Evaluation of the Impact of Herbicidal Weed Management Practices on Weed Density, Yield Attributes and Yield of Irrigated Chickpea (Cicer arietinum L.)

In the Rabi season of 2021-22, an experiment was conducted at the Agronomy Research Farm of CCS Haryana Agricultural University in Hisar. The aim was to examine how herbicidal weed management affects irrigated chickpea. The experiment was laid out in Randomised Block Design (RBD) with thirteen treatments, each repeated three times. The treatments included various herbicides applied at different stages, such as pre-plant incorporation (PPI), pre-emergence (PRE), and post-emergence (POE). Interestingly, the Ready mix (RM) herbicide application of pendimethalin + imazethapyr (RM) @ 1000 g a.i ha-1, applied both as PPI and PRE, outperformed the herbicides applied solely as PPI, PRE, or POE. Among the herbicidal treatments, the combined during PPI and PRE stages exhibited excellent control over a diverse weed population, leading to a significant increase in chickpea yield compared to the weedy check. The number of seeds per pod, pods per plant, and branches per plant varied significantly with different weed control treatments. Weed-free plots showed the highest values in these parameters. The uncontrolled growth of weeds in the weedy check resulted in a 55.2% reduction in seed yield as compared to weed-free plots. The maximum seed yield (1968 kg ha-1) and favorable yield attributes were observed in the weed- free treatment, statistically comparable to the yield obtained from two hand weeding at 30 and 50 days after sowing (1940 kg ha-1). Among herbicidal treatments, the highest seed yield was achieved with the PRE application of pendimethalin + imazethapyr (RM) @ 1000 g a.i. ha-1 (1827 kg ha-1). The dominant weed flora consisted of Chenopodium album, Fumaria parviflora and Anagallis arvensis. Density of different weed species was significantly influenced by different weed control treatments. All the weed control treatments significantly reduced the total weed density and dry matter accumulation by weeds in comparison to weedy check. Weed free and two hand hoeing reduced the weed population drastically which was statistically at par with PRE application of pendimethalin + imazethapyr (RM) at 1000 g a.i. ha-1. Chenopodium album, Fumaria parviflora and Anagallis arvensis were effectively controlled by RM irrespective of its time of application.

Effect of Herbicide (Propaquizafop and Imazethapyr) on Weed Flora Associated with Blackgram in Central India

An experiment was conducted at Product Testing Unit, Department of Agronomy, JNKVV, Jabalpur to study the effect of application of propaquizafop and imazethapyr herbicide on weeds associated with blackgram. The experimental field was having mixed weed flora comprising of grassy as well as broad leaved weeds. Nine treatments comprised of four rates of application of propaquizafop+ imazethapyr at 47+70, 50+75, 53+80 and 56+85 g/ha and alone application of propaquizafop (100 g/ha), imazethapyr (100 g/ha), pendimethalin (1500 g/ha) and hand weeding twice at 20 and 40 DAS including weedy check, were laid out in Randomized Block Design with three replications. All herbicide treatments were applied in 500 liters of water per hectare, using flat fan nozzle as per the treatments. The dominant weed flora, species wise weed density, weed biomass, Weed control efficiency and weed index were recorded at different interval. The study revealed that the Echinochloa colona (29.39%) and Dinebra retroflexa (24.30%) were the found as dominant weeds in the field whereas, other monocot weeds like Cyperus iria (18.19%) and dicot weeds like Mullugo pentaphylla (12.23%), Eclipta alba (7.58%) and Alternanthera philoxeroides (8.31%) were also present in less numbers in blackgram under weedy check plots. Among the herbicidal treatments, activity of propaquizafop+imazethapyr mixture at the dose 53+80 and 56+85 g/ha emerged as effective control for the weeds associated with blackgram.

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

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

Effect of Nitrogen and Weed Management Practices on Growth and Yield of Blackgram (Vigna mungo L.)

