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Durante 1986-89 se llevó a cabo un estudio de campo en la Subestación de Lajas para evaluar los herbicidas registrados ametryn, diuron, asulam, hexazinone (Velpar) y metribuzin y los no registrados terbutryn, pendimethalin e imazapyr para controlar la yerba peluda (Roftboellia exaltata) en caña de azúcar en cultivos sucesivos de plantilla y primer retoño. Imazapyr, pendimethalin, terbutryn y ametryn a las dosis recomendadas de 0.28, 1.78, 2.69 y 4.49 kg/ha. controlaron la yerba peluda con efectividad comparable al desyerbo a mano en caña de plantilla. En el retoño todos los herbicidas usados demostraron una efectividad mayor debido, posiblemente, a una menor población del yerbajo. El herbicida imazapyr causó fitotoxicidad a las plántulas de caña, la cual fue más severa en el retoño. Las parcelas tratadas con los herbicidas mencionados produjeron rendimientos de azúcar por hectárea para la plantilla entre 14.92 y 17.02 toneladas comparables estadísticamente con el tratamiento de desyerbo a mano (17.5 tons/ha.), pero superiores significativamente a los de tratamientos de diuron, asulam y el testigo sin desyerbo. La producción de azúcar por ha. para el retoño siguió más o menos el mismo patrón que en la plantilla, excepto que las parcelas tratadas con asulam y diuron produjeron más y las tratadas con imazapyr y ametryn produjeron menos. La producción combinada de azúcar de la plantilla y el retoño en el tratamiento con pendimethalin fue estadísticamente igual que para el desyerbo a mano, pero solo significativamente superior a hexaxinone, imazapyr y el tratamiento sin desyerbar.

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.

Uncontrolled development of unfavorable vegetation during artificial reforestation reduces survival and growth rates of planted trees, and in some cases causes their death. The use of reforestation equipment is often extremely difficult, therefore the most promising solutions are those involving creation of spruce plantations using seedlings with closed roots and manual planting tools without preliminary mechanical tillage. Long-term protection of plantations from undesirable vegetation is ensured by the use of modern herbicides registered for use in the forest sector in the Russian Federation. The article presents the results of 3-year field experiments on the use of herbicides and their mixtures to supress undesirable vegetation in the first years after planting European spruce (Picea abies (L.) Karst.) in the Leningradregion. High efficiency of herbicides for long-term suppression of shrubs, and herbaceous and woody plants was found. A mixture of herbicides Roundup, WS (360 g/L glyphosate acid), Anchor-85, WDG (750 g/kg sulfometuron-methyl potassium salt) and Arsenal, WC (250 g/L imazapyr) inhibited the development of herbaceous weeds for at least two growing seasons. The processes of undesirable vegetation development after spraying plantations with herbicides, the reaction of seedlings to the use of chemicals, indicators of conditions and growth of conifers were also studied. Analysis of the obtained data proved the possibility of combining a protective chemical pretreatment with herbicides and planting seedlings in a single technological procedure or planting seedlings within a few months after chemical treatment, whichsignificantly reduces the risk of damage to seedlings by herbicides. The survival rate of plantations created by planting one- or two-year-old seedlings with closed roots was 93–98 %; and the biometric indicators were such that spruce plants could successfully compete with undesirable vegetation. The application of the developed method ensures a substantial reduction in labor and other reforestation costs compared to traditional technologies involving preliminary mechanical tillage and subsequent agrotechnical weeding of plantations. For citation: Egorov A.B., Postnikov A.M., Bubnov A.A., Pavluchenkova L.N., Partolina A.N. Cultivation of Spruce Plantations Using Modern Herbicides without Agrotechnical Weeding. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 9–23. DOI: 10.37482/0536-1036-2021-3-9-23Funding: The study was financially supported by the Federal Agency for Forestry within the state assignment of the Saint Petersbutg Forestry Research Institute No. 053-00003-17 ПР, approved by Order No. 552 of 26.12.16.

There are increased concerns about the thyroidal effects of many anthropogenic substances in the environment. These substances include agricultural pesticides and industrial and pharmaceutical chemicals among others. Their potential thyroidal effects are of serious health and ecological concerns, as thyroid hormones mediate numerous physiological processes, including growth regulation, general metabolism and metamorphosis in metamorphic animals. This study assessed thyroidal activities of Arsenal formulation (Imazapyr) at environmentally relevant concentrations of 0.5, 2.0 and 3.5 mg/L following a Xenopus metamorphosis assay (XEMA). The result shows that the Arsenal formulation significantly delayed the tadpole development, reduced the hind-limb length (HLL) and increased the whole-body mass (WBM) at a concentration of 3.5 mg/L relative to the control exposure. In histopathology, the formulation increased the epithelium height, at all exposure concentrations, but reduced the colloidal area at 0.5 and 2 mg/L, respectively, and the gland area at 2 mg/L relative to the control. Consequently, the Arsenal formulation is thyroid-active at environmentally relevant concentrations and poses a threat to both human and wildlife, especially metamorphic organisms. With this exposure impact, more studies are imperative to further characterise other endocrine-disrupting potential of this formulation, while future applications should be reduced or restricted to less risk environment, if it cannot be stopped from sensitive aquatic systems.

In this probe, a convenient template was practiced to fabricate mesoporous PdO–TiO2 nanocomposites using a sol–gel routine. Photo-destruction of the herbicide imazapyr was adapted to figure out the photonic efficacies of the formulated nanocomposites. Furthermore, the appraised photonic efficacies were correlated with the photonic efficacies retained by commercial P25 Degussa as well as mesoporous titania. Progression of the tetragonal anatase phase of titania was entrenched via X-ray diffraction inquire. PdO–TiO2 nanocomposite accommodating 0.9% PdO possessed superlative photonic efficacy of 34.8% whereas, commercial P25 Degussa and mesoporous titania possessed photonic efficacies of 1.0 and 2.0% respectively revealing the superior photonic efficacy of the fabricated nanocomposites in comparison to other relevant photo-catalysts. In conclusion, PdO–titania nanocomposites acquiring enhanced charge carriers’ separation could be fabricated along with the collaborating action of both titania and PdO nanoparticles. Furthermore, the tremendous stability of the fabricated nanocomposites was ascertained via its implementation up to five cycles keeping its photo-catalytic performance without alteration. Hence, PdO nanoparticles could be formulated as fruitful promoters for the photo-catalytic aspects possessed by mesoporous titania.

Mesoporous CoAl2O4–TiO2 nanocomposites have been tested in this investigation to photo-destruct imazapyr herbicide waste. Numerous percentages of CoAl2O4 were utilized in the preparation of mesoporous CoAl2O4–TiO2 nanocomposites through the sol–gel method. It is terminated from Raman spectra and XRD data that practicing lower CoAl2O4 percentage brings about the progression of intensely crystalline anatase TiO2 phase, which is diminished by extending CoAl2O4 ratio. The surface texture investigation showed that specific surface areas of fabricated TiO2 NPs and 3.0% CoAl2O4–TiO2 nanocomposites are 180 and 160 m2 g−1, respectively, revealing that inclusion of CoAl2O4 has a negative effect on the surface area of TiO2 NPs. Photo-destruction of imazapyr herbicide has been selected to evaluate photocatalytic efficacy of the formulated CoAl2O4–TiO2 nanocomposites, and at the same time, it has been correlated with commercial P25 Degussa covered by irradiation of visible light. CoAl2O4–TiO2 nanocomposite, including 3.0 mass% CoAl2O4 has been established as the optimal composite to achieve the most favorable destruction. Indeed, the photo-destruction of imazapyr herbicide was 100% after 180 min of the reaction. Also, it was found that CoAl2O4–TiO2 nanocomposite incorporating 3.0 mass% of CoAl2O4 photodegraded the imazapyr herbicide 10.2 and 5.1 times faster correlated to P25 Degussa and mesoporous TiO2, respectively.

