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Pre‐emergent herbicides can reduce the abundance of invasive annual plants, but they can also harm native plants, particularly annuals or perennial seedlings, including seeds planted during restoration. We assessed the effects of imazapic and indaziflam on invasive target and nontarget native plants in the Great Basin, a region with extensive invasive annual grasses. We tested nontarget effects on native annual forbs in an agricultural field previously used to grow native annual forbs, which contained a large seed bank. We seeded perennial grass (Elymus elymoides) at multiple depths to determine susceptibility and resistance. Herbicides were applied at full and reduced rates to mimic the effect of litter in natural systems. We observed reductions in most non‐native species in all treatments, but also extensive reductions of native annual forbs, although these were offset at lower application rates, and some species (e.g. Amsinckia tessellata and Microsteris gracilis) were less susceptible than others. Herbicides, particularly indaziflam, reduced E. elymoides emergence, but planting seeds at 2–3 cm depths improved emergence, particularly for imazapic, with 15–68% greater emergence than seeds planted at 1 cm. We suggest surveys for native annual forbs and resistant invaders before applying herbicides and field testing to determine whether reduced rates could provide weed control while maintaining annual forbs. We suggest planting E. elymoides at 2–3 cm when applying herbicides, an approach that may be effective for other species. Herbicide use can be an effective tool, but our results indicate that mitigation of nontarget effects will be needed to maintain native plant diversity. [ABSTRACT FROM AUTHOR]

Community‐type conversions, such as replacement of perennials by exotic annual grasses in semiarid desert communities, are occurring due to plant invasions that often create positive plant–soil feedbacks, which favor invaders and make restoration of native perennials difficult. Exotic annual grass control measures, such as pre‐emergent herbicides, can also alter soil ecosystems directly or indirectly (i.e. via the plant community), yet there are few studies on the topic in natural, non‐cropped landscapes. We asked how spray treatments applied to soil post‐fire with the intention of inhibiting invasive annual grasses (such as Bromus tectorum L.) and releasing existing native perennial grasses affected soil resources, a microbial process, and invertebrates in three climatically varied sagebrush steppe sites. Spray treatments included chemical herbicides (imazapic and rimsulfuron) that strongly affected plant communities and a bioherbicide (Pseudomonas fluorescens strain D7) that did not. Chemical herbicides increased soil mineral nitrogen in proportion to their negative effects on plant cover for 2 years after treatments in all sites and increased soil water and net N mineralization (measured at one site) but did not affect total carbon, nitrogen, or organic matter. Invertebrate responses to herbicides varied by site, and invertebrates increased with chemical herbicides at the highest, wettest site. We show that herbicide treatments can exacerbate pulses of mineral nutrients, which previous studies have shown can weaken ecosystem resistance to invasion. Thus, restoration strategies that increase the likelihood that desired plants can capture mineralized nutrients after herbicide application will likely be more successful. [ABSTRACT FROM AUTHOR]

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Preemergent herbicides are a frequent weed control strategy. Considering different crop germinative fluxes, these products must present long-lasting weed control. This study evaluated preemergent herbicides in different germination fluxes of Merremia aegyptia, Mucuna aterrima and Ricinus communis when applied to different quantities of straw and different simulated dry periods. The experiment was conducted in a 4 × 2 × 2 factorial design with four replications. The treatments included four dry periods (0, 30, 60, and 90 days), two straw quantities (0 and 10 t ha 1), and two germination fluxes. The herbicides amicarbazone (1225 g ha-1), imazapic (147 g ha- 1), sulfentrazone (800 g ha-1), and tebuthiuron (900 g ha-1) were applied for preemergence weed control, and germination flush fluxes were evaluated at 7, 14, 21, 28, and 35 days after emergence (DAE) while verifying plant dry mass. Amicarbazone controlled less than 80% of the studied species at the 90-day dry period in the presence of straw. Imazapic did not present control residue for any of the species analyzed. Sulfentrazone showed the same control pattern at all germination fluxes, regardless of the amount of straw. Tebuthiuron successfully controlled all species in the first germination flush, exceeding 80% regardless of the amount of straw. Herbicides associated with straw quantities and dry periods have a significant impact on M. aegyptiaca, M. aterrima and R. communis. Highlights: • The herbicide amicarbazone demonstrated efficacy in controlling during the first germination period of the three weed species. • The presence of sugarcane straw significantly influenced the herbicides' control efficacy, especially during prolonged dry periods. • The combination of straw and extended dry periods resulted in a reduction in control rates with tebuthiuron.

Pre‐emergent herbicides, commonly employed for managing invasive annual plants, often fail to meet restoration targets due to the absence of remnant perennial plants, which leaves sites vulnerable to re‐invasion and hinders effective control of annual grasses. Combining an herbicide treatment with seeding is therefore desirable, but seeded plants can also be negatively impacted by pre‐emergent herbicides. Herbicide protection (HP) seed technologies use activated carbon to adsorb herbicide near seeds and have shown promise for allowing simultaneous deployment of herbicide and seed, but recent research recommends numerous additional refinements be tested. We addressed some of these recommendations through one laboratory and a field trial replicated at multiple sites to explore whether commercially produced, single‐seed HP coatings with two different rates of activated carbon can prevent herbicide‐related damage to two perennial bunchgrasses native to the western United States. We also investigated how these coated prototypes compare in performance to the multi‐seed extruded herbicide protection pellets (HPPs) tested in prior research. In the laboratory, neither coating treatment reduced total emergence, emergence rate, survival, or biomass in the absence of herbicide. In the presence of herbicide, both provided several‐fold higher survival and aboveground biomass compared to untreated bare seed, but this represented incomplete protection from herbicide. In field trials where conditions were harsher than the laboratory, we found no evidence of HP from any treatment, and HPPs reduced seedling count for one species. We conclude that the tested HP coating prototype is an improvement over HPPs but requires additional refinements and testing. [ABSTRACT FROM AUTHOR]

Imazapic is an acetolactate synthase-inhibiting herbicide labeled for weed control in pastures, rangeland, and noncrop areas. Field research was conducted in Knoxville, TN, USA, during 2020 and 2021 to evaluate the tolerance of four hybrid bermudagrass (Cynodon dactylon × Cynodon transvaalensis Burtt Davy) cultivars to applications of imazapic for growth suppression. Separate experiments were conducted on 'TifTuf', 'Tifway', 'Tahoma 31', and 'Latitude 36' hybrid bermudagrass. Experiments included plots (1.5 m2) arranged in a randomized complete block design with four replications and were repeated. Treatments were applied 14 Aug 2020 and 6 Aug 2021, and were mixed with methylated seed oil. Imazapic rates were 0, 35, 52.5, 70, or 105 g·ha-1. Cultivar tolerance was assessed via visual ratings of turfgrass injury relative to untreated check plots. Normalized differential vegetation index data were collected on each date turfgrass injury was evaluated. Growth suppression was quantified via reductions in dry clipping weight after mowing. Hybrid bermudagrass injury increased with imazapic rate for all cultivars, and peak injury (> 30%) following all imazapic treatments occurred within 14 days. At the lowest imazapic rate (35 g·ha-1), injury was transient, with all hybrid bermudagrass cultivars fully recovered by 28 days. All rates of imazapic reduced hybrid bermudagrass dry clipping weight for 21 days for all cultivars. Further research is warranted to explore lower application rates than those tested in our study, in addition to determining tolerance and growth suppression of other turfgrass species commonly managed on golf courses. [ABSTRACT FROM AUTHOR]