A research trail was conducted in Kharif 2022, at Crop research form, SHUATS, Prayagraj. To study the “Effect of nitrogen and weed management practices on growth and yield of Blackgram” (Vigna mungo L.). The treatments consist of three levels of nitrogen (15, 30 and 45 kg/ha) and weed management practices (Hand weeding twice (20 & 40 DAS), Pendimethalin (0.75ml/ha) Pre-emergence (5 DAS), Imazethapyr (75g/ha) Post-emergence (25 DAS) are included. Experiment were laid out in randomized block design with 10 treatments each replicated thrice. The result showed that viz: significantly higher plant height (64.49 cm), number of nodules/plant (23.80), number of branches/plant (6.40), pods/plant (32.13), seeds/pod (8.20), grain yield (1223.33 kg/ha), Stover yield (2472.67 kg/ha), lower weed population/m2 (4.06) recorded in (treatment 9) Nitrogen (45 kg/ha) + Imazethapyr (75 g/ha) Post-emergence.

Leaching and residual activity of imidazolinone herbicides in lowland soils / Lixiviação dos herbicidas imidazolinonas em solo de várzea

ABSTRACT: Herbicides used in the Clearfield® rice (Oryza sativa L.) production system have a potential for leaching. This can result in contamination of underground water resources and cause injury to not tolerant crops that are sown in a succession and/or crop rotation. The objective of this study was to determine the leaching potential and the residual activity of the herbicides used in the Clearfield® rice system. The experiment was conducted over a period of two years and consisted of conducting a field test to be followed by two bioassays with a year of difference between their implementation. Initially an experiment was conducted in lowland area where it was planted the cultivar of rice ‘PUITA INTA CL’. Approximately one and two years thereafter, soil samples from each plot were collected at intervals of 5cm to a depth of 30cm (B factor) for the bioassay to evaluate persistence of herbicides. Factor A was composed of mixtures formulated of imazethapyr + imazapic (75 + 25g a.i. L-1), imazapyr + imazapic (525 + 175g a.i. kg-1) in two doses, imazethapyr (100g a.i. L-1) and treatment control without application. Basing on results, it was concluded that the mixtures imazethapyr + imazapic, imazapyr + imazapic and imazethapyr leached into the soil, reaching depths of up to 25cm in lowland soil. Imidazolinone herbicides used today in the irrigated rice Clearfield® system are persistent in soil, and their phytotoxic activity can be observed up to two years after application.

RESUMO: Os herbicidas utilizados no sistema Clearfield® de produção de arroz irrigado (Oryza sativa L.) apresentam potencial de lixiviação. Isso pode causar contaminação de mananciais hídricos subterrâneos e fitotoxicidade as culturas não tolerantes semeadas em sucessão e/ou rotação. O objetivo deste trabalho foi determinar o potencial de lixiviação e o efeito residual dos herbicidas utilizados no sistema Clearfield® de arroz irrigado. O experimento foi conduzido durante dois anos e consistiu da realização de dois bioensaio com diferença de um ano entre a implantação dos mesmos. Inicialmente foi instalado o experimento em área de várzea onde foi semeada a cultivar de arroz ‘Puitá INTA CL’ em área de várzea. Aproximadamente um e dois anos após, foram coletadas amostras de solo de cada parcela, em intervalos de 5cm até a profundidade de 30cm (fator B) para a realização do bioensaio a fim de avaliar persistência dos herbicidas. O fator A foi constituído pelas misturas formuladas imazethapyr + imazapic (75 + 25g i.a. L-1), imazapyr + imazapic (525 + 175g i.a. kg-1) em duas doses, imazethapyr (100g i.a. L-1) e um tratamento testemunha sem aplicação. Com os resultados obtidos, foi possível concluir que as misturas imazethapyr + imazapic, imazapyr + imazapic e imazethapyr lixiviam no solo, atingindo profundidades de até 25cm em solo de várzea. Os herbicidas imidazolinonas, hoje utilizados no sistema Clearfiel® de arroz irrigado, são persistentes no solo podendo seus efeitos fitotóxicos serem observados até dois anos após sua aplicação.

