew when the herbicide-coated fertilizer was applied. The initial injury was transient, as the cotton generally had recovered by 28 DAT for all herbicides. No differences in seed cotton yield or groundcover among the herbicide treatments occurred either year. These results highlight the potential of using several POST-applied, residual herbicides coated on fertilizer that are not currently registered for over-the-top use in cotton.

Optimizing Pyroxasulfone-Coated Fertilizer in Cotton

Abstract Two studies were conducted in 2022 and 2023 near Rocky Mount and Clayton, NC, to determine the optimal granular ammonium sulfate (AMS) rate and application timing for pyroxasulfone-coated AMS. In the rate study, AMS rates included 161, 214, 267, 321, 374, 428, and 481 kg ha-1, equivalent to 34, 45, 56, 67, 79, 90, and 101 kg N ha-1, respectively. All rates were coated with pyroxasulfone at 118 g ai ha-1 and top-dressed onto 5- to 7-leaf cotton. In the timing study, pyroxasulfone (118 g ai ha-1) was coated on AMS and top-dressed at 321 kg ha-1 (67 kg N ha-1) onto 5- to 7-leaf, 9- to 11-leaf, and first bloom cotton. In both studies, weed control and cotton tolerance to pyroxasulfone-coated AMS was compared to pyroxasulfone applied postemergence (POST) and postemergence-directed (POST-directed). The check in both studies received non-herbicide-treated AMS (321 kg ha-1). Before treatment applications, all plots (including the check) were maintained weed-free with glyphosate and glufosinate. In both studies, pyroxasulfone applied POST was most injurious (8 to 16%), while pyroxasulfone-coated AMS resulted in ≤ 4% injury. Additionally, no differences in cotton lint yield were observed in both studies. With the exception of the lowest rate of AMS (161 kg ha-1; 79%), all AMS rates coated with pyroxasulfone controlled Palmer amaranth ≥ 83%, comparable to pyroxasulfone applied POST (92%) and POST-directed (89%). In the timing study, the application method did not affect Palmer amaranth control; however, applications made at the mid- and late timings outperformed early applications. These results indicate pyroxasulfone-coated AMS can control Palmer amaranth comparable to pyroxasulfone applied POST and POST-directed, with minimal risk of cotton injury. However, the application timing could warrant additional treatment to achieve adequate late-season weed control.

Confirmation of glyphosate-resistant waterhemp (Amaranthus tuberculatus) in New York

Abstract Waterhemp has become a serious management challenge for New York (NY) field crop growers. Two putative glyphosate-resistant (GR) waterhemp populations (NY1 and NY2) were collected in 2023 from two soybean fields in Seneca County, NY. The objectives of this research were to (1) confirm and characterize the level of glyphosate resistance in waterhemp populations from NY relative to a known glyphosate-susceptible Nebraska (NE_SUS) population and (2) evaluate the efficacy of various postemergence (POST) herbicides for GR waterhemp control. Based on the shoot dry weight reductions (GR50 values) in a dose-response study, the NY1 and NY2 populations exhibited 5.6- to 8.3-fold resistance to glyphosate compared with the NE_SUS population. In a separate study, POST herbicides such as dicamba, glufosinate, lactofen, and 2,4-D applied alone or in a mixture with glyphosate or glufosinate had provided 89% to 99% control and ≥ 97% shoot dry weight reduction of NY1 and NY2 populations 21 days after treatment (DAT). Greater than 98% control of the NE_SUS population was achieved with tested POST herbicides, except mesotrione (62% control). Furthermore, atrazine, chlorimuron + thifensulfuron, and mesotrione were the least effective in controlling NY1 and NY2 populations (42% to 59% control and 50% to 67% shoot dry weight reductions, respectively). These results confirm the first report of GR waterhemp in NY. Growers should adopt effective alternative POST herbicides tested in this study to manage GR waterhemp.

Efficacy of pre and post emergence herbicides on diverse weed flora of direct seeded rice

A field experiment was conducted during kharif (Rainy) season of 2023 at Crop Research Farm, SHUATS. The treatments consisted of pre emergence application of Pendimethalin at 0.75 and 1.0 kg/ha in combination with hand weeding, pre - emergence application of pretalachlor at 0.40 and 0.75 kg/ha in combination with hand weeding, pre - emergence application of pendimethalin at 0.75 and 1.0 kg/ha, pre emergence application of pretalachlor at 0.40 kg/ha and 0.75 kg/ha in combination with post - emergence application of bispyribac sodium at 0.025 kg/ha, hand weeding and weedy check (control). Next to hand weeding preemergence application of pendimethalin at 1.0 kg/ha in combination with hand weeding recorded highest weed control efficiency(76.97%), effective tillers (185.53) and yield attributes namely more no. of grains/ panicle(108.40) and grain yield (5.98t/ha).