Land managers rely heavily on herbicides to mitigate exotic plant invasions but the nontarget effects of herbicides on treated plant, animal, and soil communities are often overlooked. Biological soil crusts (biocrusts) are important components of ecosystems yet the effects of different herbicides on biocrusts are rarely considered. We tested the impact of three widely used herbicides, indaziflam, imazapic, aminocyclopyrachlor, and chlorsulfuron, two of which were applied with or without a surfactant, on biocrusts dominated by mosses or lichens in intermountain grasslands. We found that neither the herbicides nor surfactant impacted biocrust moss or lichen cover within 2 years of their application. [ABSTRACT FROM AUTHOR]

【Objective】The study was conducted to monitor the effects of imazapic on the number of culturable microorganisms, the number of herbicide-resistant microorganisms and soil enzyme activities of rice fields in Guangdong area, aiming to provide a reference basis for the effects of herbicide application on soil ecology in agricultural fields.【Method】The number of culturable microorganisms and herbicide-resistant bacteria in paddy field soil under water direct-seeding and dry direct-seeding modes were monitored by plate counting method. Activities of soil urease, phosphatase, peroxidase and peroxidase were determined by sodium phenol-sodium hypochlorite colorimetric method, sodium phosphate colorimetric method, o-phenylene triol-ether extraction method and potassium permanganate titration method.【Result】After planting one crop of rice, the application of imazapic enhanced soil peroxidase activity significantly by 30% under water direct-seeding mode, and increasing soil acid phosphatase and urease enzyme activities significantly by 136.2% and 9.6% respectively under dry direct-seeding mode. Under both direct-seeding modes, the imazapic had no significant influence on the number of culturable fungi. However, under water direct-seeding mode, the number of bacteria and imazapic-tolerant bacteria decreased by 28.7% and 29.5%, respectively. The total number of actinomycetes and imazapic-resistant actinomycetes decreased by 24.2% and 40.7%, respectively. Under the dry direct-seeding mode, imazapic treatment had little effect on bacteria. The total number of actinomycetes decreased by 26.7%, and the number of herbicide-tolerant actinomycetes decreased by 45.9%.【Conclusion】The application of imazapic was effective in enhancing soil peroxidase activity under water direct-seeding mode, and enhancing the enzyme activities of soil acid phosphatase and urease under dry direct-seeding mode. Compared with manual weeding treatments, application of imazapic under water direct-seeding mode inhibited the growth of soil bacteria, and the application of herbicide inhibited the growth of soil actinomycetes under both water- and dry direct-seeding modes.

Sericea lespedeza (Lespedeza cuneata) is an invasive nonnative legume that commonly occurs on sites managed for northern bobwhite (Colinus virginianus). Sericea reduces bobwhite habitat availability by outcompeting native plants that provide food and cover. Sericea can be controlled with postemergence herbicides such as glyphosate as well as a mixture of triclopyr with fluroxypyr, but these herbicides do not provide preemergence control. Imazapic has been effective at controlling a limited number of planted sericea seeds, but the efficacy of imazapic at various application rates to control sericea seedbank response following treatment with a postemergence herbicide has not been evaluated. We designed a field experiment to evaluate sericea control and changes in the plant community as related to bobwhite habitat with 2 postemergence herbicides followed by preemergence treatment of imazapic at 3 sites in Tennessee and Alabama, USA, 2018–2022. Specifically, we treated sericea with postemergence broadcast applications of glyphosate or triclopyr with fluroxypyr in 2018 and applied spot treatment with the same herbicides in 2019–2021. We applied imazapic at 4 rates following prescribed fire in 2019 and 2022. We measured coverage of sericea, native forbs, annual grasses, perennial grasses, and bobwhite food plants before treatment in 2018 and after all treatments in 2022. Nearly all postemergence treatments reduced sericea coverage, but imazapic did not increase control compared to postemergence herbicides alone. Perennial grasses used for nesting and bobwhite foraging were maintained following treatments. We recommend managers use either glyphosate or triclopyr with fluroxypyr to control sericea postemergence and consider using a low rate of imazapic to reduce annual grasses if coverage is a problem on the site. [ABSTRACT FROM AUTHOR]

Sagebrush ecosystems of western North America are threatened by invasive annual grasses and wildfires that can remove fire‐intolerant shrubs for decades. Fuel reduction treatments are used ostensibly to aid in fire suppression, conserve wildlife habitat, and restore historical fire regimes, but long‐term ecological impacts of these treatments are not clear. In 2006, we initiated fuel reduction treatments (prescribed fire, mowing, and herbicide applications [tebuthiuron and imazapic]) in six Artemisia tridentata ssp. wyomingensis communities. We evaluated long‐term effects of these fuel treatments on: (1) magnitude and longevity of fuel reduction; (2) Greater Sage‐grouse habitat characteristics; and (3) ecological resilience and resistance to invasive annual grasses. Responses were analyzed using repeated‐measures linear mixed models. Response variables included plant biomass, cover, density and height, distances between perennial plants, and exposed soil cover. Prescribed fire produced the greatest reduction in woody fuel over time. Mowing initially reduced woody biomass, which recovered by year 10. Tebuthiuron did not significantly reduce woody biomass compared to controls. All woody fuel treatments reduced sagebrush cover to below 15% (recommended minimum for Greater Sage‐grouse habitat), but only prescribed fire reduced cover to below controls. Median mowed sagebrush height remained above the recommended 30 cm. Cheatgrass (Bromus tectorum) cover increased to above the recommended maximum of 10% across all treatments and controls. Ecological resilience to woody fuel treatments was lowest with fire and greatest with mowing. Low resilience over the 10 posttreatment years was identified by: (1) poor perennial plant recovery posttreatment with sustained reductions in cover and density of some perennial plant species; (2) sustained reductions in lichen and moss cover; and (3) increases in cheatgrass cover. Although 10 years is insufficient to conclusively describe final ecological responses to fuel treatments, mowing woody fuels has the greatest potential to reduce woody fuel, minimize shrub mortality and soil disturbance, maintain lichens and mosses, and minimize long‐term negative impacts on Greater Sage‐grouse habitat. However, maintaining ecological resilience and resistance to invasion may be threatened by increases in cheatgrass cover, which are occurring regionally. [ABSTRACT FROM AUTHOR]

Abstract Sagebrush ecosystems of western North America are threatened by invasive annual grasses and wildfires that can remove fire‐intolerant shrubs for decades. Fuel reduction treatments are used ostensibly to aid in fire suppression, conserve wildlife habitat, and restore historical fire regimes, but long‐term ecological impacts of these treatments are not clear. In 2006, we initiated fuel reduction treatments (prescribed fire, mowing, and herbicide applications [tebuthiuron and imazapic]) in six Artemisia tridentata ssp. wyomingensis communities. We evaluated long‐term effects of these fuel treatments on: (1) magnitude and longevity of fuel reduction; (2) Greater Sage‐grouse habitat characteristics; and (3) ecological resilience and resistance to invasive annual grasses. Responses were analyzed using repeated‐measures linear mixed models. Response variables included plant biomass, cover, density and height, distances between perennial plants, and exposed soil cover. Prescribed fire produced the greatest reduction in woody fuel over time. Mowing initially reduced woody biomass, which recovered by year 10. Tebuthiuron did not significantly reduce woody biomass compared to controls. All woody fuel treatments reduced sagebrush cover to below 15% (recommended minimum for Greater Sage‐grouse habitat), but only prescribed fire reduced cover to below controls. Median mowed sagebrush height remained above the recommended 30 cm. Cheatgrass (Bromus tectorum) cover increased to above the recommended maximum of 10% across all treatments and controls. Ecological resilience to woody fuel treatments was lowest with fire and greatest with mowing. Low resilience over the 10 posttreatment years was identified by: (1) poor perennial plant recovery posttreatment with sustained reductions in cover and density of some perennial plant species; (2) sustained reductions in lichen and moss cover; and (3) increases in cheatgrass cover. Although 10 years is insufficient to conclusively describe final ecological responses to fuel treatments, mowing woody fuels has the greatest potential to reduce woody fuel, minimize shrub mortality and soil disturbance, maintain lichens and mosses, and minimize long‐term negative impacts on Greater Sage‐grouse habitat. However, maintaining ecological resilience and resistance to invasion may be threatened by increases in cheatgrass cover, which are occurring regionally.

