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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.

Asulam is an herbicide that is structurally analogous to sulfonamide antibiotics (sulfas), with the potential to contribute to the global antibiotic resistance crisis by cross-selecting for sulfa-resistant bacteria. To determine if asulam can select for antibiotic resistant bacteria, isothermal titration calorimetry (ITC) was used to assess the binding affinity of asulam with the target protein of sulfas, dihydropteroate synthase (DHPS). ITC confirmed asulam interacts with DHPS, and in vitro directed evolution experiments showed that prolonged asulam exposure can select for sulfa-insensitive DHPS in E. coli. Since mobile sul genes also encode for sulfa-insensitive DHPS, the potential effect of asulam on the dissemination of the sul genes in a simulated bacterial community was assessed. These data suggested that asulam can promote sulfa-resistance by increasing the frequency of chromosomal folP mutations, and/or acquisition of sul genes in E. coli, and uniquely induce deletions of multiple genes at concentrations exceeding environmental relevance.

The influence of acifluorfen and bentazon in the control of weeds in soybean was studied at the Students’ Research and Demonstration Farm, Kogi State University, Anyigba during the 2016 growing season. A low shattering and early maturity soybean cultivar with high oil content, TGX 1830-20E was used in this trial. The two herbicides were applied post-emergence at two rates each. Acifluorfen (5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid) was applied at 0.2 and 0.4 kg a.i/ha;bentazon (3-(1-methylethyl(-(1H) -2, 1, 3 –benzothiadazin -4(3H) –one 2,2 – dioxide ) at 0.5 and 1.0 kg a.i/ha, while their mixtures, acifluorfen + asulam applied at 1.3 and 1.6 kg a.i /ha and bentazon + asulam at 1.4 and 1.7 kg a.i/ha. Parameters measured included phytotoxicity of the herbicides to soybean, weed control effectiveness, plant height, number of pods/plant, number of seeds/plant, seed weight /plant and total grain yield (kg/ha). Results showed that weed control effectiveness was higher and the crop performance most especially in terms of total grain yield (Kg/ha) was better in plots that received mixture formulation of acifluorfen + asulam and bentazon + asulam than where acifluorfen or bentazon was applied as single formulation irrespective of rates. The highest grain yield (1066 kg/ha) obtained from plots to which 1.6 kg a.i/ha of acifluorfen + asulam was applied compared favourably with that realized from the hoe weeded plots (1044.5 kg a.i/ha). Abysmally low grain yield was obtained from the weedy check.

Pteridium aquilinum is a problematic, perennial, invasive species worldwide that poses serious problems in the British uplands. However, there is a lack of knowledge on long-term success in terms of weed control and land improvement. We assessed the effects of six P. aquilinum-control treatments at two acid-grassland sites in the Scottish Borders (Sourhope 1 & 2). There were six treatments: (i) untreated, (ii) cutting once-yearly, (iii) cutting twice-yearly, (iv) asulam sprayed in year 1, (v) cutting once in year 1/asulam in year 2, and (vi) asulam in year 1/cut in year 2. The annual cutting treatments were stopped after 9/10 years. We measured the response of three variables over 25/26-years assessing P. aquilinum-performance, agricultural-improvement and species richness. We estimated the treatment “effect window”, defined as the period over which the P. aquilinum-control treatments had a significant effect relative to untreated experimental-controls. Results were completely different for all variables in the two experiments. At Sourhope 1 the cutting treatments had much longer “effect windows” than the herbicide-based treatments in reducing P. aquilinum performance, especially the cut twice-yearly treatment with a 25-year window. At Sourhope 2, the treatment differences were much reduced with the best treatment (cut twice yearly) producing a 13-year window. At both experiments, asulam-based treatments produce a minimum “effect window” of 10 years. Increases in both the agricultural-improvement index and species richness were also obtained at both sites. “Effect windows” for both agricultural-improvement index (TVI) and species richness also showed some improvement; “effect windows” were obtained of 12–20 and 9–20 years for TVI, and 7–17 and 2–10 years for species richness at Sourhope 1 and Sourhope 2 respectively. Species richness declined though time in both experiments. Cutting, and preferably twice per year, was the most effective treatment but also the costliest, with the most cost-effective approach being a single asulam spray. However, the length of the “effect windows” suggest that repeat-spraying every 10-years is needed. Unfortunately, where the aim is to recover biodiversity interventionist techniques such as seeding will also be needed. The use of “effect windows” for estimating long-term impact of perennial weed control is novel and may be of use in other situations. We thank DEFRA (Project BD1226) and the Basque-Country Government (J.G.A BFI-2010-235) for financially supporting the original experimental work and early analyses; the Heather Trust and the Leverhulme Trust (EM-2018-073/2) funded the field data collection in 2013 and 2019 respectively. J.G.A. was supported by Ramon y Cajal fellowship (RYC-2016-20528) and I.A. was supported by a scholarship from the Ministry of National Education of the Turkish Republic. The James Hutton Institute and R.W. and S.D. Flintoff allowed the experiments to be sited and maintained on the Sourhope Estate.