Made available in DSpace on 2021-06-25T10:23:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Universidade Federal do Paraná One of the factors that limit grain yield in soybean crops is weed competition. The objective of the present work was to evaluate the agronomic performance of an AHAS-transgene soybean cultivar (BRS 397; Cultivance®) subjected to different rates of Soyvance® (525 g kg-1 imazapyr, and 175 g kg-1 imazapic). Two field experiments were conducted in the 2015-2016 crop season in two sites with different soil and weather characteristics located in the state of Paraná, Brazil. A completely randomized block design was used, with 11 treatments consisted of different rates of Soyvance®. Phytotoxicity, chlorophyll index, first pod height, plant height, number of pods per plant, 100-seed weight, and grain yield were evaluated. The use of high rates of the herbicide decreased the final height and grain yield of soybean plants in approximately 25% in both locations, but did not affect their 100-seed weight and chlorophyll index. The use of rates of the commercial product higher than that recommended by the manufacturer (100 g ha-1) may affect the agronomic performance of AHAS-transgene soybean plants. São Paulo State University (UNESP) School of Agricultural Sciences Federal University of Paraná (UFPR) Department of Agricultural Sciences, Palotina State University of Maringá (UEM) Program of Agricultural Science, Maringá São Paulo State University (UNESP) School of Agricultural Sciences

Callery pear (Pyrus calleryana Decne.) is rapidly spreading in the United States, gaining attention in the last two decades as a serious invasive pest. Recommended control methods include foliar, basal bark, cut stump, and hack-and-squirt application of herbicides, but there are few published studies with replicated data on efficacy. Four readily available herbicidal active ingredients and a combination of two active ingredients were tested for control efficacy against P. calleryana in old-field areas and loblolly pine (Pinus taeda L.) understory. Basal bark applications (triclopyr, triclopyr + aminopyralid), foliar applications (glyphosate, imazapyr), and a soil application (hexazinone) effectively killed P. calleryana with the exception of hexazinone at one site, where rainfall may not have been optimal. Foliar application of glyphosate provided the most consistent control. Our results demonstrate efficacy of registered herbicide formulations for P. calleryana control in two geographic locations and two habitat types. The need for development of integrated pest management programs for P. calleryana is discussed.

Eucalyptus species are grown for fiber, fuel, and other uses on more than 17.8 million ha worldwide, yet some species are considered invasive and may have adverse environmental or social impacts outside their native range. Aminocyclopyrachlor (AMCP) and standard applications of imazapyr and triclopyr herbicides were compared for eucalyptus control using a basal stem application method. At 6 and 12 mo after treatment (MAT), basal stem applications using 5% (vol/vol) AMCP (120 g ae L−1) in methylated soybean oil (MSO) resulted in 97% to 99% eucalyptus crown reduction and generally provided greater control across all diameter classes than standard treatments of 28% imazapyr (240 g ae L−1) or 75% triclopyr ester (480 g ae L−1). AMCP at 5% was as effective as 40% vol/vol. Increases in stem live height at 24 MAT suggest that the effect of triclopyr ester basal stem treatment may be impermanent. AMCP treated trees did not have regrowth by 24 MAT.

In this case study, we used point mapping data to evaluate long-term treatment of invasive tree-of-heaven [Ailanthus altissima(Mill.) Swingle]. This study at the Buffalo National River included 21 project areas ranging in size from 0.02 to 11.3 ha and spanned 5 to 8 yr depending on the site. The control techniques varied depending on the year and included the application of herbicide, which also varied over the course of the study and included imazapyr, triclopyr, and triclopyr+fluroxypyr. Treatments during the first year reduced localA. altissimapopulations by an average of 66%. Long-term repeated treatments led to decreases of at least 90% in 70% of the project areas and at least 73% in 95% of the project areas. Only one project area was found to support no plants during the final treatment year.Ailanthus altissimaincreased at most project areas during an unusually wet year and was more likely to increase than decrease in intervals >1 yr with no treatment. Over the temporal and spatial scales of this case study, we observed high levels of control that will likely meet the specified levels and ecological benefits required in many similar efforts. Land managers must, however, make a long-term commitment of resources to achieve lasting control of this invasive species.

São limitadas as informações sobre a atividade residual de herbicidas aplicados no controle das soqueiras do algodoeiro e o seu potencial para afetar o desenvolvimento e a produtividade do milho semeado na safra seguinte. O objetivo desse trabalho foi identificar o efeito carryover promovido pela aplicação única e sequencial de herbicidas utilizados no controle das soqueiras do algodoeiro e estimar o intervalo de segurança entre o manejo químico da soqueira do algodoeiro e a semeadura do milho. Foram conduzidos simultaneamente dois experimentos em casa de vegetação, um para aplicação única e outro para aplicação sequencial dos tratamentos herbicidas. Os experimentos foram instalados em esquema fatorial 15 x 5, delineados em blocos casualizados com quatro repetições. O primeiro fator foi composto por tratamentos herbicidas e o segundo fator por cinco épocas de semeadura do milho após a aplicação (0, 30, 60, 90 e 120 dias). As parcelas experimentais foram compostas de vasos plásticos com capacidade para 3 dm3 preenchidos com solo de textura argilosa (470 g kg-1 de argila), seco e peneirado. Os herbicidas utilizados foram 2,4-D, glyphosate, saflufenacil, [imazapic+imazapyr], dicamba, fluroxypyr e sulfentrazone. Conclui-se que a aplicação sequencial da maioria dos tratamentos proporcionou um aumento na atividade residual dos herbicidas avaliados. Os tratamentos 2,4-D (1340 g ha-1), 2,4-D + glyphosate (1340 + 720 g ha-1) e 2,4-D + glyphosate + saflufenacil (1340 + 720 + 105 g ha-1) apresentaram os menores intervalos de segurança e foram aqueles que apresentaram o menor risco de afetar o milho semeado em sucessão, mesmo em aplicações sequenciais. Contudo, os tratamentos constituídos pela associação com herbicidas de maior atividade residual no solo como o dicamba, fluroxypyr, sulfentrazone e [imazapic+imazapyr], apresentaram maior potencial de carryover para a cultura do milho, sendo observado intervalo de segurança superior a 94 dias após a aplicação sequencial de 2,4-D + glyphosate + sulfentrazone.

Treatment of individual trees in hardwood stands typically is conducted with herbicides that have no soil activity, such as triclopyr. However, triclopyr is not effective on some tree species. Applying a mixture of triclopyr and imazapyr would broaden the spectrum of species controlled, but nontarget mortality may be problematic as imazapyr may affect other trees through soil activity. We applied herbicide via girdle-and-spray as part of a forest stand improvement treatment in four upland hardwood stands in the Upper Coastal Plain of Alabama. We compared effects of using triclopyr alone with a mixture of triclopyr and imazapyr 18 months posttreatment. Only one untreated sweetgum (Liquidambar styraciflua) out of 440 trees was killed in the stands treated with the herbicide mixture (0.5 percent nontarget mortality rate). Nontarget mortality did not differ between treatments. However, the herbicide mixture controlled hickory (Carya spp.) and sourwood (Oxydendrum arboreum) better than triclopyr alone, with 56 percent of hickory treated with triclopyr still alive 18 months later, compared with 0 percent of hickory treated with the mixture. Our results indicate a mixture of triclopyr and imazapyr provides better control than triclopyr alone, and there is minimal risk to nontarget tree species in hardwood stands when used according to label recommendations.

Thyroid hormones play critical roles in body growth and development as well as reproduction. They also influence the activities of a wider variety of tissues and biological functions, such as osmoregulation, metabolism, and especially metamorphosis in organisms, such as frogs. These complex activities of thyroid hormones are prone to disruption by agricultural pesticides, often leading to modulation of growth and the reproductive system in particular. These substances include Glufosinate ammonium, Glyphosates, Imazapyr, Penoxsulam, and Diquat dibromide among other herbicides. In this study, the standardized Xenopus Metamorphosis Assay protocol was used to assess the potential thyroid-modulatory properties of the Glufosinate ammonium Basta formulation, at relevant environmental concentrations (0.05 mg/L, 0.15 mg/L, and 0.25 mg/L) for 21 days. The results showed that this formulation only reduced the hind-limb length among the morphological endpoints. Histological evaluation showed that the mean thyroid gland area and the mean thyroidal follicle epithelium height were significantly increased following 0.15 and 0.25 mg/L exposures. The present study confirmed that this Basta formulation interacts with the thyroid axis and therefore potentially pose health hazard to amphibian in particular and potentially metamorphic aquatic vertebrates. Furthermore, the result is a signal of inherent potential thyroid disrupting activities that must be further investigated and characterised in some of the aquatic herbicide formulations to safeguard the aquatic biodiversity.

