Cyhalofop Butyl Research Articles

A comparative study of drone and manual herbicide application for weed management in wet direct-seeded rice (Oryza sativa L.)

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, during the Navarai season (January-April) of 2024 to assess the efficiency of drone-based herbicide application in terms of weed control, energy use, and cost effectiveness in wet direct-seeded rice (Oryza sativa L.). The study compared the effectiveness of weed control using herbicide combinations applied as pre-emergence followed by early post-emergence, with both drone and knapsack sprayer. The treatments included the application of pretilachlor followed by early post-emergence bispyribac sodium, and pyrazosulfuron followed by penoxsulam + cyhalofop butyl, using both drone and knapsack sprayer. Additionally, weed-free and unweeded control plots were included. Results indicated that the application of pretilachlor followed by bispyribac sodium using a drone sprayer significantly reduced weed density and weed dry weight compared to the unweeded plot. This treatment also resulted in a higher grain yield (5286 kg ha-1). Moreover, drone application of pretilachlor followed by bispyribac sodium provided a higher net return (? 51631/ha), benefit-cost ratio (2.17), energy-use efficiency (9.53), and energy productivity (0.30 kg/MJ). The experiment concluded that drone-based spraying of pretilachlor followed by bispyribac sodium is an effective weed management strategy for wet direct-seeded rice, offering superior yield attributes, energy use efficiency, and profitability.

Growth, nutrient uptake and yield ofdirect seeded rice as influenced by weed management practices

A field experiment was conducted during the rainy (Kharif) seasons of 2018 and 2019 at the Kerala Agricultural University, Kerala, to evaluate the effect of herbicides and herbicide combinations on the weed management and growth, nutrient uptake and yield of direct seeded rice (DSR). The experiment was laid out in a randomized block design with three replications. Nine weed control treatments were used, including sole application of three herbicides (cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha, fenoxaprop-p-ethyl@ 60 g/ha), five herbicidal combinations (penoxsulam + cyhalofop butyl commercial formulation @ 150 g/ha, cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha, bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and stale seedbed followed by (fb) glyphosate @ 800 g/ha + oxyfluorfen @ 150 g/ha at 15-20 days after land preparation + cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha), and hand weeding twice at 20 and 40 days after sowing. Weeds removed 27.72, 4.61 and 67.95 kg of N, P and K/ha respectively at 45 days after treatment application (DATA) under unweeded conditions in direct seeded rice. Herbicidal treatments enhanced grain yield by 23.89 to 58.84 % and herbicide combinations increased grain yield by 56 to 59 % compared to the unweeded control in direct seeded rice. Tank mix combination of bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha and premix combination of penoxsulam + cyhalofop butyl @ 150 g/ha recorded higher nutrient uptake and grain yields (5.03, 4.76 and 4.79 t/ha, respectively) and were on par to hand weeding twice. Unweeded control recorded the lowest pooled grain yield (2.07 t/ha) and uncontrolled weed competition resulted in 59.95 % reduction in grain yield. Keywords: Crop competition, Herbicide combinations, Herbicide interactions, Nutrient removal, Nutrient uptake, Yield reduction

Weed management options in drum seeded wetland rice

High labour requirement and cost for raising nursery and transplanting of the seedlings has necessitated the shift from transplanted rice to direct-seeded rice. To reduce the requirement of large quantity of seeds, incidence of pests and diseases in broadcasting and to ensure uniform seed distribution for consistent crop growth and easier maintenance, mechanization is needed in direct-seeded rice. The major constraint experienced in wet DSR is the occurrence of high weed infestation as emerging seedlings in direct-sown fields are less competitive with concurrently emerging weeds. An experiment was conducted at M. S. Swaminathan Rice Research Station, Moncompu, Kerala Agricultural University during kharif and rabi 2021-22, with eight treatments and three replications in randomised complete block design to identify suitable cost-effective agronomic management practices to enhance the productivity of drum seeded rice and to maximise its resource-use-efficiency. The results revealed wet DSR using drumseeder as a viable crop establishment method for reducing the seed requirement, cultivation time, energy, cost of cultivation, pest and disease infestation, minimise plant stress due to transplanting and sustaining yield. There was significant variation in the yield and yield attributes in drum seeding depending on the weed management strategies adopted viz., two conoweedings, post emergent herbicide application, pre followed by post emergent herbicide application, post emergent herbicide application followed by conoweeding. Post-emergence application of Chlorimuron ethyl + Metsulfuron methyl @ 0.004 kg/ha and Penoxsulam + Cyhalofop butyl @ 0.135 kg/ha as tank mix at 18 DAS followed by conoweeding at 30 DAS was found economical in drum seeding which was on par yield with broadcasted crop yield under post emergent herbicide application.