Seven algal species were used to conduct toxicity assays with 12 herbicides to determine differences in species sensitivity. A fluorescence microplate toxicity assay was used as an efficient and economical high-throughput assay. The obtained toxicity data were standardized based on the species sensitivity distribution concept. The most-sensitive individual species differed among herbicides: Desmodesmus subspicatus was most sensitive to chloronitrofen and pendimethalin; Achnanthidium minutissimum was most sensitive to chlorpropham; Nitzschia palea was most sensitive to diquat, glyphosate, and dichlobenil; Navicula pelliculosa was most sensitive to trifluralin; and Pseudanabaena foetida was most sensitive to glufosinate, asulam, and 2,4-D. Surprisingly, Raphidocelis (formerly Pseudokirchneriella) subcapitata, a standard green alga, was not the most sensitive to any of the herbicides. The results clearly showed that a single algal species cannot represent the algal assemblage in terms of sensitivity. Therefore, multispecies algal toxicity data sets are essential for assessing the ecological effect of herbicides.

Herbicides are vital for modern agriculture, but their utility is threatened by genetic or metabolic resistance in weeds as well as heightened regulatory scrutiny. Of the known herbicide modes of action, 6-hydroxymethyl-7,8-dihydropterin synthase (DHPS) which is involved in folate biosynthesis, is targeted by just one commercial herbicide, asulam. A mimic of the substrate para-aminobenzoic acid, asulam is chemically similar to sulfonamide antibiotics – and while still in widespread use, asulam has faced regulatory scrutiny. With an entire mode of action represented by just one commercial agrochemical, we sought to improve the understanding of its plant target. Here we solve a 2.6 Å resolution crystal structure for Arabidopsis thaliana DHPS that is conjoined to 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and reveal a strong structural conservation with bacterial counterparts at the sulfonamide-binding pocket of DHPS. We demonstrate asulam and the antibiotics sulfacetamide and sulfamethoxazole have herbicidal as well as antibacterial activity and explore the structural basis of their potency by modelling these compounds in mitochondrial HPPK/DHPS. Our findings suggest limited opportunity for the rational design of plant selectivity from asulam and that pharmacokinetic or delivery differences between plants and microbes might be the best approaches to safeguard this mode of action.

Contains fulltext : 235792.pdf (Publisher’s version ) (Closed access) BACKGROUND: Residential exposure to pesticides may occur via inhalation of airborne pesticides, direct skin contacts with pesticide-contaminated surfaces, and consumption of food containing pesticide residues. The aim was to study the association of dermal exposure to pesticides between the use and non-use periods, between farmer and non-farmer families and between dermal exposure and the excretion of metabolites from urine in residents living close to treated agricultural fields. METHODS: In total, 112 hand wipes and 206 spot urine samples were collected from 16 farmer and 38 non-farmer participants living within 50 m from an agricultural field in the Netherlands. The study took place from May 2016 to December 2017 during the use as well as the non-use periods of pesticides. Hand wipes were analysed for the parent compound and urines samples for the corresponding urinary metabolite of five applied pesticides: asulam, carbendazim (applied as thiophanate-methyl), chlorpropham, prochloraz and tebuconazole. Questionnaire data was used to study potential determinants of occurrence and levels of pesticides in hand wipes according to univariate and multivariate analysis. RESULTS: Carbendazim and tebuconazole concentrations in hand wipes were statistically significantly higher in the pesticide-use period compared to the non-use period. In addition, especially during the use periods, concentrations were statistically significantly higher in farmer families compared to non-farmer families. For asulam, chlorpropham and prochloraz, the frequency of non-detects was too high (57-85%) to be included in this analysis. The carbendazim contents in urine samples and hand wipes were correlated on the first and second day after taking the hand wipe, whereas chlorpropham was only observed to be related on the second day following the spray event. CONCLUSIONS: Concentrations in hand wipes were overall higher in pesticide use periods compared to non-use periods and higher in farmer families compared to non-farmer families. Only for carbendazim a strong correlation between concentrations in hand wipes and its main metabolite in urine was observed, indicating dermal exposure via contaminated indoor surfaces. We expect this to be related to the lower vapour pressure and longer environmental lifetime of carbendazim compared to the other pesticides studies.

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom, for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam‐sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Inspired by the photoelectrochemical (PEC) properties of TiO2 nanotubes arrays (TNA) and their application as a super vessel for immobilizing biomolecules, we constructed an inhibition-effect PEC biosensor for determination of asulam based on the in-situ generation of CdS quantum dots (QDs) on TNA using an enzymatic reaction. Horseradish peroxidase (HRP) enzyme was covalently assembled on the inner-wall of TNAs, which exhibited good electrochemical and catalytic properties. In the mixture solution containing H2O2, CdY and S2O32-, HRP enzyme in TNAs catalyzed H2O2 reduce S2O32- to S2-. The generated S2- reacted with CdY to form CdS QDs in situ on the TNAs, improving the PEC performance of TNA under visible light irradiation. The photocurrent would decrease after addition of asulam due to its inhibitory effect towards HRP enzyme activity. Under the optimal experimental conditions, the constructed PEC TNA/HRP biosensor exhibited a satisfying linear range (0.02–2.0 ng mL−1), low limit of detection (4.1 pg mL−1) and good selectivity towards asulam determination, and has been successfully applied for the analysis of real environmental water samples with good accuracy of the recoveries ranged from 90% to 114%.

