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We developed, tested, and optimized two laboratory denitrification assays for both managers and scientists to assess the effects of xenobiotics on the denitrification process over 7 days (short batch assay, SBA) and 28 days (long semi-continuous assay, LSA). The assays facilitate (1) measuring the efficiency of nitrate removal under the influence of xenobiotics, (2) determining the removal of the tested xenobiotics via adsorption or biotic decomposition, and (3) testing the influencing parameters for optimizing the denitrification process. The adsorption of the xenobiotics was assessed by inhibiting all biological processes through the addition of HgCl2. Our tests demonstrate that the ratio of the initial nitrate concentration to the amount of bioavailable organic matter provided is essential to avoid organic carbon or nitrate limitation. While a pH < 7 resulted in decreased denitrification, a pH > 8 led to nitrite accumulation, indicating incomplete denitrification. Over durations of more than a week, weekly replenishments of the nitrate and HgCl2 and weekly purging with argon gas to reduce the oxygen concentrations are needed. The assays provide information about the accumulation of xenobiotics in the bioreactors that is necessary for the environmentally friendly treatment of the bioreactor fillings and provide insight into the potential of the bioreactors to remove pesticides from polluted water resources.

Nanoparticle incorporated membranes are potential tools to remove hazardous organic pollutants from drinking water sources. Cellulose acetate membranes were impregnated by incorporating zinc nanoparticles, produced using a green synthesis with Mentha plant extract utilizing microwave energy. The synthesized nanoparticles were extensively characterized using ultraviolet–visible spectroscopy, X-ray diffraction, Scanning electron microscopy, energy dispersive X-ray spectroscopy and Nanoparticle tracking analysis. The spectroscopy results showed an absorbance peak at 300 nm, confirming the successful synthesis, while X-ray diffraction confirmed that the particles are crystalline with a mean particle size of 36 nm. The surface roughness and topography of the zinc nanoparticle impregnated membranes was studied using atomic force microscopy to check the homogeneity of dispersion of the nanoparticles in the membrane. The efficiency of the zinc nanoparticles and the zinc nanoparticle loaded cellulose acetate membranes for adsorption of organic herbicides such as metolachlor and acetochlor was studied. The particles themselves and the particle-embedded membranes proved to be very adsorbent due to their unique structural properties, providing large surface area and high adsorption capacity. The incorporation of zinc nanoparticles into the membrane decreased the time needed for the removal of the selected herbicides relative to that of the nanoparticles alone, and provides a promising method for water purification.

The purpose of this study was to explore the stability and toxicity of the herbicides and their degradation byproduct after exposure to different environmental factors. Triazines (atrazine, propazine, simazine) and chloroacetanilides (acetochlor, alachlor, metolachlor) which are commonly used herbicides were evaluated for cytotoxicity in different UV (254 nm and 365 nm) and temperature (4 °C, 23 °C, and 40 °C) conditions as well as degradation rates. Atrazine with the highest LD50 (4.23 μg mL−1) was less toxic than the other tested triazine herbicides Chloroacetanilides tested were more toxic than tested triazines, with LD50 0.08–1.42 μg mL−1 vs 1.44–4.23 μg mL−1, respectively. Alachlor with LD50 0.08 μg mL−1 showed the strongest toxic response as compared with other tested herbicides. Temperatures only did not alter cytotoxicity of the tested herbicides, except for acetochlor and alachlor showing about 45 % more cell death after exposure to 40 °C for 2 h. At all 3 tested temperatures, 2 h of UV treatments did not affect cytotoxic effects of the tested herbicides, except for acetochlor and alachlor. At 4 °C, acetochlor toxicity was attenuated about 63 % after UV 365 nm exposure; but alachlor toxicity was enhanced after either UV 254 or 365 nm exposure for about 40 % and 24 %, respectively. At 23 °C, acetochlor toxicity was enhanced about 35 % after UV 254 nm exposure, but attenuated about 48 % after UV 365 nm exposure. Alachlor toxicity was enhanced about 34 % after UV 254 nm and 23 °C exposure. In combination of UV 254 nm and 40 °C, acetochlor toxicity was lowered by 63 % and alachlor toxicity was no change as compared with 4 °C, no UV group. After co-treatment with UV 365 nm and 40 °C both acetochlor and alachlor toxicity was enhanced 55 % and 80 %, respectively. Through degradation analysis by LC-MS/MS, alachlor showed the most dramatic degradation (only 0.58 %–10.58 % remaining) after heat and UV treatments.