Efficient Biodegradation of Multiple Aryloxyphenoxypropionate Herbicides by Corynebacterium sp. Z-1 and the Proposed Degradation Mechanism.

Esterases are crucial for aryloxyphenoxypropionate herbicide (AOPP) biodegradation. However, the underlying molecular mechanisms of AOPP biodegradation by esterases are poorly understood. In the current work, Corynebacterium sp. Z-1 was isolated and found to degrade multiple AOPPs, including quizalofop-p-ethyl (QPE), haloxyfop-p-methyl (HPM), fenoxaprop-p-ethyl (FPE), cyhalofop-butyl (CYB), and clodinafop-propargyl (CFP). A novel esterase, QfeH, which catalyzes the cleavage of ester bonds in AOPPs to form AOPP acids, was identified from strain Z-1. The catalytic activities of QfeH toward AOPPs decreased in the following order: CFP > FPE > CYB > QPE > HPM. Molecular docking, computational analyses, and site-directed mutagenesis indicated the catalytic mechanisms of QfeH-mediated degradation of different AOPPs. Notably, the key residue S159 is essential for the activity of QfeH. Moreover, V222Y, T227M, T227A, A271R, and M275K mutants, exhibiting 2.9-5.0 times greater activity than QfeH, were constructed. This study facilitates the mechanistic understanding of AOPPs bioremediation by esterases.

Life cycle assessment of hepatotoxicity induced by cyhalofop-butyl in environmental concentrations on zebrafish in light of gut-liver axis

Cyhalofop-butyl (CB) poses a significant threat to aquatic organisms, but there is a discrepancy in evidence about hepatotoxicity after prolonged exposure to environmental levels. The aim of this study was to investigate long-term hepatotoxicity and its effects on the gut-liver axis through the exposure of zebrafish to environmental concentrations of CB (0.1,1,10 μg/L) throughout their life cycle. Zebrafish experienced abnormal obesity symptoms and organ index after a prolonged exposure of 120 days. The gut-liver axis was found to be damaged both morphologically and functionally through an analysis of histology, electron microscopy subcellular structure, and liver function. The disruption of the gut-liver axis inflammatory process by CB is suggested by the rise in inflammatory factors and the alteration of inflammatory genes. Furthermore, there was a noticeable alteration in the blood and gut-liver axis biochemical parameters as well as gene expression linked to lipid metabolism, which may led to an imbalance in the gut flora. In conclusion, the connection between the gut-liver axis, intestinal microbiota, and liver leads to the metabolic dysfunction of zebrafish exposed to long-term ambient concentrations of CB, and damaged immune system and liver lipid metabolism. This study gives another knowledge into the hepatotoxicity component of long haul openness to ecological centralization of CB, and might be useful to assess the potential natural and wellbeing dangers of aryloxyphenoxypropionate herbicides.

Enhanced Herbicide Metabolism and Target Site Mutation Enabled the Multiple Resistance to Cyhalofop-butyl, Florpyrauxifen-benzyl, and Penoxsulam in Echinochloa crus-galli.

This study investigated the multiple herbicide resistance (MHR) mechanism of one Echinochloa crus-galli population that was resistant to florpyrauxifen-benzyl (FPB), cyhalofop-butyl (CHB), and penoxsulam (PEX). This population carried an Ala-122-Asn mutation in the acetolactate synthase (ALS) gene but no mutation in acetyl-CoA carboxylase (ACCase) and transport inhibitor response1 (TIR1) genes. The metabolism rate of PEX was 2-fold higher, and the production of florpyrauxifen-acid and cyhalofop-acid was lower in the resistant population. Malathion and 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) could reverse the resistance, suggesting that cytochrome P450 (CYP450) and glutathione S-transferase (GST) contribute to the enhanced metabolism. According to RNA-seq and qRT-PCR validation, two CYP450 genes (CYP71C42 and CYP71D55), one GST gene (GSTT2), two glycosyltransferase genes (rhamnosyltransferase 1 and IAAGLU), and two ABC transporter genes (ABCG1 and ABCG25) were induced by CHB, FPB, and PEX in the resistant population. This study revealed that the target mutant and enhanced metabolism were involved in the MHR mechanism in E. crus-galli.