This study reports 2 new simple derivatization-based dispersive liquid-liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively. Beer's law was obeyed in the ranges of 1.0-80.0 and 0.1-5.0 ng mL$^{-1}$ for asulam and sulfide, respectively. Limits of detection for asulam and sulfide determination by the DLLME methods were 0.18 and 0.019 ng mL$^{-1}$, respectively. Various foreign cations, anions, organics, and pesticides were tested to evaluate the selectivity of the DLLME methods. The methods were successfully applied to the determination of asulam and sulfide in various environmental, wastewater, and urine samples.

The first approach of this research paper explores the simultaneous characterization and determination of the Asulam active ingredient and its associated nine impurities in bulk batch production by the gradient reverse-phase high-performance liquid chromatographic (RP-HPLC) method. The best separation from its potential impurities and reproducible method was achieved by selecting the Cosmosil C-18 (250 × 4.6 mm, 5 μm particle size) analytical column with a run time of 40 min. The pumping chromatographic mobile phase was composed of 0.1% formic acid in milli-Q water (pH ~2.72) and methanol (80 + 20, v/v). An ambient column-oven temperature and UV detection at 260 nm were used. For this broad resolution, a gradient program was employed at a flow rate of 1.20 mL/min. All potential related substances in Asulam bulk manufacturing were ascertained by mass, proton nuclear magnetic resonance, and infrared spectroscopy. The developed HPLC method was validated with respect to linearity (25.64–151.83 mg/L for Asulam and 0.71–16.29, 1.02–12.26, 1.01–20.29, 0.60–10.01, 1.04–16.65, 0.94–22.47, 0.93–16.60, 1.00–12.45, 1.00–12.45, and 0.71–12.17 mg/L for Impurities A to I with a correlation coefficient 0.999 for Asulam and all the impurities), precision (RSD, % for active analyte Asulam and impurities were

This study was performed to find the effective post-emergence herbicides to control of Poa annua that has already emerged from the soil in Kentucky bluegrass. A total of 8 treatments consist of various post- emergence herbicides applied at recommended concentration or lower concentration than recommended concentration to prevent Kentucky bluegrass injury in this study. Methiozolin showed the least injury in Kentucky bluegrass during 40 days after treatments and there were no footprints by methiozolin in creeping bentgrass green during 20 days. However, Poa annua control was 60.4%, which was less than those of other 7 treatments in this study. Both of asulam sodium and iodosulfuron plus asulam sodium exhibited the higher Poa annua control of 81.7% and 82.2% respectively without serious injury in Kentucky bluegrass during 40 days, and they showed a slight footprints damage in creeping bentgrass green. On the other hand, critical Kentucky bluegrass injuries and the vivid and numerous footprints were occurred in treatments of trifloxysulfuron-sodium, foramsulfuron, rimsulfuron and flazasulfuron, even though they were applied with only 1/4 of recommended concentration. Methiozolin is available to reduce gradually Poa annua population on Kentucky bluegrass without severe turfgrass damage. Asulam sodium or iodosulfuron plus asulam sodium could be useful to remove Poa annua by spot treatment but it is prohibited to spray directly on green even spot.

Elephantgrass has been proposed as a potential feedstock for biofuel production in south Florida. To limit future invasion of escapes in sugarcane and vegetables, the response of newly established elephantgrass to glyphosate, clethodim, sethoxydim, asulam, and trifloxysulfuron was determined using dose–response curves. Log-logistic models were used to determine the herbicide dose required to produce 90% growth reduction (GR90). The GR90values for shoot biomass at 21 d after treatment (DAT) were 477 g ae ha−1of glyphosate, 262 g ai ha−1of clethodim, 381 g ai ha−1of sethoxydim, 12 kg ai ha−1of asulam, and 94 g ai ha−1of trifloxysulfuron. The GR90values for root biomass at 35 DAT were 570 g ae ha−1of glyphosate, 257 g ai ha−1of clethodim, 432 g ai ha−1of sethoxydim, 17 kg ai ha−1of asulam, and 183 g ai ha−1of trifloxysulfuron. Elephantgrass was predicted to exhibit 97, 98, 75, 1, and 5% mortality after application of glyphosate, clethodim, sethoxydim, asulam, and trifloxysulfuron, respectively, at the label use rates 35 DAT. Results suggest that glyphosate and clethodim will provide control of newly established elephantgrass at label use rates for spot treatments and in vegetables, respectively. Rates higher than the label use rate of sethoxydim will be required to provide acceptable control of newly established elephantgrass in vegetables. However, newly established elephantgrass was not controlled by asulam and trifloxysulfuron at label use rates, implying that control of escapes will be difficult in sugarcane.