A sensitive micellar-enhanced thermochemically induced fluorescence derivatization (ME-TIFD) method for a rapid determination of metolachlor (MET) residues based on the O-phthalaldehyde (OPA)-thermoproduct complex of MET (OPA-MET) was investigated. Both SDS and Brij-700 have been used as surfactant micelles. This study advocates the TIFD method analytical parameters curation. Fluorescence enhancement and its stabilization were highlighted for the OPA-MET equimolar complex in micellar aqueous solutions. The new analytical features (K: binding constant and ΔG°: Gibbs energy) for controlling thermodynamic interactions were carried out at 25 °C. Under the optimized conditions, the calibration curves were linear with correlation coefficients ranging from 0.9788 to 0.9896 at the concentration level of 10-580 ng mL–1, and the limits of detection were 0.04-0.7 ng mL−1 at a signal-to-noise (S/N) of 3. The SPE/ME-TIFD applications combined with analysis of well and tap water spiked samples with metolachlor yield satisfactory mean recoveries (RSD) 102.2–108.1% (5.1–7.3%) and 103.6–106.0% (6.3–7.6%), respectively.

While there has been intensive research on the influence of microplastics (MPs) on aquatic organisms and humans, their effect on microorganisms is relatively little-known. The present study describes the response of the Trichoderma harzianum strain to low-density polyethylene (LDPE) microparticles. MPs, either separately or with metolachlor (MET), were added to the cultures. Initially, MP was not found to have a negative effect on fungal growth and MET degradation. After 72 h of cultivation, the content of fungal biomass in samples with MPs was almost three times higher than that in the cultures without MPs. Additionally, a 75% degradation of the initial MET was observed. However, due to the qualitative and quantitative changes in individual classes of phospholipids, cell membrane permeability was increased. Additionally, MPs induced the overproduction of reactive oxygen species. The activity of superoxide dismutase and catalase was also increased in response to MPs. Despite these defense mechanisms, there was enhanced lipid peroxidation in the cultures containing the LDPE microparticles. The results of the study may fill the knowledge gap on the influence of MPs on filamentous fungi. The findings will be helpful in future research on the biodegradation of contaminants coexisting with MPs in soil.

In this paper, a novel metolachlor microcapsules suspension (CS) was prepared by interfacial polymerization. Metolachlor polyurea microcapsules suspension was successfully prepared by urea instead of polyamines which could reduce the use of organic solvents and production costs. The synthesized microcapsules were characterized by Fourier Transform Infrared Spectrometer, Scanning Electron Microscope, Ultraviolet Spectrometry, Thermogravimetric analyses and particle size analyzer. In conclusion, the diameter of the urea microcapsules were the smallest (11.52 μm) and excellent encapsulation efficiency (81.45%). In addition, Urea microcapsules had compact microstructures and global shapes, which had a good thermal stability and metolachlor could be preserved better in the polyurea microcapsules. These results indicated that the prepared microcapsules by urea had better thermal storage properties and physicochemical property. The microcapsule suspension of metolachlor hasn’t been researched yet. Therefore, it is significant to prepare microcapsule suspension. More importantly, there is no use of organic solvents in the preparation of microcapsules suspension, which avoided the pollution of solvents to the ecological environment. It is hoped that this polyurea material will be applied in the field of pesticide synthesis and polymers.

Three activated carbons from lignocellulosic residues and a commercial carbon have been tested for the removal of the herbicide metolachlor and its two degradation transformation products, named ESA and OXA, in aqueous solutions. The kinetics and equilibrium adsorption were studied for the four materials, showing higher adsorption capacities for the three molecules on the carbon materials chemically activated by potassium carbonate, mainly associated with its greater porous development, especially in the range of microporosity. Additionally, the chemical composition of the adsorbents also highlighted their important influence on the ESA and OXA adsorption process. The efficient adsorption of both compounds—even at low initial concentrations—allows a removal efficiency of up to 80% to be reached, revealing promising perspectives for the use of biomass-derived carbon materials for the elimination of not only the herbicide metolachlor, but also its degradation compounds from contaminated wastewater.