Yield, Yield Attributes and Weed Biomass of Rice (Oryza sativa L) as Influenced by Weed Control Treatments

The present investigation was conducted during the Kharif of 2019 at Research cum Instructional Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh. The experiment was laid out in randomized complete block design (RCBD) with three replications and ten weed management treatments viz. Pretilachlor (PE )750 g ha-1 , BispyribacNa (PoE ) 25 g ha-1 , Fenoxaprop-p-ethy (PoE) l 56.25 g ha-1 , Cyhalofop-buty (PoE ) l 80 g ha-1 ,Penoxsulam+ Cyhalofop butyl (PoE ) 135 g ha-1, Penoxsulam(PoE ) 22.5 g ha-1 , Metsulfuronmethy ( early PoE ) l 4 g ha-1 , 2,4-D Ethyl Ester (PoE ) 750 g ha-1 ), weed free (HW) , at 20, 40 and 60 days after sowing and weedy check . Result was found that among the weed management treatments, the weed free treatment registered significantly highest value and was at par the application of Penoxsulam+ Cyhalofop butyl 135 g ha-1 , yield attributing characters, grain and straw yield and dry matter of Alternanthera sessilis it was found the lowest value in the application of Penoxsulam+ Cyhalofop butyl 135 g ha-1 (T5).

Effect of water regimes and weed-management practices on growth, yield and weed-control efficiency of rice under system of rice intensification

A field experiment was conducted during the rainy (kharif) seasons of 2012 and 2013 at Khudwani, Jammu and Kashmir, to evaluate the effect of water regimes and weed-management practices on growth and yield of rice (Oryza sativa L.) grown on silty clay loam soil. The treatments comprised 3 irrigations schedules, viz. alternate wetting and drying (AWD), saturated conditions (SC) and continuous flooding (FL), and 7 weed-management op tions including 4 herbicidal treatments, viz. pyrazosulfuron ethyl @ 20 g/ha at 3 days after transplanting (DAT, W1 ); cyhalofop butyl @ 80 g/ha at 15 DAT (W2 ); pyrazosulfuron ethyl 20 g followed by (fb) cyhalofop butyl 80 g/ha at 3 and 15 DAT (W3 ); butachlor @ 1.5 kg/ha at 3 DAT (W4 ); 3 cono weeding at 15, 25 and 35 DAT (W5 ) along with weedy check (W6 ) and weed free (W7 ). The experiment was laid out in a split-plot design with 3 replications under SRI. The data revealed that significant higher growth parameters like leaf-area index (LAI), dry-matter accumula tion and tillers/plant and yield attributes, i.e. panicle length, panicles/m2, grains/panicle, panicle weight, grains/ panicles, 1,000-grain weight, and higher grain yield were recorded in saturated water regime. On an average a yield superiority of 2.2 and 5.8% was recorded by saturated water regime over AWD and continuous flooding. Among the herbicides tested, pyrazosulfuron-ethyl @ 20 g/ha (3 DAT) fb cyhalofop-butyl @ 80 g/ha (15 DAT) re sulted in significantly higher panicle length, panicles/m2, panicle weight, grains/panicles, 1,000-grain weight and higher grain yield comparable to the weedy check. The mean yield advantage recorded by the use of pyrazosulfuron-ethyl fb cyhalofop-butyl was 19.3, 14.0 and 10.3% over cyhalofop-butyl, cono-weeding and butachlor, respectively, during both the years of experimentation.