There is a need for management strategies to control dominant perennial weeds and restore seminatural communities. We compared the effects of five weed control treatments on dense Pteridium aquilinum relative to an untreated experimental control over an 8‐year period with the aim of restoring acid grassland. The weed control treatments tested were as follows: cutting and bruising, both twice and thrice annually, and herbicide treatment (asulam in year 1 followed by annual spot retreatment of all emergent fronds). Pteridium aquilinum performance and plant species composition were monitored. Data were analysed using Bayesian mixed‐effect models and multivariate techniques. Cutting twice and thrice yearly and the asulam treatment all reduced frond density to zero; both bruising treatments were ineffective. The plant communities in the cut and asulam‐treated plots showed differences from the untreated and bruised plots; the asulam‐treated plots contained more ruderal species and the cut plots were more typical of acid grassland. Acid grassland recovery was fastest in the asulam‐treated plots, but the cut plots caught up after approximately 5 years. There were two important conclusions. First, an intractable weed like P. aquilinum can be eradicated and a vegetation more suited for grazing can be achieved by the continuous application of some treatments over many years. Here, success was achieved by cutting twice/thrice annually, or by a single asulam application followed by annual spot spraying of all emergent fronds for 8 years. Second, bruising, a treatment favoured by some conservation organisations, did not work and cannot be recommended. The use of long‐term, continuously applied treatments might be considered for all perennial weeds with large underground root/rhizome systems.

In this study, we attempted to control invaded hetero-species turfgrass in golf courses with herbicides. Asulam sodium SP and trifloxysulfuron-sodium WG (to control creeping bentgrass in zoysiagrass), trifloxysulfuron-sodium WG (to control kentucky bluegrass in zoysiagrass), and mesotrione SC (to control creeping bentgrass in kentucky bluegrass) were selected as efficient herbicides. To creeping bentgrass, asulam sodium SP and trifloxysulfuron-sodium WG until 70 days after application (DAA), mesotrione SC until 230 DAA and to kentucky bluegrass trifloxysulfuron-sodium WG until 110 DAA; the applications showed 90% herbicidal effect. At 4 X recommended application dose, asulam sodium SP, trifloxysulfuronsodium WG (to zoysiagrass) and mesotrione (to kentucky bluegrass) showed insignificant harmful effect. With recommended dose, asulam sodium SP showed 80% control effect of creeping bentgrass in zoysiagrass until 40 DAA and trifloxysulfuron-sodium WG demonstrated 85% control efficiency until 30 DAA. Trifloxysulfuron-sodium WG controlled 85% of kentucky bluegrass in zoysiagrass until 40 DAA. Mesotrione SC with recommended dose showed 95% control efficiency to creeping bentgrass in kentucky bluegrass.

Giant reed has been proposed as a bioenergy crop in the sugarcane production region of south Florida, where it has a high invasive potential. In an effort to limit future invasion of giant reed escapes in sugarcane, currently labeled sugarcane herbicides asulam and trifloxysulfuron were evaluated for its management. Greenhouse and field dose–response studies were conducted at the Everglades Research and Education Center in Belle Glade, FL, between 2010 and 2011. Herbicides were applied at rates ranging from 0.46 to 7.4 kg ha−1asulam and 2 to 32 g ha−1trifloxysulfuron, which represent 0.125× to 2× sugarcane labeled use rates, respectively. In the greenhouse, asulam and trifloxysulfuron reduced giant reed relative shoot dry weight by a maximum of 50% at 21 d after treatment (DAT). The probability of giant reed resprouting 35 d following herbicide treatment was greater for trifloxysulfuron when compared with asulam. In the field, it was predicted that a maximum of 69 and 55% giant reed control occurred with application of asulam and trifloxysulfuron, respectively, at 14 DAT. Relative shoot dry weight of giant reed treated with asulam and trifloxysulfuron was reduced by a maximum of 43% at 42 DAT. Application of asulam and trifloxysulfuron did not provide complete control of giant reed at twice the labeled sugarcane use rate, indicating that control of established giant reed in sugarcane with currently available herbicides would not be an option.

It has been suggested that trifloxysulfuron might increase the efficacy of asulam for control of johnsongrass. Container and field studies were conducted to determine the efficacy of POST applications of trifloxysulfuron and asulam for johnsongrass control in sugarcane. Asulam was applied at 460 and 920 g ai/ha to container-grown johnsongrass plants, with and without 8 g ai/ha of trifloxysulfuron. Combinations of asulam and trifloxysulfuron generally reduced johnsongrass height, rhizome length, and biomass more than when either was applied alone. Results suggested that combinations of asulam and trifloxysulfuron were synergistic in their control of johnsongrass biomass 8 wk after treatment. In a sugarcane field heavily infested with rhizome johnsongrass, asulam was applied at 1,800, 2,800, and 3,700 g/ha with and without trifloxysulfuron at 16 g/ha. Asulam plus trifloxysulfuron generally controlled johnsongrass more effectively than either herbicide alone. The control of johnsongrass with asulam at 1,800 g/ha resulted in an increase in sugar yield of more than twice that in the nontreated control. Sugar yield increased further when asulam was applied at 2,800 g/ha or combined with trifloxysulfuron, but application of trifloxysulfuron alone did not increase yield. Combinations of asulam and trifloxysulfuron might slow the spread of rhizome johnsongrass enough to allow an increased number of ratoon crops before sugarcane fields need to be replanted.