Globally, amphibians are experiencing widespread abnormalities and population declines. One potential contributor to these challenges is the use of pesticides, particularly aquatic herbicides applied to aquatic habitats inhabited by amphibians. Critical issues of concern are the potential toxicity and teratogenicity of these herbicides towards amphibians. Using the FETAX protocol, three globally used formulations, including diquat dibromide (Midstream), glufosinate ammonium (Basta), and imazapyr (Arsenal), were assessed for embryotoxicity, teratogenicity, and growth inhibition. Developing Xenopus laevis embryos were exposed for 96 h at concentrations of 0.5–3.0 mg/L, 1.6–3.0 mg/L, and 20–45 mg/L for Midstream, Basta, and Arsenal respectively. The 96-h LC50 estimates were 0.83 mg/L acid equivalent (a.e.), 36 mg/L a.e., and 2.2 mg/L a.e., whereas the EC50 estimates were 0.24 mg/L a.e., 28.13 mg/L a.e., and 2.01 mg/L a.e. for the Midstream, Arsenal, and Basta formulations, respectively. These two estimates produced Teratogenic Index of 3.5, 1.3, and 1.1 for Midstream, Arsenal, and Basta, respectively, indicating a high risk of malformation induction by Midstream and moderate risk for Arsenal. Regarding growth inhibition, lowest observable effect concentrations of 0.5 mg/L, 25 mg/L, and 2.0 mg/L were computed for Midstream, Arsenal, and Basta, respectively, producing the minimum concentration inhibiting growth (MCIG) ratios of 0.62, 0.69, and 0.89 for the three formulations. These MICG values are higher than the standard 0.30 growth inhibitors benchmark, suggesting that the formulations are not growth inhibitors at the evaluated concentrations. This study provides evidence of the embryotoxic and teratogenic status of Midstream and the embryotoxicity of Basta. There is a need to further characterise the physiological and ecological impacts of these formulations to ensure responsible use and the safety of amphibians and other wildlife.

Herbicide mixtures, use of multiple sites of action, and other weed management practices are necessary to avoid cases of biotype resistance. The aim of this study was to evaluate the efficiency of imazapic/imazapyr and other herbicides in mixtures to control Digitaria insularis at burndown before soybean sowing. This field research was conducted in Umuarama, State of Parana (PR), Brazil, in the 2018/19 soybean season. The experiment was conducted in a randomized block experimental design with four replications and 11 treatments composed of the application of glyphosate, clethodim, haloxyfop, imazapic/imazapyr, glufosinate, 2,4-dichlorophenoxyacetic acid (2,4-D), dicamba, triclopyr, and saflufenacil, in mixtures. Weed control was evaluated as well as soybean injury and yield. An analysis of variance and F-test were performed, and the treatment means were compared by the Scott-Knott test. All treatments showed great control over the weed and low crop injury rate while maintaining soybean yield. The application of imazapic/imazapyr in mixtures with other herbicides was effective in controlling glyphosate-resistant D. insularis in burndown before soybean sowing and with sequential application of haloxyfop + glyphosate at V3 stage of soybean. This chemical management was also selective for soybean.

Witchweed [Striga hermonthica (Del.) Benth] is a major parasitic weed of most cereal crops in Africa, including maize. Seed treatment with low doses of acetolactate synthase–inhibiting herbicides, such as imazapyr, was introduced in the 1990s to control witchweed. Field trials were conducted in four locations in Nigeria in 2007 and 2008, to assess the effect of coating seeds of several maize hybrids with imazapyr on witchweed control. The hybrids had genes for imidazolinone herbicide resistance (IR), as well as genetic tolerance to witchweed (ST). Treatments were 12 IR maize hybrids with ST and three checks without the IR gene (commercial, witchweed tolerant, and witchweed susceptible hybrids). Averaged across all locations, the coated IR hybrids with ST yielded more and supported fewer witchweed plants than the uncoated IR hybrids with ST. The IR hybrids with ST yielded 57%–60% more than the commercial and witchweed tolerant hybrid checks that were not coated. The witchweed susceptible hybrid check suffered a yield loss of 88% under infestation without seed coating. The IR hybrids with ST yielded 3564 kg ha−1 of grain when coated with imazapyr and 3266 kg ha−1 otherwise. The findings indicate that coating of IR/ST maize seeds with imazapyr improved tolerance to witchweed.

In this work, mesoporous Gd2O3-TiO2 nanocomposites synthetized by a sol–gel with vary Gd2O3 concentration were investigated for photo-destruction of imazapyr herbicide waste. Textural, structural and surface properties of the synthetized nanocomposites are verified by N2 physisorption, X-ray diffractometry, HRTEM and various spectroscopic techniques (FTIR, DRS UV–Vis, Raman, PL and XPS). HRTEM micrographs of the calcined Gd2O3-TiO2 revealed the existence of a mesoporous matrix consisting of homogeneously distributed TiO2 nanoparticles (NPs, 12 nm) which are decorated with Ga2O3 nanoparticles. It was found a reverse correlation between the amount of Gd2O3 concentration and the TiO2 nanoparticle size: the formation of smaller TiO2 nanoparticles was favored by the use of high Gd2O3 concentration. The photocatalytic efficiency of the synthetized Gd2O3-TiO2 nanocomposites was appraised in the photo-destruction of imazapyr herbicide below visible-light irradiation. The best herbicide destruction was achieved using 3%Gd2O3-TiO2 photocatalyst and degraded the imazapyr herbicide 20.5 and 8.2 times faster than a commercial P25 and non-promoted TiO2, respectively, indicating that modification of TiO2 with Gd2O3 led to a significant improvement of photocatalyst efficiency. This was explained as due to a lessening of the apparent optical bandgap and the formation of a large amount of surface defect states favoring the separation between electrons and holes. Besides its high efficiency, the 3%Gd2O3-TiO2 photocatalyst demonstrated to be recyclable and stable in the visible-light-driven photocatalytic destruction of imazapyr herbicide.

A elevada fitointoxicação após a aplicação de herbicidas tem se tornado cada vez mais frequentes em função da mistura em tanque de herbicidas praticada a campo, pressionadas pelo aumento do espectro de controle e pelo avanço da resistência de plantas daninhas a herbicidas. Objetivou-se, neste trabalho avaliar a interação do tratamento de sementes com uma formulação comercial de fungicida e inseticida com a aplicação de mistura em tanque de herbicidas no arroz irrigado, cultivado no sistema pré-germinado, na região do Alto Vale do Itajaí, SC. O experimento foi conduzido em uma área comercial sistematizada para o sistema pré-germinado, com a cultivar SCS 121 CL. O delineamento experimental utilizado foi o de blocos casualizados com tratamentos arranjados em esquema fatorial 4 x 2, com quatro repetições. Avaliou-se dois níveis de tratamento de sementes (com ou sem) e quatro tratamentos herbicidas (sem herbicida, [imazapyr + imazapic] + bentazon, [imazapyr + imazapic] + saflufenacil e [imazapyr + imazapic] + bentazon + saflufenacil). A primeira aplicação foi realizada em V2 apenas com a mistura comercial de [imazapyr + imazapic] e a segunda aplicação foi realizada em V3 com tratamentos. As variáveis avaliadas foram fitointoxicação, número de plantas por metro quadrado, número de perfilhos por planta, número de panículas por metro quadrado, número de grãos por panícula, massa da panícula, esterilidade de espiguetas, massa de mil grãos e produtividade de grãos. Concluiu-se que o tratamento de sementes com a mistura formulada de fungicida e inseticida reduziu a fitointoxicação da mistura de [imazapyr + imazapic] + bentazon + saflufenacil. Além disso, houve superioridade numérica nos componentes de rendimento e na produtividade de grãos com o tratamento de semente.

Herbicide spraying on eucalyptus regrowth prior to planting reform is a common practice in the forest sector. However, several operations are needed in the same area for an effective sprout control. The objective of this work was to evaluate the efficiency of the herbicides glyphosate and imazapyr, applied to the main stem before the harvesting of the tree to eucalyptus sprouts control. There were set up 7 treatments, with application of doses of 3.0; 4.0; and 5.0 mL/stem of glyphosate (Gli-Up ® 360g i.a L -1 ) and doses of 0.3; 0.5; and 0.7 mL/stem of imazapyr (Chopper Florestal ® 250g i.a. L -1 ), in addition to a control treatment. The herbicide spraying consisted of the directed spraying of the herbicides on incisions carried out on the stem of the trees. The harvest of the trees was carried out 30 days after the herbicide spraying. Assessments about the number of sprouts per stump were carried out, the number of stump with presence of coppice, height and control efficiency of the coppice 150 days after harvesting. The glyphosate spraying promoted reduction of the sprout development and vigor. However, even with this reduction, it was observed presence of sprouts in at least 80% of the assessed stumps. The spraying of the dose of 3 mL of glyphosate promoted values next to 80% of control efficiency. Nevertheless, it was observed that new control operations would be necessary. The spraying of imazapyr was inefficient with control efficiency values less than 25%. In conclusion, the application of glyphosate to the main stem before the harvesting of the tree presents reduction in the eucalyptus sprout development. Additionally, the application of imazapyr, in the doses and form application tested, is not recommended to eucalyptus sprout control.