Productivity of Dry Direct Seeded Rice as Influenced by Herbicide Combinations

A field experiment was conducted during Kharif, 2022, in Institute of Rice Research, Rajendranagar, Hyderabad in Telangana state, India. Fourteen weed management practices were evaluated in a randomized complete block design, replicated thrice. Weed management in Dry DSR can be done by adopting mechanical/ Hand weeding at 20, 40, 60 DAS under labour available conditions. Under labour scarcity conditions PE application of Pendimethalin 38.4% + Pyrazosulfuron ethyl 0.85% ZC 900 + 20 g/ha (Ready mix) followed by Metsulfuron Methyl 10% + Chlorimuron ethyl 10% WP 4 g/ha + Cyhalofop Butyl 10% EC 75g/ha (Tank mix) PoE weed followed by mechanical weeding at 40-45 DAS is the best option. Other suitable Pre emergence herbicides that can be used are Pyrazosulfuron ethyl 10% WP 20 g/ha, Pendimethalin 38.4% + Pyrazosulfuron ethyl 0.85% ZC 900 + 20 g/ha (Ready mix) and Pendimethalin 38.7 % CS 677.25 g/ha. Post emergence application of Triafamone 20% + Ethoxysulfuron l0% WG 44+22.5 g/ha (Ready mix) and Penoxsulam 1.02 % + Cyhalofop-butyl 5.1% OD 135 g/ha (Ready mix) at 2-4 weed leaf stage.

Evaluation of different weed management practices on growth and yield of transplanted rice (Oryza sativa L.) in Northeastern Zone of Tamil Nadu

Weeds cause a 57 per cent yield loss in transplanted rice and an 82 per cent yield loss in direct seeded rice, resulting in a $4.20 billion monetary loss per year. Weed infestation, species richness, density, dry matter accumulation and duration of association significantly affects rice grain production. Therefore, a field experiment was conducted in farmer’s field in Thiruvennainallur village, Villupuram District, Tamil Nadu, India during Navarai season of 2021, in order to evaluate the different weed management practices on growth and yield of rice under transplanted conditions. The experiment was laid out in a randomized block design, having fourteen treatment and replicated thrice. Treatment consists of hand weeding, butachlor, pretilachlor, pyrazosulfuron ethyl, bispyribac sodium, fenoxaprop-p-ethyl, Triafamone + ethoxy sulfuron, metsulfuron methyl + chlorimuron ethyl and penoxsulam + cyhalofop butyl were used as herbicides. Among the different herbicides tried out, pre emergence application of pyrazosulfuron ethyl 10% WP @ 0.15 g/ha fb post emergence application of bispyribac sodium 10% SC @ 0.25 l/ha recorded least weed density (15.55, 29.56 m-2), weed biomass (8.25, 16.02 g/m2) with weed index (2.18 %) and highest weed control index (89.22%, 85.18%), plant height (97.21 cm), dry matter production (12735 kg/ha), number of productive tillers/m2 (349.23), grain yield (6416 kg/ha) and straw yield (7839 kg/ha). Sequential application of pre-emergence followed by post emergence enhance the reduction of weed leads to higher productivity of transplanted rice.

Propyrisulfuron plus cyhalofop butyl as one-shot herbicides provide high weed control efficiency and net economic performance in mechanically transplanted rice.

Propyrisulfuron is a novel pyrimidinylsulfonylurea herbicide with good activity for controlling annual weed in rice fields. To evaluate the economic performance of propyrisulfuron, a field study was conducted in 2021 and 2022 on a farm of the Jiangsu Academy of Agricultural Sciences, China. Eight different herbicide treatments were employed, including CB (cyhalofop butyl), Py (propyrisulfuron), CBPy (cyhalofop butyl plus propyrisulfuron), PrBe 3, PrBe 10, and PrBe 3+PrBe 10 (pretilachlor plus bensulfuron applied at different times [at 3 (PrBe 3) and 10 (PrBe 10) d] or sequentially, respectively), 2PrBe+PeCBBz (pretilachlor plus bensulfuron [applied sequentially] followed by penoxsulam plus cyhalofop butyl plus bentazone), 2PrBe+MeCBBz (pretilachlor plus bensulfuron [applied sequentially] followed by metamifop plus cyhalofop butyl plus bentazone), along with weed-free and nontreated weedy check treatments. Herbicide treatments did not cause visual phytotoxicity to rice, and bending and leaf rolling were not observed. Only the two propyrisulfuron treatments had temporary negative effects on rice height, but rice recovered quickly. Compared with the weed-free treatment, CBPy did not affect rice tiller number or dry matter accumulation. Compared with the nontreated weedy check, herbicide treatments reduced total weed density by 29.4% to 99.1% and dry biomass by 32.2% to 98.7%. The CBPy treatment provided the best weed control, reducing weed density and biomass by 96.7% and 95.9% in 2021 and 97.4% and 95.6% in 2022, respectively. Rice grain yield was not significantly different between CBPy and the weed-free treatment in either year. Economic analysis showed that CBPy provided the highest net profit, followed by that in 2PrBe+PeCBBz and 2PrBe+MeCBBz, with the lowest net profit in the nontreated weedy check. Thus, CBPy provides good weed control and could be promoted in mechanically transplanted rice fields in China.