This paper describes the effectiveness of a range of bracken* control and heathland restoration treatments, in factorial combination, on heath development over an 18-year period. Control treatments included cutting once and twice yearly between 1978 and 1996: spraying the herbicide asulam at the recommended rate (4.4 kg a.i. ha -1 ) in two treatments. 1978 and 1978 plus 1979, each followed by repeat doses in 1984 and 1990: and spraying asulam followed by cutting once yearly. Calluna * seeds were added to half the plots to aid heathland establishment. After 6 years the experiment was split and bracken control was continued/re-applied on half the plots and stopped on the remainder. The effects of all treatments on the cover of colonizing species between 1986 and 1996 is described. Twenty-five species were recorded in the 10 years, but some were present only for a very short time. Initially Calluna establishment was good in some treatments. especially where Calluna seed was added and bracken was controlled ; cutting bracken twice yearly was most effective. Other plots developed either a grass heath flora dominated by Agrostis capillaris. Deschampsia flexuosa. Dicranum scoparium. Festuca ovina and Rumex acetosella, or were dominated by either Calamagrostis epigejos or Carex arenaria. Some plots were invaded by Betula spp.; mortality was high but some survived to overtop the bracken by 1996. In 1990 and 1991 there was considerable mortality of Rumex acetosella and Calluna, respectively, almost certainly as a direct effect of the weather: these 2 years were the hottest and driest during the experimental period. The grass heath species showed distinct spatial effects during colonization, and tended to have a greater cover where bracken control was continued. Bracken litter was maintained at a low cover where treatment was continued, but increased to near untreated levels within 10 years, except where bracken was cut twice yearly. The cut twice yearly plots started from a lower level, but litter cover was still increasing at the end of the experimental period. A major influence on the vegetation development was the increasing numbers of rabbits which occurred during the course of the experiment. Rabbits had invaded all treatments by 1996 and increased the amount of bare ground in many treatments. Rabbit activity was greatest where the bracken control was increased. The original objectives of the restoration scheme 'to restore a Calluna heathland' have not been met, as the Calluna died. However, a reasonable Breck grass heath flora developed in many plots, which is a better community from a conservation viewpoint than dense bracken. The implications for the restoration of heathland on dense bracken communities is discussed and an integrated management approach is suggested.

The coastal heathlands of north-western Europe are endangered habitats of great conservation value. Invasion by bracken Pteridium aquilinum is a major challenge for conservation and restoration of these heathlands, including the under-studied northern regions. Today, the herbicide asulam is the most widely applied bracken control measure, but increasing focus on organic farming and nature conservation calls for alternative, preferably mechanical, approaches. In a 7-year replicated field experiment in western Norway, we investigated efficiencies of the four bracken control measures asulam, Gratil, annual cutting and biannual cutting, in restoring the characteristic heathland vegetation structure and species composition. We specifically tested herbicide effects on diversity and composition of non-target species. Effects of treatments over time were evaluated by repeated measures ANOVA, and for multivariate data, Principal Response Curves. Our results show that UK based control methods are largely applicable to bracken at its northern limit in the European heathland habitat. Asulam resulted in the fastest reduction in cover but cutting proved equally efficient long-term. Community compositions progressed towards desired heathland vegetation, but successional trajectories differed. Asulam had unintended effects on a number of heathland species not predictable by species characteristics or functional groups. Gratil failed to have any long-term effects. In summary, cutting is as efficient as herbicide application in reducing bracken, and more so in restoring northern heathland vegetation over time.

Bracken (Pteridium aquilinum) is a major problem for livestock-based extensive agriculture, conservation, recreation, and game management globally. It is an invasive species often achieving dominance to the detriment of other species. Control is essential to maintain plant communities such as grassland and lowland heath or if extensive grazing by domestic stock, particularly sheep, is to be viable on upland margins. Bracken is managed primarily by herbicide application or cutting but other techniques including rolling, burning, and grazing are also utilized. Here we evaluate the evidence regarding the effectiveness of asulam for the control of bracken. Thirteen studies provided data for meta-analyses which demonstrate that application of the herbicide asulam reduces bracken abundance. Subgroup analyses indicate that the number of treatments had an important impact, with multiple follow-up treatments more effective than one or two treatments. Management practices should reflect the requirement for repeated follow-up. There is insufficient available experimental evidence for quantitative analysis of the effectiveness of other management interventions, although this results from lack of reporting in papers where cutting and comparisons of cutting and asulam application are concerned. Systematic searching and meta-analytical synthesis have effectively demonstrated the limits of current knowledge, based on recorded empirical evidence, and increasing the call for more rigorous monitoring of bracken control techniques. Lack of experimental evidence on the effectiveness of management such as rolling or grazing with hardy cattle breeds contrasts with the widespread acceptance of their use through dissemination of experience.

Questions: The objectives of this study were to assess the effect of Pteridium aquilinum (bracken) control treatments, at the national scale, and the impact of restoration practices, at the local scale, on P. aquilinum performance. Hypotheses: 1. Geographical location (locally between and within sites) affects the control of P. aquilinum through time. 2. Are the P. aquilinum control treatments successful at all sites, and if so which ones? 3. The treatments applied at the individual site level to restore vegetation influences the performance of P. aquilinum through time. Location: Four geographically distinct acid grassland and heathland sites infested with P. aquilinum across Great Britain. Methods: Six main-plot, bracken control treatments were applied to all sites with site-specific vegetation restoration treatments. Response variables (P. aquilinum cover, frond length and density) were monitored twice yearly, in June and August between 1993 and 2003. Results: Between- and within-site spatial ...