The affinity of different soil colloids to retain carbaryl, carbofuran and metolachlor in sandy loam and loam soil from mineral, surface horizons was investigated. The undisturbed soil samples and soils amended with colloids—kaolinite (K), montmorillonite (Mt), illite (Il), goethite (G), humic acid (HA)—were mixed with the pesticides for sorption–desorption studies. Their sorption magnitude in pristine soils followed the sequence metolachlor > carbaryl > carbofuran, with loam soil being a better pesticides retarder than sandy soil. The biggest magnitude of carbaryl sorption in light soil was observed in samples with the addition of HA (92.7%), Il (92.3%) and Ge (87.5%), whereas for carbofuran it was goethite (52.3%). Metolachlor uptake was significantly enhanced by 2:1 clays (Mt-85.0%, Il-69.4%), goethite (73.3%) and humic acids (75.4%). The loamy soil sorption capacity of the studied pesticides was blocked by the natural organic matter potentially due to the formation of organo-mineral complexes. HA (66.8%) was the most effective sorbent for carbaryl in the loamy soil, whereas Mt (55.1%) and HA (40.3%) for carbofuran. Metolachlor was retained to the same extent in all loamy soil variants (75.8–83.6%) and its desorption values were the lowest. Carbofuran demonstrated the greatest ability to leach among the studied chemicals.

In agricultural areas, ponds are suitable wetland environments to dissipate and reduce the occurrence of pesticides in aquatic environments. However, their impact at a catchment scale is still poorly understood. This study aims to determine how these organic contaminants were trapped in a pond located in an agricultural critical zone from SW France (Auradé catchment). The spatial distribution of pesticide concentrations and their different controlling factors were investigated in waters and sediments collected during two distinct seasons. The results highlighted (i) the link between the presence of the molecules and the agricultural practices upstream, (ii) the influence of hydrological/seasonal conditions, especially on hydrophobic molecule accumulation such as tebuconazole, (iii) the key role of clay content in sediments on the control of moderately hydrophilic pesticides (metolachlor and boscalid), but also the unexpected role of coarse particles for boscalid; and (iv) the influence of sediment depth on pesticide storage. Nevertheless, other physico-chemical parameters, such as mineralogical composition of sediment, needed to be considered to explain the pesticide patterns. This study brings a new hypothesis to be investigated in the future about pesticide behaviour in such pond environments.

Background and Objective: With industrial development and population growth, the emerging contaminants enter into the natural water resources. Therefore, adsorption potential of Ammonium Chloride-induced activated carbon (NAC) to remove metolachlor pesticide from contaminated water was investigated in this study. Materials and Methods: The effects of operational conditions including solution pH, NAC concentration, metolachlor initial concentration and contact time on the removal of metolachlor by Ammonium Chloride-induced activated carbon (NAC) and standard activated carbon (SAC) were studied. Results: Over 92.4% of 50 mg/L metolachlor was adsorbed using 0.3 g NAC/L within 5 min, and by increasing the reaction time to 60 min the removal efficiency reached to 100%. Under similar experimental conditions, standard activated carbon (SAC) could only adsorb 20% of metolachlor within 5 min and increase of contact time to 40 min caused the improvement of metolachlor adsorption onto SAC to 48%. The adsorption onto SAC was not influenced by the contact time over 40 min. Kinetic analysis showed that experimental adsorption data for both NAC and SAC were best fitted to the pseudo-second-order model. The maximum adsorption capacities of metolachlor onto NAC and SAC calculated by the Langmuir model were 344.8 and 238.1 mg/g, respectively. Conclusion: Generally, these results showed that developed NAC was an efficient adsorbent with high removal efficiency for eliminating the halogenated pesticides from the contaminated water streams.