Nitrogen dose and type of herbicide used for growth regulation on the green coloration intensity of Emerald grass / Intensidade da coloração verde das folhas da grama esmeralda submetida a doses de nitrogênio e ao uso de herbicidas como reguladores de crescimento

ABSTRACT: Nitrogen (N) is the main nutrient responsible for the green coloration of lawns but also stimulates the growth of the aerial portion of grass, thus increasing mowing expenses. Therefore, herbicides may be used as a growth regulator. The ideal herbicide will reduce lawn height without affecting esthetics. Toward this end, the aim of the present study was to evaluate the green coloration of Emerald grass ( Zoysia japonica Steud.) under the effect of different N doses or herbicides used as growth regulators. The study site consisted of randomized blocks containing 20 treatments arranged in a 5×4 factorial design with four treatment groups: four herbicides (glyphosate, imazaquin, imazethapyr, and metsulfuron-methyl, accounting for 200, 420, 80, and 140g ha-1 of the active ingredient, respectively) and the control sample (no herbicide); and three doses of N in the form of urea (5, 10, and 20g m-2), divided into five applications per year, in addition to a treatment without N. Leaf chlorophyll content (LCC) was assessed and the aerial portion of the lawn was measured with digital image analysis. Doses of N ranging from 10 to 20g m-2, divided into five applications a year, provided the lawn with intense green coloration, and the herbicides glyphosate (200g ha-1), imazaquin (420g ha-1), and imazethapyr (80g ha-1) were reported to be suitable for use as growth regulators of the study species, considering maintenance of esthetic quality (green coloration). The digital image analysis of the aerial portion provided more accurate results than use of a chlorophyll meter with regard to the recommendation of both N dose and herbicides to be used as growth regulators of Emerald grass.

RESUMO: Embora o nitrogênio (N) seja o principal nutriente responsável pela coloração verde dos gramados, o mesmo estimula o crescimento da parte aérea, resultando em maior dispêndio com cortes. Assim, a utilização de herbicidas como reguladores de crescimento seria alternativa, sendo ideal aquele que reduzisse a altura sem afetar a estética do gramado. Diante do exposto, objetivou-se avaliar a coloração verde da grama esmeralda ( Zoysia japonica Steud.) sob o efeito de doses de N e do uso de herbicidas como reguladores de crescimento. Utilizou-se o delineamento em blocos casualizados com 20 tratamentos dispostos num fatorial 5x4 com quatro repetições, sendo quatro herbicidas: glyphosate, imazaquin, imazethapyr e metsulfuron-methyl (200, 420, 80 e 140g ha-1 do ingrediente ativo (i.a.), respectivamente) e a testemunha (sem herbicida); e três doses de N na forma de ureia: 5, 10 e 20g m-2, parceladas em cinco aplicações ao ano, além do tratamento sem N. Avaliaram-se o índice de clorofila foliar (ICF) e a análise por imagem digital da parte aérea do gramado. Doses de 10 a 20g m-2 de N, parceladas em cinco vezes ao ano, propiciaram coloração verde intensa do gramado e os herbicidas glyphosate (200g ha-1), imazaquin (420g ha-1) e imazethapyr (80g ha-1) foram adequados para utilização como reguladores do crescimento da espécie estudada, considerando a qualidade estética (cor verde). A análise por imagem digital da parte aérea forneceu resultados mais precisos que o uso do clorofilômetro, quanto à recomendação da dose de N, bem como dos herbicidas a serem utilizados como reguladores de crescimento da grama esmeralda.

