Application Of Mesotrione Research Articles

Effect of Different Doses of Herbicides on Growth and Yield in Maize (Zea mays L.)

A field experiment was conducted at Chandra Shekhar Azad University of Agriculture and Technology, Kanpur during Kharif season of 2021, to evaluate effect of different doses of Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC on growth and yield of maize (Zea mays L.). The experiment was laid down in the Randomized block design with ten treatments which was replicated three times. At 45, 60 and 90 DAS among different herbicidal treatments maximum plant height was observed in Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC) @ 1.0 kg a.i. ha-1. Among the herbicidal treatments, highest cob length (15.67 cm), grain rows per cob (13.26), grains per row (26.93) and grains per cob (370.83) was observed in the treatment T4 (Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC) @ 1.0 kg a.i. ha-1) followed by treatment T3 (Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC) @ 0.875 kg a.i. ha-1). Data from experiment revealed that significantly highest grain yield was recorded in weed free plot (35.65 q ha-1). While among herbicidal treatments, application of Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC @ 1.0 kg a.i. ha-1 (35.18) resulted in significantly higher grain yield followed by (T3) Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC @ 0.875 kg a.i. ha-1 (34.38 q ha-1). Among all the treatments all the parameters of crop growth and yield was highest in the weed free treatment (T9).

Impact of Different Doses of Herbicides on Weed Density and Weed Control Efficiency in Maize

A field experiment was conducted at Chandra Shekhar Azad University of Agriculture and Technology, Kanpur during Kharif season of 2021. To evaluate the effect of different doses of Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC on growth and yield of maize (Zea mays L.). The experiment was laid down in the Randomized block design with ten treatments which was replicated three times. Experimental Field was infested with Echinochloa colona, Digitaria sanguinalis, Dactyloctenium aegyptium, Commelina benghalensis, Trianthema and Cyperus rotundus. Ready-mix herbicide, Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC (Calaris Xtra) manufactured by Syngenta was used in the experiment. Among the herbicidal treatments, the application of Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC @ 1.750 kg a.i. ha-1 recorded the lowest weed density and highest weed control efficiency (approx. 90%) at every growth stage of maize. However, among herbicidal treatments, grain yield of maize was maximum with the application of Mesotrione 2.27% w/w + Atrazine 22.7% w/w SC @ 1.0 kg a.i. ha-1(T4) which might be due do toxicity effect of herbicide.

Confirmation of a four-way herbicide-resistant Palmer amaranth (Amaranthus palmeri) population in Iowa

Abstract Palmer amaranth (Amaranthus palmeri S. Watson) was first reported in Iowa in 2013 and has continued to spread across the state over the last decade. Importantly, A. palmeri is widely recognized as one of the more economically important weeds in production agriculture. The presence of A. palmeri in Iowa is concerning as the species has evolved resistance to nine herbicide sites of action, however, no formal characterization has been conducted on Iowa populations. Therefore, herbicide assays were conducted on an A. palmeri population collected in Harrison County, Iowa in 2023 (Southwest Palmer Amaranth, SWPA) and a known herbicide-susceptible population collected from Nebraska in 2001 (Palmer Amaranth Susceptible, PAS). The two populations were treated with preemergence and postemergence herbicides commonly used in Iowa. The treatments included preemergence applications of atrazine, metribuzin, and mesotrione and postemergence applications of atrazine, imazethapyr, glyphosate, lactofen, mesotrione, glufosinate, 2,4-D and dicamba at 1x and 4x the labeled rates. Survival frequency of SWPA was >90% when treated postemergence with 1x rates of imazethapyr, atrazine, glyphosate, and mesotrione compared to ≤6% for PAS. Both SWPA and PAS had 0% survival when treated with lactofen, glufosinate, 2,4-D, and dicamba at the 1x or 4x rates. Plant population density reduction for SWPA was 53% and 40% in response to 1x rates of preemergence-applied mesotrione and atrazine, respectively. Metribuzin applied preemergence reduced SWPA plant population density by >90% at both rates. Dose-response experiments revealed the 50% effective doses (ED50) of mesotrione, glyphosate, imazethapyr, and atrazine for SWPA were 9.5-,8.5-, 71- and 40-fold greater than for PAS, respectively. The results confirm that SWPA is four-way multiple herbicide-resistant. Amaranthus palmeri infestations are likely to continue to spread within Iowa, therefore diversified weed management programs that include early detection, rapid response, and effective multi-tactic management strategies will be required for control.