Metolachlor is extensively used and the most persistent chloroacetamide herbicide, thereby which its metabolites have been frequently detected in soils and surface and groundwaters. Microbial degradation is predominantly responsible for the removal of metolachlor from soil and water. However, few microbial strains reported previously are highly efficient in degrading potentials for metolachlor. We isolated the fungal strain MET-F-1 from an activated sludge, characterized as Penicillium oxalicum, which could degrade 88.6% of 50 mg/L metolachlor coupled with 0.1% glucose plus 0.1% yeast extract within 384 h under optimal conditions. Compared with metabolites produced by previously isolated microorganisms, different degradation products, i.e., MOXA, M2H, and MDES, detected by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), were produced through hydrolytic and reductive dechlorination by MET-F-1. This is the first report on the degradation of metolachlor by Penicillium oxalicum sp. Furthermore, field plot experiments using the wheat bran inoculum method were performed and demonstrated good metolachlor-degrading activity of this strain. This study serves as a steppingstone to promote MET-F-1 strain usage as a promising agent for metolachlor-contaminated soil remediation.

Salicylic acid (SA) is an endogenous plant hormone that has a wide range of pharmacological effects. Studies have indicated that SA has herbicide safening activity. In this study, the herbicide safening activity of SA and 20 substituted molecules were tested on agar-cultured rice. Biological assay results indicated that SA and substituted SA had a low inhibitory effect on the growth of rice seedlings (Oryza sativa), and partially alleviated the effects of metolachlor toxicity. Moreover, at 0.25 mg L−1, the safening effect of compounds l and u lessened the effects of metolachlor phytotoxicity on plant height and fresh weight when compared to the effects of the control, fenclorim. The effects of metolachlor toxicity were reduced on root length due to the safening effects of compounds l, n, and u; these effects were greater than those of fenclorim. These compounds could facilitate the development of novel herbicide safeners.

The effect of mixtures of pre-emergence herbicides on weed infestation and yield of leek was evaluated. Three tank mixtures were applied: s-metolachlor (Dual Gold 960 EC at a dose of 80 ml/da) + oxyfluorfen (Goal 2 E at a dose of 100 ml/da); s-metolachlor (Dual Gold 960 EC at a dose of 60 ml/da) + oxyfluorfen (Goal 2 E at a dose of 75 ml/da); and s-metolachlor (Dual Gold 960 EC at a dose of 40 ml/da) + oxyfluorfen (Goal 2 E at a dose of 50 ml/da). The number of weeds was recorded following the application of the tank mixture. It was found that treatment with a tank mixture of herbicides Dual Gold 960 EC and Goal 2 E caused a reduction in weed infestation at all three application rates as compared to the control. The lowest weed infestation was established after treatment with the highest doses of herbicides. It was suggested that the applied herbicide mixture could be used effectively at the leeks growth stage.

The aim was to compare the efficacy, selectivity to sunflower and dissipation of three chloracetamide herbicides (acetochlor, metolachlor and pethoxamid) in dependence on precipitation after application. A small plot field trial was carried out with sunflower in Central Bohemia in 2010 and 2011. The remaining concentration of active ingredient in the soil of all studied herbicides was lower in the year with a higher temperature and a low level of total natural precipitation at the beginning of the growing season. Higher leaching of metolachlor and pethoxamid was recorded in irrigated plots. No leaching was found in the case of acetochlor. The highest leaching was found for metolachlor (9.2-25.5% in soil layer 5-10 cm). The highest phytotoxicity was found for acetochlor (9.8%) > pethox-amid (4.6%) > metolachlor (1.8%). The mean phytotoxicity in the irrigated plots was 6.9%, compared with 3.9% in the non-irrigated plots. The efficacy of the tested herbicide was affected by wet conditions. The highest efficacy on Chenopodium album, Amaranthus retroflexus, Echinochloa crus-galli and Solanum physalifolium was recorded after application of acetochlor and irrigation.