Associação de glyphosate e imidazolinonas no controle de arroz-vermelho em arroz Clearfield® / Association of glyphosate and imidazolinones on red rice control in Clearfield™ rice

O objetivo do presente trabalho foi o de avaliar os efeitos da utilização de glyphosate e herbicidas imidazolinonas, em aplicações isoladas ou associadas, sobre o controle de arroz-vermelho (Oryza sativa) e produtividade de grãos de arroz Clearfield®. O experimento foi conduzido a campo na safra 2007/08, em Cachoeirinha, RS, Brasil, com delineamento em blocos ao acaso e tratamentos dispostos em arranjo fatorial (2x6), usando-se quatro repetições. O fator A constou de dois níveis do herbicida glyphosate, aplicados no subperíodo semeadura-emergência da cultura por ocasião do início da emissão do coleóptilo do arroz (ponto de agulha); o fator B constou de seis tratamentos com imazethapyr+imazapic, aplicados em associação ao glyphosate ou quando a cultura atingiu o estádio de três folhas expandidas. As três variáveis explicativas analisadas foram a população de plantas de arroz e arroz-vermelho, a eficácia do controle de arroz-vermelho e a produtividade de grãos da cultura. O uso de glyphosate no ponto de agulha reduziu em 75% a população do arroz-vermelho e aumentou em 40% a produtividade de grãos de arroz, em relação à testemunha. O uso isolado de herbicidas imidazolinonas e sua associação com o dessecante proporcionou controle eficaz do arroz-vermelho e incrementou a produtividade de grãos, em comparação à situação sem controle da infestante, independente da dose e do sistema de aplicação.

The objective of this research was to evaluate the effects of the utilization of glyphosate and imidazolinones herbicides, in isolated or associated applications, on the effectiveness of red rice (Oryza sativa) control and grain yield of Clearfield-rice. The experiment was conducted under field conditions in 2007/08, in Cachoeirinha, RS, Brazil, using a randomized block design in a two-factorial design 2x6, with four replicates. The factor A was composed by two levels of glyphosate, applied during the subperiod between sowing and crop emergence at the early coleoptile stage of the rice plants; and the factor B consisted of six treatments with imazethapyr+imazapic, applied in association with glyphosate or when the rice crop plants had three expanded leaves. The crop and weed populations, red rice control and grain yield of crop were evaluated. The results show that the glyphosate application at the early coleoptile stage of the crop reduced 75% the red rice population and increased 40% the grain yield, in relation to the situation without weed control. The use of imidazolinones and their association with glyphosate provided effective control of red rice and increased the grain yield, independent of rates and application system.

Interações entre herbicidas e protetores para o controle de capim-annoni em pastagem natural / Interactions among herbicides and safeners for the south african lovegrass control in natural grassland

A similaridade botânica do capim-annoni com as espécies forrageiras nativas ou cultivadas dificultam o seu controle em pastagens naturais. O objetivo deste trabalho foi avaliar o efeito de associações entre herbicidas e protetores sobre o controle de capim-annoni e a seletividade em pastagem natural. Foram realizados dois experimentos a campo em área de pastagem natural típica do Bioma Pampa avaliando-se herbicidas aplicados em pré e pós-emergência. Outro experimento foi conduzido em casa de vegetação com as espécies capim-annoni e grama forquilha onde foram avaliados os herbicidas glufosinate-ammonium e imazethapyr. Em ambos os experimentos os herbicidas foram avaliados isolados ou em associação com os protetores anidrido naftálico, dietholate e fluxofenim. Os experimentos a campo demonstraram que os herbicidas aplicados em pré ou pós-emergência em interação com os protetores não proporcionaram controle satisfatório do capim-annoni e nem aumento da seletividade à pastagem natural. Por outro lado, o experimento em condições controladas indicou a ocorrência de sinergismo do herbicida glufosinate-ammonium em interação com os protetores anidrido naftálico, dietholate e fluxofenim sobre o capim-annoni. As diferenças relacionadas a estádio de desenvolvimento e densidade de infestação estão relacionadas as variações das respostas nos estudos a campo e em condições controladas. A utilização de herbicidas em associações com protetores apresenta potencialidade de controle seletivo de capim-annoni quando aplicado em plantas em estádios iniciais de desenvolvimento.