The invasion of Spartina alterniflora (S. alterniflora) has caused serious damage to coastal wetland ecosystems in China, especially the mangrove wetlands in South China. This study aimed to validate the effect of imazapyr on S. alterniflora and soil. The controlled experiment was conducted in May 2021 at the Zhangjiangkou Mangrove Wetland Reserve. In the experiment, 25% (W) imazapyr was used, and six treatments were set up: 3035, 6070, and 9105 mL/acre 25% imazapyr and 1299, 2604, and 5202 mL/acre of AGE 809 + 6070 mL/acre 25% imazapyr. The results showed no side effects on mangrove plants in the spraying area. The highest control efficiency (95.9%) was given by 2604 mL/acre of AGE 809 + 6070 mL/acre 25% imazapyr. The residues of imazapyr in different soils were reduced to 0.10–0.59 mg/kg. The sequencing results showed no significant difference in the overall bacterial communities under different treatments (p &gt, 0.05). The soil bacterial diversity in the samples with adjuvant was higher than that in the samples without adjuvant, while the abundance values were the opposite. There were 10 main communities (&gt, 0.3%) at phylum level in all soil samples, among which Proteobacteria, Bacteroidetes, Acidobacteria, Chloflexi, and Actinobacteria were the dominant communities, and the latter four’s abundance changed significantly (p &lt, 0.05). There were significant abundance differences between the groups of oligotrophic and eutrophic bacteria. The redundancy analysis and Monte Carlo tests showed that the total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), ammonia nitrogen, and total nitrogen were the main factors affecting soil bacterial diversity. At the same time, TOC, AP, and TP were the most critical factors affecting the overall characteristics of soil bacterial communities in different treatments, while soil residues had no significant effect on bacteria. This might be due to the addition and degradation of imazapyr and the coverage of S. alterniflora. The best recommendation is 2604 mL/acre of AGE 809 + 6070 mL/acre 25% imazapyr to be applied in China’s mangrove wetland reserves and coastal wetlands.

Glyphosate-based foliar spray herbicides are the most common method for urban weed control due to their broad-spectrum and efficacy for burndown applications. As interest in glyphosate alternatives has increased in recent years, this project assessed the efficacy of the following non-glyphosate-based alternative weed management strategies: glufosinate, imazapyr, MCPA + dicamba, prodiamine, pine oil, clove oil, nonanoic acid, acetic acid + hydrochloric acid and steam against untreated (negative) controls and glyphosate-treated sites. Across all four seasonal treatments (winter, spring, summer and autumn), glyphosate and glufosinate reduced weed coverage (&gt, 65% after 4 and 12 weeks), imazapyr reduced weed coverage by &gt, 80% after 12 weeks, and steam reduced weed coverage by &gt, 80% after 4 weeks, and after 12 weeks showed to reduce weed coverage by &gt, 20% after the second application. The MCPA + dicamba, prodiamine, pine oil, clove oil, nonanoic acid and acetic acid + hydrochloric acid treatments had mixed impacts on weed coverage. Minimal alterations to soil physicochemical properties were observed across the two sites for all treatments. Assessment of impacts the different weed management strategies had on arthropod and microbial relative abundance showed minimal alterations, with only steam observed to reduce relative microbial abundance. Glufosinate, imazapyr and steam may be considered alternatives to glyphosate for reducing weed coverage but may not be as effective or have undesirable off-target effects. Overall, glyphosate provided the most consistent weed reduction at both sites over 12 weeks, without any recorded negative off-target or soil biota impacts.

Selection pressure caused by continuous use of imazapyr and imazapic herbicides in rice fields without crop rotation, has selected for resistant biotypes of Echinochloa crusgalli var. mitis. To know the mechanism of resistance involved becomes important in order to define effective management strategies. Therefore, the objective of this work was to verify if enhanced metabolism of herbicide is responsible for imazapyr and imazapic resistance in Echinochloa crusgalli var. mitis biotypes from Rio Grande (ECH38 resistant and ECH44 susceptible), Pelotas (ECH1 resistant and ECH14 susceptible) and Arroio Grande (ECH27 resistant) in the state of Rio Grande do Sul. For this purpose, forty-nine biotypes were collected from the southern region of the state in areas with barnyard grass control difficulties with ALS inhibitor herbicides. The treatments of study consisted of application of malathion (1000 g a.i. ha-1) and piperonyl butoxide (525 g a.i. ha-1), inhibitors of the cytochrome P450 mono-oxygenase enzymes and after 60 minutes, preceding herbicide application (73.5 + 24.5 g a.e. ha-1. Visual control evaluations were taken at 14 and 28 days after treatments (DAT) and shoot dry mass (SDM) determination at 28 DAT. The results indicate that the application of inhibitors does not alter the control response of the ECH38, but shows a significant increase in phytotoxicity in 28 DAT, with values of 78% for the ECH1. The use of Malathion associated with the herbicide provided a reduction in the SDM of 1.34 g.plant-1 in relation to the isolated application of herbicide and for piperonyl butoxide (PBO) of 1.28 g.plant-1 for the resistant biotype from Pelotas. For ECH27, the SDM reduction was lower than the values of 0.87 g.plant-1 for Malathion and 1.04 g.plant-1 for PBO. The resistance mechanism to imazapyr + imazapic herbicide in Pelotas and Arroio Grande biotypes is related to increased metabolism of the herbicide, and it cannot be stated that this mechanism is involved in the resistance of the ECH38 biotype.

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

Giant miscanthus has the potential to move beyond cultivated fields and invade noncrop areas, but this can be overshadowed by aesthetic appeal and monetary value as a biofuel crop. Most research on giant miscanthus has focused on herbicide tolerance for establishment and production rather than terminating an existing stand. This study was conducted to evaluate herbicide options for control or terminating a stand of giant miscanthus. In 2013 and 2014, field experiments were conducted on established stands of the giant miscanthus cultivars ‘Nagara' and ‘Freedom.’ Herbicides evaluated in both years included glyphosate, hexazinone, imazapic, imazapyr, clethodim, fluazifop, and glyphosate plus fluazifop. All treatments were applied in summer (June or July) and September. For both years, biomass reduction ranged from 85% to 100% when glyphosate was applied in June or July at 4.5 or 7.3 kg ae ha–1. No other treatment applied at this timing provided more than 50% giant miscanthus biomass reduction 1 yr after application. September applications of glyphosate were not consistent: treatments in 2013 reduced biomass by 40% or less, whereas in 2014, at all rates provided at least 78% biomass reduction. Glyphosate applied in June or July was the only treatment that provided effective and consistent control of giant miscanthus 1 yr after treatment.Nomenclature: Clethodim; fluazifop; glyphosate; hexazinone; imazapic; imazapyr; giant miscanthus, Miscanthus x giganteus J.M. Greef & Deuter ex. Hodkinson & Renvoize [sacchariflorus × sinensis]

This study aimed to synthesize chitosan-modified biochars with the objective of producing an efficient biosorbents for immobilization of imazapic and imazapyr herbicides in soil. Two biochars were produced separately from oil palm empty fruit bunches and rice husk biomasses and then modified with chitosan in a nitrogen gas environment. The biosorbents characterization showed that biochars modification with chitosan decreased their total surface areas. However, their cation exchange capacities significantly increased. The outcomes also showed that soil amendment with chitosan-modified biochars remarkably enhanced its capacity for sorption of imazapic and imazapyr herbicides as compared with pure soil and soil amended with unmodified biochars. Based on the linear distribution coefficients, the capacity of soil for imazapic sorption enhanced by 50% after mixing with unmodified empty fruit bunches biochar, and by 73% after amendment with the chitosan-modified empty fruit bunches biochar. For imazapyr herbicide, soil sorption capacity improved by 8% owing to amendment with unmodified empty fruit bunches biochar, and by approximately 84% after mixing with chitosan-modified empty fruit bunches biochar. Likewise, amendment of soil with unmodified and chitosan-modified rice husk biochars increased its sorption capacity for imazapic herbicide by 25% and 36%, respectively, and for imazapyr herbicide by 36% and 67%, respectively. Freundlich and Langmuir adsorption isotherms showed similar trends. In conclusion, biochar modification with chitosan would remarkably improve their sorption capacity for imidazolinone herbicides including imazapic and imazapyr herbicides.

Chemical control of unwanted trees can be a cost-efficient tool for forest management and restoration. In California, United States, the response of merchantable conifers to hardwood control is poorly understood. We studied the tree growth of coast redwood (Sequoia sempervirens (Lamb. ex D. Don) Endl.) following herbicide frill treatment of competing tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, C.H. Cannon, & S. Oh), coinciding with a partial harvest of conifers. The radial growth of 420 redwoods in 45 plots was measured using increment cores. With or without partial harvesting, herbicide treatment of tanoak enhanced growth of most redwoods: 23% of redwoods in herbicide-only plots and 34% of redwoods in herbicide + harvest plots had ≥100% higher posttreatment basal area increment (BAI). In untreated plots, 67% of redwoods displayed declining BAI. The response of redwoods (the ratio of 8-year postharvest BAI to 8-year preharvest BAI) was 59% higher in herbicide-only plots and 108% higher in herbicide + harvest plots compared with untreated control plots over the same period. Redwoods with long crowns maintained rapid growth with or without treatment. Trees growing slowly before treatment exhibited the greatest response, provided that they had relatively long crowns and were not left in suppressed crown positions. Forest managers implementing partial harvesting and (or) chemical control of hardwoods can expect to maintain or promote rapid growth of most residual redwoods.