Current status of cyhalofop-butyl and metamifop resistance and diversity of the ACCase gene mutations in Chinese sprangletop (Leptochloa chinensis) from China

Leptochloa chinensis populations in China have evolved widespread resistance to acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicides cyhalofop-butyl (CyB) and metamifop (Met). 124 L. chinensis populations, randomly collected from rice fields in Jiangsu Province, were surveyed for CyB and Met resistance status, and all potential ACCase gene resistance-conferring mutations and effective pre-emergence herbicides for its control were investigated. Single-dose tests confirmed that 82 (66.1%) and 70 (56.4%) populations evolved resistance to CyB and Met, respectively. ACCase sequencing revealed that 56.4% of the populations contain plants with diverse target-site ACCase mutations (Ile1781Leu, Trp1999Cys, Trp2027Cys, Trp2027Ser, Ile2041Asn, Gly2096Ala, and in particular, a Leu1818Phe mutation). Notably, the Leu1818Phe mutation had been detected in 8 resistant populations, indicating this mutation was prone to occur in L. chinensis. Additionally, 9.7% of the populations may have single metabolic resistance to CyB, as these populations was susceptible to Met, and no any ACCase mutations were found. Moreover, the resistant populations with different ACCase mutations showed 6.5 to 33.6-fold resistance to CyB, and 4.4 to 82.6-fold resistance to Met. Importantly, five pre-emergence herbicides, including pretilachlor, pendimethalin, clomazone, pyraclonil, and mefenacet, all exhibited good control effect on resistant L. chinensis populations. This work confirmed the prevalence and distribution of CyB and Met resistance in L. chinensis. Target-site ACCase mutations made a major contribution to CyB and Met resistance. Pre-emergence herbicides could be valuable tools for management of resistant L. chinensis populations.

ACCase gene mutations and P450-mediated metabolism contribute to cyhalofop-butyl resistance in Eleusine indica biotypes from direct-seeding paddy fields

Eleusine indica causes problems in direct-seeding rice fields across Jiangsu Province in China. Long-term application of chemical herbicides has led to the widespread evolution of resistance in E. indica. In this study, we surveyed the resistance level of cyhalofop-butyl (CyB) in 19 field-collected E. indica biotypes, and characterized its underlying resistance mechanisms. All 19 biotypes evolved moderate- to high-level resistance to CyB (from 5.8- to 171.1-fold). 18 biotypes had a target-site mechanism with Trp-1999-Ser, Trp-2027-Cys, or Asp-2078-Gly mutations, respectively. One biotype (JSSQ-1) was identified to have metabolic resistance, in which malathion pretreatment significantly reduced the CyB resistance, and cyhalofop acid was degraded 1.7- to 2.5-times faster in this biotype compared with a susceptible control. Furthermore, the JSSQ-1 biotype showed multiple resistance to acetyl-CoA carboxylase (ACCase) inhibitor metamifop (RI = 4.6) and fenoxaprop-p-ethyl (RI = 5.1), acetolactate synthase (ALS) inhibitor imazethapyr (RI = 4.1), and hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor mesotrione (RI = 3.5). In addition, 11 out of 19 E. indica biotypes exhibited multiple resistance to glyphosate. This research has identified the widespread occurrence of CyB resistance in E. indica, attributed to target-site mutations or enhanced metabolism. Moreover, certain biotypes have exhibited resistance to multiple herbicides or even cross-resistance. Consequently, there is an urgent need to implement diverse weed management practices to effectively combat the proliferation of this weed in rice fields.

