Post-emergence Application Of Imazethapyr Research Articles

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).

Application of ALS inhibitors at pre-emergence is effective in controlling resistant barnyardgrass biotypes depending on the mechanism of resistance

Echinochloa species are one of the most troublesome weeds in rice crops, and their control is hampered due to herbicide resistance. The aim of this study was to identify the cross-resistance pattern and the differential resistance level for pre- and post-emergence applications of imazethapyr and penoxsulam in populations of barnyardgrass [Echinochloa crus-galli (L.) Beauv.] with different ALS gene mutations. Of 26 biotypes, 23 were imazethapyr-resistant, and 10 were cross-resistant to penoxsulam. The resistance index (RI) to imazethapyr was 5.7–19.5 for Ser653Asn, 26.7–68.3 for Ala122Thr and Ala205Asn, and 70.9–252.9 for Trp574Leu. Only Trp574Leu also resulted in resistance to penoxsulam. The double ALS mutation Ala122Asn + Trp574Leu resulted in a RI for imazethapyr and penoxsulam higher than 2800. The ED50 for penoxsulam applied at pre-emergence was three and six times lower than at post-emergence for the susceptible and resistant biotypes, respectively. The application of imazethapyr at pre-emergence was more effective than at post-emergence only for the biotypes with low resistance level mutation Ser653Asn. The efficacy of the herbicide quinclorac was similar for the application at pre- and post-emergence for susceptible and resistant biotypes. The ALS mutations Ala205Asn and Ala122Asn + Trp574Leu are reported for the first time in barnyardgrass. The use of ALS inhibitors at pre-emergence should be prioritized over post-emergence in fields with resistant barnyardgrass and in need of using these products to control other non-resistant weeds.

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

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

Response of different weed management practices on growth and yield of black gram (Vigna mungo L.) under irrigated conditions of Punjab

The field experiment was carried out during the summer season of 2021-2022 to study the response of different weed management practices on growth and yield of black gram. Cyperus sp., Phyllanthus niruri, Trianthema portulacastrum, Amaranthus viridis were the dominant weeds. It was observed that besides weed free treatment the lowest weed count, dry weight of weeds (3.66 g m-2), weed index (2.73%) as well as highest weed control efficiency (60.06%) were found with the pre-emergence (PE) application of pendimethalin1 kg ha-1 followed by one hand weeding at 40 days after sowing (DAS). The maximum growth attributes, yield attributes and yield were found with the pre-emergence application of Pendimethalin 1 kg a.i. ha-1 followed by one hand weeding at 40 DAS which was statistically at par with pre emergence application of Pendimethalin 1 kg a.i. ha-1 followed by post emergence application of imazethapyr 75 g a.i. ha-1 at 40 days after sowing. The economics parameters were recorded highest with the application of Pendimethalin (PE) 1 kg a.i. ha-1 followed by one hand weeding at 40 days after sowing. Hence Pendimethalin is most effective treatment among the other treatments.

Evaluation of different post-emergence herbicides in chickpea (Cicer arietenum L.)

A field experiment was conducted during rabi season of 2018-2019 at research farm of Bihar Agricultural University, Sabour, Bhagalpur to assess the effect of various post-emergence herbicides in chickpea. The results indicated that among different herbicides, post-emergence application of imazethapyr + imazamox @ 60 g a.i. ha-1 at 20 days after sowing recorded significantly lowest weed density &amp; weed dry weight at 60 days after sowing and highest weed control efficiency at harvest, which was statistically at par with quizalofop-ethyl + imazethapyr @ 60+50 g a.i. ha-1 at 20 days after sowing. As a consequence of effective weed control, quizalofop-ethyl + imazethapyr @ 60+50 g a.i. ha-1 at 20 days after sowing recorded significantly highest grain yield, straw yield and harvest index which was significantly superior over hand weeding twice at 30 and 50 days after sowing. In weedy check, uncontrolled weed growth caused significant reduction in grain yield of chickpea. Net returns and B:C ratio was found maximum with quizalofop-ethyl + imazethapyr @ 60+50 g a.i. ha-1 at 20 days after sowing which was significantly superior over weedy check.