Abstract Invasions by exotic annual grasses (EAGs) are replacing native perennials in semiarid areas globally, including the vast sagebrush‐steppe rangelands of western North America. Efforts to eradicate EAGs and restore perennials have had mixed success, especially in relatively warm and dry areas where EAGs had high dominance prior to intervention. Greater consideration of the ecological sources of variability in EAG treatment outcomes may improve success. We hypothesized that herbicide and restoration outcomes would be influenced by restoration strategy (type of herbicide, seeding or planting, timing of treatment) and underlying spatial variability associated with plant community patch type and litter, all applied in a landscape‐scale experiment in a severely invaded area in Southern Idaho, USA. EAGs, specifically medusahead (Taeniatherum caput‐medusae [L.] Nevski), were strongly reduced for up to 3 years (maximum observation period) by the pre‐emergent herbicide indaziflam, whereas the pre/post‐emergent imazapic reduced EAGs only when applied twice. Indaziflam effects were greater when post‐spray moisture was greater, and also when co‐applied with imazapic, but reapplying indaziflam did not lead to additional reduction of EAGs. Imazapic and indaziflam each stimulated species‐specific, secondary invasion by exotic and/or invasive tall forbs. Application of the broadleaf herbicide aminopyralid provided only a fleeting 1 year of control of a dominant, highly noxious forb skeletonweed (Chondrilla juncea L.). Underlying heterogeneity in plant community patch type (dominant herb species) explained only ∼5% of variation in the herbicide effects, and manipulation of litter prior to spraying had no effect. Several years of seedings and planting resulted in no establishment of native perennials. Herbicides, especially indaziflam, appear to be an effective tool for reducing EAGs for multiple years in the challenging restoration conditions we evaluated, particularly if their application coincides with suitable moisture. However, restoring the perennials required for longer term resistance to reinvasion is a serious challenge that could be avoided with preservation of perennials.

Questions: Selective herbicide application is a common restoration strategy to control exotic invaders that interfere with native plant recovery after wildfire. Whether spraying with pre-emergent or bio-herbicides releases native plants from competition with exotics (“spray-and-release” strategy) and makes communities resistant to reinvasion by exotic annual grasses (e.g. cheatgrass, medusahead), without risks to non-target native plants or secondary invasion, is a major question for land managers of semiarid plant communities. Location: Sagebrush steppe of southwest Idaho, USA. Methods: We applied chemical herbicides (imazapic, rimsulfuron) and weedsuppressive bacteria (Pseudomonas fluorescens strains MB906 and D7) to three sagebrush steppe communities after fire. We measured plant cover prior to burning and for four years (five for exotic annual grasses) post treatment. Results: Both chemical herbicides significantly reduced exotic annual grass cover in all communities in the first post-spraying year, but rimsulfuron plots were re-invaded after 1–2 years, while imazapic plots continued to resist reinvasion four and even five years post spraying, well after the herbicide should have degraded. We did not detect any increase in native perennial grass cover with either herbicide, and herbicides had both positive and negative effects on individual bunchgrass basal diameter, depending on species and plant community. Rimsulfuron was more damaging than imazapic to shallow-rooted perennial bunchgrasses. Moss and lichen cover, key components of soil integrity, increased with chemical herbicide treatments in some communities. Both herbicides increased secondary invaders (exotic forbs or grasses), which varied by plant community and herbicide. Weed-suppressive bacteria treatments had no significant effects on cover of any functional group. Conclusions: While short-term effects of chemical herbicides that target exotic annual grasses were relatively consistent and predictable, longer-term effects were specific to the herbicide and plant community. The “spray-and-release” strategy may confer resistance to re-invasion by exotic annual grasses if herbicides prevent re-invasion for an extended period. [ABSTRACT FROM AUTHOR]

The effect of herbicide residues in leaves and fruits of some crops is one of the important issues of concern for the environment and health in general. This includes a number of pesticides that are currently widely used, including imazepic, chlorosulfuron and glyphosate. The three herbicides were used in three concentrations: 100, 200 and 400 ppm in three sprays. The study included determining the quantities of the three herbicides residues in the leaves and fruits of the tomato crop after spraying and during nine periods (a month after the first spray, at the second and third spray, or after two weeks or four weeks after each spray). The results showed a significant decrease in the residual herbicides under study in the leaves and the concentration rate of the pesticide decreased after the end of the spraying period and returned to higher levels after the second or third spraying. In general, the concentration of pesticide residues in leaves or fruits increased with increasing pesticide concentration. The concentrations of herbicides residues decreased significantly after two months of spraying and were in fruits below the detection levels. [ABSTRACT FROM AUTHOR]

Virginia's pasturelands are dominated by tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons. [Poaceae]), a competitive, non-native grass. Tall fescue has limited value for wildlife and insect pollinators, and it can pose issues for livestock if infected with an endophyte that produces a toxic alkaloid. Potential exists for developing more biodiverse pasturelands that would help reduce problems associated with tall fescue while increasing ecosystem services associated with improved wildlife and pollinator habitat. Native warmseason grasses (NWSG) and wildflowers (WF) have potential forage and conservation benefits; however, more research is needed to determine effective strategies that land managers can use to establish these species. This article summarizes 4 field experiments designed to evaluate establishment methods for NWSG and WF in tall fescue pasturelands. Experiments were established from 2016 to 2020 in central and western Virginia. Three evaluated preemergent imazapic herbicide applications while the fourth evaluated other methods, including glyphosate application, glyphosate combined with raking, prescribed fire, and tillage, to establish NWSG and WF. In the 3 experiments evaluating imazapic applications, the herbicide consistently suppressed wildflowers, with the exception of Rudbeckia hirta L. (Asteraceae), Desmanthus illinoensis (Michx.) MacMill. ex B.L. Rob. & Fernald (Fabaceae), Coreopsis lanceolata L. (Asteraceae), and Leucanthemum vulgare Lam. (Asteraceae). In the fourth experiment, tillage was the most effective method to establish wildflowers. Overall, we found imazapic can improve NWSG establishment, but suppresses most WF species tested in this environment. Methods to achieve more consistent WF establishment are needed if adoption of more biodiverse pasturelands becomes a future management goal. [ABSTRACT FROM AUTHOR]