A study of the impact of two acetanilide herbicides, viz. alachlor and metolachlor on bacterial and fungal populations and biomass in the Sungai Buluh soil series samples was carried out under laboratory conditions. The effects of the two herbicides were monitored for 70 days under ambient conditions. Metolachlor caused greater reduction in bacterial counts than on fungal populations. There was approximately 75% reduction in bacterial counts 14 days after treatment (DAT) with 2 µg/g metolachlor. Alachlor however was less toxic to bacterial and fungal populations. Alachlor caused a reduction in bacterial counts at 7 and 14 DAT with 2µg/g or above. Fungal population decreased significantly in the presence of 20 µg/g alachlor at 7 DAT but no further effects were observed as the incubation period was prolonged. The study showed that the microbial biomass immediately decreased significantly in the presence of 2 µg/g or more of metolachlor at 0 and 28 DAT. Alachlor, on the other hands, at the lowest experimental dose of 2 µg/g reduced the microbial biomass almost immediately upon incubation, but had no further effects when the incubation period was prolonged.

O objetivo deste trabalho foi avaliar a lixiviação no solo dos herbicidas metolachlor e fomesafen aplicados com água de irrigação de pivô central, nos plantios direto (palha de milho e de plantas daninhas) e convencional, na cultura do feijão (Phaseolus vulgaris) em um Argissolo Vermelho-Amarelo câmbico. Foi conduzido um experimento, com três repetições, no qual o metolachlor (2,4 kg ha-1) foi aplicado, em pré-emergência, com lâminas de água de 5, 10 e 15 mm, e o fomesafen (0,225 kg ha-1), em pós-emergência, com 3, 6 e 9 mm. Os herbicidas também foram aplicados com pulverizador costal. Para a avaliação da lixiviação, foram conduzidos bioensaios em casa de vegetação, coletando-se amostras de solo, quinzenalmente, nas camadas de 0-5, 5-10 e 10-15 cm de profundidade, num total de três repetições. A primeira amostra, de um total de quatro, foi retirada 15 dias após a aplicação. Como planta-teste foi utilizado sorgo (Sorghum bicolor), híbrido BR 304. Quinze dias após a semeadura, as plantas foram coletadas inteiras (parte aérea e raízes) para a determinação da massa seca. No plantio direto, o metolachlor, independentemente do método de aplicação, não sofreu lixiviação nem apresentou atividade no solo aos 15 dias após a aplicação. No plantio convencional, a herbigação do metolachlor só afetou o crescimento do sorgo cultivado na camada de solo mais superficial (0-5 cm de profundidade) aos 15 dias após a aplicação. O fomesafen, independentemente do método de aplicação e do sistema de plantio, foi lixiviado até 10 cm de profundidade e detectado até na última data de amostragem (60 dias após a aplicação). A aplicação do metolachlor e do fomesafen com água de irrigação apresentou-se segura em relação à movimentação no solo.The aim of this study was to evaluate the leaching of the herbicides metolachlor and fomesafen in an Alfisol soil trough irrigation water under no-till and conventional tillage systems. One experiment consisted of three replications with metolachlor (2,4 kg ha-1) applied in pre-emergence, at water depths of 5, 10 and 15 mm, and fomesafen (0,225 kg ha¹) applied in post-emergence, at water depths of 3, 6 and 9 mm. The herbicides had also been applied by spraying. Bioassays were carried out under greenhouse conditions using soil samples from the plots. The soil samples were taken each fifteen days from layers of 05, 5-10 and 10-15 cm depth. The first sample, out of a total of four, was collected 15 days after herbicides aplication. The samples were sowed with sorghum bicolor, hybrid BR 304, which was used as test-plant. Fifteen days after sowing, the whole plants (shoot and roots) were collected for dry mass weight. Under no-till, metolachlor was not detected in the soil at 15 days after aplication, regardless of the application method. Under the conventional system, only metolachlor herbigation affected sorghum growth at the 0-5 cm soil layer. Fomesafen was leached down to 10 cm depth, being detected at the last sampling date (60 days after application), regardless of the application methods. Herbigation of metolachlor and fomesafen showed to be reliable in relation to soil movement.

Possibilities of herbicide applications to the self-heal (Prunella vulgaris L.) growth were tested in 1997-1998. Experiments showed that the application of pre-emergence herbicides in the Prunella vulgaris L. growth was efficient when 3 l/ha ofherbicide with 500 g/lisoproturon as an active ingredient were used. Herbicide applications had no influence on the emergence rate of direct seeding. Among the post-emergence herbicides it is possible to use glyphosate-IPA in 50% concentration by the wick applicator to Elytrigia repens (L.) Nevski. The results of these experiments can be used as a basis for testing the herbicide biological efficacy in the framework of minority indications for cultivated medicinal plants. .