Effect of planting methods and weed management practices on yield of green gram {Vigna radiata (L.) R. Wilczek}, weed dynamics vis a vis phytotoxicity in green gram

An experiment was carried out to find out suitable method of planting and weed management in green gram grown during the kharif season of 2014 and 2015. The density of E. colona and C. rotundus was significantly reduced in raised bed planting method. Significant reduction in total dry weight of weeds was obtained in raised bed planting method as compared to conventional and zero till planting method. Maximum weed control efficiency was found in raised bed planting method. Significantly more number of seeds pod-1 were observed in raised bed planting method as compared to conventional and zero till planting method. Seed yield and straw yield were found maximum in raised bed planting method during both years of study and were statistically at par in conventional and zero till planting method. Harvest index was not influenced by planting methods. Phytotoxicity on crop due to different herbicides was similar under different planting methods. Among different weed management treatments, HW at 15 and 30 DAS was found most effective in reducing density and dry weight of weeds during crop growing period except at 15 DAS (where weeding was done after taking observation). Maximum weed control efficiency was observed in HW (15 and 30 DAS). Weedy check treatment resulted in minimum while weed free treatment resulted in maximum number of seeds pod-1. Among the treatments having herbicide application, post emergence application of Imazethapyr @ 100 g ha-1 resulted in maximum seed and stover yield.

Pre-and post-emergence herbicides for weed control in blackgram

Application of imazethapyr at all the rates of application (60, 75, 100 and 150 g/ha) significantly reduced the weed density and biomass as compared to quizalofop-ethyl followed by pendimethalin, alachlor and hand hoeing. Hand weeding superseded over all the treatments with the highest weed control efficiency of 96.5% followed by imazethapyr at 150 g/ha (71.9%), 100 g/ha (70.2%) and quizalofop-ethyl (70.3%). The post-emergence application of imazethapyr at 60, 75, 100 and 150 g/ha recorded significantly higher seed yield than pre emergence application of pendimethalin and alachlor and post emergence grass weed killer quizalofop-ethyl. The net monetary returns was maximum with hand weeding twice followed by imazethapyr at 150 g, 100 g and 75 g/ha. However, the benefit: cast ratio was the highest under imazethapyr at 75 g/ha followed by 100 g/ha

Growth, development and yield as affected by planting pattern and weed management in field pea and baby corn intercropping system

A field experiment was conducted during two consecutive seasons of rabi 2011-13 at Dr. Norman E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar to find out the effect of planting pattern and weed management practices on growth, development and yield of field pea and baby corn in field pea (Pant P-13) + baby corn (Surya) intercropping system. The experiment was laid out in split plot design keeping four planting patterns as main plot and four weed management practices as sub plot with three replications. Most of the growth parameters viz. number of branches per plant, dry matter accumulation (g/plant), crop growth rate and relative growth rate of field pea were comparatively higher under sole planting of field pea as compared to intercropping systems. Sole planting of field pea recorded significantly higher grain (2264 and 1434 kg ha-1) and straw yields (3263 and 2540 kg ha-1) during 2011-12 and 2012-2013 than yield obtained as a component crop in paired planting of maize (30/60 cm) + field pea (2:2) and planting of maize + field pea (1:1). Baby corn yield was similar in sole, paired (2:2) and 1:1 planting but significantly higher stover yield of baby corn (3576 kg ha-1 and 3533 kg ha-1, during 2011-12 and 2012-2013 respectively) was obtained from sole crop than other planting methods during both the years. Hand weeding at 30 days after sowing, pre emergence application of pendimethalin 1 kg ha-1 and post emergence application of imazethapyr 50 g ha-1 30 days after sowing improved all the growth and yield parameters of field pea and baby corn than weedy check.