Metabolic Exploration for Cyhalofop-Butyl Antagonism in Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] Following Pretreatment of Malathion.

The present study investigated the effects of broad-spectrum metabolic inhibitors malathion (cytochrome P450 inhibitor) and/or 4-chloro-7-nitrobenzofurazan (NBD-Cl; glutathione S-transferase inhibitor) on the metabolism of cyhalofop-butyl (CyB) in barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] biotypes confirmed previously with multiple resistance to two herbicides CyB and florpyrauxifen-benzyl. The metabolic inhibitors were not effective at recovering the sensitivity of resistant barnyardgrass biotypes to CyB treated at the labeled rate (313 g ai ha-1). Rather, treatment with malathion followed by CyB caused antagonism, reducing the efficacy of CyB and promoting the growth of resistant biotypes. Pretreatment with malathion did not influence absorption/translocation of the applied form CyB and its conversion to the active herbicide form cyhalofop-acid (CyA), in both susceptible and resistant biotypes. In contrast, metabolism of the applied form (CyB) decreased 1.5 to 10.5 times by the malathion pretreatment. Taken together, the maintained CyA production against the reduced CyB metabolism could be the mechanism to account for the cause of CyB antagonism observed in barnyardgrass following malathion pretreatment. Additionally, the evolution of CyB resistance in barnyardgrass might be associated with reduced production of CyA in resistant biotypes, independent of activities of cytochrome P450 or GST enzymes.

Cyhalofop-butyl exposure induces the severe hepatotoxicity and immunotoxicity in zebrafish embryos

Cyhalofop-butyl (CyB) is a highly effective herbicide and is widely used for weed control in paddy fields. Because CyB is easily residual in the aquatic environment, its potential harm to aquatic organisms has attracted much attention and has not been fully understood. In this study, we systematically explored the hepatotoxic and immunotoxic effects of CyB exposure in zebrafish embryos. Firstly, CyB induced a decrease in the survival rate of zebrafish and led to a series of developmental abnormalities. Meanwhile, CyB can significantly reduce the size of zebrafish liver tissue and the number of hepatocytes in a dose-dependent manner. Secondly, the number of macrophages and neutrophils significantly decreased but the antioxidant enzyme activities such as CAT and MDA were greatly elevated upon CyB exposure. Thirdly, RNA-Seq analysis identified 1, 402 differentially expressed genes (DEGs) including 621 up-regulated and 781 down-regulated in zebrafish embryos after CyB exposure. KEGG and GO functional analysis revealed that the metabolic pathways of drug metabolism-cytochrome P450, biosynthesis of antibiotics, and metabolism of xenobiotics, along with oxidation-reduction process, high-density lipoprotein particle and cholesterol transport activity were significantly enriched after CyB exposure. Besides, hierarchical clustering analysis suggested that the genes involved in lipid metabolism, oxidative stress and innate immunity were largely activated in CyB-exposed zebrafish. Moreover, CyB induced zebrafish liver injury and increased hepatocyte apoptosis, which increased the protein expression levels of Bax, TLR4, NF-kB p65 and STAT3 in zebrafish. Finally, specific inhibition of TLR signaling pathway by TLR4 knock-down could significantly reduce the expression of inflammatory cytokines induced by CyB exposure. Taken together, these informations demonstrated that CyB could induce the hepatotoxicity and immunotoxicity in zebrafish embryos, and the expression levels of many genes involved in lipid metabolism and immune inflammation were obtained by RNA-Seq analysis. This study provides valuable information for future elucidating the aquatic toxicity of herbicide in aquatic ecosystems.

Self-Assembled Sphere Covalent Organic Framework with Enhanced Herbicidal Activity by Loading Cyhalofop-butyl.