The effect of chemical weed control with reduced herbicide rates (pre-em., pre-em. + post-em., post-em.) on weed population density and maize yield was compared in three tillage systems (mouldboard, chisel, disk harrowing) for lessive pseudogleyic soil in north-eastern Croatia(1997-1999). These main weeds were present in all tillage variants: Echinochloa crus-galli (L.) PB., Chenopodium album L., Ambrosia artemisiifolia L., Polygonum lapathifolium L., Equisetum arvense L. and Calystegia sepium (L.) R.Br. The density of all weeds was significantly affected by tillage and it ranged from 204 plants on untreated plots with mouldboard to 372 and 421 plants per m2 with chisel ploughing and disk harrowing, respectively. In comparison with standard tank-mixture of atrazine herbicide (metolachlor 50% & atrazine 20%) at the recommended rate, atrazine-free herbicide combinations (metolachlor + 50% prosulfuron & 30% primisulfuron-methyl; sulcotrione + bromoxynil; thifensulfuron-methyl + nicosulfuron) showed a similar total efficacy of weed control (95-96%). Band spraying with standard treatment at a half-recommended rate combined with mechanical weed control brought a satisfactory total weed reduction (83-87%). The weed control methods had no effects on maize yields that were significantly affected by year and tillage. Compared to the highest yield with mouldboard ploughing (10.2 t/ha), average percent yield depressions with chisel ploughing and disk harrowing were 10 and 22%, respectively.

Os sistemas de manejo do solo podem alterar a bioatividade dos herbicidas cloroacetamidas e influir na sua persistência no solo, seletividade às culturas e eficácia de controle das plantas daninhas. Um experimento foi conduzido na Universidade Federal do Rio Grande do Sul, durante o ano agrícola de 2000/2001, para avaliar a eficácia de controle das plantas daninhas pelos herbicidas cloroacetamidas, em solo Argissolo Vermelho, manejado sob semeadura direta e preparo convencional. Foram avaliados os herbicidas acetochlor e alachlor, cada um na dose de 3.360 g ha-1, metolachlor a 2.400 g ha-1, s-metolachlor a 1.440 g ha-1, s-metolachlor + antídoto à 1.440 e 1.800 g ha-1, respectivamente, além da testemunha sem herbicida, nos sistemas convencionais e semeadura direta. As avaliações foram de eficácia de controle, população de plantas daninhas e matéria seca da parte aérea das plantas daninhas, realizadas aos 30 e 50 dias após aplicação dos tratamentos (DAT). Os herbicidas cloroacetamidas foram mais eficientes no controle das plantas daninhas no preparo convencional, comparado à semeadura direta, em ambas as épocas de avaliação. Os herbicidas acetochlor, alachlor a 3.600 g ha-1 e s-metolachlor + protetor a 2.400 g ha-1 foram mais eficientes no controle destas plantas, em relação aos demais herbicidas e formulações. A produção de matéria seca e a população das plantas daninhas foram menores no preparo convencional.Soil management systems can affect chloroacetamide herbicide bioactivity and its soil persistence, crop selectivity and weed control. An experiment was carried out at the University of Rio Grande do Sul, Brazil, during the growing season 2000/2001, to evaluate the weed control efficacy of the chloroacetamide herbicides, in a Paleudult soil, under conventional tillage and no-tillage systems. The following treatments were tested: acetochlor and alachlor, each at the rate of 3.360 g ha-1, metolachlor at 2.400 g ha-1, s-metolachlor at 1.440 g ha-1, and s-metolachlor + protector at 1.440 and 1.800 g ha-1, respectively, besides a check plot without herbicide, applied under conventional and no-tillage systems. Assessments included weed population, weed dry matter and weed control at 30 and 50 days after herbicide application. The chloroacetamides herbicides were more effective in controlling weeds under conventional tillage, compared to no tillage, in both evaluation times. The herbicides acetochlor, alachlor at 3,600 g ha-1 and metolachlor + protector at 2,400 g ha-1 were more efficient in controlling these plants when compared to the other herbicides and formulations. Dry biomass production and weed populations were lower under conventional tillage.