Total vegetation control (TVC) is an essential management practice to eliminate all vegetation for the purpose of protecting infrastructure, people, or natural resources on sites where vegetation poses major fire, visibility, and infrastructure risks. TVC is implemented on sites such as railroads, power substations, airports, roadsides, and oil and gas facilities. Current research has identified that tank-mixing two effective mechanisms of action is a superior resistance management strategy compared to rotating mechanisms of action; however, effective tank mixes for TVC have not been thoroughly evaluated. A field experiment was conducted from 2013 to 2014 at five sites in Colorado to compare 32 treatment combinations to two industry standards for TVC. Research objectives were (1) to identify herbicide tank-mix combinations for TVC with multiple effective mechanisms of action for resistance management, (2) to evaluate lower use rate alternatives to minimize nontarget impacts, and (3) to determine the efficacy of fall versus spring application timings. Seven treatments were identified as top-ranking treatments, averaging 96% bare-ground (BG) across five sites and two application timings. Four out of the seven top-ranked treatments included aminocyclopyrachlor, chlorsulfuron, and indaziflam. The industry standard diuron plus imazapyr was in the top ranking, whereas the other industry standard bromacil plus diuron performed inconsistently across sites. Probability modeling was used to predict the probability of achieving 97% or 100% BG with various treatment combinations. The combination of aminocyclopyrachlor, chlorsulfuron, indaziflam, and imazapyr had the highest predicted BG probability, with 88% predicted probability of achieving 100% BG, compared to 67% and 52% predicted probabilities for the industry standards diuron plus imazapyr and bromacil plus diuron, respectively. In three of the five sites, fall applications outperformed the same treatments applied in the spring. Several top-ranking treatments represent newer, lower use rate herbicide combinations that provide multiple mechanisms of action to manage herbicide-resistant weeds and minimize nontarget impacts. Nomenclature: Aminocyclopyrachlor; bromacil; chlorsulfuron; diuron; imazapyr; indaziflam

Invasive shrubs like Tamarix spp. are ecological and economic threats in the U.S. Southwest and West, as they displace native vegetation and require innovative management approaches. Tamarix control typically consists of chemical and mechanical removal, but these methods may have negative ecological and economic impacts. Tamarisk leaf beetles (Diorhabda spp.) released for biocontrol are becoming increasingly established within Western river systems and can provide additional control. Previous Diorhabda research studied integration of beetle herbivory with fire and with mechanical management methods and herbicide application (e.g., cut stump), but little research has been conducted on integration with mowing and foliar herbicide application, which cause minimal soil disturbance. At Caballo Reservoir in southern New Mexico, we addressed the question: “How does Tamarix respond to chemical and mechanical control when Diorhabda is well established at a site?” A field experiment was conducted by integrating mowing and foliar imazapyr herbicide at standard (3.6 g ae L−1 [0.75% v/v] and low (1.2 g ae L−1 [0.25% v/v]) rates with herbivory. Treatments were replicated five times at two sites—a dry site and a seasonally flooded site. Beetles and larvae were counted and green foliage was measured over 2 yr. Mowing and full herbicide rates reduced green foliage and limited regrowth compared with low herbicide rate and beetles alone. Integrating conventional management such as mowing and herbicide with biocontrol could improve Tamarix management by providing stresses in addition to herbivory alone.

The long residual period of pre-emergent herbicides can interfere with successor crops, causing a phenomenon named carryover. This study evaluated the residual effect of imazapyr + imazapic herbicides on cotton crop grown in succession to soybean. The experiment was conducted between September 2016 and March 2017, in a randomized block design with 4 replicates, where the treatments were four doses of imazapyr + imazapic, 75, 150, 225 and 300 g a.i. ha-1, and the control. The analyzed variables were chlorophyll a fluorescence, shoot height, root length and volume, dry shoot mass and root dry mass. The data were submitted to analysis of variance and Tukey’s test, at p ≤ 0.05. The reduction in photosynthetic performance indexes for treatments of 150, 225 and 300 g a.i. ha-1 at 15 days after emergence (DAE) and of 75 g a.i ha-1 at 60 DAE indicated a photoinhibitory effect of these herbicides on plants. However, shoot height, length, volume and root dry mass were not affected in the treatments tested. Therefore, the persistence of the herbicide in the soil was not enough to characterize a carryover effect in cotton 135 days after application (DAA). RESUMO O longo período residual dos herbicidas pré-emergentes pode interferir em culturas sucessoras, ocasionando o fenômeno denominado de efeito residual (carryover). O trabalho teve como objetivo avaliar o efeito residual dos herbicidas imazapir + imazapic na cultura de algodão em sucessão à soja. O experimento foi conduzido entre setembro de 2016 a março de 2017, no delineamento em blocos, com quatro repetições, sendo os tratamentos quatro doses de imazapir + imazapic, 75, 150, 225 e 300 g i.a. ha-1 e a testemunha. As variáveis analisadas foram fluorescência da clorofila a, altura da planta, comprimento e volume da raiz, massa seca da parte aérea e massa seca da raiz. Os dados gerados foram submetidos à análise da variância e ao teste de Tukey, a p ≤ 0,05 de probabilidade. A diminuição nos índices de desempenho fotossintético no algodão nos tratamentos com doses de 150, 225 e 300 g i.a. ha-1 aos 15 dias após emergência (DAE), e com dose de 75 g i.a. ha-1 aos 60 DAE, indica o efeito fotoinibitório destes herbicidas sobre as plantas, entretanto, as variáveis altura da planta, comprimento, volume e massa seca da raiz não foram afetados nos tratamentos testados. Portanto, a persistência do herbicida no solo não foi suficiente para caracterizar o efeito residual (carryover) em algodão 135 dias após a aplicação (DAA).

Ailanthus altissima ((Mill.) Swingle, tree-of-heaven, Chinese sumac, stink tree) is a nonnative invasive tree that is common throughout much of the eastern United States. It can invade and expand dramatically when forests are disturbed. Anecdotal evidence suggests that fire might facilitate its spread, but the relationship between fire and this prolific invasive tree is poorly understood. To better understand the impacts of fire on Ailanthus, we conducted a study at Tar Hollow State Forest in southeastern Ohio, USA where Ailanthus is widely distributed. Our objective was to quantify the direct effects of prescribed fire on the demography of Ailanthus populations, with and without the pre-burn application of the stem-injected herbicide, imazapyr. We quantified demographic attributes (survival, density, and sprouting) of Ailanthus germinants, seedlings, saplings, and trees in a field experiment with four treatment combinations: (1) no fire and no herbicide, (2) herbicide, (3) fire, and (4) herbicide plus fire. Ailanthus stems >3 cm dbh were stem-injected with the herbicide, imazapyr in late summer to early fall followed by prescribed fire in April. We determined that herbicide plus prescribed burn treatment was highly effective in killing large saplings and trees, with no resprouting evident after four growing seasons. In the season immediately after the burn with and without herbicide treatment, small Ailanthus sapling and seedling abundance increased, but did not persist. Over time, Ailanthus germinants and sprouts from top-killed stems were poor competitors with faster-growing post-fire woody regeneration as forest floor shading increased. In addition, the late growing season application of imazapyr was highly effective in killing Ailanthus and subsequent sprouts. This study, the first to quantify the direct effects of fire on Ailanthus, demonstrates that prescribed fire alone does not appear to facilitate the spread of Ailanthus.

Excessive application of agro-chemicals is a major factor in undesired environmental problems. Imidazolinone herbicides having high activity, leaching potential, and persistence are probable risks to ecosystems. Herbicides’ stabilization using biochar is an efficient and cheap strategy to protect the environment against their contaminations. The present study aimed to evaluate the effects of biochars produced from oil palm empty fruit bunches (EFB) and rice husk (RH) on imazapyr fate in soil. Initially, the optimized biochars were compared for their sorption-desorption capacities as soil modifiers. The herbicide leaching in the amended soils was investigated by leaching columns. The herbicide photolysis and bio-degradations’ rates in the media were also evaluated during 70 days. Results indicated that the soil amendment significantly increased soil sorption capacity (up to 2.34-folds) and reduced the herbicide leaching. The lowest percentage of leached herbicide (2.8%) and the highest percentage of retained herbicide (97.1%) were achieved in EFB biochar-amended soil. The herbicide photo-degradation rate significantly reduced with a half-life of 38.5 days in non-amended soil to 53.3 days in EFB biochar-amended soils. The herbicide bio-degradation, however, increased with the biochars applications. In a conclusion, the optimized biochars have a high potential to protect the environment against herbicides hazards.