Imidazolinones are a group of herbicides with high potential of leaching and long half-lives that are posing a threat to water resources' quality especially in tropical areas. Biochar, a carbon-rich bio-sorbent, has shown its ability to stabilise organic substances in soils and therefore, potentially is able to reduce their leaching. Biochar is a sustainable and cost-effective material which can be produced from locally available wastes. This work, for the first time, evaluated the biochar's effects on leaching of two polar members of imidazolinones family namely imazapic and imazapyr, and also Onduty® which is a mixture of these two herbicides, in heavy soil of tropical paddy fields. Leaching columns accompanied with artificial irrigation were used during the laboratory experiment. The herbicides were extracted from both collected leachates and soil columns. Soil amendment with designed biochars significantly reduced the herbicides' leaching percentages. Oil palm empty fruit bunch (OPEFB) and rice husk (RH) were used as pyrolysis feedstock. About 16% of the applied imazapic was leached out from biochar-free soil. For RH and OPEFB biochar-amended soils, the amounts were 4.3% and 3.6%, respectively. The highest percentage of imazapyr leached out from non-amended soil was (14.2%) followed by RH (4.0%) and OPEFB (2.8%) in biochar-amended soils. Also, 15.2% of the applied Onduty® was leached from non-amended soil. Adding RH and OPEFB biochars could reduce the herbicide leaching to 4.2% and 3.0%, respectively. Soil amended with biochars retained the higher percentages of the herbicides in top 7.5 cm depths. The media sorption capacities were negatively correlated to the amounts of herbicides leached out from soils but positively to the amounts of the herbicides remaining in the soil. Total amount of herbicides adsorbed by biochars-amended soils was more than 95%. Cation/water bridging ion exchange, ligand exchange, electrostatic attraction, and hydrophobic partitioning are the main ways imidazolinones can be adsorbed to soil. It was concluded that biochar application has the potential to reduce polar imidazolinones' leaching and their environmental pollution. The custom-engineered biochars can specifically control the pesticides transfer and then can certainly enhance the biochars' commercial values for their applications in the environment. [ABSTRACT FROM AUTHOR]

Invasion by exotic grasses is degrading dryland ecosystems worldwide and efforts to restore native vegetation in invaded areas have been largely unsuccessful. Control of invasive grasses with herbicide also limits restoration efforts using native seed. In this study, we evaluated two approaches that could allow for the restoration of a native species Pseudoroegneria spicata while reducing an invasive annual grass Bromus tectorum with a herbicide mixture in the sagebrush steppe ecosystem (the United States). We used two methods to protect native seeds from herbicide: activated carbon was applied as a seed coating with the intent of absorbing the herbicide around the seed, and furrows were used to side‐sweep soil sprayed with herbicide away from the planted seed. Our results indicate that imazapic + glyphosate herbicide application had a strong negative effect on the invasive annual grass, reducing B. tectorum cover 91% after 1 year, and 39% after 2 years. Herbicide also had strong negative effects on P. spicata without a carbon‐coating or furrow treatment, reducing seedling emergence 38%, 2‐year plant density 65%, and 2‐year total growth 90%. Both activated carbon seed coatings and furrow treatments limited herbicide effects on P. spicata 2‐year growth, but neither treatment alone mitigated herbicide effects on all life stages. Combining carbon coatings and furrow treatments mitigated harmful herbicide effects on several plant stages (seedling emergence, plant densities, and growth). Our results suggest that combining activated carbon coatings and furrow results in similar establishment of a native perennial as a non‐herbicide seeding and lowers B. tectorum abundance. [ABSTRACT FROM AUTHOR]

ABSTRACT In the plantation of sugarcane, Imazapic has used pre- or post-emergence, alone or in combination with other herbicides. When applied to the soil in pre-emergence, Imazapic can undergo the sorption, leaching and/or degradation processes due to physical, chemical and biological effects, besides being absorbed by weeds. The objective of this work was to evaluate the interaction and mobility of the Imazapic herbicide in the soil where the soil columns with a dystrophic Yellow Ultisol (YUd) and a dystrophic Red-Yellow Oxisol (RYOd) from northeastern Brazil were used. The higher adsorption potential of the RYOd is associated with higher clay content, higher Fed and Feo concentrations, and soil acidic pH. The CDE – 2 sorption sites model adequately represented the experimental data from the Imazapic breakthrough curves to the RYOd and YUd soils. From the Kd partition coefficients for RYOd and YUd, high values of the GUS index (5.94 and 7.04, respectively) were calculated, confirming the high leaching potential of the Imazapic molecule in these soils.

Top-down and bottom-up factors affecting invasive populations are rarely considered simultaneously, yet their interactive responses to disturbances and management interventions can be essential to understanding invasion patterns. We evaluated post-fire responses of the exotic perennial forb Chondrilla juncea (rush skeletonweed) and its biocontrol agents to landscape factors and a post-fire combined herbicide (imazapic) and bacteria (Pseudomonas fluorescens strain MB906) treatment that targeted invasive annual grasses in a sagebrush steppe ecosystem. Biocontrol agents released against C. juncea in previous decades included Cystiphora schmidti (gall midge), Aceria chondrillae (gall mite), and Puccinia chondrillina (rust fungus). C. juncea abundance was greater in sprayed than unsprayed plots, and where soils were coarser, slopes faced southwest, solar heat loads and topographic water accumulation were greater, and cover of deep-rooted native perennials was lower. Mite infestation was greater in unsprayed plots, midge infestation was greater at higher elevations on steeper slopes, and midges were more abundant while rust was less abundant on gravelly soils. Biocontrol infestation levels varied considerably between years and could not be predicted in 2019 from 2018 infestation levels. Multiple biocontrol species were often present at the same plots but were rarely present on the same C. juncea individuals. These results suggest that spatial patterns of invasion by C. juncea are related to deep-soil water availability, warmer conditions, and alleviation of competition. Treatments designed to reduce invasive annual grasses may inadvertently release C. juncea by both reducing plant competition for soil resources and affecting biocontrol agent (mite) abundance. [ABSTRACT FROM AUTHOR]

Semiconductor nanoparticle-mediated photocatalysis is an attractive option for water decontamination, being the semiconductors as SnS2 with a bandgap in the visible region, the most promising materials. In the present work, we evaluated the influence of important parameters in the photocatalytic application of SnS2 nanoparticles. Our results show that the presence of citric acid (used as a capping agent) restricts the formation of hexagonal nanoparticles. We also demonstrated that using thioacetamide as a sulfur source results in smaller nanoparticles than thiourea, 24.0 nm and 616 nm respectively. Moreover, small hexagonal nanoparticles play a key role in the photocatalytic activity of SnS2 nanoparticles. Compared with TiO2 performance, SnS2 nanoparticles exhibited faster kinetics for methyl orange (MO) degradation, Kapp = 0.0102 min−1, and 0.029 min−1, respectively. We proved that SnS2 is capable of breaking the azo bond of methyl orange by direct reduction. Furthermore, our analyses indicate that SnS2 nanoparticles do not degrade atrazine and imazapic, but the photocatalytic route of metribuzin competed with photolysis, resulting in a particular transformation product that was not obtained with light irradiation only. We demonstrated that SnS2 nanoparticles have high bond selectivity for azo breaking. Furthermore, they represent an advance for the development of designed materials (such as heterostructures), where the properties of SnS2 can be tuned. [ABSTRACT FROM AUTHOR]