Sequential application of different pre and post emergence herbicides for weed management in Bt cotton

Sequential application of different pre and post emergence herbicides for weed management in Bt cotton

Performance of pre and post emergence herbicides on weed dynamics, yield and productivity of boro rice in red and lateritic soil of West Bengal

The effect of herbicides on weed suppression, crop growth and yield in transplanted rice were evaluated in at Agricultural Farm of Palli Siksha Bhavana, Visva-Bharati, Sriniketan during boro season of 2018 and 2019. Eight different weed management treatments comprised of pretilachlor 50 EC @ 500 g ha-1 and pyrazosulfuron ethyl 10 WP @ 30 g ha-1 as pre- emergence; ethoxysulfuron 15 WDG @ 15 g ha-1 and penoxsulam 21.7 SC @ 22.5 g ha-1 as early post emergence, bispyribac-sodium 10 SC @ 25 g ha-1 as post emergence, hand weeding at 20 and 40 DAT, weed free check and weedy check. Results revealed that pyrazosulfuron ethyl 30 at g ha-1 and pretilachlor at 500 g ha-1 resulted lower population and dry matter accumulation of weeds as well as increased plant height, dry matter accumulation, leaf area index and grain yield (6.09 and 5.99 t ha-1 in 2018 and 5.86 and 5.63 t ha-1 in 2019, respectively). Pretilachlor at 500 g ha-1 and pyrazosulfuron ethyl 30 at g ha-1 increased grain yield over other herbicidal treatments in both the years. The maximum loss of grain yield due to unrestrained weeds in transplanted summer rice was 55.85% and 52.3% in 2018 and 2019, respectively. Hand weeding done at 20 and 40 DAT also controlled weeds efficiently but recorded lower net return and return per rupee invested than pyrazosulfuron ethyl 30 at g ha-1 and pretilachlor at 500 g ha-1 where net return was higher (Rs. 94425 ha-1 and Rs. 92909 ha-1 in 2018; and Rs. 91206 ha-1 and Rs. 86926 ha-1 in 2019, respectively) and return per rupee invested (Rs. 3.64 and Rs. 3.63 in 2018; and Rs. 3.40 and Rs. 3.32 in 2019, respectively).

Evaluating Tillage Practices and Herbicide Applications for Improved Rice Yield and Weed Control

Weed infestation, water scarcity and intensive tillage practices are resulting in low yield of rice crop. Direct seeded rice (DSR) and alternate wetting and drying (AWD) have emerged as alternative and resource efficient rice production methods. A field experiment was conducted to study the effect of weed control methods on weed management in rice under different tillage practices at research field of Department of Agronomy, Faculty of Agricultural Sciences, University of the Punjab, Lahore during rice growing season in 2022. The experiment was carried out in two factorials randomized completely block design (RCBD) with three replications. First factor had four tillage practices [Puddling; Alternate wetting and drying; Direct seeded rice (Drill sowing) and direct seeded rice (Broadcast sowing)] and second factor had four weed control treatments [Control; Pre-emergence weed control (Pendimethalin 33 % EC @ 1000 g a.i. ha-1; Post-emergence weed control (Bispyribac sodium (18 % w/w) + Bensulfuron methyl (12 % w/w) @0.15 a.i. Kg ha-1 and combination of pre+ post emergence weed control]. In the experiment, 12 weed species from 7 families were observed as part of the weed flora. Among them 6 were grasses, 1 sedge and 5 broadleaf weeds. Under AWD, a combination of pre- and post-emergence herbicide spraying resulted in the greatest weed species reduction (14.34/m2). Herbicides applied as pre+ post emergence produced the highest grain production (7.60 t ha-1) under puddling and it was statistically similar to grain yield acquired in application of pre-emergence weed control under AWD. In direct seeded rice highest grain yield (6.02 t ha-1) was produced by application of both pre+ post emergence herbicides under broadcast sowing. The potential yield loss was higher in drill sowing when no herbicide was used or only post- emergence herbicide was applied. AWD is found most promising technology with respect to production and resource conservation.