[EN] This paper presents the analytical determination of the pesticide Asulam based on its native fluorescence. The method was optimized in either a flow injection analysis (FIA) assembly or in batch. The maximum fluorescence intensity was observed for basic pH solutions and at a lambda(ex) of 258 nm and lambda(em) of 342 nm. The influence of different empirical parameters, such as the pH, the presence of surfactants, solvent polarity or solved oxygen amount, was studied. The calibration range was fitted with a linear equation from 0.01-3 mg l(-1) Asulam and 0.005-15 mg l(-1) Asulam for batch and continuous-flow, respectively. The RSD for both procedures was 1.0%. After testing the influence of a large series of potential interferents, the method was applied to water samples from different locations., This research was supported Ministerio Educación y Ciencia (Spanish Government), Project BQU2002-04248-C02-01

Protonemata of three mosses (Bryum rubens Mitt., Campylopus introflexus (Hedw.) Brid,. and Polytrichum formosum Hedw.) were exposed in sterile cultures to low concentrations of the bracken herbicide asulam, added to the solidified growth medium. Protonemata were either exposed for 24 hours and then transferred onto media without asulam, or exposed constantly to the asulam media. Growth was measured over a three-week period as the mean of two plug diameters, and development of leafy gametophores was noted. A 24-hour exposure period to asulam had no effect on the growth or development of the mosses at concentrations of 0.001–1 g a.i. (active ingredient) l−1. The growth and development of all three species was significantly affected by continuous exposure to asulam at concentrations of 0.01 g a.i. l−1 and above. Dose-response curves were fitted to the data and EC50 values calculated. Campylopus introflexus was the least sensitive species tested and P. formosum the most sensitive, with a 10-fold diff...

This paper deals with a straightforward automated method for the determination of asulam in water based on the use of a flow manifold including three computer-controlled solenoid valves. The method involves irradiating on an aqueous solution of asulam in glycine buffer at pH 8.3 with UV light during 90 s, then follows the oxidation with potassium permanganate in a sulphuric medium and chemiluminescence-based detection of the resulting photoproducts. The limit of detection thus achieved is 40 mug l(-1). The detector response is linear up to a 5 mg l(-1) asulam concentration and the throughput is 30 samples h(-1). In parallel tests, oxidation with alkaline ferricyanide was also assessed and the results compared (sensitivity, selectivity and reproducibility) with those from oxidation with potassium permanganate in acidic medium. The use of a flow based on solenoid valves results in substantial reagent savings and constitutes a further extension of clean chemistry procedures. To the authors' knowledge, this is the first chemiluminescence-based determination of asulam and also the first based on multicommutation analysis. (C) 2004 Elsevier B.V. All rights reserved.

Tropical signalgrass is one of the most serious weed problems in the St. Augustinegrass sod production in Florida, and its presence increases production costs and lowers turfgrass quality. The objectives of our research were to: (1) evaluate herbicides preemergence and postemergence for control of tropical signalgrass and (2) compare control of tropical signalgrass and other problem weeds (torpedograss, blanket crabgrass, and India crabgrass) with postemergence herbicides. In preemergence herbicide field trials, only benefin + oryzalin, imazapic, imazapic + 2,4-D, and oryzalin provided ≥75% tropical signalgrass control 8 wk after application (WAA). By 11 WAA, only benefin + oryzalin and imazapic + 2,4-D provided ≥75% tropical signalgrass control. In greenhouse experiments, eight herbicide treatments were applied postemergence to tropical signalgrass seedlings at the two-, four-, six-, and eight-leaf stages. Asulam and CGA 362622 provided ≥89% tropical signalgrass control at all application timings. Imazaquin controlled tropical signalgrass ≥98% when applied before the eight-leaf stage. However, in field trials with mature tropical signalgrass (>20 cm stolons), none of the 20 herbicide treatments applied postemergence provided acceptable control.

The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure.

Asulox is a herbicide used to control bracken. Its effects on mosses were investigated to ascertain whether exposure proved as detrimental as found in parallel studies on pteridophytes. Mature gametophytes of 18 mosses were exposed to a range of concentrations of Asulox under standard conditions and the effects on growth monitored. Plants were cut to a standard length, exposed to Asulox solution for 24 h, grown for 3 weeks and total elongation (main stem and branches) measured. EC50 values were calculated and species ranked according to sensitivity. The effects of exposure on total elongation were compared with those on main stem elongation alone. Under the conditions tested, the total elongation of all species was inhibited after exposure to Asulox. The amount of elongation observed after exposure was different for different species and inhibition of elongation occurred at different exposure concentrations. A single regression equation was not adequate to describe the dose response curves of all species tested. An ability to produce secondary branches may confer increased tolerance to Asulox exposure. It is concluded that mosses suffer detrimental effects after exposure to Asulox at concentrations similar to those that affect fern gametophytes such as bracken.