The botanical similarity of the invasive weed Eragrostis plana Nees (South African lovegrass) difficult its selective control in natural pastures. The aim of this study was to evaluate the effect of the association between herbicides and safeners on the control of E. plana and on the selectivity to the natural pastures. Two experiments were conducted at field conditions in area of natural grassland of the Biome Pampa where several herbicides were evaluated in pre and post-emergence. A third experiment was carried out in greenhouse evaluating the herbicides glufosinate-ammonium and imazethapyr and the species E. plana and Paspalum notatum. In both experiments, the herbicides were evaluated isolated and in association with the safeners anhydride naphtalic, dietholate and fluxofenim. The field experiments indicated that the evaluated safeners did not increase E. plana control and native grassland selectively. The greenhouse experiment indicated the occurrence of synergism on E. plana for the herbicide glufosinate-ammonium in mixture with the safeners anhydride naphtalic, dietholate and fluxofenim. The different results in the field and greenhouse experiments are related to the plant stage and density. The use of herbicides in association with safeners indicated a potentiality for selective control of E. plana when applied to plants in the early stages of development.

Produtividade, fitotoxicidade e controle de arroz-vermelho na sucessão de cultivo de arroz irrigado no Sistema CLEARFIELD® / Productivity, injury and control of red rice in succession of irrigated rice cultivation in System CLEARFIELD®

O objetivo deste trabalho foi avaliar o sistema CLEARFIELD® quanto ao controle do arroz-vermelho, influência sobre a produtividade, bem como a fitotoxicidade ocasionada pelo possível residual no solo da mistura formulada de imazethapyr e imazapic em genótipo de arroz tolerante (IRGA 422CL) e não-tolerante (IRGA 417), os quais serviram como plantas indicadoras. O delineamento experimental foi de blocos ao acaso em esquema bifatorial (4x3) com parcelas subdivididas, sendo as parcelas principais representadas pela rotação entre arroz tolerante (IRGA 422CL) e o arroz não-tolerante a imidazolinonas (IRGA 417). Nas sub-parcelas foram aplicados os tratamentos para o controle de arroz-vermelho em diferentes épocas de aplicação (pós-emergência (V4), pré+ pós emergência (no dia da semeadura + V4). A fitotoxicidade foi caracterizada com base na cor das folhas, largura, crescimento e desenvolvimento do limbo foliar. Observou-se que a fitotoxicidade foi maior quando o herbicida foi aplicado em pós-emergência permanecendo seus efeitos até 383 dias após a aplicação. O controle de arroz-vermelho não é eficiente com a utilização de apenas um ano agrícola do sistema CLEARFIELD® e o melhor nível de controle e produtividade foi obtido após dois ou três anos consecutivos desse sistema.

The objective of this study was to evaluate the CLEARFIELD ® system regarding the control of red rice, influences on productivity, as well as the possible phytotoxicity caused by carryover soil formulated mixture of imazethapyr and imazapic in tolerant rice genotype (IRGA 422CL) and non-tolerant (IRGA 417), which served as indicator plants. The experimental design was randomized blocks in a factorial scheme (4x3) with subplots, the main plots represented by rotating tolerant rice (IRGA 422CL) and rice not tolerant to imidazolinone (IRGA 417). In sub-plot treatments were applied to control red rice in different stages of the post-emergence (V4), pre + post emergence (day of seeding V4). Phytotoxicity was characterized based on the color of the leaves, width, growth and development of the leaf. It was observed that phytotoxicity was greater when the herbicide was applied post-emergence, effects remaining until 383 days after application. The control of red rice is not efficient with the use of only one agricultural year of CLEARFIELD® system and the best level of control and yield was obtained after two or three consecutive years of this system.