Control of giant ragweed (Ambrosia trifida) in mesotrione-resistant soybean

Abstract Preemergence applications of mesotrione, an herbicide that inhibits 4-hydroxyphenolpyruvate dioxygenase (HPPD), have recently gained regulatory approval in soybean varieties with appropriate traits. Giant ragweed is an extremely competitive broadleaf weed, and biotypes resistant to acetolactate synthase inhibitors (ALS-R) can be particularly difficult to manage with soil-residual herbicides in soybean production. This study investigated control of giant ragweed from preemergence applications of cloransulam (32 g ai ha–1), metribuzin (315 g ai ha–1), and S-metolachlor (1,600 g ai ha–1) in a factorial design with and without mesotrione (177 g ai ha–1) at two different sites over 2 yr. Treatments with mesotrione were also compared with two commercial premix products: sulfentrazone (283 g ai ha–1) and cloransulam (37 g ai ha–1), and chlorimuron (19 g ai ha–1), flumioxazin (69 g ai ha–1), and pyroxasulfone (87 g ai ha–1). At 42 d after planting, control and biomass reduction of giant ragweed were greater in treatments with mesotrione than any treatment without mesotrione. Giant ragweed biomass was reduced by 84% in treatments with mesotrione, whereas treatments without mesotrione did not reduce biomass relative to the nontreated. Following these preemergence applications, sequential herbicide treatments utilizing postemergence applications of glufosinate (655 g ai ha–1) plus fomesafen (266 g ai ha–1) and S-metolachlor (1,217 g ai ha–1) resulted in at least 97% control of giant ragweed at 42 d after planting, which was greater than sequential applications of glufosinate alone in 3 of 4 site-years. Preemergence applications of mesotrione can be an impactful addition to soybean herbicide programs designed to manage giant ragweed, with the potential to improve weed control and delay the onset of herbicide resistance by providing an additional effective herbicide site of action.

Sistema de consórcio de milho com gramíneas forrageiras e o uso de doses reduzidas do herbicida mesotrione

ABSTRACT Sowing forage grass species of the genera Urochloa and Panicum simultaneously with corn can hinder crop grain yield, requiring the application of low herbicide rates for suppressing their growth and preventing potential competition with corn plants. Therefore, the objective of this study was to evaluate the use of low rates of the herbicide mesotrione for inhibiting the growth of forage grass species (Urochloa ruziziensis and Panicum maximum, cultivars BRS Tamani and BRS Zuri) sown simultaneously with corn crop, as well as the recovery capacity of these grasses. Two experiments were installed, as first and second crop seasons, in a randomized experimental block design with four replications, using a 3×4 factorial arrangement and three control treatments with corn alone. Each of the three forage grasses was sown simultaneously with corn and subjected to post-emergence application of four mesotrione rates (0, 48, 96, and 144 g ha-1) with atrazine (1.25 kg ha-1). Weeds, forage grasses, and corn plants were evaluated. BRS Tamani was the most tolerant forage to mesotrione, while BRS Zuri was the most sensitive. The application of mesotrione + atrazine in the corn-forage grass intercropping system contributed to weed control. The tested forage grasses did not affect corn grain yield in the first or second crop season, even with no herbicide application.

Evaluation of sequential mesotrione application rates and sequential tolpyralate and mesotrione applications for narrow-leaved goldenrod management in lowbush blueberry

Sequential mesotrione applications of 72 g a.i. ha−1 gave similar control of narrow-leaved goldenrod as sequential applications of 144 g a.i. ha−1. This use pattern is recommended for narrow-leaved goldenrod management in lowbush blueberry. Early POST tolpyralate applications exhibited good crop tolerance and could be considered as part of a sequential herbicide program for lowbush blueberry.