Questions: Invasive-plant treatments often target a single or few species, but many landscapes are diversely invaded. Exotic annual grasses (EAGs) increase wildfires and degrade native perennial plant communities in cold-desert rangelands, and herbicides are thus sprayed to inhibit EAG germination and establishment. We asked how EAG target and non-target species responded to an herbicide mixture sprayed over a large, topographically diverse landscape after wildfire. We focused on how whole-community and natural EAG-pathogen treatment responses varied over years and physical properties of sites. Location: Sagebrush steppe of southwest Idaho, USA. Methods: We monitored plant cover and diversity in 41 pairs of plots located inside or outside areas (486 ha total) treated with a combined aerial broadcast spray of pre-emergent herbicide (imazapic) and weed-suppressive bacteria (Pseudomonas fluorescens, "MB906") to target EAGs after wildfires. Results: EAG cover and exotic species richness were initially less in treated plots but increased to levels similar to or greater than those of untreated plots by the third post-treatment year. The EAG pathogen Ustilago bullata was not directly affected by the treatment. The treatment increased exotic perennial forb cover in all plots and exotic annual forb cover in cooler/wetter plots but reduced exotic annual forb cover in warmer/drier plots. Cover of the invasive biennial grass Poa bulbosa decreased more across study years in untreated than treated plots. Among natives, the treatment reduced perennial grass cover and annual forb presence but led to marginal increases in perennial forb cover and, on soils with less gravel, increased shrub presence. Conclusions: A treatment targeting a single plant functional group did not achieve lasting success in these diversely invaded communities. Spraying alone did not release native perennials sufficiently to counteract the simultaneous release of secondary invaders and the return of target invaders. Planting or seeding may also be needed to achieve management goals. [ABSTRACT FROM AUTHOR]

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The phytostimulation is a phytoremediation technique that can be used to remediate area contaminated with herbicides. It is necessary to select plants with high capacity to stimulate soil microbial activity. The present work aimed at evaluating seven plant species regarding their ability to phytostimulate soil and enhance the degradation of the herbicides imazethapyr, imazapic and imazapyr in a lowland soil. An Alfisol Albaqualf was cultivated with the following species, Canavalia ensiformis, Glycine max, Oryza sativa cultivar PUITÁ INTA CL, Lolium multiflorum, Vicia sativa and consortium Lotus corniculatus + Trifolium repens. The rhizosphere of these plants and non-rhizospheric (uncultivated soil) as a control were contaminated in laboratory with analytical standart of the three herbicides, at rates of 0, 150, 300 and 750 g a.i. ha−1, in separate assays. Biodegradation was estimated by quantifying C–CO2 production and through analysis of herbicides residues in soil using liquid chromatography. Results show that biodegradation of herbicides imazethapyr, imazapic and imazapyr was higher in vegetated soil than in unvegetated soil. The leguminous species Canavalia ensiformis, Glycine max, Vicia sativa and consortium of Lotus corniculatus + Trifolium repens showed a great capacity to promote soil microbial, resulting in average biodegradation rates of 91, 92 and 93% for herbicides imazethapyr, imazapic and imazapyr in soil, respectively. [ABSTRACT FROM AUTHOR]

Detections of the regulated noxious parasitic weed branched broomrape (Phelipanche ramosa) in California tomato fields have led to interest in eradication, sanitation, and management practices. Researchers in Israel developed a decision-support system and herbicide treatment regime for management of Egyptian broomrape (P. aegyptiaca) in tomato. Research was conducted in 2019 and 2020 to evaluate whether similar treatments could be used to manage branched broomrape in California processing tomatoes and to provide registration support data for the herbicide use pattern. Treatment programs based on preplant incorporated (PPI) sulfosulfuron and chemigated imazapic were evaluated in 2019 and 2020 to determine safety on the processing tomato crop and on common rotational crops. Three single-season tomato safety experiments were conducted and a single rotational crop study was conducted in which a tomato crop received herbicide treatments in 2019 and several common rotational crops were planted and evaluated in 2020 in a site without branched broomrape. In 2020, an efficacy study was conducted in a commercial tomato field known to be infested with branched broomrape to evaluate the efficacy of PPI sulfosulfuron and chemigated imazapic, imazapyr, imazethapyr, and imazamox. After two field seasons, sulfosulfuron and imazapic appeared to have reasonable crop safety on tomato in California; however, rotational crop restrictions will need to be considered if sulfosulfuron is used to manage branched broomrape. In the efficacy study, there was a trend in which the sulfosulfuron and imidazolinone treatments had fewer broomrape shoots per plot than the grower standard treatments, however, none were fully effective and there were no significant differences among the various sulfosulfuron and imidazolinone treatment combinations. Additional research is needed to optimize the treatment timing for management of branched broomrape in this cropping system. Because of registration barriers with imazapic in the California market, future research will focus on treatment combinations of PPI sulfosulfuron and chemigated imazamox rather than imazapic.

Analysis of herbicides sorption behavior in soil is critical in predicting their fate and possible harmful side effects in the environment. Application of polar imidazolinone herbicides is growing in tropical agricultural fields. Imidazolinones have high leaching potential and are persistent. In this study, adsorption–desorption of imazapic and imazapyr herbicides were evaluated in different types of Malaysian agricultural soils. Effects of soil parameters were also investigated on the soils' sorption capacities. The adsorption data fitted best to Freundlich isotherm (R2 > 0.991). The herbicides adsorptions were physical and spontaneous processes as ΔG values were negative and below 40 kJ/mol. The adsorption correlated positively with clay content, total organic carbon (TOC) content, and cation exchange capacity (CEC). There were strong negative correlations between hysteresis index and these factors indicating their importance in imidazolinones immobilization and, thus, their pollution reduction in the environment. [ABSTRACT FROM AUTHOR]

Native warm-season grass (NWSG) roughs provide environmental and aesthetic value to golf courses; however, weed competition is a constraint during establishment. This research evaluated the effects of common turfgrass preemergence herbicides on establishment of newly seeded 1:1 mixture of little bluestem [Schizachyrium scoparium (Michx.) Nash] and sideoats grama [Bouteloua curtipendula (Michx.) Torr.] (14.3 lb total seed acre-1) rough. Herbicides applied immediately after drill-seeding included: atrazine (1.0 lb a.i. acre-1), dimethenamid-P (1.5 lb acre-1), dithiopyr (0.38 lb acre-1), imazapic (0.06 lb acre-1), indaziflam (0.029 lb acre-1), isoxaben (1.0 lb acre-1), Smetolachlor (2.48 lb acre-1), oxadiazon (4.0 lb acre-1), pendimethalin (1.47 lb acre-1), prodiamine (0.75 lb acre-1), and simazine (1.0 lb acre-1). Effects upon NWSG plant density and biomass, as well as smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. exMuhl.] control, were evaluated in 2017 and 2018. Across years, imazapic, dimethenamid, oxadiazon, and metolachlor controlled crabgrass >90%. In 2017, little bluestem plant density assessed 4 months after treatment was 2 to 13 times greater in imazapic-treated plots than all other treatments except for those treatedwith isoxaben and simazine. Application of imazapic resulted in greater little bluestem aboveground biomass than all other herbicide treatments, except simazine, in 2017. In 2018, imazapic resulted in greater little bluestem plant density than the untreated control, atrazine, prodiamine, oxadiazon, isoxaben, or simazine. Although it was a minor component of the sward, sideoats grama was generally tolerant of imazapic. Imazapic application during seeded establishment of little bluestem and sideoats grama golf course rough provides acceptable crop tolerance and smooth crabgrass control. [ABSTRACT FROM AUTHOR]

Water pollution by pesticides and other chemical contaminants is a subject of major importance due to the risk for human health and the environment. The search for remediation processes able to withdraw chemical contaminants from water and to allows water reuse is an urgent need. Herein, a simple and cheap system for pesticides removal was constructed and evaluated using water samples contaminated with two widely used herbicides (imazapic and imazethapyr, at g L−1 level). Operation parameters and process efficiency, in terms of removal rate in the reclaimed water and degradation rate of pesticides in the dry residue, were quantitatively determined. The model was tested in real-world field experiments and was able to remove more than 99.95% of both contaminants from a 10 L solution containing 4.16 ± 0.94 g of imazethapyr and 1.31 ± 0.17 g of imazapic, generating reusable water with minimum volume loss (<2.5%). Liquid chromatography coupled to mass spectrometry was used to determine the herbicides content in all samples and to estimate the degree of degradation of the substances as well as the occurrence of transformation products of imazapic and imazethapyr. The system efficiency in removing contaminants of emerging concern from surface water was also evaluated. The process have generated output water with undetected levels for two fungicides present in a local river in Southern Brazil. • A new system to pesticides removal from water was evaluated. • Removal of imazapic and imazethapyr from highly contaminated effluents was achieved. • The system was able to remove >99.95% from a water source with grams per liter of both pesticides. • Nearly 97.8% of the contaminated effluent volume was recovered as reusable water. • The system was verified using real field conditions and a commercial pesticide formulation. [ABSTRACT FROM AUTHOR]