Nanopesticides are considered to be a novel and efficient kind of tool for controlling pests in modern agriculture. Covalent organic frameworks (COFs), with high surface areas, ordered structures, and rich functional groups for loading pesticides, are a class of promising carrier materials that can be used to develop efficient nanopesticide delivery systems. However, until now, only a strong ionic interaction between the pesticide and COF can be utilized to achieve the combination between the pesticide and COF. On the basis of this method, charged pesticide molecules are the only choice for COF-based nanopesticides, which limits the exploitation. The way to load the uncharged pesticide molecules into COF still needs to be explored. Herein, in this research, we provided a commonly mild and high-efficacy strategy for loading an uncharged pesticide molecule into COF. The herbicide cyhalofop-butyl (CB), as a neutral model pesticide molecule, was loaded into the sphere COF (SCOF, a model COF synthesized at room temperature) without any ionic interaction via the host-guest strategy. The loading capacity of CB into SCOF (CB@SCOF) was determined at 57% (w/w). Smaller CB@SCOF particles (150-200 nm) can efficiently enter the weed leaves and stems, enhancing the accumulation of the effective concentration in weeds, thus increasing herbicidal activity, in comparison to CB emulsifiable (EC, micrometer scale). Furthermore, CB@SCOF had a solubilization effect for CB in water and can improve the photostability of CB. Thus, the CB-loaded COF nanosphere showed excellent herbicidal activities against the target weeds Echinochloa crus-galli and Leptochloa chinensis compared to commercial CB EC. In conclusion, this study also provides a mild and high-efficacy pesticide loading strategy for COFs. The constructed efficient delivery system and pesticide formulation containing herbicidal COF nanospheres exhibit great potential applications for controlling weeds in sustainable agriculture.

Effect of herbicides on weed dynamics, soil fertility, energetics and productivity of upland rice in an acidic subtropical soil of the Eastern Himalayas, India

ABSTRACT Weed management in upland rice under subtropical climate with high rainfall is challenging. The diverse weed flora in upland rice ecosystem emerges in several flushes, necessitating sequential application of herbicides. A 4-year study conducted in Meghalaya (950 m above sea level), India indicated that sequential application of Cyhalofop butyl [2-{4-(4-cyano-2-fluorophenoxy) phenoxy} propionic acid, butyl ester (R)], a grass weed killer high efficacy low volume herbicide applied 80 g ha−1 at 25 days after sowing (DAS) and 2,4-D, a broadleaf weed killer herbicide applied 0.75 kg ha−1 at 35 DAS was effective for weed control and produced significantly higher grain yield (3572 kg ha−1) of rice with the highest weed control efficiencies than other treatments. Application of Pretilachlor followed by (fb) 2,4-D or Fenoxaprop-p-ethyl fb 2,4-D yielded significantly higher chlrophyll (chl) a, chl b and total leaf chl content compared with other herbicides at 90 DAS. The highest net energy (111,443 MJ ha−1), energy profitability and benefit:cost ratio was recorded with sequential application of Cyhalofop butyl and 2,4-D. Thus, sequential application of Cyhalofop butyl and 2,4-D could provide a sustainable weed management option in upland rice under high rainfall conditions in the Eastern Himalayas, India.

Efficacy of New Herbicide Mixtures on Weed Control, Yield, and Economics in Transplanted Rice

Aim: To evaluate the efficacy of new herbicide mixtures on the weed control and performance of transplanted rice.
 Study Design: Randomized Complete Block Design.
 Place and Duration of Study: AlI India Coordinated Research Project on Weed Management, PJTSAU, Hyderabad between August to December, 2021.
 Methodology: The efficacy of herbicide mixtures either ready mix or as tank mixtures were evaluated for effective and broad spectrum weed control in transplanted rice during kharif season, 2021 at AICRP on Weed Management, PJTSAU, Rajendranagar, Hyderabad. The experiment was laid out in a randomized complete block design with nine treatments and three replications. The treatments included five ready mixes (RM) one tank mix combination of new herbicides tested against one single herbicide, weedy check and hand weeding twice at 20 and 40 DAT.
 Results: The results of the study revealed that bispyribac sodium 10% SC 25 g ha-1+ penoxsulam 1.02% (20 g ha-1) (tank mix) as post-emergence (POE) fb hand weeding (HW) at 40 DAT or penoxsulam 0.97% (20 g ha-1) + butachlor (38.8%) @ 820 g ha-1 (RM) as POE fb HW at 40 DAT or penoxsulam 1.02% (20g ha-1) + cyhalofop butyl 5.1% (100 g ha-1 ) (RM) as POE fb HW at 40 DAT or bensulfuron methyl 0.6% (60 g ha-1) + pretilachlor 6% (600g ha-1) GR (RM) as pre-emergence (PE) fb HW at 40 DAT were equally effective to hand weeding twice at 20 and 40 DAT with respect to suppression of weeds at 60 DAT. The yield attributes like a number of tillers/m2, panicles no, panicle length, grains panicle-1 and test weight were found to be higher with penoxsulam 1.02% (20 g ha-1) + cyhalofop butyl 5.1% (100 g ha-1) as POE fb HW at 40 DAT which also recorded higher grain yield, straw yield, gross returns, net returns and B-C ratio but it was found to be at par with other herbicide combinations.
 Conclusion: It can be concluded that new herbicide mixtures either as ready mix or tank mix performed better than sole application or hand weeding alone.