A naked-eye visible aluminium (III)-based complex fluorescence sensor for sensitive detection of mesotrione

Mesotrione, which is a kind of herbicide to control broad-leaved weeds, has been increasingly used due to its excellent selectivity, rapid process and low toxicity. However, the excessive application of mesotrione have led to widespread contamination. Herein, a turn-on competitive coordination-based fluorescent probe, 2-hydroxy-1-(9-purin)-methylidenehydrazinenaphthalene (HPM), has been successfully synthesized. HPM could effectively detect Al3+ in CH3OH/HEPES (1/9, v/v) with low limit of detection (LOD) being 0.2 µM via coordination. HPM also exhibited excellent imaging capabilities for Al3+ in living cells with low cytotoxicity. On the basis of the competitive coordination of HPM with Al3+, the [HPM-Al3+] complex could also serve as a potential fluorescence sensor for detecting mesotrione with the LOD of 0.2 µM. Furthermore, [HPM-Al3+] complex was applied for the detection of mesotrione in real samples and test paper. Finally, the mechanism of [HPM-Al3+] for sensing mesotrione was investigated deeply as well. This work designed a new convenient method for on-site detection of mesotrione without the large-scale equipment or complicated pre-treatment.

Mesotrione: A New Herbicide for Productivity and Profitability of Maize (Zea mays L.)

The field experiment was conducted at Zonal Agricultural Research Station, University of Agricultural Sciences, GKVK, Bengaluru during summer 2021 to evaluate the effect of new generation mesotrione herbicide on growth and yield of maize (Zea mays L.). The experiment consists of application of different doses of mesotrione herbicide as early post emergent (EPoE) and weed free check and unweeded control were replicated thrice in RCBD. Major weeds observed were Alternanthra sessilis, Borreria articularis, Euphorbia geniculata, Cynodon dactylon, Dactyloctenium aegyptium, Echinochloa colonum, Eleusine indica and Cyperus rotundus. Post-emergent application of mesotrione 48% SC @ 120 ml ai. ha-1 recoded higher kernel yield, stover yield of maize and BC ratio (6273 kg ha-1, 7583.7 kg ha-1 and 2.94 respectively) and it was on par with mesotrione 48% SC @ 144 ml a.i. ha-1 (6075 kg ha-1, 7430 kg ha-1 and 2.79 respectively). Weedy check recorded a kernel yield (3090.7 kg ha-1), lower stover yield (4096.3 kg ha-1) of maize and lower BC ratio (1.03) compared to other treatments.

Developing a Localized Emergence Model of Echinochloa crus-galli to Predict Early Post-Herbicide Effectiveness in Maize

In order to achieve integrated weed management, precision timing is just as important an aspect to consider as spatial precision: the stage of the plant at the time of action will impact its successful control or survivability and thus the selection pressure for herbicide resistance. Weed emergence models are one aspect of this precision timing, but they are yet underutilized. One critique has been that models based on bare ground emergence are not always validated with emergence in the crop, and yet also residual herbicides and their timing may also affect the model. In this work, we compare emergence of Echinochloa crus-galli on bare ground and in maize and the impact of early post-residual herbicides at several timings. Experiments on bare ground and in maize were set in Prague, Czech Republic, in 2021, 2022, and 2023. Bare-ground quadrats of 0.25 m2 were randomly assigned in a space of 100 m2. Maize plot treatments of four herbicides at each of five timings were assigned in a randomized complete block design (dimethenamid-P at 1008 g ai ha−1, pethoxamid at 1200 g ai ha−1, isoxaflutole at 96 g ai ha−1, and mesotrione at 480 g ai ha−1). Three 0.25 m2 quadrats were enumerated in each plot from first emergence to full canopy closure (May to July). Model fit to emergence from the bare-ground plots using thermal time with a base temperature of 10 °C resulted in an AIC of −494. The bare-ground model was validated with emergence from the nontreated control plots in maize in 2022 and 2023, which accounted for over 85% of the variability in observed emergence. At canopy closure, total emergence since herbicide application was affected by herbicide and application timing. All herbicides at all timings reduced the emergence after application except for mesotrione. When beginning thermal time from the day of application, the emergence pattern after mesotrione application at all timings could be modeled with a single equation. E. crus-galli had a reliable emergence pattern within a local population; the predictive model created using bare-ground plots adequately predicted emergence in maize. This information can be used to time herbicides to coincide with the most effective moment in the flush in areas where E. crus-galli is the driver weed species.

Effect of Mesotrione 40% SC on Weed Growth, Yield and Economics of Maize (Zea mays L.)