Weed control in clusterbean through post-emergence herbicides

Field experiment was conducted at Bikaner for two consecutive years during Kharif seasons of 2012 and 2013 to test the efficacy of different weed control measures against weeds in clusterbean Cyamopsis tetragonoloba (L.) Taub. The experiment consisting of seven treatments, viz. imazethapyr 40 g/ha, quizalofop-ethyl 37.5 g/ha, fenoxaprop-p-ethyl 50 g/ha, imazethapyr + imazamox 40 g/ha, pendimethalin 0.75 kg/ha as pre-emergence (PE), hand weeding twice at 20 and 40 DAS and weedy check. Among herbicids, post-emergence application of imazethapyr + imazamox (ready mix) 40 g/ha applied at 3–4 leaf stage (around 20 DAS) recorded lowest weed density and dry weight of both grassy and broad-leaved weeds with maximum weed control efficiency (88.1%). Application of imazethapyr alone at 40 g/ha applied at 3–4 leaf stage (around 20 DAS) significantly reduced the density and dry weight of broadleaved weeds but not effective significantly against grassy weeds. Yield attributes i.e pods/plant, seed and straw yields, net return and B: C ratio were also superior with imazethapyr + imazamox 40 g/ha applied at 3–4 leaf stage (around 20DAS).

Weed management with pre-and post-emergence herbicides in linseed

Field experiment was conducted at Research farm, College of Agriculture, JNKVV, Tikamgarh during Kharif 2013–14 to study the effect of herbicides for controlling weeds in linseed. There was prevalence of dicot weeds in experimental field as these weeds constituted the higher relative density (67.8%) at harvest as compared to monocot weeds which had only 18.04% relative density. On the basis of results, it can be concluded that hand weeding twice at 20 and 40 DAS recorded significantly the lowest weed density as well as weed dry weight followed by pre-emergence application of pendimethalin at 1.0 kg + imazethapyr at 1.0 kg/ha. The seed and straw yields of linseed was significantly higher under twice hand weeding at 20 and 40 DAS followed by pre-emergence application of pendimethalin at 1 kg/ha + imazethapyr at 1 kg/ha, pendimethalin at 0.75 kg/ha + imazethapyr at 1.0 kg/ha and post-emergence application of imazethapyr at 100 g/ha. The highest net monetary return obtained with twice hand weeding whereas the B: C ratio was the highest with the application of imazethapyr at 100 g/ha followed by imazethapyr at 75 g/ha.

Weed dynamics and productivity of blackgram (Vigna mungoL.) as influenced by pre-and post-emergence herbicides

A field experiment was conducted during kharif seasons of 2012 and 2013 at the Research Farm of Mahatma Gandhi Chitrakoot Gramodaya Vishwa Vidhyalaya, Chitrakoot, Satna (M. P.) to study the weed dynamics and productivity of blackgram [Vigna mungo (L.) Hepper.] as influenced by pre-and post-emergence herbicides. Among weed control treatments, six treatments including pre-emergence herbicides (pendimethalin @ 1 kg/ha and oxyflourfen @ 0.2 kg/ha), post-emergence herbicide (imazethapyr @ 0.1 kg/ha) and their combinations were tested. All the growth and productivity parameters were influenced significantly due to single and double herbicidal applications to control the existing weed flora. The dual herbicides comprising pendimethalin+imazethapyr (W5) brought about significantly higher seed yield (858 kg/ha), straw yield (1155 kg/ha) and harvest index (42.64%) of blackgram over remaining treatments. While both the dual herbicides (pendimethalin or oxyflourfen as pre-emergence followed by post-emergence application of imazethapyr) proved equally superior to other single herbicides in respect to weed control efficiency (89.57 to 91.62%)

Direct and residual effect of herbicides on weed dynamics and productivity of soybean (Glycine max) -wheat (Triticum aestivum) cropping system

A field experiment aimed to evaluate the bio-efficacy of new low dose herbicides applied in soybean and their residual effect on succeeding wheat was conducted during 2007-08 and 2008-09 at New Delhi. Results revealed that in soybean, post-emergence application of imazethapyr (100 g/ha) was more effective against Trianthema portulacastrum, Commelina benghalensis, Digitaria sanguinalis and Dactyloctenium aegyptium but pendimethalin (1500 g/ha) against Dactyloctenium aegyptium, Digitaria sanguinalis and Trianthema portulacastrum. Chlorimuron-ethyl provided effective control of broad-leaved weeds but failed to control grasses and sedges. Application of imazethapyr (100 g/ha) increased the seed yield of soybean by 66.49% over weedy check. Herbicidal application significantly suppressed the microbial population at 30 DAS which recovered at the harvest of soybean. The residual effect of chlorimuron-ethyl (6-12 g/ha) and imazethapyr (50-100 g/ha) applied in soybean resulted in significant reduction in population of all major weeds except Avena ludoviciana in wheat grown in rotation. No injury to wheat plant was observed due to residues of chlorimuron-ethyl (6-12 g/ha) and imazethapyr (50-100 g/ha) and other herbicides applied in soybean.

Response of chickpea cultivars to pre- and post-emergence herbicide applications

Taran, B., Holm, F. and Banniza, S. 2013. Response of chickpea cultivars to pre- and post-emergence herbicide applications. Can. J. Plant Sci. 93: 279–286. Weed control is one of the major constraints of chickpea (Cicer arietinum L.) production in western Canada. There are no highly selective herbicides registered for broadleaf weed control in this crop in western Canada, consequently herbicide injury to the crop is an issue in many situations. Experiments were conducted at Saskatoon and Elrose, SK, to examine the effects of herbicide treatments on ascochyta blight severity, days to flowering, days to maturity, plant height and yield of several chickpea cultivars. Results in 2008 and 2009 showed that sulfentrazone was the safest option evaluated for broadleaf weed control in chickpea. The results also showed that although a pre-emergence application of low-rate imazethapyr caused minor levels of injury to the plants and slightly increased ascochyta blight severity, it had only minor effects on plant development and yield compared with sulfentrazone. In contrast, post-emergence applications of imazethapyr, imazamox and metribuzin increased ascochyta blight severity significantly, delayed flowering and maturity and reduced yield. The extent of the effects of pre- and post-emergence herbicide applications varied with cultivars.

Potential Use of Imazethapyr Mixtures in Drill-Seeded Imidazolinone-Resistant Rice

The efficacy of imazethapyr in drill-seeded imidazolinone-resistant rice was evaluated in Louisiana in 2000 and 2001. Imazethapyr was applied preemergence (PRE), or no PRE, followed by a postemergence (POST) application of imazethapyr alone, or in a mixture with bensulfuron, bentazon plus aciflurofen, carfentrazone, halosulfuron, propanil plus molinate, triclopyr, or V-10029. Imazethapyr applied PRE followed by a POST application of imazethapyr controlled barnyardgrass equivalent to or higher than other treatments evaluated. Red rice control at 35 days after postemergence treatment (DAT) was 66 to 81% with imazethapyr applied PRE followed by any POST application, but a reduction in control was observed with a POST application of imazethapyr. Although alligatorweed control increased with POST applications, these treatments suggested only suppression. Hemp sesbania control never exceeded 10% with imazethapyr-only treatments and at 35 DAT, all POST applications, except bensulfuron, increased control above 84%. Rice yield increased with treatments receiving a PRE application of imazethapyr compared with no imazethapyr applied PRE.

Characterization of two biotypes of imidazolinone-resistant eastern black nightshade (Solanum ptycanthum)

Biotypes of eastern black nightshade were found in Illinois and Indiana that were not controlled by postemergence applications of imazethapyr. Greenhouse studies were conducted to determine whole-plant responses to the imidazolinone herbicides imazethapyr and imazamox and to the sulfonylurea herbicide primisulfuron-methyl. The Illinois and Indiana resistant biotypes were highly resistant to imazamox and imazethapyr but were not cross-resistant to primisulfuron-methyl. DNA sequencing of acetolactate synthase (ALS) genes showed that the molecular basis for resistance in both resistant biotypes was a single base-pair mutation within Domain C that changed an alanine to a threonine in their encoded enzymes. In vitro enzyme assays showed that the Illinois resistant biotype's ALS enzyme was 789- and 881-fold less sensitive than that of the susceptible biotype to imazamox and imazethapyr, respectively. The Indiana resistant biotype's ALS enzyme was 110- and 158-fold less sensitive than that of the susceptible biotype to imazamox and imazethapyr, respectively. These results are consistent with the amino acid substitution found in the ALS enzyme of both resistant biotypes of eastern black nightshade.

Control of Red Rice (Oryza sativa) in Imidazolinone-Tolerant Rice (O. sativa)1

Field experiments were conducted near Beaumont, TX, to evaluate red rice control in imidazolinone-tolerant rice. Imazethapyr was applied preplant incorporated (PPI) and preemergence (PRE) at 70 and 105 g ai/ha and postemergence (POST) at 36, 52, and 70 g/ha. Single imazethapyr applications were made at each rate and timing and in sequential PPI or PRE followed by POST treatments. Red rice control ranged from 92 to 98% with sequential imazethapyr applications. Red rice control was higher when imazethapyr was applied PPI alone than PRE alone. But when these treatments were followed by a POST application of imazethapyr, there were no differences in red rice control between PPI and PRE application. Red rice control with sequential treatments was not improved with increased rates of imazethapyr POST. Visual injury to the 93AS3510 imidazolinone-tolerant variety was 5% or less 20 d after treatment (DAT), and there was no injury by 45 DAT. But POST applications of 70 g/ha imazethapyr may produce minor yield reduc...

Effective weed management in clusterbean (Cyamopsis tetragonoloba) through post-emergence herbicide

A field experiment was conducted at the Research Farm of Agricultural Research Station, Swami Keshwanand Rajasthan Agricultural University, Bikaner during the rainy (kharif) seasons of 2012, 2013 and 2014 to test the effi- cacy of different weed control measures against weeds in clusterbean [Cyamopsis tetragonoloba (L.) Taub.]. The experiment comprising seven weed control treatments, viz. imazethapyr 40 g/ha, quizalofop ethyl 37.5 g/ha, fenoxaprop-p-ethyl 50 g/ha, imazethapyr + imazamox 40 g/ha, pendimethalin 0.75 kg/ha as pre-emergence (PE), hand-weeding twice at 20 and 40 days after sowing (DAS) and weedy check was laid out in a randomized block design with four replications. Amongst the herbicidal treatments, post-emergence application of imazethapyr + imazamox 40 g/ha applied at 34-leaf stage resulted in the lowest weed density and dry weight of both grassy and broad-leaf weeds. Application of imazethapyr alone at 40 g/ha applied at 34-leaf stage significantly reduced the density and dry weight of broad-leaf weeds, but it was not effective against grassy weeds. Pods/plant and seed and straw yields, net returns and benefit: cost ratio were also superior with imazethapyr + imazamox 40 g/ha com- pared to the other treatments.

Flumioxazin for Weed Control in Texas Peanuts (Arachis hypogaea L.)1

Abstract Field experiments were conducted in 1991 and 1993 to evaluate flumioxazin alone and in various herbicide programs for weed control in peanut. Flumioxazin alone provided inconsistent control of annual grasses, while the addition of pendimethalin or trifluralin improved control considerably. Pitted morningglory (Ipomoea lacunosa L.) and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] control was &amp;gt; 75% when flumioxazin was used alone. Flumioxazin caused early season peanut stunting with some recovery within 4 to 6 wk. Postemergence applications of imazethapyr or lactofen increased peanut stunting.

Dry Edible Bean (Phaseolus vulgaris) Response to Imazethapyr

Imazethapyr at 0.07 and 0.10 kg ai ha-1applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) was evaluated at two locations in 1988 and 1989 for safety to dry edible beans. Bean stunting, leaf crinkling, and interveinal chlorosis were evident from imazethapyr and varied from 1 to 57%. Imazethapyr significantly reduced bean height and delayed maturity. PPI and POST applications of imazethapyr at 0.07 and 0.10 kg ha-1did not reduce bean seed yields compared to yields of the untreated control. Bean cultivar by herbicide interactions were significant for bean injury but varied with year and location.

Common Lambsquarters (Chenopodium album) and Rotational Crop Response to Imazethapyr in Pea (Pisum sativum) and Snap Bean (Phaseolus vulgaris)

Field studies were conducted in 1987 and 1988 to investigate the control of common lambsquarters in pea and snap bean following preplant incorporated, preemergence, and postemergence applications of imazethapyr at 36 to 69 g ai/ha. The residual activity of imazethapyr on rotational crops of sweet corn, grain sorghum, and cucumber was evaluated. All rates of imazethapyr provided good (&gt;80% initially) control of common lambsquarters. Although imazethapyr caused some injury to both pea and snap bean, yields were not reduced except for snap bean following postemergence applications. Imazethapyr residues resulting from the applications of 36 to 69 g/ha caused visible injury and fresh weight reductions to all three rotational crops.