Made available in DSpace on 2022-05-01T08:44:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Successive mowing are the major maintenance costs of lawns. Thus, both the expenditure with mowing and the visual and physiological aspect of the lawn have led to the search for alternatives to mechanical management. Thus, this work aimed to study the effects of different rates of imazapic herbicide applied alone or combined with imazapyr as a growth regulator of Bahiagrass (Paspalum notatum) and St. Augustine grass (Stenotaphrum secundatum). The experimental design was a randomized block with four replicates, and the treatments consisted of six rates of imazapic herbicide (35; 70; 105; 140; 175 and 210 g a.i. ha-1) for both species, three rates of imazapic + imazapyr in tank mix (15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for Bahiagrass and four rates of imazapic + imazapyr mixture (7.875 + 2.625; 15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for St. Augustine grass. The effect of the treatments was evaluated by observing visible injury symptoms, canopy height, height and number of inflorescences and total dry matter of clippings. Applications of imazapic alone or combined with imazapyr were effective in reducing plant height, number and height of inflorescences and total amount of dry matter of clippings produced by Bahiagrass plants. Imazapic provided satisfactory control of St. Augustine growth, but its utilization caused an increase in the number of inflorescences present in the lawns. São Paulo State University Department of Agronomy State University of Mato Grosso Department of Plant Science São Paulo State University São Paulo State University Department of Plant Science São Paulo State University

Weeds represent an increasing challenge for crop systems since they have evolved adaptability to adverse environmental conditions, such as salinity stress. Herbicide effectiveness can be altered by the quality of water in which the weed is growing. This research aimed to study the combined effect of salt stress and recurrent selection with a sublethal dose of imidazolinone herbicides in the shifting of the sensitivity of Echinochloa colona (L.) Link (junglerice) to imidazolinone herbicides. This study was divided into two experiments, in experiment I, three recurrent selection cycles were conducted in Pelotas/RS/Brazil with imazapic + imazapyr at 0.125× the field rate, and in experiment II, three recurrent selection cycles were conducted in Fayetteville/AR/USA with imazethapyr, at 0.125× the recommended dose. Salt stress was implemented by irrigation with 120 mM sodium chloride (NaCl) solution. The effective dose for 50% control of the population (ED50) values increased from the field population to the second generation (G2) after recurrent selection with a sublethal dose of imidazolinone combined with salt stress, supporting the hypothesis of reduced susceptibility by the combination of these abiotic factors. Recurrent exposure to a sublethal dose of imazapic + imazapyr or imazethapyr, combined with salt stress, reduced susceptibility of Echinochloa colona (L.) plants to imidazolinone herbicides.

The present study sought to verify the existence of interactions between the soil water conditions, nitrogen and herbicides commonly used to control alexandergrass in irrigated rice crop. The experimental design was completely randomized, arranged in a 2 x 3 x 4 factorial scheme, corresponding to two soil water conditions (5 cm water depth and 100% soil water holding capacity [WHC]), three nitrogen doses (0, 80 and 160 kg of N ha-1) and four doses of herbicides (0, 0.5, 1 and 2 times the registration dose). The herbicides evaluated were cyhalofop-butyl, imazapyr + imazapic and imazethapyr. The treatments were repeated four times. Phytotoxicity and dry mass were evaluated 28 days after application. For cyhalofop-butyl and imazapyr + imazapic, the phytotoxicity at 100% WHC and 5 cm water depth conditions was higher in treatments with nitrogen fertilization. However, for imazethapyr under the 100% WHC condition of soil increased phytotoxicity in the absence of nitrogen fertilization. For the flooded condition, from the dose of 35 g of a.i. ha-1, the result in the control for the herbicide imazethapyr was optimized under the conditions of fertilization with 80 and 160 kg of N ha-1. Cyhalofop-butyl and imazapyr + imazapic undergo synergistic interaction with nitrogen fertilization and water status in the control efficiency, yet with imazethapyr, the synergistic interaction only occurs under 100% of soil WHC. RESUMO Buscou-se constatar a existência de interações entre condições hídricas do solo, nitrogênio e herbicidas comumente utilizados para controle de papuã no cultivo do arroz irrigado. O delineamento experimental utilizado foi inteiramente casualizado, arranjado em um esquema fatorial 2 x 3 x 4, sendo duas condições hídricas do solo (lâmina d’água de 5 cm e 100% de capacidade de retenção de água do solo), três doses de nitrogênio (0, 80 e 160 kg de N ha-1) e doses de herbicidas (0, 0,5, 1 e 2 vezes a dose de registro). Os herbicidas avaliados foram cyhalofop-butyl, imazapyr + imazapic e imazethapyr. Os tratamentos foram repetidos quatro vezes. Avaliou-se a fitotoxicidade e a massa seca aos 28 dias após a aplicação. Para cyhalofop-butyl e imazapyr + imazapic, a fitotoxicidade nas condições de 100% da capacidade de retenção de água do solo e lâmina d’água foi superior nos tratamentos com adubação nitrogenada. Entretanto, para imazethapyr na condição de 100% da capacidade de retenção de água do solo houve aumento de 45% da fitotoxicidade na ausência de adubação nitrogenada em comparação à condição com adubação. Para a condição de alagamento, a partir da dose de 35 g de i.a. ha-1, o resultado no controle para o herbicida imazethapyr foi otimizado nas condições de adubação com 80 e 160 kg de N ha-1. Cyhalofop-butyl e imazapyr + imazapic sofrem interação sinérgica com a adubação nitrogenada e a condição hídrica na eficiência do controle, já com imazethapyr, a interação sinérgica só ocorre em 100% da capacidade de retenção de água do solo.

The degradation of imazapyr (C13H15N3O3), an active element in the aqueous solution of commercial herbicide, was investigated. This study was the first to evaluate in a comprehensive manner the efficiency of advanced oxidation processes for imazapyr degradation. Results showed that Imazapyr degradation is significantly affected by operational conditions such as TiO2 concentration, ozone concentration, initial concentration of imazapyr and pH. The kinetics of Imazapyr consumption was the first order with respect to Imazapyr concentration and zero order with respect to ozone concentration with a constant rate of 0.247 min&minus, 1 and 0.128 min&minus, 1 for photocatalytic ozonation and heterogeneous photocatalysis, while it was the first order with respect to Imazapyr and the first order with respect to ozone concentrations when only ozone was used with a constant rate of 0.053 mol L&minus, 1 min&minus, 1 at pH 7. The results revealed that more than 90 percent of the removal efficiency representing the elimination of imazapyr was held up to 7 &mu, M. Further increase in the concentration of imazapyr leads to a drop in the removal efficiency, however the total imazapyr degradation was reached in 20 min utilizing photocatalytic ozonation for 5 &mu, M of Imazapyr in the presence of 100 mg L&minus, 1 of TiO2, 10 mg L&minus, 1 of ozone at pH 7. Photocatalytic ozonation and heterogeneous photocatalysis utilizing TiO2 as a semiconductor process appeared possible and well suited for the treatment of organic contaminants such as imazapyr herbicides, although at certain dosages of pH and common time for wastewater treatment, imazapyr was not degraded with ozonation on its own. The association of two oxidation processes, ozonation and photocatalysis, has improved oxidation efficiencies for water treatment under optimal conditions, leading to the development of non-selective hydroxyl and more reactive radicals in the oxidation medium, as well as the resulting synergistic effects between photocatalysis and ozonation that react more rapidly with imazapyr herbicide.

The removal of the commonly used herbicides is essential for environmental remediation. In this study, mesoporous TiO2 photocatalysts modified with PtO were synthetized by the template-assisted scheme to develop highly effective materials for the elimination of Imazapyr herbicide under visible-light preservation. The effect of the PtO loading was investigated, and the xPtO-TiO2 materials were deeply considered by N2 physisorption, XRD, HRTEM, FTIR, DRS UV-Vis, Raman, XPS, PL and photocurrent measurements. Total Imazapyr photodegradation was archived on mesoporous TiO2 photocatalysts loaded with 0.6 and 0.8 wt% of PtO. The optimized xPtO-TiO2 photocatalyst degrades the Imazapyr under solar light more efficiently than the pure TiO2 and the commercial Degussa P25 (photoefficiency of 35%, 1%, and 0.5%, respectively). The improvement in the photoefficiency of the xPtO-TiO2 photocatalysts respect to the pure TiO2 was associated to the cooperative effect between PtO and TiO2 nanoparticles leading to a lessening in the energy gap and lower recombination of excited electron-hole pairs. The optimized 0.6PtO-TiO2 photocatalyst demonstrated to be stable and recyclable after up to five consecutive photocatalytic runs. Therefore, it can be a potential candidate for the significant mineralization of Imazapyr herbicide under solar light irradiation.