Newer herbicides are required to reduce the losses cause by the weeds in maize crop. Therefore, a field experiment was conducted during kharif 2019 at Research Farm, AICRP on Forage Crops, Department of Agronomy, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (Madhya Pradesh) to study the effect of different weed management practices on productivity of Maize (Zea mays L.). The experiment was conducted in randomized block design with eight treatments (six herbicidal treatments with hand weeding twice at 20 and 40 DAS and weedy check) replicated thrice. Observations were recorded for various weed parameters and crop growth parameters. All the weed management treatments significantly reduced the total weed density and total dry weight of weeds as compared to weedy check. Among herbicidal treatments, mesotrione 350 g ha-1 recorded the lowest total weed density and total dry weight of weeds as compared to other herbicides. While highest total weed density and total dry weight were recorded under weedy check treatment. Significantly higher growth parameters and yield attributing traits were recorded with the application of mesotrione 350 g ha-1 which resulted in higher grain and stover yields (2447.22 and 21804.72 kg ha-1) followed by mesotrione 300 g ha-1. Maximum net returns and Benefit: Cost ratio was also obtained with the application of mesotrione 350 g ha-1.

Effect of Pre and Post-emergence Herbicides on Weed Flora of Maize

Weeds have been a problem creator in crops since time immemorial competing with them for all the growth resources. Weeds cause around 28-100% loss in the maize crop which necessitates their control. The usage of herbicides for the control of weeds has been the most prominent method among farmers. However, the continuous usage of similar herbicides can develop herbicide resistance which needs the exploration to newer herbicides. Therefore, a field experiment was carried out to assess the effect of broad-spectrum herbicide, mesotrione on the weed flora and seed yield of maize at JNKVV, Jabalpur (M.P.) in the kharif season of 2019. The experiment was carried out in randomised block design consisting of eight treatments of weed control including six herbicidal treatments with hand weeding and weedy check and replicated thrice. Based on the results, it was concluded that the post emergence application of mesotrione 350 g ha-1 at 30 DAS had most effectively controlled the weeds resulting in highest weed control efficiency (69.25%) and lowest weed index (12.62%) than the rest of the treatments. It also resulted in highest grain and stover yield (2.44 and 21.80 t ha-1) in maize. Thus, the application of mesotrione @ 350 g ha-1 can be a promising technology for the control of complex weed flora in maize.

Asiatic dayflower (Commelina communis) control in Douglas fir

AbstractAsiatic dayflower (Commelina communis L.) is becoming increasingly invasive in Christmas tree plantations in the U.S. Northeast. Response of C. communis to preemergence or postemergence herbicides was evaluated in separate field and greenhouse experiments. The preemergence herbicides consisted of two application rates of flumioxazin (215 and 429 g ai ha−1), hexazinone plus sulfometuron-methyl (316 and 527 g ai ha−1), indaziflam (41 and 82 g ai ha−1), and S-metolachlor (2,136 and 4,272 g ai ha−1). The postemergence herbicides were: bentazon at 1,121 g ai ha−1, clopyralid at 280 g ae ha−1, mesotrione at 526 g ai ha−1, topramezone at 294 g ai ha−1, and triclopyr at 842 g ae ha−1. At 16 wk after treatment, higher rates of flumioxazin (429 g ha−1), hexazinone plus sulfometuron-methyl (527 g ha−1), indaziflam (82 g ha−1), and S-metolachlor (4,272 ha−1) provided 80% to 92% control and reduced C. communis plant density by 84% to 93% compared with the nontreated control. The lower rates of flumioxazin (215 g ha−1), hexazinone plus sulfometuron-methyl (316 g ha−1), and S-metolachlor (2,136 ha−1) gave 65% to 72% control and reduced C. communis plant density by 27% to 75% compared with the nontreated control. The postemergence application of mesotrione at 526 g ha−1, topramezone at 294 g ha−1, and triclopyr at 842 g ha−1 resulted in 76% to 90% control and reduction in dry biomass of 10- to 12-leaf C. communis at 28 d after treatment. Bentazon at 1,121 g ha−1 and clopyralid at 280 g ha−1 applied postemergence were ineffective with <10% control and reduction in C. communis dry biomass. This study showed that C. communis can be managed effectively with currently registered preemergence and postemergence herbicides in Christmas trees.