The residual activity of herbicides may be detrimental to the environment, requiring analysis of the persistent residues in the soil and water. A field study was conducted to measure the residues of Imidazolinone (IMI) in three Clearfield® rice field soils at three different locations in Malaysia. The analyses of IMI in the soil samples were carried out using a high-performance liquid chromatography (HPLC). These herbicides are widely used; however, few studies have been conducted on both residues, especially in the context of Malaysian soil. Residues of imazapic and imazapyr were found to fall within 0.03–0.58 µg/mL and 0.03–1.96 µg/mL, respectively, in three locations. IMI herbicides are persistent in the soil, and their residues remain for up to 85 days after application. A pre-harvest study was suggested for these herbicides on water, which will provide a clearer indicator on the use of IMI in Clearfield® rice fields. [ABSTRACT FROM AUTHOR]

Microalgae are commonly used in ecotoxicity testing due to their ease of culturing and rapid cell division rates. These tests generally utilise a single species of algae; however, microalgae occur in the environment as complex communities of multiple species. To date, routine multispecies toxicity tests using tropical microalgae have not been available. This study investigated four tropical freshwater microalgal species for use in a chronic multispecies toxicity test based on the population growth (cell division) rate: Pediastrum duplex, Monoraphidium arcuatum , Nannochloropsis -like sp. and Chlorella sp. 12. Flow cytometric analysis identified the different fluorescence and light scattering properties of each algal species and quantified each species within multispecies mixtures. Following optimisation of test media nutrients and pH, a toxicity testing protocol was developed with P. duplex , M. arcuatum and Nannochloropsis -like sp. There were no significant differences in growth rates of each alga when tested over 72 h as single species or in multispecies mixtures. Atrazine and imazapic, two herbicides with different modes of action, were used to assess the sensitivity of the multispecies toxicity test. Atrazine was toxic to all species with 72-h IC10 values of 7.2, 63 and 280 μg/L for P. duplex , M. arcuatum and Nannochloropsis -like sp. respectively, while imazapic was not toxic to any species at concentrations up to 1100 μg/L. The toxicity of atrazine and imazapic to each microalgal species in the multispecies toxicity test was the same as that determined from single-species toxicity tests indicating that the presence of these microalgae in a mixture did not affect the toxicity of these two herbicides. This study is the first to develop a multispecies tropical microalgal toxicity test for application in freshwaters. This time- and cost-effective tool can be utilised to generate data to assist environmental decision making and to undertake risk assessments of contaminants in tropical freshwater environments. Image 1 • Multispecies toxicity test developed using three tropical freshwater microalgae. • No differences in growth rate for each species in single or multispecies tests. • Flow cytometric analysis used to identify and quantify individual species. • Toxicity of atrazine and imazapic were assessed for each species simultaneously. • Time and cost effective tool for assessing risk of contaminants in freshwater. This study developed a novel multispecies microalgal toxicity test for application in assessing environmental risk of contaminants in tropical freshwater systems. [ABSTRACT FROM AUTHOR]

Parasitic plants belonging to the Orobanchaceae family include species that cause heavy damage to crops in Mediterranean climate regions. Phelipanche aegyptiaca is the most common of the Orobanchaceae species in Israel inflicting heavy damage to a wide range of broadleaf crops, including processing tomatoes. P. aegyptiaca is extremely difficult to control due to its minute and vast number of seeds and its underground association with host plant roots. The highly efficient attachment of the parasite haustoria into the host phloem and xylem enables the diversion of water, assimilates and minerals from the host into the parasite. Drip irrigation is the most common method of irrigation in processing tomatoes in Israel, but the delivery of herbicides via drip irrigation systems (herbigation) has not been thoroughly studied. The aim of these studies was to test, under laboratory and greenhouse conditions, the factors involved in the behavior of soil-herbigated imazapic, and the consequential influence of imazapic on P. aegyptiaca and tomato plants. Dose-response Petri dish studies showed that imazapic does not impede P. aegyptiaca seed germination and non-attached seedlings, even at the high rate of 5000 ppb. Imazapic applied to tomato roots inoculated with P. aegyptiaca seeds in a PE bag system revealed that the parasite is killed only after its attachment to the tomato roots, at concentrations as low as 2.5 ppb. Imazapic sorption curves and calculated Kd and Koc values indicated that the herbicide Kd is similar in all soils excluding a two-fold higher coefficient in the Gadash farm soil, while the Koc was similar in all soils except the Eden farm soil, in which it was more than twofold lower. In greenhouse studies, control of P. aegyptiaca was achieved at >2.5 ppb imazapic, but adequate control requires repeated applications due to the 7-day half-life (t1/2) of the herbicide in the soil. Tracking of imazapic in soil and tomato roots revealed that the herbicide accumulates in the tomato host plant roots, but its movement to newly formed roots is limited. The data obtained in the laboratory and greenhouse studies provide invaluable knowledge for devising field imazapic application strategies via drip irrigation systems for efficient and selective broomrape control.

ABSTRACT The commercial mixture of imazethapyr and imazapic herbicides has been used for the control of red rice and several other species of weeds found in rice crops; this system called Clearfield. However, its use may limit the succession of non-tolerant crops for long residual activity. The research objective with this work was to determine the persistence of imazethapyr, imazapic and their mixture in three soils in the Brazilian state of Tocantins. Three experiments were conducted in a completely randomized design with four replications, each corresponding to the evaluated soil (Haplic Plinthosol (FX), red-yellow Latosol (LVA) and Haplic Gleysol (GX)). The treatments were arranged in a split plot design, with the allocated plots herbicides (imazethapyr and imazapic alone and commercial mixture) and the plots allocated the 11 evaluation times (1, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 days after treatment (DAT)), and a control without application. Contacted up long residual effect of imazethapyr and commercial mixture of imazethapyr and imazapic, regardless of assessed soil. After 150 days of applying herbicides or the commercial mixture, their residues in the soil also inhibited approximately 94% of the mass of the dry matter accumulation of the indicator plants. When imazapic was applied alone, there was a higher dry matter accumulation of the indicator plants, indicating less residual effect of this herbicide in the soil and this was attributed to the lower dose of this herbicide applied. The attributes of the soil pH, texture and iron oxides were what most affected the persistence of the herbicides. It can be concluded that the persistence of imazethapyr and imazapic is too long in the Brazilian state of Tocantins soils and the use of these herbicides in the region should be avoided due to the high risk of the occurrence of carryover,or be well planned, as land use in rotation for susceptible crops.

Highlights • Imidazolinone herbicides were resistant to hydrolysis degradation. • Soil amendment with EFB and RH biochars reduced photolysis rates of imidazolinones. • EFB biochar had the greater effects on photo-degradation. • Soil amendment with EFB and RH biochars enhanced bio-degradation of imidazolinones. • RH biochar had the greater effects on bio-degradation. Abstract Imidazolinones as a persistent and active herbicides group have potential risks to non-target organisms in the environment. Biochar is a carbon-rich sorbent used as an amendment to change soil properties and its microbial communities effective on pesticides degradation rate. The present study was the first to compare empty fruit bunch (EFB) of oil palm and rice husk (RH) biomasses as biochar feedstock for remediation of imidazolinones-contaminated soils. Degradations of imazapic, imazapyr, and a mixture of them (Onduty®) was investigated in the presence of the optimized biochars in the soil during a 70-days incubation. Based on the results, the polar herbicides were resistant to hydrolysis degradation. Photolysis rates of the herbicides reduced significantly in the presence of the biochars in the soil. EFB biochar had greater effects due to its chemical compositions and surface functional groups. Photo-degradation of imazapyr was more affected by biochars amendment. The imidazolinones bio-degradation, however, accelerated significantly with the presence of EFB and RH biochars in soil with the greater effects of RH biochar. It was concluded that the application of the optimized EFB and RH biochars as an innovative sustainable strategy has the potential to decrease the persistence of the imidazolinones and minimize their environmental hazards. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Competition control is essential for successful eucalyptus plantation establishment, yet few selective herbicides have been identified. Five herbicides, flumioxazin, imazamox, imazapic, oxyfluorfen, and sulfometuron methyl, were evaluated at either pre- or post-weed emergence timing for selective weed control in the establishment of Eucalyptus benthamii, a frost-tolerant species showing promise for commercial plantations in the southeastern United States and southern Brazil. Herbicides were applied at two or three rates and compared to a non-treated control and to near-complete weed control obtained with repeated glyphosate directed sprays. Herbicides were most efficacious when applied prior to weed emergence, at 2 weeks after planting 16-week-old containerized eucalyptus seedlings. Pre-emergence imazapic treatments resulted in broad-spectrum and persistent weed control, with 77-82% bare-ground at 60 days after treatment, but both pre- and post-emergence applications of imazapic caused excessive eucalyptus injury at the highest rate tested. Imazapic, sulfometuron, and imazamox were most effective for grass control. Both timings of flumioxazin were effective for forb control at the early assessment. All pre-emergence treatments enhanced stem volume compared to the non-treated control, but post-emergence treatments did not, suggesting the need for early weed control to facilitate E. benthamii growth. Pre-emergence applications of medium and high sulfometuron, low imazapic, high imazamox, and high oxyfluorfen rates increased stem volume four-fold to six-fold compared to the non-treated control. Repeated glyphosate directed sprays increased stem volume nearly three-fold compared to the control. These results confirm one early report of flumioxazin effectiveness and identify imazamox and imazapic as new selective herbicides for eucalyptus culture. [ABSTRACT FROM AUTHOR]

Sunflower broomrape ( Orobanche cumana ) is a root holoparasitic plant causing major damage to sunflower ( Helianthus annuus L.). Parasite infection initiates source-sink relations between the parasite (sink) and the host (source), allocating carbohydrates, water and nutrients to the parasite. The primary aim of the current study was to explore responses of sunflower to broomrape parasitism, specifically to examine alternations in leaf area, leaf mass per area (LMA), mesophyll structure and root hydraulic conductivity. Leaf changes revealed modifications similar to described previously in shade adapted plants, causing larger and thinner leaves. These traits were accompanied with significantly higher root hydraulics. These changes were caused by carbohydrate depletion due to source-sink relationships between the host and parasite. An Imazapic herbicide (ALS inhibitor) was used for controlling broomrape attachments and by to investigate the plasticity of the traits found. Broomrape infected plants which were treated with Imazapic had leaves similar to non-infected plants, including mesophyll structure and carbon assimilation rates. These results demonstrated source-sink effects of broomrape which cause a low-light-like acclimation behavior which is reversible. [ABSTRACT FROM AUTHOR]

Medusahead ( Taeniatherum caput-medusae [L.] Nevski) and other exotic annual grasses have invaded millions of hectares of sagebrush ( Artemisia L.) steppe. Revegetation of medusahead-invaded sagebrush steppe with perennial vegetation is critically needed to restore productivity and decrease the risk of frequent wildfires. However, it is unclear if revegetation efforts provide long-term benefits (fewer exotic annuals and more perennials). The limited literature available on the topic questions whether revegetation efforts reduce medusahead abundance beyond 2 or 3 yr. We evaluated revegetation of medusahead-invaded rangelands for 5 yr after seeding introduced perennial bunchgrasses at five locations. We compared areas that were fall-prescribed burned immediately followed by an imazapic herbicide treatment and then seeded with bunchgrasses 1 yr later (imazapic-seed) with untreated controls (control). The imazapic-seed treatment decreased exotic annual grass cover and density. At the end of the study, exotic annual grass cover and density were 2-fold greater in the control compared with the imazapic-seed treatment. The imazapic-seed treatment had greater large perennial bunchgrass cover and density and less annual forb (predominately exotic annuals) cover and density than the untreated control for the duration of the study. At the end of the study, large perennial bunchgrass density average 10 plant ∙ m − 2 in the imazapic-seed treatment, which is comparable with intact sagebrush steppe communities. Plant available soil nitrogen was also greater in the imazapic-seed treatment compared with the untreated control for the duration of the study. The results of this study suggest that revegetation of medusahead-invaded sagebrush steppe can provide lasting benefits, including limiting exotic annual grasses. [ABSTRACT FROM AUTHOR]

Cucumis melo L. var. agrestis Naud. (field muskmelon), a troublesome weed affecting corn, soybean and peanut fields, is difficult to control and drastically reduces crop yields. Farmers have reported that nicosulfuron, imazapic, fomesafen, and bentazon, which are common herbicides used in corn, soybean and peanut fields, do not control field muskmelon effectively. This lack of control might be due to the evolution of resistance to these herbicides in field muskmelon. Thus, this study was designed to determine the sensitivity of field muskmelon to nicosulfuron, imazapic, fomesafen and bentazon. Eleven putative resistant populations and 1 sensitive population were used to evaluate the sensitivity of field muskmelon to these herbicides. Further, we analyzed the cross resistance and multiple resistance in field muskmelon plants. Among the 11 putative resistant populations, 10 populations evolved resistance to nicosulfuron, 6 populations were resistant to imazapic, and 4 populations evolved resistance to fomesafen, whereas none of the populations were resistant to bentazon. Moreover, field muskmelon has evolved resistance to the ALS-inhibiting herbicides nicosulfuron and imazapic, and to the PPO-inhibiting herbicide fomesafen. Fortunately, most of the resistance levels were low. The findings indicate that effective measures are needed to control resistant field muskmelon and avoid the further development of resistance in this plant. [ABSTRACT FROM AUTHOR]

It is not clear why herbicides targeting aromatic and branched-chain amino acid biosynthesis successfully control broomrapes—obligate parasitic plants that obtain all of their nutritional requirements, including amino acids, from the host. Our objective was to reveal the mode of action of imazapic and glyphosate in controlling the broomrape Phelipanche aegyptiaca and clarify if this obligatory parasite has its own machinery for the amino acids biosynthesis. P. aegyptiaca callus was studied to exclude the indirect influence of the herbicides on the parasite through the host plant. Using HRT – tomato plants resistant to imidazolinone herbicides, it was shown that imazapic is translocated from the foliage of treated plants to broomrape attachments on its roots and controls the parasite. Both herbicides inhibited P. aegyptiaca callus growth and altered the free amino acid content. Blasting of Arabidopsis thaliana 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) and acetolactate synthase (ALS) cDNA against the genomic DNA of P. aegyptiaca yielded a single copy of each homolog in the latter, with about 78 and 75% similarity, respectively, to A. thaliana counterparts at the protein level. We also show for the first time that both EPSPS and ALS are active in P. aegyptiaca callus and flowering shoots and are inhibited by glyphosate and imazapic, respectively. Thus leading to deficiency of those amino acids in the parasite tissues and ultimately, death of the parasite, indicating the ability of P. aegyptiaca to synthesize branched-chain and aromatic amino acids through the activity of ALS and EPSPS, respectively.

Imazethapyr and imazapic are widely used in South Brazil to control weeds in rice fields, mainly through agricultural aviation. The environmental legislation requires that agricultural aviation companies have environmental licensing, which implies that the effluent treatment system must be compliant with the regulations of the Brazilian Ministry of Agriculture, which advises the use of an ozone-based system. An evaluation of the efficiency of this system through the analysis of the content of imazethapyr and imazapic (from the herbicide Only®) in the treatment of effluent with two distinct rates of ozone (1.0 and 2.0 g O/h) was performed. It was found that for each tank wash is generated an average volume of 132 L of effluent (112 L of water plus 20 L of surplus diluted spray solution). After the treatment with 1.0 and 2.0 g O/h, imazethapyr concentration decreased − 92.4 and − 95.2%, respectively. For imazapic, the concentration in the washing effluent decreased − 69.1 and − 80.1%, respectively. The results indicate that the system was effective in the treatment of the effluent containing residues of the herbicide Only®. [ABSTRACT FROM AUTHOR]

BACKGROUND Indaziflam is a cellulose-biosynthesis-inhibiting (CBI) herbicide that is a unique mode of action for resistance management and has broad spectrum activity at low application rates. This research further explores indaziflam's activity on monocotyledons and dicotyledons and evaluates indaziflam's potential for restoring non-crop sites infested with invasive winter annual grasses. RESULTS Treated Arabidopsis, downy brome, feral rye and kochia were all susceptible to indaziflam in a dose-dependent manner. We confirmed that indaziflam has increased activity on monocots (average GR50 = 231 p m and 0.38 g AI ha−1) at reduced concentrations compared with dicots (average GR50 = 512 p m and 0.87 g AI ha−1). Fluorescence microscopy confirmed common CBI symptomologies following indaziflam treatments, as well as aberrant root and cell morphology. Across five application timings, indaziflam treatments resulted in superior invasive winter annual grass control 2 years after treatment (from 84 ± 5.1% to 99 ± 0.5%) compared with imazapic (36% ± 1.2%). Indaziflam treatments significantly increased biomass and species richness of co-occurring species 2 years after treatment. CONCLUSION Indaziflam's increased activity on monocots could provide a new alternative management strategy for long-term control of multiple invasive winter annual grasses that invade >23 million ha of US rangeland. Indaziflam could potentially be used to eliminate the soil seed bank of these invasive grasses, reduce fine fuel accumulation and ultimately increase the competitiveness of perennial co-occuring species. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Southeastern wildrye [Elymus glabriflorus (Vasey ex L.H. Dewey) Scrib & C.R. Ball] is a native, cool-season, perennial grass that shows promise as a forage crop for the southeastern United States. Little is known about the proper methods of establishment for this species, particularly its ability to tolerate pre- and post-emergence applications of imazapic. Replicated field trials were established in Newton and Starkville, MS, in the fall of 2014 and 2015. Pre- and post-emergence treat- ments included an untreated control, and application rates of 0.035, 0.07, 0.105, and 0.14 kg ai ha-1, which were applied to conventionally seeded plots. Seedling counts and height data were collected at bi-weekly intervals, along with visual ratings for weed control. End of season dry matter (DM) yields were also recorded for both establishment years. As expected, higher rates (0.105 and 0.14 kg a.i. ha-1) of imazapic caused significant damage to emerging seedlings in both pre- and post-emergence applications. These rates resulted in greater weed control, but ultimately, in reduced DM yields. Lower pre-emergence application rates (0.035-0.07 kg a.i. ha-1) resulted in acceptable weed control, and minimal seedling damage. Results from these field trials demonstrates the ability to successfully establish southeastern wildrye with the use of imazapic, thus providing beneficial information for the development of this species as a forage crop for the Southeast. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate residues of imidazolinone (IMI) in soil. Samples were taken from three Clearfield® rice fields as IMI which have been used for six years. IMI herbicides (imazapic/imazapyr) were widely used in Clearfield® rice soils. To date, few studies are available on the residues of these herbicides, especially in the context of Malaysian soil. Therefore, for this purpose, high performance liquid chromatography (HPLC) with UV detection was performed using a Zorbax stable bond C18 (4.6 × 250 mm, 5 μm) column, with two mobile phases. The average percentage recovery for imazapyr and imazapic varied from 76%-107% and 71-77%, with 0.1-5 μg/ml fortification level, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 1.05 and 4.09 for imazapic and 0.171 and 0.511 μg/ml for imazapyr respectively, in the top 15 cm. In the extracted soil sample, it was 0.19 μg/ml for imazapic and 0.04 μg/ml for imazapyr, respectively. Based on this study, a pre-harvest period of 40-60 day is suggested for rice crops after IMI application. [ABSTRACT FROM AUTHOR]

Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] is commonly established along roadside rights-of-way in adapted zones due to its tolerance of drought, heat, and wear; however, its upright growth habit coupled with seedhead production can impair motorist vision. Field research was conducted in 2013 and 2014 to quantify tall fescue mowing requirements following imazapic {(±)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)- 5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, an herbicide commonly used for plant growth regulation, application (53 g a.i. ha-1) alone, as well as tank-mixed with clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) + triclopyr {[(3,5,6-trichloro- 2-pyridinyl)oxy]acetic acid} (158 + 473 g a.i. ha-1). Plots were mown at a 23- or 30-cm foliage intervention height following treatment. Nontreated-mown and nontreated-nonmown controls were included for comparisons. Evaluated herbicide treatments caused 0 to 20% tall fescue injury, which recovered following mowing. Additionally, imazapic provided 100% tall fescue seedhead suppression through 56 days after treatment (DAT). Imazapic reduced tall fescue mowing requirements at both intervention heights through 70 DAT. Two mowing cycles were reduced across intervention heights in 2013, while three and two cycles were reduced at 23 and 30 cm heights, respectively, in 2014. Lastly, imazapic + clopyralid + triclopyr application increased tall fescue cover 84 DAT. This information will allow vegetation managers to more efficiently allocate resources to maintain clear motorist sightlines on tall fescue roadside rights-of-way. [ABSTRACT FROM AUTHOR]

Herbicides with high mobility can leach to deeper layers of the soil and to contaminate underground aquifers. The potential of herbicide leaching in soil can be monitored by chromatography or bioassay methods. This study evaluated the leaching of imazethapyr, imazapic and its commercial mixture (imazethapyr + imazapic) in three tropical soils via a bioassay method. The herbicides were applied in a polyvinyl chloride column and an 80 mm rainfall was simulated. The bioindicator species sorghum (Sorghum vulgare) BRS 655 was sown. Imazethapyr, imazapic and the commercial herbicide mixture showed high leaching in the soils. The presence of imazethapyr and the commercial mixture was detected up to 25 cm deep in Haplic Plinthosol and Oxisol. Imazapic showed less leaching to tree soil, being found at depth 10–15 cm. The pH, texture and iron oxide amount levels affected herbicide leaching. The mobility of the herbicides imazethapyr and imazapic in the Haplic Plinthosol and the Oxisol at depth 25 cm indicates a high risk of groundwater contamination. [ABSTRACT FROM PUBLISHER]