The electrochemical behaviour of the herbicide Asulam was studied by cyclic and square wave voltammetry. Asulam may be irreversibly oxidised at a glassy carbon electrode. Maximum currents were obtained at pH=1.9 in aqueous electrolyte solution. Based on the electrochemical behaviour of Asulam, two analytical methodologies were developed for its determination in water samples, using square wave voltammetry (SWV) and flow injection analysis (FIA) coupled with an amperometric detector. Limits of detection of 7.1x10-6 mol L-1 and 1.2x10-8 mol L-1 for SWV and FIA respectively, were achieved. Repeatability was calculated by assessing the relative standard deviation (%) for 10 consecutive determinations of one sample. The found values were 2.1% for SWV and 5.0% for FIA. Validation of the results provided by SWV and FIA methodologies was performed by comparison with results from an HPLC-DAD technique. Good relative deviations were found (

Ullucus tuberosus and Amorphophallus konjac are new root crops being evaluated for commercial development in New Zealand. Eighteen herbicides were screened in glasshouse experiments for pre- or postemergence use in these crops. Methabenzthiazuron, chlorpropham, diuron and linuron were well tolerated by Ullucus when applied preemergence, while dimethanamid, oryzalin and simazine warrant further study. All the post-emergence treatments damaged Ullucus although linuron might show acceptable tolerance at a lower rate. Acetochlor, chlopropham, dimethanamid, linuron, methabenzthiazuron, oryzalin, oxadiazon, oxyfluorfen and pendimethalin were all well tolerated by Amorphophallus when applied pre-emergence, while asulam, flumetsulam and tribenuron were safely used post-emergence. Bromoxynil was also safe on Amorphophallus if applied before leaves emerged from the developing shoot.

Bracken is often perceived as a widespread and increasing land management problem. The pollen record of a wide range of sites in Great Britain suggests that the current abundance of bracken is less than or, at worst, equivalent to maximum historical levels. Recently gathered data also suggest that bracken cover is declining. Results of risk assessments of land use change, and experimental and modelling investigations into the effects of climate change are synthesized. This synthesis suggests that there is the potential for increased bracken dominance in northern Britain, spread into new areas at high altitudes, and possible spread into areas with reduced grazing. However, this must be set against any changes in the extent of other vegetation types at the expense of bracken. There is now a long history of bracken control, both in Great Britain and globally. Conventional methods of control (cutting, asulam application) are well understood, but many control attempts do not result in long-term success, as control is often not followed by aftercare. Bracken control is just one part of the process to ensure a sustainable use of resources and to maintain biodiversity. A coherent strategy for bracken control is put forward, a necessary part of which includes the restoration of vegetation and subsequent land management which takes into account an understanding of bracken ecology.

Fern spores were germinated, grown and exposed to different concentrations of asulam (the active ingredient of Asulox) in liquid culture. Gametophytes of Pteridium aquilinum [L. (Kuhn)] (bracken) were exposed to 100 g l − 1for 24 h at the following three stages: germination; during filamentous growth; and after transition had occurred. This treatment severely inhibited germination and killed photosynthetic gametophytes outright. Gametophytes of all species tested [ Pteridium aquilinum, Cryptogramma crispa(L.) Hook and Dryopteris filix-mas(L.) Schott] varied in their responses to lower concentrations. This variation was in terms of the response of the gametophytes and the numbers of gametophytes showing each response. Some gametophytes suffered 100% cell mortality, but in others some cells died and some survived, while the remainder of the gametophytes suffered no cell mortality. The cells affected varied from gametophyte to gametophyte at the same dose and the proportions of gametophytes showing each response changed with concentration, mortality increasing with increasing concentration. Pteridium showed lower levels of mortality at each concentration than either of the other species. The bioassay system described provides a rapid laboratory-based method to screen for Asulox susceptibility of fern gametophytes in comparison with Pteridium.

This paper describes the vegetation change in an 18-year experiment designed to test a range of control of Pteridium aquilinum (Pteridium) and heathland restoration treatments; cutting, asulam application and Calluna vulgaris seeding, in a range of combinations at Cavenham Heath in Breckland, UK between 1978 and 1996. Vegetation change was recorded in two Phases; in Phase I (1978 - 1986) species biomass was sampled and in Phase II (1986 - 1996) cover was measured. Initially, Calluna establishment was good in some treatments, especially where Calluna seed was added and Pteridium was controlled. Other plots developed either a grass- heath flora dominated by Agrostis capillaris, Deschampsia flexuosa, Dicranum scoparium, Festuca ovina and Rumex acetosella or were dominated by clonal species such as Calamagrostis epigejos or Carex arenaria. An unconstrained ordination showed significant vegeta- tion change through time and that several treatments influ- enced the vegetation, especially those involving asulam appli- cation. When variation partitioning with constrained ordina- tion was used a different explanation emerged. In Phase I the most important factors were the management treatments ap- plied, elapsed time and spatial factors, with little overlap. In Phase II, elapsed time became irrelevant because the variation time explained overlapped that which could be explained by other variables. The most important of these were manage- ment treatments, spatial effects, weather, the amount of bare ground caused by disturbance and Pteridium litter cover (an index of Pteridium recovery). The implications of these re- sults in interpreting vegetation change are discussed.