Herbicide control of Ambrosia artemisiifolia in sunflower, soybean and maize

Abstract Ambrosia artemisiifolia L. (Asteraceae) has become a major threat to agriculture in many parts of the world. Global agriculture relies on the use of herbicides against A. artemisiifolia in the crops most at risk – sunflower, maize and soybean. This paper aims to provide an overview of the chemical control of A. artemisiifolia and to summarize the latest knowledge in this field. The sunflower is the crop most threatened by A. artemisiifolia, as both plants belong to the same family. The best control level was achieved after the preemergence application of flurochloridone and the combination of dimethenamid-P + pendimethalin. The introduction of the non-GM Clearfield and ExpressSun technologies allowed effective control with postemergence herbicides in sunflower varieties tolerant to imidazolinone and tribenuron-methyl herbicides. In soybean, the highest efficacy was observed in trials with imazamox and bentazone alone and in combination. The combination of imazamox with bentazone had a positive effect on yield compared to untreated stands. The introduction of transgenic soybeans tolerant to glyphosate led to increased glyphosate use and the predictable emergence of weed resistance in America in 1996. Preplant followed by postemergence herbicides were critical for the effective control of glyphosate-resistant A. artemisiifolia in glufosinate tolerant soybean. In maize, the highest efficacy was obtained after the application of glufosinate, bromoxynil and mesotrione + atrazine. Of the above substances for the control of A. artemisiifolia in maize, only mesotrione is currently registered in the EU.

Evaluation of broadcast and spot herbicide applications for spreading dogbane (Apocynum androsaemifolium L.) management in lowbush blueberry fields

Spreading dogbane is a creeping herbaceous perennial weed in lowbush blueberry. Management is limited primarily to spot applications of dicamba, though recent herbicide registrations facilitate the evaluation of new broadcast and spot herbicide applications. The objectives of this research were to determine (1) the effect of sequential postemergence (POST) mesotrione application interval on spreading dogbane, (2) the effect of sequential POST mesotrione and foramsulfuron applications on spreading dogbane, (3) the effect of POST herbicide tank mixtures on spreading dogbane, (4) the effect of summer and fall spot herbicide applications on spreading dogbane, and (5) the effect of spot applications of dicamba tank mixtures with sulfonylurea herbicides on spreading dogbane. Broadcast mesotrione (144 g a.i. ha−1) and foramsulfuron (35 g a.i. ha−1) applications did not control spreading dogbane. Control was not improved by sequential applications of either herbicide. Broadcast mesotrione + foramsulfuron applications reduced non-bearing-year density and may be more effective than either herbicide applied alone. Broadcast flazasulfuron applications reduced non-bearing-year shoot density and flazasulfuron + foramsulfuron applications reduced non-bearing-year and bearing-year shoot densities. Summer spot applications of foramsulfuron and flazasulfuron caused 70% injury to spreading dogbane but did not reduce shoot density, and dicamba continues to be the most effective spot herbicide treatment. Fall spot applications did not control spreading dogbane due to early senescence of spreading dogbane shoots. Spot applications of dicamba at 0.96 or 1.92 g a.e. L water−1 provided equivalent spreading dogbane control and efficacy was not improved by tank mixture with foramsulfuron, flazasulfuron, or nicosulfuron + rimsulfuron.

HPPD inhibitor-susceptible soybean growth, yield, and economic return following isoxaflutole and mesotrione applied postemergence

AbstractThe use of different herbicide-resistant soybean technologies in proximity could lead to injury and yield loss due to an application error. Research was initiated to evaluate the effect of 6.25%, 12.5%, and 100% doses of isoxaflutole and mesotrione field use doses applied postemergence to 4-hyroxyphenylpyruvate (HPPD) inhibitor-susceptible soybean, representing physical drift or misapplication doses. Visible injury manifested as chlorosis with slight necrosis, progressing to necrosis and height reduction, with visible height reduction as the only symptom. Isoxaflutole at 6.25% and 12.5% injured V2 soybean more than V1 or V4 soybean at all evaluation dates. This is supported by soybean height data at 14, 28, and 42 d after treatment (DAT). Following the 100% dose, maximum injury occurred at 28 DAT with V1, V2, and V4 soybean injured 90%, 85%, and 72%, but injury declined over time. All isoxaflutole treatments reduced yield at least 310 kg ha−1, with no differences among application timings or between the two lowest doses for a revenue loss of US$147 ha−1 to US$623 ha−1. Visible injury following mesotrione manifested as chlorosis and necrosis advancing to visible height reduction. Following mesotrione at 6.25% and 12.5%, injury ranged from 20% to 36% among application timings and did not differ at 3 to 21 DAT. Soybean heights at 28 and 42 DAT do not support injury observations; therefore, the greater injury was due to chlorosis and necrosis. Following mesotrione at 100%, sensitivity decreased at 3 to 14 DAT when applied to later growth stages, with no differences at 42 DAT. Yields did not differ among application timings, but yield losses were at least 240 kg ha−1, with revenue losses of US$60 ha−1 and US$373 ha−1. Producers are cautioned to prevent off-target movement or errant application of isoxaflutole or mesotrione to HPPD inhibitor-susceptible soybean.