Technologies that advocate the use of herbicide-resistant crops are alternatives to weed control, but they may cause oxidative stress and change secondary metabolism of plants. Therefore, this study aimed to evaluate changes in the secondary metabolism of soybean plants which contained Cultivance® (CV), sulfonylurea-tolerant soybean (STS) and Roundup Ready® (RR) technologies submitted to the application of the mixture of herbicides imazapyr and imazapic in “plant-apply” and “apply-plant” management systems. Two field experiments, in which soybean cultivars were submitted to increasing doses of the mixture of herbicides imazapyr and imazapic, were performed. Aerial parts of plants were collected 10 days after crop emergence and stored at -83oC, until quantification of variables. In general, the soybean cultivar BRS382CV exhibited lower contents of chlorophyll than cultivars CD249STS and NA5909RR. Besides, increasing doses of the mixture of herbicides imazapyr and imazapic decreased contents of chlorophyll in the cultivars. Stress caused by herbicides induced more generation of ROS and effective response of the antioxidant system through enzymes SOD, CAT and APX. RESUMO: A adoção de tecnologias que preconizam a utilização de culturas resistentes a herbicidas é alternativa para controle de plantas daninhas, porém pode causar estresse oxidativo e alterar o metabolismo secundário da cultura. Dessa forma, o objetivo deste trabalho foi avaliar as alterações no metabolismo secundário de plantas de soja contendo as tecnologias Cultivance® (CV), tolerância às sulfonilureias (STS) e Roundup Ready® (RR), submetidas à aplicação da mistura dos herbicidas imazapyr e imazapic nos sistemas de manejo em “plante/aplique e “aplique/plante”. Foram realizados dois experimentos em campo, onde cultivares de soja foram submetidos a doses crescentes da mistura dos herbicidas imazapyr e imazapic. Aos dez dias após a emergência da cultura, foi realizada coleta da parte aérea e armazenada a -83 oC, até a quantificação das variáveis. O cultivar BRS382CV apresenta, em geral, menores teores de clorofila comparado aos cultivares CD249STS e NA5909RR, e o aumento da dose da mistura dos herbicidas imazapyr e imazapic diminui o teor de clorofila das cultivares. O estresse causado pelo herbicida induz maior formação de EROs, ocasionando elevada resposta do sistema antioxidante através das enzimas SOD, CAT e APX.

Soil moisture can alter the transport and permanence of pre-emergent herbicides. The objective of this work was to evaluate the influence of water availability in the soil on the leaching of a commercial mixture of the herbicides imazapyr + imazapic, as well as the carryover effect of this herbicide in corn planted in succession to soybean. The experiment was carried out in leaching columns in a randomized block design with 4 replications. A 3x3x2 factorial scheme was used, with factor A being the irrigation (130%, 100% and 70% of field capacity (CC)), factor B the doses of the commercial mixture of the herbicides imazapyr + imazapic (0.00+ 0.00; 52.5 + 17.5 and 105 + 35 g ha-1) and factor C at soil depth (0-0.3 m and 0.3-0.6 m). Soybean sowing was performed at the top of the columns and immediately after herbicide mixture was applied. After 120 days the columns were opened, generating two sections, where corn (Zea mays) and the other watermelon (Citrullus lanatus) were sown as a bioindicator of herbicide residue. The fluorescence parameters of chlorophyll a at 15 and 30 days after germination (DAG) and shoot dry matter accumulation at 30 DAG were evaluated. There was greater retention of the herbicide imazapyr + imazapic at a depth of 0-0.3m at 70% CC condition and leaching at a depth of 0.3-0.6m at 130% CC condition, with a reduction in the mass accumulation of watermelon plants. The herbicide has a carryover potential for corn cultivation in soils maintained at 70% CC. A umidade do solo pode alterar o transporte e a permanência de herbicidas pré-emergentes. O objetivo deste trabalho foi avaliar a influência da disponibilidade de água no solo na lixiviação da mistura comercial dos herbicidas imazapyr+imazapic, bem como o efeito carryover deste herbicida no milho semeado em sucessão à soja. O experimento foi desenvolvido em colunas de lixiviação em delineamento de blocos ao acaso com 4 repetições. Foi utilizado esquema fatorial 3x3x2, sendo o fator A as lâminas de irrigação (130%, 100% e 70% da capacidade de campo (CC)), o fator B as doses da mistura comercial dos herbicidas imazapyr + imazapic (0,00+0,00; 52,5+17,5 e 105+35 g ha-1) e o fator C a profundidade (0-0,3 m e 0,3-0,6 m). A semeadura da soja foi realizada no topo das colunas e imediatamente após foi realizada a aplicação da mistura dos herbicidas. Após 120 dias as colunas foram abertas, gerando duas canaletas, onde em uma foi semeado o milho (Zea mays) e na outra melancia (Citrullus lanatus) como bioindicadora do resíduo dos herbicidas. Foram avaliados os parâmetros fluorescência da clorofila a aos 15 e 30 dias após germinação (DAG) e acúmulo de matéria seca de parte aérea aos 30 DAG. Houve maior retenção do herbicida imazapyr+imazapic na profundidade de 0-0.3m na condição de 70% CC e lixiviação para a profundidade de 0,3-0,6 m na condição de 130% CC, com redução no acúmulo de massa das plantas de melancia. O herbicida tem potencial carryover para a cultura do milho em solos mantidos a 70% CC. &nbsp

Chloris spp. are warm-season grasses that outcompete crops for scarce resources throughout Australia. In Queensland, mild winters and increased adoption of conservation tillage practices have led to an increase of this warm-season grass family in winter crops. The objective of this study is to understand whether droplet size (nozzle type) effects herbicide efficacy of summer perennial grasses, as previous research found no effect of droplet size (nozzle type) on herbicide efficacy of winter annual grasses. A study to compare droplet-size (nozzle type) effects on control of windmillgrass and its domesticated relative, rhodesgrass, was conducted at the University of Queensland in Gatton, QLD, Australia. Results showed little difference in dry weight reductions for windmillgrass or rhodesgrass across droplet size (nozzle type). Paraquat applications with the TTI nozzle resulted in significantly lower dry weight reductions compared with other droplet-size sprays (nozzle types) for rhodesgrass. Glyphosate, imazamox plus imazapyr, and clodinafop resulted in commercially acceptable control for both species, regardless of the droplet size (nozzle type) selected, indicating droplet size (nozzle type) has relatively little impact on the efficacy of these herbicides. Proper nozzle selection can result in control of Chloris spp., a hard to control weed species, while reducing the occurrence of spray drift to nearby sensitive areas.

The continuous use of herbicides with the same mechanism of action has caused the selection of resistant weed biotype that may present differences in fitness when compared with susceptible biotype. The objective of the present study was to identify and distinguish the fitness of barnyardgrass biotypes resistant and susceptible to imazapyr + imazapic herbicide under controlled and noncompetitive conditions. For that, there were used barnyardgrass biotype susceptible (ECH1 and ECH38) and resistant (ECH14 and ECH44) to ALS inhibitors, collected at Pelotas/RS and Rio Grande/RS cities, respectively, in experiment installed in a greenhouse in a completely randomized experimental design during the months from October to December 2015. The biotype were evaluated during the period of 15 to 120 days after the emergence related to plant height, foliar area, shoot dry matter mass and root dry matter mass. The results showed insignificant differences between the biotypes during the development of the plants. The susceptible biotype ECH44 showed a higher number of panicles per plant and seeds along with the resistant ECH1. There is variability among Echinochloa crusgalli var. mitis biotypes resistant and susceptible to ALS inhibitors, indicating an absence in fitness penalty caused by resistance when cultivated without the selection of pressure (herbicide).

In the Appalachian Mountains of eastern North America, mountain laurel (Kalmia latifolia) thickets in mixed-oak (Quercus spp.) stands can lead to hazardous fuel conditions, forest regeneration problems, and possible forest health concerns. Generally, land managers use mechanical means or prescribed fire to control mountain laurel thickets, but these treatments are expensive, dangerous to implement, or have short-term effectiveness. From 2012 to 2016, we compared the effectiveness of three herbicides applied as broadcast foliar treatments at varying rates and in different months for reducing mountain laurel thickets. Triclopyr (ester formulation) top-killed mountain laurel within a few weeks at most month/rate combinations, but subsequent sprouting reduced overall effectiveness by year 3. Conversely, imazapyr provided little initial control of mountain laurel, but by year 3, the herbicide had killed nearly all the treated shrubs with no subsequent sprouting regardless of the month of application or rate. Glyphosate had limited effectiveness; spraying in August at 8 and 12 L/ha killed the mountain laurel over 3 years with little sprouting while all others treatments had little or no impact. From these results, it appears that several month/rate combinations of all three herbicides have potential for controlling mountain laurel thickets and merit further testing to refine application procedures.