Life Cycle Exposure to Cyhalofop-Butyl Induced Reproductive Toxicity in Zebrafish.

Cyhalofop-butyl (CyB) is a herbicide widely used in paddy fields that may transfer to aquatic ecosystems and cause harm to aquatic organisms. In this study, zebrafish (Danio rerio) were exposed to CyB at environmental concentrations (0.1, 1 and 10 µg/L) throughout their adult life cycle, from embryo to sexual maturity. The effects of CyB on zebrafish growth and reproduction were studied. It was found that female spawning was inhibited, and adult male fertility decreased. In addition, we examined the expression of sex steroid hormones and genes related to the hypothalamus–pituitary–gonad–liver (HPGL) axis. After 150 days of exposure, the hormone balance in zebrafish was disturbed, and the concentrations of 17β-estradiol (E2) and vitellogenin (VTG) were decreased. Changes in sex hormone were regulated by the expression of genes related to the HPGL axis. These results confirmed that long-term exposure to CyB at environmental concentrations can damage the reproductive capacity of zebrafish by disrupting the transcription of genes related to the HPGL axis. Overall, these data may provide a new understanding of the reproductive toxicity of long-term exposure to CyB in zebrafish parents and offspring.

Economics of Wet Seeded Rice as Influenced by Alternate Wetting and Drying Irrigation Regimes and Weed Management

An experiment was conducted at College Farm, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad during rabi 2020-21 and 2021-22.The experiment was laid out in split plot design with two factors i.e., irrigation regimes (I1 : Farmers practice (continuous flooding of 2-5 cm from 3-4 days after sowing), I2: AWDI at 5 cm depletion of ponded water, I3: AWDI at 10 cm depletion of ponded water and I4: AWDI at 15 cm depletion of ponded water) and weed management practices (W1: Control (Unweeded check), W2: Pyrazosulfuron ethyl (10% WP) 20 g ha-1 PE fb Penoxsulam (1.02%) + Cyhalofop butyl (5.1%) 120 g ha-1 PoE, W3:Pyrazosulfuron ethyl (10% WP) 20 g ha-1 PE fb Penoxsulam (1.02%) + Cyhalofop butyl (5.1%) 120 g ha-1 PoE + Mechanical weeding at 45 DAS and W4: Weed free (Mechanical weeding at 15, 35 and 55 DAS with line weeding). Among the irrigation regimes, cost of cultivation and gross returns were highest in farmers practice (continuous flooding of 2-5 cm from 3-4 days after sowing) and lowest in AWDI at 15 cm depletion of ponded water. Net returns and B:C ratio was highest in AWDI at 5 cm depletion of ponded water and lowest net returns and B:C ratio was recorded in AWDI at 15 cm depletion of ponded water. Among weed management practices highest cost of cultivation, gross returns were achieved in weed free (mechanical weeding at 15, 35 and 55 DAS with line weeding) and lowest cost of cultivation and gross returns was achieved in Control (unweeded control). With respective to herbicide application highest gross returns, net returns and B:C ratio were achieved in pyrazosulfuron ethyl (10% WP) 20 g ha-1 PE fb penoxsulam (1.02%) + cyhalofop butyl (5.1%) 120 g ha-1 PoE + mechanical weeding at 45 DAS.