The objective of this study was to determine the selectivity of Primestra SC(200 g L-1 of atrazine + 300 g L-1 of metolachlor) on forage sorghum and the efficacy to controlweeds at different rates. The treatments were five rates of Primestra SC (1,5; 3,0; 6,0; and 12,0 L ha-1) with or without Assist (mineral oil) at 1,5 L ha-1, Gesaprim 500 (500 g L-1 ofatrazine) at 4,8 L ha-1, Primóleo (400 g L-1 of atrazine + 300 g L-1 of mineral oil) at 6,0 L ha-1,weedy check plot, and check plot without weed. The herbicides were sprayed 11 days aftersorghum (AG 2002) emergence when broadleaf weeds had two to four leaves and grassesone tiller. Symptoms recovery of herbicide toxicity were detected even when higher rates wereapplied. Fresh weight reduction of 24% was observed in the weedy check plot compared tothe check plot without weed, however dry matter did not show significantly reduction. PrimestraSC at rates higher than 6,0 L ha-1 provided excellent broadleaf weed control (98%). PrimestraSC controled efficiently grasses (94%) at 12 L ha-1. Gesaprim 500 and Primóleo reduceddensity and biomass of broadleaf weeds although no significant differences were detectedbetween the herbicides. Primóleo obtained better grass weed control than Gesaprim 500.Grass weed and total weed control did not differ significantly between Primestra SC andPrimóleo. The addition of Assist to Primestra SC reduced the efficacy of broadleaf weedcontrol indicating a possible antagonism. None of the evaluated herbicides showed efficientgrass weed control except for Primestra SC at 12,0 L ha-1 (94%).

With the objective of evaluating the forage sorghum tolerance to Primestra SC(200 g l-1 of atrazine + 300 g l-1 of metolachlor), a greenhouse experiment was conducted atEmbrapa Milho e Sorgo, Sete Lagoas, MG. The treatments were four Primestra SC rates(3,0; 6,0; 9,0 and 12,0 l ha-1) with or without Assist (mineral oil) at 1,5 l ha-1 sprayed at threesorghum (AG 2002) stages (two, four and six leaves). The experimental design was factorialwith the addition of a non-treated control for each spray stage added in a randomized completeblock with four replications. Visual evaluation of toxicity was done at 7, 14, 21 and 28 daysafter application (DAA). Plant height and root and shoot dry weight were evaluated. Plantssprayed with Primestra SC with Assist showed greater toxicity than plants sprayed withPrimestra SC without Assit meanly at higher rates. Earlier application of Primestra SC had higher toxicity values than later application. Sorghum plants recovered with time to all rates ofPrimestra SC sprayed independently of stage application.

The effect of metolachlior [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl) acetamide] at rates of 0.0, 1.5, 3.0, 4.5, and 6.0kg a.i./ha on the growth and nodulation of soybean cv. BR-4 cultivated on two substrata (soil and soil + sand) and inoculated with Bradyrhizobium japonicum (Kirchnea-1896) Jordan 1982, 137 (Denotes that this name has been validly published in the oficial publicadon, Intemational Joumal of Systematic Bacteriology), was studied under greenhouse conditions at Lages, SC, Brazil, in 1992-93. The experimental design was completely randomized with four replicates. The experimental unit was a container with two plants. Fifty-two days after the emergence (at R1 stage - beginning of flowering) the plants were harvested and evaluated for shoot, root, leaf and nodule dry matter, nodule number, and leaf area. The data were submitted to variance analysis and multiple polynomial regression. Increasing rates of metolachlor significantly reduced shoot, leaf and nodule dry matter and leaf area, the data following a linear polynomial regression, while root dry matter and nodule number were not affected. The interaction "rate x substratum" was not significant for all parameters studied. Except for root dry matter and nodule number, soybean growth was significantly reduced more on soil + sand than on soil, probably as a result of a nutritional effect. Visual phytotoxicity was not observed for all treatments.Este trabalho foi conduzido com o objetivo de estudar o efeito de cinco doses do herbicida metolachlor (0,0, 1,5, 3,0, 4,5 e 6,0 kg i.a./ha) sobre o crescimento e nodulação de soja cv. BR-4, inoculada com Bradyrhizobium japonicum (Kirchner 1896) Jordan 1982, 137 (nomenclatura válida conforme publicação oficial do Intemational Joumal of Systematic Bacteriology) e cultivada em dois substratos (solo e solo + areia) em condições de casa de vegetação, em Lages, SC, Brasil, no ciclo 1992/93. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições, sendo a unidade experimental o vaso com duas plantas. Cinqüenta e dois dias após a emergência (no estágio R1 - início do florescimento) as plantas foram colhidas, procedendo-se a determinação de matéria seca de caule, raiz, folhas e nódulos, número de nódulos e area foliar. Os dados foram submetidos à análise de variância e regressão polinomial múltipla. Doses crescentes de metolachlior significativamente reduziram a matéria seca de caule, folha e nódulos e area foliar, segundo uma regressão polinomial linear, o mesmo não ocorrendo com a matéria seca de raiz e o número de nódulos. A interação "dose x substrato" não foi significativa para todos os parâmetros avaliados. À exceção da matéria seca de raiz e do número de nódulos, o crescimento foi significativamente menor no substrato solo + areia do que no substrato solo, devido, provavelmente, a efeitos nutricionais. Nenhum tratamento casou efeito fitotóxico visual às plantas de soja.

W 3-letnim doświadczeniu polowym metolachlor 1728 g.ha -1 stosowany następnego dnia po siewie nasion zwalczał ponad 90% chwastów i nie uszkadzał roślin fasoli. Bentazon 450 g.ha -1+450 g.ha -1 stosowany ze wspomagaczem powschodowo zwalczał od 57 do 95% chwastów i powodował niewielką chlorozę liści fasoli. Oba herbicydy nie miały wpływu na wielkość plonu zielonych strąków ani plonu suchych nasion fasoli. Opóźnienie pierwszego pielenia o 3 tygodnie powodowało istotne zmniejszenie obu tych plonów, nie miało natomiast wpływu na szerokość zielonych strąków ani na masę 1000 nasion.

Três experimentos de campo foram conduzidos em Latossolos Vermelho-Escuro e Vermelho-Amarelo, nos anos 1981/82 e 1982/83 com o objetivo de determinar o efeito de herbicidas para o controle de plantas daninhas angustifoliadas e fitotoxidade sobre a cultura de soja, cultivares UFV-1 e Cristalina. O grupo das acetanilidas e pendimethalin controlaram a trapoeraba. Para as três espécies latifoliadas, o acetochlor, trifluralin e oryzalin foram eficientes. Além disso, o metolachlor controlou a poaia e o pendimethalin controlou a poaia e o apaga-fogo. Para o controle do capim-marmelada, todos os produtos foram eficientes, exceto quizalofop-etil e mefluidide, enquanto que para o capim-colchão apenas o mefluidide não foi eficiente. Finalmente, o timbete não foi eficientemente controlado por alachlor, metolachlor, pentimethalin e mefluidide. Acetochlor e oryzalin afetaram negativamente o stand inicial. Além disso, o acetochlor reduziu altura da inserção da primeira vagem. O quizalofop-etil causou uma redução na produção de grãos.Three field experiments were carried out on Dark Red Latosol and Yellow Red Latosol in 1981/82 and 1982/83 to evaluate the efficiency of herbicides upon grassy and their phytotoxicity upon “UFV-1” and Cristalina soybeans cultivars. The acetoanilide group and pendimethalin showed good epiderwort control. For the three broadleaved weed species, acetochlor, trifluralin and oryzalin were efficient. More over, metolachlor controlled Brazil pusley and A. ficoidea. For alexandergrass control all herbicides tested were efficient but quizalofop-ethyl and mefluidide, whereas crabgrass was not controlled by mefluidide only. Acetochlor and oryzalin treatments decreases initial stand. Besides, acetochlor decreased height of insertion of first pod. Quizalofop-ethil reduced grain yield of soybeans.