Mesotrione and Amicarbazone Tank-mixtures for Annual Bluegrass (Poa annua) Control in Cool-season Turfgrass

Annual bluegrass (Poa annua L.) control with postemergence herbicides in cool-season turfgrass is often inconsistent. Amicarbazone and mesotrione have complementary modes of action but have not been evaluated in tank-mixtures for control of mature annual bluegrass in cool-season turfgrass. Field experiments were conducted during 2018 in New Jersey, and in Indiana, Iowa, and New Jersey during 2019 to evaluate springtime applications of amicarbazone and mesotrione for POST annual bluegrass control in cool-season turfgrass. On separate tall fescue (Festuca arundinacea Schreb.) and kentucky bluegrass (Poa pratensis L.) sites in 2018, three sequential applications of amicarbazone (53 g⋅ha−1) + mesotrione at 110 to 175 g⋅ha−1 provided >70% annual bluegrass control, whereas three sequential applications of amicarbazone alone at 53 and 70 as well as two sequential applications at 110 g⋅ha−1 provided <15% control at 14 weeks after initial treatment (WAIT). In 2019, results in New Jersey were similar to 2018 where amicarbazone alone provided less control than mesotrione + amicarbazone tank-mixtures. In Indiana, where the annual bluegrass infestation was severe and most mature, tank-mixtures were more effective than amicarbazone alone at 6 WAIT, but at 12 WAIT all treatments provided poor control. In Iowa, where the annual bluegrass infestation was <1 year old, all treatments provided similar control throughout the experiment and by >80% at the conclusion of the experiment. This research demonstrates that sequential applications of mesotrione + amicarbazone can provide more annual bluegrass control than either herbicide alone, but efficacy is inconsistent across locations, possibly due to annual bluegrass maturity and infestation severity.

Mesotrione: a new preemergence herbicide option for wild radish (Raphanus raphanistrum) control in wheat

AbstractWild radish is the most problematic broadleaf weed in Australian grain production. The propensity of wild radish to evolve resistance to herbicides has led to high frequencies of multiple herbicide–resistant populations present in these grain production regions. The objective of this study was to evaluate the potential of mesotrione to selectively control wild radish in wheat. The initial dose response pot trials determined that at the highest mesotrione rate of 50 g ha−1 applied preemergence (PRE) was 30% more effective than when applied postemergence (POST) on wild radish. This same rate of mesotrione applied POST resulted in a 30% reduction in wheat biomass compared to 0% for the PRE application. Subsequent mesotrione PRE dose response trials identified a wheat selective rate range of >100 and <300 g ai ha−1 that provided greater than 85% wild radish control with less than 15% reduction in wheat growth. Field evaluations confirmed the efficacy of mesotrione at 100 to 150 g ai ha−1 in reducing wild radish populations by greater than 85% following PRE application and incorporation by wheat planting. Additionally, these field trials demonstrated the opportunity for season-long control of wild radish when mesotrione applied PRE was followed by bromoxynil applied POST. The sequential PRE application of mesotrione, a herbicide that inhibits p-hydroxyphenylpyruvate dioxygenase, followed by POST application of bromoxynil, a herbicide that inhibits photosystem II, has the potential to provide 100% wild radish control with no effect on wheat growth.

Impacts of herbicide sequences and vertical tuber distribution on the chemical control of yellow nutsedge (Cyperus esculentus L.)

