Post-emergence Herbicides For Weed Control Research Articles

Effectiveness and Selectivity of Pre- and Post-Emergence Herbicides for Weed Control in Grain Legumes.

Grain legumes represent important crops for livestock feed and contribute to novel uses in the food industry; therefore, the best cultivation practices need to be assessed. This study aimed to identify herbicides to meet the current need for controlling broadleaf weeds without phytotoxicity in the grain legume crop per se. Field experiments were undertaken during the 2019 and 2020 growing seasons and laid out in a randomized complete block design with three replicates as follows: four grain legume crops (vetch, pea, faba bean, and white lupine) and nine pre-emergence (PRE) or post-emergence selective (POST) herbicide treatments (PRE: aclonifen, pendimethalin plus clomazone, metribuzin plus clomazone, benfluralin, terbuthylazine plus pendimethalin, S-metolachlor plus pendimethalin, flumioxazin; POST: pyridate, imazamox) alongside weedy check plots. Plant phytotoxicity, crop dry matter, yield features, weed presence, and weed dry matter were assessed during the experiments. There was differential efficacy among the nine herbicide treatments; the weed control was more effective in the case of Veronica arvensis L. and Sonchus spp. L. compared with Chenopodium album L., Sinapis arvensis L., and Silibum marianum L. regardless of the herbicide treatment. The most effective PRE herbicide was flumioxazin, which had the greatest control over the majority of weeds (>70%) resulting in the lowest total weed biomass. The second-best treatment was benfluralin and the mixture of terbuthylazine plus pendimethalin (both had only limited control in S. arvensis). The best POST herbicide was imazamox, with only limited control in S. arvensis. The tested herbicides caused low to medium and transient levels of phytotoxicity mainly in vetch and secondly in peas but not in faba beans and lupines. Concerning all weed management treatments, benfluralin resulted in the highest grain yields for all four grain legume crops during both growing seasons. Among grain legumes, vetch had the highest competitive ability against weeds, whereas peas were the least tolerant against weed competition.

Pre- and Post-emergence Herbicides for Weed Control in Direct Sown Rice and their Residual effect on Succeeding Greengram

Pre- and Post-emergence Herbicides for Weed Control in Direct Sown Rice and their Residual effect on Succeeding Greengram

Novel phenoxy-(trifluoromethyl)pyridine-2-pyrrolidinone-based inhibitors of protoporphyrinogen oxidase: Design, synthesis, and herbicidal activity

As important chemical pesticides, protoporphyrinogen oxidase (PPO, EC 1.3.3.4) herbicides play a vital role in weed management. Herein, in a search for novel PPO herbicides, a series of phenoxypyridine-2-pyrrolidinone derivatives were synthesized and their herbicidal activities were tested. To confirm the structures of the newly synthesized compounds, a colorless single crystal of compound 9d was obtained and crystallographic data collected. PPO inhibition experiments showed that most compounds have PPO inhibitory effects. The half-maximal inhibitory concentration (IC50) of compound 9d and oxyfluorfen were 0.041 mg/L and 0.043 mg/L, respectively, which showed compound 9d was the most potent compound. Compound 9d reduced the Chlorophyll a (Chl a) and Chlorophyll b (Chl b) contents of Abutilon theophrasti (A. theophrasti), to 0.306 and 0.217 mg/g, respectively. Crop selectivity experiments and field trial indicated that compound 9d can potentially be used to develop post-emergence herbicides for weed control in rice, cotton, and peanut. Molecular docking studies showed that both oxyfluorfen and compound 9d can enter the PPO cavity to occupy the active site and compete with the porphyrin to block the chlorophyll synthesis process, affect photosynthesis, and eventually cause weed death. Compound 9d was found to be a promising lead compound for novel herbicide development.

Evaluation of pre- and post-emergence herbicides for weed control in maize (Zea mays L.)