A fluorometric determination method for asulam(methyl4-aminosulphonylcarbamate, herbicide) in environmental water samples by using solid-phase extraction(SPE) has been proposed. The method is based on the addition of EDTA to a sample solution for the elimination of interferences from metal ions and the use of ethylsilanized silica(tC2) and polystyrene gel(PS-2) combination cartridges to remove any fluorescent impurities in the matrix. Asulam in a sample solution(pH2∼3) was hardly retained in the tC2 combined upon the PS-2, and retained in the PS-2. Asulam, which was slightly adsorbed on the tC2, was retained in the PS-2 by washing with 20ml of water. Asulam was then eluted from the PS-2 with 2ml of methanol. After adjusting the pH to 8∼10 and diluting to 10ml, asulam was determined by measuring the fluorescence intensity at 343nm with excitation at 252nm. The calibration graph was linear over the range of 0.02 to 0.3mgl-1(r=0.997). The average recovery of 0.25mgl-1 asulam in 100ml of distilled water was 98.9%(n=5) with a relative standard deviation of 1.16%. The proposed method has been successfully applied to some environmental water samples with recoveries of 93∼96%.

In glasshouse experiments,Panicum repensrhizomes with more than two nodes emerged from soil depths of 1 to 20 cm. Emergence from one-node rhizomes was greatly reduced at depths more than 5 cm. In contrast, culm emergence from ginger like rhizomes decreased when burial depth (BD) was greater than 20 to 30 cm.P. repensemerged from deeper soil levels with an increasing number of nodes per cutting. Culms emerged from 36% of total underground regenerative organs. About 75 and 95% of the emerged culms were recorded 30 and 60 d after burial, respectively, and 91% emergence was recorded from 20-cm BD. In field studies, only 9% of nodes produced culms following cross-plowing. About 61 and 67% of the emerged culms were recorded 50 and 60 d after land preparation, respectively. Results indicate that mechanical and chemical control methods could be most effective forP. repenswhen applied approximately 50 d after land preparation. Burying deeper than 30 cm by deep plowing and reducing rhizome length by cross-plowing might effectively reduce emergence ofP. repens.

Capillary LC/Frit-FAB-MS was used for the determination of 24 thermolabile and polar pesticides including 9 neutral/basic and 15 acidic ones which are not amenable to routine GC/MS. The base ions of acidic pesticides in negative mode were a deprotonated molecular ion except for asulam, MCPB, 2,4-DB, and warfarin, and those for neutral/basic pesticides and asulam in positive mode were a protonated one. More than one diagnostic ion were obtained except for hymexazol and bentazone. High sensitivity was obtained for neutral/basic pesticides and asulam by adopting a mobile phase composed of CH3CN and 0.1% acetic acid, while for the other acidic pesticides, a mobile phase composed of CH3CN and 5 mM din-butylammonium acetate (pH=6.7) was effective. The detection limits of the pesticides were in the range of 10∼300 μg/l, except for benazolin whose limit was 1000 μg/l. Environmental samples (1 L) were taken from raw water for water supply and applied to analysis after concentration by using a solid phase extraction method. 0.2 μg/l dymron (in full-scan mode) and 0.05 μ/l 2,4-D (in selected ion monitoring mode) were detected in a sample, which indicated that the LC-frit-FAB-MS method could be used for determining thermolabile and polar pesticides in environmental water with relatively high sensitivity.

1. The effects of six bracken control treatments applied in combination with a Calluna* seeding treatment on the rhizome system of bracken Pteridium aquilinum at Cavenham Heath in Breckland was assessed after 18 years. Bracken control included cutting once and twice yearly between 1978 and 1996; spraying the herbicide asulam at the recommended rate (4·4 kg a.i. ha−1) in two treatments (1978 and 1978 plus 1979), each followed by repeat doses in 1984 and 1990, and spraying asulam followed by cutting once yearly. After 6 years the experiment was split and bracken control was continued/reapplied on half the plots and stopped on the remainder. The effects of treatment on the numbers of active and dormant buds and the length and biomass on both frond-bearing and storage rhizomes were measured. 2. When applied continuously over the 18 years, all treatments reduced all rhizome measures, but treatments that included cutting were more effective than ones that just used asulam. The best treatment after 10–12 years was cutting twice yearly, but after 18 years this treatment had apparently reached an equilibrium and the cutting-once-yearly treatment was superior. No treatment eradicated the bracken in 18 years of continuous treatment. 3. When bracken control treatments were stopped after 6 years rhizome recovery started within 4 years and there was significant recovery thereafter. After 12 years the least effective treatment, cut once yearly, although still showing a significant reduction in rhizome biomass, had recovered to 88% of the untreated plots. The most effective treatment was cutting twice yearly for 6 years, where most measures of rhizome performance remained at approximately 50% of untreated plots 12 years after cutting stopped. 4. Regression analysis was used to investigate the relationship between frond production and rhizome characteristics. Rhizome biomass, especially of the storage rhizome component, was consistently the most important variable; frond bud numbers were less important. 5. Simple models, developed making assumptions that the response of the rhizome to treatment is linear through time, have been shown to be invalid over the longer time period. This is because the impacts of the treatments reduce through time. 6. These results are discussed in relation to long-term bracken control and the assessment of bracken stocks. If bracken is to be suppressed on a long-term basis a continuous control strategy is needed. It is unlikely that complete eradication will be possible with current control technology. The long time scale found for the total recovery of the bracken from only 6 years of treatment (>12 years) means that the large areas of bracken that have been treated in the past will take some time to recover to pretreatment levels. This recovery is an unknown factor in bracken stock assessments.