AbstractCyperus esculentus is an invasive perennial sedge threatening agricultural production. In Belgium, best in‐crop control options involve, amongst other methods, growing maize in monoculture which allows the sequential use of selective herbicides with activity against C. esculentus. Two pot experiments were carried out to investigate the effect of genetically different clones and chemical control strategy on C. esculentus control. Additionally, the effect of two vertical tuber distributions (uniform in the 0–26 cm layer or non‐uniform with 60% of the tubers in the 6 cm top‐layer) was studied. Strategies were based on S‐metolachlor, dimethenamid‐P, mesotrione, bentazon, pyridate, nicosulfuron, glyphosate, halosulfuron‐methyl, foramsulfuron and thiencarbazon‐methyl used in mixture and/or sequence and applied at different crop stages. Control efficacy was measured by analysing tuber number, dry tuber biomass and above‐ground dry biomass. Tuber number of clones treated by chemical control strategies was up to 100% lower and up to 41% higher relative to the untreated control. Clones showed up to 74% percentage point difference in control of tuber number. In both experiments, strategies with pre‐plant incorporated dimethenamid‐P followed by two post‐emergence applications of mesotrione and pyridate, in 5–6 leaf and 8–9 leaf stage of maize, was most effective and consistent across C. esculentus clones. In general, C. esculentus control was up to 27% better in plots with high proportion of superficially buried mother tubers than in plots with more uniform vertical mother tuber distribution. Hence, the vertical tuber distribution may significantly affect the performance of C. esculentus herbicidal strategies. Overall, chemical control strategies should be complemented with alternative methods (e.g. competitive cropping systems and non‐inversion tillage) to achieve satisfactory control.

Recurrent Selection with Sub-Lethal Doses of Mesotrione Reduces Sensitivity in Amaranthus palmeri.

Amaranthus palmeri, ranked as the most prolific and troublesome weed in North America, has evolved resistance to several herbicide sites of action. Repeated use of any one herbicide, especially at lower than recommended doses, can lead to evolution of weed resistance, and, therefore, a better understanding of the process of resistance evolution is essential for the management of A. palmeri and other difficult-to-control weed species. Amaranthus palmeri rapidly developed resistance to 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors such as mesotrione. The objective of this study was to test the potential for low-dose applications of mesotrione to select for reduced susceptibility over multiple generations in an A. palmeri population collected from an agricultural field in 2001. F0 plants from the population were initially treated with sub-lethal mesotrione rates and evaluated for survival three weeks after treatment. All F0 plants were controlled at the 1× rate (x = 105 g ai ha−1). However, 2.5% of the F0 plants survived the 0.5× treatment. The recurrent selection process using plants surviving various mesotrione rates was continued until the F4 generation was reached. Based on the GR50 values, the sensitivity index was determined to be 1.7 for the F4 generation. Compared to F0, HPPD gene expression level in the F3 population increased. Results indicate that after several rounds of recurrent selection, the successive generations of A. palmeri became less responsive to mesotrione, which may explain the reduced sensitivity of this weed to HPPD-inhibiting herbicides. The results have significance in light of the recently released soybean and soon to be released cotton varieties with resistance to HPPD inhibitors.

Breeding and Evaluation of Fine Fescues for Increased Tolerance to Mesotrione Herbicide

Fine fescues (Festuca sp.) are a group of species that require fewer inputs, such as fertilizer, than other cool-season species managed for turf. They are adapted to infertile, acidic soils; shade; and drought. One area that poses additional challenges is the lack of weed control options for fine fescues during establishment from seed. Mesotrione is a herbicide that provides preemergence control of many broadleaf and grassy weeds, such as annual bluegrass (Poa annua), but is currently not labeled for use in fine fescues at seeding. The objectives of this research were 1) to use a recurrent selection technique to develop mesotrione-tolerant chewings fescue (Festuca rubra ssp. commutata), hard fescue (Festuca brevipila), and strong creeping red fescue (F. rubra spp. rubra); and 2) to conduct field trials to compare the new selections to commercially available cultivars and experimental lines not selected for tolerance to mesotrione. Progress was made after each of the three generations of recurrent selection. The top statistical grouping of entries for injury following application of mesotrione at the 8-oz/acre rate included all the third-generation (G3) hard fescues, all the G3 chewings fescues, and the G3 strong creeping red fescue STB1 Composite. After three generations, selections of hard, chewings, and strong creeping red fescues had equivalent or better tolerance to mesotrione than tall fescue (Festuca arundinacea) and kentucky bluegrass (Poa pratensis) cultivars, which are on the label for safe use at seeding. These new selections would provide turf managers an option to control weeds using mesotrione during seedling establishment of fine fescues.