A field experiment was conducted during 2014–2015 to investigate the efficacy of herbicides [Merlin flexx (isoxaflutole), pre- and post-emergence; Equip (foramsulfuron), post-emergence; and Maister (foramsulfuron + iodosulfuron-methyl-sodium), post-emergence] in maize (cv NSC 444) crops grown in the Prishtina region of Kosovo. The field experiment was set in a randomised block design with four replications and elementary plots of 10 m2. A total of 14 weed species were documented in the maize crop in 2014, which increased to 27 in 2015, with the dominant species being Amaranthus retroflexus (87.0 plants*m-2 in 2014 versus 43.3 plants*m-2 in 2015). The most efficient herbicides in both years were pre-emergence (98.1% vs 92.5%; 2014 vs 2015) and isoxaflutole post-emergence (98.8% vs 89.9%; 2014 vs 2015). All plots treated with herbicides significantly influenced the increase of maize yield in comparison with the control plots. In conclusion, the use of isoxaflutole either pre-emergence or post-emergence is recommended in the study region for successful weed control and high maize grain yields.

Efficiency of some herbicides and manual weeding for weed control in irrigated Bt cotton

To evaluate the efficacy of some pre and post-emergence herbicides for weed control in Bt cotton (var. Beejdhan 2), a field experiment was conducted during rainy seasons of 2014-15, 2015-16 and 2016-17 at Junagadh (Gujarat, India). The dominant weed flora in cotton field were Digera arvensis, Eluropus villosus, Cyperus rotundus, Cynodon dactylon, Echinochloa crusgalli, Chenopodium album, Convolvulus arvensis, Trianthema monogyna, Amaranthus spinosus, Commelina benghalensis and Asphodelus tenuifolius. The results revealed that treatments viz., hand weeding (HW) and interculturing (IC) at 30, 60 and 90 DAS, pendimethalin 0.9 kg ha-1 as pre-emergence fb HW and IC at 30 and 60 DAS, and pendimethalin 0.9 kg ha-1 as pre-emergence fb quizalofop 40 g ha-1 as post-emergence at 45 DAS were found superior to the unweeded check in enhancing growth and yield attributes viz., plant height, number of monopodial and sympodial branches plant-1, number of bolls plant-1, single boll weight and seed cotton weight plant-1 and ultimately increased seed cotton and stalk yields. These treatments also recorded lower dry weight of weeds and weed index along with higher weed control efficiency, net return and B:C ratio as compared to unweeded check.

Efficacy of post-emergence herbicides for weed control in soybean

A field experiment was conducted at Punjab Agricultural University, Ludhiana to study the efficacy of post-emergence herbicides for weed control in soybean. The herbicides (pendimethalin, imazethapyr, imazethapyr + imazamox and quizalofop-p-ethyl) did not show any significant adverse effects on the number, dry weight and leghaemoglobin content of nodules. Application of pendimethalin 0.45 kg/ha as pre-emergence (PE) + hand weeding (HW) at 40 days after sowing (DAS) recorded significantly higher seed yield than other treatments, however, it was at par with two hand weeding. Among the herbicides, imazethapyr at 75 g/ha applied at 3 weeks after sowing (WAS) recorded significantly higher seed yield than pendimethalin 0.45 kg/ha (PE) and weedy check and was at par with imazethapyr + imazamox 70 g/ha and quizalofop-p-ethyl 50 g/ha applied at 3 WAS. Application of pendimethalin 0.45 kg/ha (PE) + HW at 40 DAS provided the highest net returns (` 49496/ha) followed by two hand weedings. However, application of post-emergence herbicides imazethapyr at 75 g/ha and imazethapyr + imazamox 70 g/ha at 3 WAS were found promising in controlling weeds, providing optimum seed yield and higher B: C ratio. In case of scarcity of labour, post-emergence herbicides can play an important role in controlling weeds effectively.

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

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

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

Efficacy of pre-and post-emergence herbicides for weed control in greengram

A field experiment was conducted during rainy seasons in 2011 and 2012 to study the efficacy of pre-and post-emergence herbicides on weeds, growth, symbiotic traits and grain yield of greengram. Preemergence application of pre-mix pendimethalin + imazethapyr at 1.0 kg/ha showed lowest weed index and highest weed control efficiency, followed by pre-mix pendimethalin + imazethapyr at 0.75 kg/ha and two hand weedings done at 20 and 40 days after sowing. Post-emergence application of quizalofop-ethyl at 37.5 g/ha reduced the number and dry weight of nodules/plant compared to other herbicides. Weed free treatment provided the highest grain yield, gross returns and net returns. Among the herbicides, preemergence application of pre-mix pendimethalin + imazethapyr at 1.0 and 0.75 kg/ha recorded higher grain yield (1.41 and 1.31 t/ha, respectively) and provided higher net returns (` 52970 and ` 48390, respectively) and B: C ratio (2.57 and 2.44, respectively) than the other treatments of herbicides due to significant reduction in the dry weight of weeds and higher weed control efficiency and consequently improving the yield attributing parameters.

Post-emergence herbicides for weed control in sesame

On the basis of above findings, it may be concluded that treatment Two hand weeding at 20 and 40 DAS, followed by treatment Propaquizafop 10% EC (PoE) 50 g/ha are most effective and remunerative weed control practices for controlling the weeds in sesame under sandy clay loam soils of Northern M.P.. The higher grain yield and net return were obtained from treatment two hand weeding at 20 and 40 DAS.

Effective post-emergence herbicides for weed control in rice nurseries

On farm experiments were conducted during Kharif seasons of 2011 and 2012 to study efficacy of postemergence herbicides bispyribac-sodium 25 g/ha for broad-spectrum weed control in rice nursery. Among the different treatments, post-emergence application of bispyribac-sodium 25 g/ha applied at 15 DAS (days after sowing) significantly reduced total weed density with weed control efficiency of 90.9 to 97.6% for Echinochloa crus-galli, Trianthema portulacastrum and Cyperus iria. Among other treatments, pre-emergence application of pretilachlor + safener 0.15 kg/ha also recorded significantly lower weed density as compared to control (unweeded). Although weed control efficiency of this treatment was relatively higher for E. crus-galli (84.7%) but for T. portulacastrum and C. iria, this treatment recorded weed control efficiency of 75.9 and 71.2%, respectively. Farmers practice (increased seed rate 100 g/m2) also recoded significantly lower weed density as compared to control (unweeded) but the weed control efficiency was quite low against E. crus-galli (36.8%) and C. iria (28.1%); however, it was relatively higher for T portulacastrum (66.0%) with mean of 43.7%.

Pre-and post-emergence herbicides for weed control in greengram and their residual effect on succeeding crops

Comparative efficacy of pre-and post-emergence herbicides in greengram and their residual effect on succeeding crops was studied during Kharif season of the year 2011–2013. Inter-culturing and hand weeding carried out at 20 and 40 DAS produced the lowest weed dry weight with higher weed control efficiency. Among herbicidal treatments, pre-emergence application of pendimethalin at 500 g/ha or imazethapyr 75 g/ha followed by interculturing and hand weeding at 30 DAS proved to be efficient in reducing weed dry weight with more than 70% of weed control efficiency and recorded higher seed and haulm yield of greengram. Further, it was observed that none of the herbicides applied at tested rates had adverse effect on succeeding wheat, chickpea and mustard crops.

Post-emergence herbicides for weed control in blackgram

Experiment was conducted in the Research cum Instructional Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh during Kharif season 2009. The treatment comprised of 14 weed management practices and blackgram variety “TU94-2 ”. The results revealed that higher plant population, plant height, number of leaves, number of branches, dry matter accumulation, number of nodules, dry weight of nodules, crop growth rate, seed yield, weed growth rate, weed control efficiency and harvest index were obtained under hand weeding twice (20 and 40 DAS), followed by imazethapyr at 25 g/ha pre-emergence and minimum was obtained under unweeded check

Large Genetic Variability in Chickpea for Tolerance to Herbicides Imazethapyr and Metribuzin

Chickpea (Cicer arietinum L.) is known to be sensitive to many herbicides and, therefore, choices for using post-emergence herbicides for weed control are limited. The present study was aimed at identifying sources of tolerance to two herbicides with different modes of action (imazethapyr—amino acid synthesis inhibitor; and metribuzin—photosynthesis inhibitor) for use in breeding herbicide tolerant cultivars. Screening of 300 diverse chickpea genotypes (278 accessions from the reference set and 22 breeding lines) revealed large genetic variations for tolerance to herbicides imazethapyr and metribuzin. In general, the sensitivity of the genotypes to metribuzin was higher compared to that for imazethapyr. Several genotypes tolerant to metribuzin (ICC 1205, ICC 1164, ICC 1161, ICC 8195, ICC 11498, ICC 9586, ICC 14402 ICC 283) and imazethapyr (ICC 3239, ICC 7867, ICC 1710, ICC 13441, ICC 13461, ICC 13357, ICC 7668, ICC 13187) were identified, based on average herbicide tolerance scores from two experimental locations each. The herbicide tolerant lines identified in this study will be useful resources for development of herbicide tolerant cultivars and for undertaking genetic and physiological studies on herbicide tolerance in chickpea.

Dry-seeded rice culture in Punjab State of India: Lessons learned from farmers

Dry-seeded rice (DSR) is an emerging production system in Asia in the face of looming water scarcity, labor scarcity, and the energy crisis. The rice yield in this production system is highly variable. A survey was conducted during the kharif seasons of 2011 and 2012, comprising 320 randomly selected farmers covering all the major agroclimatic regions of Punjab State of India to understand the cultural practices, farmers’ perceptions, and reasons for the yield gap in DSR. Farmers used seeding rates from 15 to 40kgha−1, depending upon the type of seed drill used and agroecological conditions. About 65% of the farmers used drills with inclined plates, a seed-metering device, and on a “custom hiring” basis. More than 90% of the farmers chose cultivars for dry seeding by considering their yield potential, suitability to agroecological zones, and being easy to sell. Among the farmers surveyed, about 45% of them adhered to recommended practices of fertilizer application. Weeds were reported as the main biological constraints in DSR culture. Only 46% of the farmers applied both pre- and postemergence herbicides for weed control. About 67% of the farmers used flood jet or cone-type nozzles for herbicide spray, resulting in additional hand-weeding by 42% of the farmers due to poor weed control. The survey revealed that non-adherence to a recommended fertilizer schedule and weed control package (appropriate herbicides, optimum application time of herbicides, optimum volume of water for spraying, and selection of the right nozzles) is one of the reasons for the existing yield gap. Site-specific agrotechnologies for DSR need to be developed and transferred to farmers to achieve high yield. The survey also revealed that tailoring cultivars for dry-seeding conditions is needed for further productivity gains in DSR.

Pre and postemergence herbicides for weed control in castor crop

Weed management is among the main factors limiting cultivation of castor (Ricinus communis) in extensive fields, particularly when labor is scarce or expensive. This experiment evaluated the efficiency of weed management programs using preemergence (clomazone, pendimethalin, and trifluralin) and a postemergence herbicide (chlorimuron-ethyl) applied at 20 days after emergence in castor plants cv. BRS Energia under rainfed conditions in Apodi, Brazil. No phytotoxicity was observed on the castor plants, and the postemergence herbicide significantly increased castor seed yield to 1466kgha−1 complementing the weed control of preemergence herbicides treatments in which seed yield was 1207kgha−1. Seed yield on weedy and weed-free treatments was 760 and 1971kgha−1, respectively. Weeds were kept under a satisfactory control up to 40 days after emergence. This program resulted in reasonable weed control because the preemergence herbicides controled monocotyledon weeds, while the postemergence herbicide controlled broad leafed species being selective to castor plants.

Manejo de plantas daninhas em milho safrinha em cultivo solteiro ou consorciado à braquiária ruziziensis

O objetivo deste trabalho foi avaliar a eficiência de herbicidas pós-emergentes no controle das plantas daninhas, e sua seletividade à braquiária (Urochloa ruziziensis) e ao milho safrinha, em cultivo solteiro ou consorciado. O experimento foi conduzido em delineamento de blocos ao acaso, com quatro repetições, em esquema fatorial 2x14: cultivo do milho consorciado ou não à braquiária e 14 tratamentos químicos, além de duas testemunhas, com ou sem controle das plantas daninhas. Avaliou-se o controle das plantas daninhas, a fitotoxicidade para braquiária e a produtividade do milho. Todos os tratamentos com herbicidas proporcionaram controle acima de 80% das plantas daninhas aos 14 dias após a aplicação. As misturas formuladas de atrazina+óleo, a 800 e a 1.200 g ha-1, compuseram o grupo de herbicidas mais seletivos a U. ruziziensis; o grupo de menor seletividade consistiu da aplicação isolada de tembotrione ou de suas associações com atrazina. A competição com a braquiária reduziu a produtividade do milho em até 45,3%. Contudo, não houve diferença entre os tratamentos nas parcelas tratadas com herbicidas.

Evaluation of some pre and postemergence herbicides for weed control in yacon

Weed control was investigated in yacon (Smallanthus sonchifolius Asteraceae) a herbaceous perennial that produces edible tubers Eight preemergence (alachlor acetochlor simazine diuron pendamethalin dimethanamid methabenzthiazuron and metribuzin) and two postemergence (linuron and methabenzthiazuron) herbicides were evaluated in field trials at Pukekohe All preemergence herbicides except metribuzin were tolerated by yacon but the best weed control was achieved with acetochlor metribuzin and dimethanamid Weeds in the untreated control caused a 62 reduction (Plt;005) in root weight relative to acetochlor alachlor metribuzin and dimethanamid The postemergence herbicides were both phytotoxic to yacon top growth but the plants subsequently recovered and plant crown production at harvest was not reduced relative to the control (P>005)

Tolerance of Grindelia chiloensis (Asteraceae) to pre- and postemergence herbicides

Several species of Grindelia (Asteraceae) are known to produce diterpene resin acids with potential uses in the naval stores industry. In recent years, the focus has changed from G. camporum to Grindelia chiloensis as the main candidate for domestication, because of its significantly higher resin content. Most agronomic technology developed for G. camporum has been adapted to G. chiloensis, although weed competition continues to be a problem during establishment, resulting in reductions in plant stands. The objective of this work was to evaluate pre- and postemergence herbicides for weed control in irrigated stands of G. chiloensis. Two greenhouse and field experiments were conducted to evaluate the effect of commercially available broad-spectrum herbicides on biomass production and resin content. Only Dual 8E, Karmex 80DF, AAtrex, and Caparol 4L at intermediate to low doses can be used safely as preemergent herbicides. Once the stand has been established, either by direct seeding or by clone transplanting, pendimenthalin, linuron, propaquazifop, haloxifop- R-methyl, or fluazifop- p-butyl, can be used, because, biomass accumulation was not affected by these herbicides. MCPA when applied at the six to ten leaf stage caused severe damage and plant mortality. Resin content ranged between 22 to 25% (dry weight basis) and no differences were present between the treated and control plants.

Thrips Injury Can Reduce Peanut Yield and Quality under Conditions of multiple Stress

AbstractSevere injury from tobacco thrips [Frankliniella fusca (Hinds)] to seedling peanut (Arachis hypogaea L.) has not been documented to reduce yield and quality. However, thrips injury may be economically important when combined with another factor, such as postemergence herbicide injury. This note reports results of a field experiment in which control of tobacco thrips during an unusually dry early season greatly increased peanut seed yield and quality. ‘Florunner’ peanut was grown using preplant and postemergence herbicides for weed control. Treatments consisted of an untreated control and four labeled insecticides applied at planting or soon after crop emergence. Populations of adult tobacco thrips were significantly suppressed by aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde O‐(methylcarbamoyl) oxime]; all insecticides significantly suppressed immature thrips. Aldicarb, the most efficacious insecticide treatment, significantly improved peanut yield by 32% and quality as determined by percentage of total sound mature kernels. All but one of the remaining insecticide treatments significantly improved seed yield, with increases ranging from 9 to 31%. Rainfall was extremely low early in the growing season, and (based on 41 yr of records at the site) drier conditions occur 10% of the time. This is a frequency great enough to matter, but low enough to make further research difficult. The observations reported here suggest that early‐season moisture stress intensifies peanut yield and quality losses associated with combined injury from thrips and postemcrgence herbicides.