Imazapyr is a herbicide that can be used in irrigation canals to control a range of aquatic weed species, however, its residual nature, combined with its phytotoxicity to crops at low concentrations, means that the water in canals must be carefully managed following imazapyr application. Residues of the herbicide imazapyr (isopropylamine salt) in irrigation water were analysed and modelled after application to irrigation canals in south-eastern Australia. A treatment program to control delta arrowhead (sagittaria, Sagittaria platyphylla (Engelm.) J.G. Sm.) in over 400 km of irrigation canals was enacted by applying imazapyr to dewatered canals during winter. Following imazapyr application, canals were left dewatered for a period (up to eight weeks) and then refilled. After refilling, canals were ponded for a period (up to 28 days) to allow degradation of imazapyr in the water via photolysis. Upon refilling canals, ~650 water samples containing imazapyr were collected across the treatment area and data modelled to measure the extent of water contamination and to guide efforts to reduce the subsequent irrigation hazard to crops. Modelled data demonstrates that imazapyr behaviour in irrigation water following canal refilling was predictable when 1) amount of imazapyr applied, 2) the dewatered period following herbicide application, 3) the water ponding period, and 4) solar exposure during water ponding were taken into account. Minimising the amount applied (g imazapyr per km of canal) and maximising the time between spraying and refilling (dewatered period) reduced the initial concentration in the water following canal refilling. The amount of imazapyr in the canal water following refilling was reduced by half for every 16 days (confidence interval = 10 &ndash, 38 days) that the canal remained dewatered after imazapyr application. Imazapyr dissipation during the ponding period following canal refilling occurred at a rate that depended on solar exposure. Dissipation did not occur when solar exposure was &lt, 8.5 MJ m&minus, 2. However, when solar exposure was &gt, 10 MJ m&minus, 2, imazapyr concentration in the water reduced by half for every 4.4 days of ponding period (confidence interval = 2.9&ndash, 9.5 days). Our two models, combined with local climate data on solar exposure, can be used by canal managers to determine the optimal time to refill canals so that imazapyr dissipation is maximised, and thus risk of damaging irrigated crops is minimised.

While farmers have used glyphosate to control the growth of weeds such as Cynodon dactylon (cynodon) in sugarcane fields for many years, its use has problems which include poor persistence in the s...

Background Acetohydroxyacid synthase large subunit 1 (Ahasl1) is a multiallelic locus involved in herbicide resistance in sunflower. Ahasl1-1 and Ahasl1-4 alleles harbor different point mutations that lead to different amino acid substitutions (Ala205Val and Trp574Leu, respectively). The objectives of this work were to evaluate the effect of these alleles at the enzymatic and whole-plant levels, and to determine the dominance relationships for imazapyr and metsulfuron-methyl herbicides. Results Resistant near-isogenic lines showed significantly lower specific AHAS activity than susceptible near-isoline. However, kinetic studies indicated that mutations did not change AHAS pyruvate affinity. Dose-response for six near-isolines carrying different combinations of Ahasl1-1 and Ahasl1-4 alleles and two herbicides (imazapyr and metsulfuron-methyl) were evaluated at whole-plant and enzymatic levels. Ahasl1-1 allele conferred moderate resistance to imazapyr and low resistance to metsulfuron-methyl. Conversely, Ahasl1-4 allele endowed high levels of resistance for both herbicides. Dominance of resistance at whole-plant level showed a semi-dominant behavior among the alleles for both herbicides. Conclusion Ahasl1-4 allele confers higher resistance levels than Ahasl1-1 when evaluated with imazapyr and metsulfuron-methyl. Dominance estimations suggested that both parental lines should carry a resistance trait when developing hybrids. © 2018 Society of Chemical Industry.

In Australia, winter annual grasses provide the strongest competition against wheat for resources which detrimentally affects grain yield. With increasing action from government, industry, and grower groups to reduce herbicide spray drift, adoption of drift reduction technologies (DRTs) especially DRT nozzles has increased over recent years. Some herbicides are less effective when sprays are too coarse as droplets may not be retained on target weed surfaces or not intercepted by target leaves. This is particularly an issue with winter annual grasses, whose small, narrow leaves and ability to grow within the wheat canopy makes their control more difficult. This study sought to understand the effect of droplet size on herbicide efficacy by evaluating the effect of six nozzles, five of which have DRT features across six different herbicides (amitrole, clodinafop, glyphosate, imazamox plus imazapyr, metribuzin, and paraquat) for the control of four winter annual grasses (annual ryegrass, Italian ryegrass, rescuegrass, and tame oats). Plants were grown in pots outdoors on the University of Queensland Gatton campus and were sprayed at 28 days after emergence in August and repeated in October 2015. Results from this study indicate DRT nozzles that produce sprays classified as Ultra-Coarse (>650 μm Dv0.5) can preserve efficacy for some herbicides. Differences were not observed for herbicide efficacy of clodinafop, imazamox plus imazapyr, and glyphosate across both years. Coarse sprays appear to provide the most herbicide efficacy across a wide array of modes of action, and yet reduce spray drift potential compared to finer sprays.

This study evaluated the effectiveness of 14 herbicide treatments for purple loosestrife (Lythrum salicariaL.) control over a period of 10 yr. The study commenced in 2000/2001 at four wetland locations in Nebraska. The evaluated herbicides included: glyphosate at 2.2 and 3.4 kg ha−1; 2,4-D dimethylamine at 1.4 and 2.8 kg ae ha−1; triclopyr at 1.3 and 2.1 kg ae ha−1; imazapyr at 1.1 and 1.7 kg ae ha−1; metsulfuron at 0.042 and 0.084 ai kg ha−1; fosamine at 13.5 and 22.4 kg ai ha−1; triclopyr at 1.3 kg ae ha−1plus 2,4-D amine at 1.4 ae kg ha−1; and metsulfuron at 0.042 kg ai ha−1plus 2,4-D amine at 1.4 kg ae ha−1. Some treatments provided excellent control (90%) that lasted only one season, while others suppressedL. salicariagrowth for multiple seasons, depending on the location and the age ofL. salicariastand. Application of higher rates of glyphosate, imazapyr, and metsulfuron consistently provided excellent control (≥90%) ofL. salicariathat lasted 360 d after treatment at most locations. Application of fosamine and the lower rate of 2,4-D amine provided the leastL. salicariacontrol at most locations. The older theL. salicariastand, the more multiple applications of herbicides were needed to completely controlL. salicaria. Generally, there were higher percentages of grasses in the 2,4-D-, triclopyr-, and metsulfuron-treated plots compared with higher percentages of broadleaf species in the glyphosate- and imazapyr-treated plots at each location.

Imidazolinones are powerful herbicides that inhibit branched-chain amino acid biosynthesis by targeting the catalytic subunit of acetohydroxyacid synthase (AHAS). Imidazolinone application in the advanced vegetative or early reproductive developmental stages is associated with male sterility in resistant sunflower (Helianthus annuus L.); however, the underlying mechanism of this sterility remains unknown. This study describes the morphological, cytoem-bryological, and molecular alterations induced by imazapyr (IM) treatment on reproductive tissues at different developmental stages in two sunflower genotypes, resistant and intermediate resistant, respectively. Pollen and seed physiological variables were compared between the treated and control plants. The number of pollen grains per flower and viable seeds were negatively affected by IM treatment in the intermediate-resistant genotype, and the biometric traits of early developed disc flower were also significantly different in this genotype. Differential interference contrast microscopy revealed that IM treatment slightly accelerates megagamethophyte development. Anther observations at microsporogenesis using confocal microscopy show that the sporogenous tissue was damaged. Furthermore, the expression profiles of the sunflower AHAS paralogs (ahas1, ahas2, and ahas3) were measured by quantitative polymerase chain reaction in the anthers and pistils of two developmental stages in treated and control plants. Imazapyr treatment in early reproductive growth stages clearly induces divergent expression patterns in the ahas gene family. These findings provide new insight into a novel chemical method for inducing male sterility in sunflowers and enhance our understanding of the effects of AHAS-inhibitor herbicides in reproductive tissues. Fil: Ochogavía, Ana Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina Fil: Novello, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina Fil: Bianchi, Marta Beatriz. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentina Fil: Picardi, Liliana Amelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina Fil: Nestares, Graciela María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina