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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.

The variability in the success of Pteridium aquilinum (bracken) control and vegetation restoration has been highlighted as a major issue in the United Kingdom. Experiments were set up at four different regional locations to assess bracken control at the national scale and the impact of restoration practices at the local scale. Bracken control treatments (cutting once or twice per year, a combination of cutting and asulam spraying, and asulam in year 1) were combined with site-specific treatments designed to restore appropriate heathland or acid grassland vegetation. This article considers the effects on the developing understorey vegetation, testing the following hypotheses: (1) local differences between sites would affect community change; (2) treatments applied to control Pt. aquilinum (same at all sites) influences community change; and (3) treatments applied at the individual site level to restore vegetation influences community change toward the target vegetation. There were a considerable number of spatial effects. It is, therefore, difficult to develop a one-size-fits-all policy for vegetation restoration within a national Pt. aquilinum control strategy. Few bracken control treatment effects were found, and, where they were detected, it was only at single sites. Thus, the development of target vegetation requires a combination of control and restoration treatments that take into consideration the aspects of that site. Only three species, Deschampsia flexuosa, Galium saxatile, and Campylopus introflexus, increased as a direct effect of the control treatments. Vegetation restoration was most successful in the cutting-twice-per-year plots, the treatment with the greatest reduction in Pt. aquilinum cover.

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 ...

The systemic herbicide asulam is used extensively to control the weedy fern bracken ( Pteridium aquilinum (L.) Kuhn). Other ferns were thought to be highly sensitive to asulam exposure, but there has been a dearth of experimental evidence. Eight fern species were exposed to asulam spray at three different application rates or a control of water. Asulam was applied at the recommended field application rate for bracken clearance, and at two further rates corresponding to 10 and 50 m downwind of an aerial spray event. Damage was assessed over two seasons. All ferns tested were severely damaged by exposure to the highest application rate, but sensitivity varied between species. Maximum damage occurred 1 year after spraying, and limited signs of recovery could be seen by the second season. The effects of adding the adjuvant Agral® to applications of asulam were tested on the threatened pteridophyte Pilularia globulifera L. No damage additional to that caused by exposure to asulam was observed. This work supports the view that 50 m buffer zones are sufficient to protect sensitive ferns from the effects of aerial spraying with asulam, provided that drift-reducing nozzles are used and the manufacturer’s application guidelines are observed.

Bracken (Pteridium aquilinum) is a major weed of seminatural vegetation in Great Britain, as in many other countries. As a consequence, large areas have been subject to control with the intention of restoring the former vegetation. The use of aerial spraying with asulam, a narrow spectrum, carbamate herbicide, has become a common method of control. However, its long-term efficacy has not been assessed in terms of either controlling the bracken or in producing suitable restored habitats. This study undertook such an assessment by comparing the results of a 2002 survey of the sites subject to bracken control by aerial spraying of asulam with previous (1990/1991 and 1994) surveys of the same sites. This showed that a single application of asulam was effective in eradicating bracken ( 80%) and on the remainder it was still present in patches (>20% of quadrats), often at high density. More than half the sprayed sites had seen good recovery of moorland vegetation, the target of the restoration, because they were now classified as having upland heathland vegetation within the National Vegetation Classification. Considerable amounts of bracken control are grant aided as part of agri-environment schemes. These schemes should be adapted to encourage good practice, namely, intensive follow-up treatment by spraying any emerging fronds, and to encourage treatment of previously sprayed areas rather than spraying of new areas in order to protect previous investment of grant aid.

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...

Bracken (Pteridium aquilinum) is a major weed of considerable economic concern in upland pastures in Bulgaria and elsewhere in Europe. Between 1993 and 1998, a field experiment was carried out to test methods for restoring productive meadows. Initially, spraying asulam (4·8 kg a.i. ha−1) was used to control the bracken on the site; this was achieved in terms of reduced frond densities and a higher level of grassland establishment. This grassland was dominated by Vicia cassubica and the perennial grasses Agrostis vulgaris, Dactylis glomerata, Festuca rubra, Holcus lanatus and Poa pratensis. After 2 years, a fertilizer addition experiment was started with four treatments (no fertilizer; addition of phosphorus; addition of nitrogen and phosphorus; addition of nitrogen, phosphorus and potassium. The phosphorus and potassium fertilizers were applied annually in the early spring at 80 kg of P ha−1 year−1 and 50 kg of K ha−1 year−1, and nitrogen was added at the start of grass growth at 60 kg of N ha−1 year−1. At the same time, a twice-yearly hay-cutting regime was implemented. Fertilizer addition increased both the quantity and the quality of the resulting grassland. The herbage dry matter was increased by at least a factor of two depending on fertilizer combination, and there was an increase in grass and legume cover and a decrease in both weed cover and bracken recovery. However, although bracken recovery was inversely related to grassland production, there was a consistent increase in bracken density across all treatments between 1997 and 1998, suggesting that increasing herbage biomass merely delays bracken recovery. The implications of these findings are discussed.

Application of asulam herbicide by helicopter, as a primary treatment of bracken, requires appropriate buffer zones to protect non-target plants, conservation areas and water catchments from spray drift. Drift from large-scale applications of asulam were monitored at two moorland sites where helicopters were fitted with Delavan RD ‘Raindrop’ drift-reducing, hollow-cone nozzles. Drift was measured on 10 m vertical ‘strings’ and on flat cards at intervals to 200 m downwind. Potted seedlings of Rumex acetosa, as a bioassay, were exposed over similar distances. At 200 m downwind, levels of drift were close to limits of detection by high performance liquid chromatography (HPLC). With wind speeds at the legal limit for helicopter spraying, total drift fallout (integrated to 1 km downwind) accounted for 0.61% of the applied asulam. In these conditions, fallout dropped below 1% of the applied dose rate approximately 35 m downwind of the sprayed area. In general terms, beyond 15 m from the sprayed areas, drift levels from the helicopters proved similar to those reported from tractor-operated boom-sprayers. Bioassay data correlated with asulam fallout. A zero-effect level of 100 g ha−1 after 7 weeks (2.25% of the dose for bracken eradication) suggested a buffer zone of 15 m which might be doubled to 30 m to allow for inaccurate flying, late shut-off, dosage errors and species with greater sensitivity than Rumex. On the basis of this work, and also to protect private water abstractions, the Environment Agency approved a 50 m buffer zone for helicopters fitted exclusively with RD Raindrop nozzles.

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.

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.

The vegetation of 117 bracken-dominated sites that had been sprayed with asulam from the air over a wide range of dates was recorded. There is a high variability in initial efficacy and sites displayed considerable differences in regeneration in the years following treatment. Sites treated more than 10 years previously all showed good control of bracken. The absence of sites where bracken has regenerated completely was attributed to either respraying at a later date or the poor records kept of previous unsuccessful control measures. There was also a high degree of variation in the amount and type of herbaceous vegetation present below untreated bracken. The data presented suggest that aerial spraying of bracken with asulam can be a long-term and cost-effective control method. However, in the light of experimental results from other studies, the success of an individual operation is critically dependent on the initial efficacy of treatment, the initial floristic composition (if any) and suitable follow-up management.

Heathlands tend to occur on low fertility soils, but where heathland has been invaded by bracken Pteridium soil nutrient concentrations may be increased. In order to reestablish Calluna-dominated heathland these elevated soil nutrient concentrations may have to be reduced. This paper describes an attempt to re-create an area of Calluna-dominated heath on land which had been invaded by bracken. Several management techniques were implemented in a hierarchical manner to control a dense bracken stand, including: litter stripping, ploughing and traditional bracken control methods such as cutting and herbicide treatment. Finally a heathland propagule source, which was rich in Calluna seeds, was added. The effects of these treatments on both nutrient budgets and soil chemical properties were also investigated. Litter stripping removed a large amount of nutrients, ranging between 19 and 98 years' worth of rainfall inputs depending on the element. Ploughing caused an initial reduction in frond density and biomass but effects were not significant thereafter. Cutting twice yearly was the most effective treatment in reducing frond biomass. The establishment of Calluna seedlings was directly related to the success of the bracken control treatments.

Summary A nationwide bracken control experiment provided data over a three-year period for testing the accuracy of a bracken growth model (BRACON). Objective assessments of model validity identified the model as a reasonably accurate predictor of bracken stand dynamics given the range of environmental conditions currently prevailing in Great Britain, in relation to (1) cutting regimes and (2) spraying asulam. Ranking of treatment efficacy at individual sites was closely reflected in model predictions. Predicted response of the rhizome system to cutting treatments underestimated bracken resilience. Failure to consider the consequences of frond regrowth in the latter portion of the growing season as a means to offsetting energy loss was identified as a potential explanation for this discrepancy. The role of the model as a practical management tool is discussed with particular reference to relating model predictions, based upon generalised environmental data (40 km plusmn; 40 km grid cells), to bracken management at individual sites.

Summary Bracken control field experiments were conducted at six locations across Great Britain. The effects of various cutting and herbicide management regimes upon the seasonal dynamics of bracken fronds and rhizomes were examined over a three year period. This enabled a national overview towards bracken control to be constructed. Initially, spraying with asulam was the most effective treatment in reducing frond biomass and density but was least effective in reducing rhizome biomass. Differential reductions in rhizome biomass were observed in relation to cutting frequency, with cutting twice yearly giving superior control. The national trends confirmed a number of previous observations from independent single-site studies; however, others were contradicted. Comparable management options were ranked consistently between the current and former investigation, however, the initial importance of differences in cutting frequencies did not agree between studies. This multiple-site study improves understanding of the consequences of a national bracken control programme by reducing the influence of confounding site-specific factors, and recommendations for the most appropriate bracken control techniques are made. The extent to which individual sites reflect a national trend in response to bracken control is considered and sites are compared. The hierarchy of treatments identified at the national scale was found to apply generally within individual sites. However, several responses which proved significant at the countrywide level were not so clearly defined at the site scale. Cutting once yearly was the only management regime which appeared to give different bracken control between sites. All other treatments gave similar responses between sites. This result was found in the Scottish Borders, during the second year of control, when frond biomass and density (relative to untreated plots) were greater than that recorded at other sites. This contrast was not found in subsequent monitoring. In terms of rhizome biomass depletion, poorer control was achieved following cutting once yearly at the northern sites (Mull, Scottish Borders, Lake District) compared with the southern sites (Clwyd, Breckland, Devon). The implications of experimental results are discussed in relation to increased cost effectiveness of national bracken control programmes.

A range of moorland sites in the North York Moors, North Yorkshire, UK, where bracken control with the herbicide asulam has been carried out, has been re-surveyed. The trajectory of vegetation change at each site has been analysed using a range of techniques. Vegetation change after spraying appears to depend on three things—the species present at the time of control, the initial effectiveness of treatment and the amount of subsequent disturbance (mainly by sheep). Where grazing pressure was low, there was little invasion or spread of plants, except on sites with an initial moderate cover of Vaccinium myrtillus . Where high sheep activity disturbed the litter layer, invasion by the moss Campylopus introflexus characteristically occurred, followed by an increase in dominance by grasses, especially Deschampsia flexuosa . Where grazing pressure was high enough, it appeared that bracken regeneration was slowed, otherwise the bracken canopy and the stand recovered. However, in the timescale of the study, sufficient variety and cover of other species remained after the canopy regenerated to prevent the complete progression to vegetation characteristic of untreated areas.

Asulam is often applied from the air to control bracken. This herbicide affects other ferns and spray drift could affect their survival. This paper discusses the use of bioassays to assess drift (a) spatially around a single bracken patch, (b) downwind from sprayed areas, and (c) spatially in undulating terrain and with different vegetation cover types. The aims were to develop policies to protect sensitive habitats. It is suggested that “no-spray” buffer zones in excess of 160–180 m are needed to minimise risk. Protection of rare ferns from overstorey vegetation or from steep slopes did not occur. Although less drift was found upwind there was significant damage at the end of the helicopter runs because of errors in switching the sprayer on and off.

Summary This paper examines the initial effects of bracken control on frond numbers and biomass, and the biomass, carbohydrate reserves and bud densities of bracken stands cut once per year, twice per year, subject to a single application of asulam or left untreated. The seasonal dynamics of these parameters are displayed; carbohydrate and biomass are both removed from the rhizome system to produce frond tissue, and are replenished at the end of the growing season. Asulam application reduced densities of both active and dormant buds, and both frond biomass and density. It did not significantly reduce rhizome biomass or carbohydrate reserves in the two years after treatment. Cutting, either once or twice per year reduced both rhizome biomass and rhizome carbohydrate reserves, as well as bud densities, though the latter were reduced in proportion to biomass. Cutting twice a year reduced the production of fronds, both in numbers and biomass. The collected data were used to evaluate a model of bracken growth, and subsequently to improve estimates of some of the model parameters. The model simulations of control treatments were compared to field data. The effects of cutting once per year and spraying with asulam were predicted accurately, but the bracken stand was more resilient to cutting twice per year than would be expected from model predictions. The combination of cutting and spraying is discussed as a potential tool in land management and the deficiencies of the model are discussed in relation to the need for future research into the biology of bracken.

Bracken is a weed of economic importance to hill farming, conservation, and forestry in many parts of the world. It is an aggressive competitor, capable of rapid spread by means of its persistent underground rhizomatous system, and it is highly toxic and carcinogenic to domestic stock. In addition, it harbors large populations of ticks that transmit disease to animals and humans.Control by husbandry or by mechanical frond destruction is labor-intensive and often inadequate. Chemical control continues to be a subject of intensive research, with particular emphasis on the use of adjuvants, including surfactants. There is evidence that formulation of systemic herbicides such as asulam or glyphosate with low concentrations (e.g., 0.05%) of certain nonionic surfactants can effectively increase foliar absorption and translocation to the underground rhizome buds.Biological methods of control using either insects or fungi are under investigation. Certain bracken-feeding South African insects are specific ...

We describe six experiments set up at four regional locations in Great Britain, in 1993 and 1994, to examine the impact of control treatments on bracken and associated vegetation. Present discussion is limited to the effects of treatments on bracken frond variables (density, length and dry mass). These variables would be used by a land manager to judge the extent of infestation and the efficacy of control methods. Results of statistical analyses are reported for the period 1994 to 1998, inclusive. The treatments showed great variability in effectiveness between both sites and years. Great inter-regional differences were seen, but stands at sites within a short distance of each other also varied in their response to treatment. Meso- and micro-climatic differences are suggested as possible causes, together with stand growth phase and genetic effects. The most effective treatments in the short-term were found to be combinations of cutting and herbicide spraying, applied once. Annual cutting usually gave a better result in the longer term. All treatments had greatly improved effects when combined with a follow-up application of herbicide several years after commencement. A number of recommendations are given for management, such as best methods for short- and long-term results. Systematic monitoring is urged as changes in frond density, for example, may reveal the extent of the problem for control at a particular site.

The effect of three bracken control treatments on the rhizome system of bracken (Pteridium aquilinum (L.) Kuhn) at Cavenham and Weeting Heaths in Breckland was assessed. Control treatments included cutting once and twice yearly between 1978 and 1990, and spraying the herbicide asulam at the recommended rate (4-4 kg a.i. ha −1 ) in 1978 and 1985. In addition, the effect of continuous treatment was compared with plots in which bracken control ceased after 6 years. The effects on rhizome biomass and length, numbers of active and dormant buds, and starch and solubIe carbohydrate concentrations were measured. Cutting twice yearly was the most effective treatment, but rhizomes persisted even after 12 years of continous treatment. Cutting once yearly and applying asulam gave intermediate reductions in all rhizome variables (...)

1. The effects of treatments to control bracken and to restore either Calluna heath or grassland on the amounts of bracken rhizomes, the distribution of nutrients in the vegetation, and selected aspects of soil chemistry, were studied. 2. The effects of the bracken control treatments on bracken rhizomes were similar to those reported earlier for midsummer bracken-frond yields. The most successful treatment was cutting bracken twice yearly for at least 10 years, which reduced frond-bearing rhizomes to 2-4% and storage rhizomes to 8-11% of untreated levels. 3. There were differences in the amounts of nutrients found in the bracken rhizomes and litter in the untreated plots at the two study sites. The maximum potential flux of nutrients to the soil was lower for some elements in plots with maximum heath development or bracken recovery, but for other elements no significant effects were found. 4. There were a few significant differences in soil chemical properties between the different management treatments, but they were difficult to interpret. There was no evidence of any reduction in soil chemical properties in these experiments where Calluna heath and grassland have re-established. If soil fertility is to be reduced during such restoration schemes this problem needs to be addressed further.

1. This paper investigates the effects of disturbing the bracken-litter layer on the re-establishment of heathland vegetation after spraying with asulam at a grass and a Calluna heath in Breckland. Three litter disturbance treatments were applied: (i) raking and removal of the litter; (ii) incorporating the litter by rotovation; (iii) burning. All treatments were done with and without sowing seed of heathland species. 2. At both sites, litter disturbance increased the speed of colonization and subsequent development of the sown heathland species. At the Calluna site, litter removal was the most effective treatment. 3. At both sites the rapid establishment of the sown species reduced natural colonization of other species. 4. After 11 years, bracken reinvasion was reduced 15-20 m away from surrounding dense bracken edges at the grass heath. 5. The implications of these results for conservation management and heathland restoration are discussed.

1. This paper examines the effectiveness of a range of bracken control and heathland restoration treatments on bracken performance and the redevelopment of heath vegetation over a 10-year period on a Callunaand a grass-heath in Breckland. Initial treatments were a combination of cutting and spraying with asulam, with and without sowing seeds of heathland species. After 6 years a further two treatments were added, with the bracken control treatments being either continued/reapplied or discontinued. 2. No treatment eradicated bracken completely, although all had some control. Asulam was the most effective treatment in the 2 years after treatment, but bracken recovered rapidly thereafter. Yearly cutting reduced bracken fronds by 70%, and cutting twice yearly by >90%. 3. After cutting was stopped, bracken recovered rapidly on plots cut yearly, but more slowly where it was cut twice-yearly. Reapplication of asulam produced a similar response to the initial application, with a rapid decrease followed by recovery. 4. Heathland at the Calluna site took 6 years to reach maximum biomass levels, and seeding had no effect on biomass. On the grass heath, vegetation developed much faster on the seeded plots where bracken was also controlled. At both sites cutting appeared to accelerate vegetation establishment probably because of litter disturbance. 5. At the grass heath, vegetation development suppressed bracken recovery 5-6 years after treatment started, when there was a maximum difference in grass biomass between unseeded and seeded plots. 6. The relevance of these results to both conservation management and the assessment of bracken distribution and encroachment are discussed.

Asulam reaching the soil either directly as spray drift or as rain washings from bracken fronds would, due to its rapid mobility in soil, be expected to leach down the soil profile into the drainage water and thereby contaminate streams and water catchments. The mobility of asulam in soil is influenced by pH, where undissociated asulam will leach less rapidly than the associated form (asulam pKa 4·82). This is particularly relevant in the case of bracken as it can grow satisfactorily over a wide range of pH values (3·6 – 7·6). Adsorption coefficients expressed as Kd values [(μg asulam/g soil)/(μg asulam/ml solution)] were 2·54, 1·94 and 0·96 at pH readings of 4·0, 4·3 and 4·9 respectively. Another factor involved, the breakdown of asulam, was shown to be temperature dependent, 30·95, 7·65 and 2·50% remaining after 28 days at 5, 18 and 25°C respectively, thus underlining the influence of geographical regions and climatic conditions on asulam behaviour.

SynopsisThe chemical, physical and biological properties of asulam make this herbicide well suited for the selective control of bracken in various situations. These properties are reviewed and conditions considered to optimise the control of bracken and minimise the effect on the environment on both a short- and long-term basis.The role of surfactants and mineral oils is considered.

Aerial sprays of asulam (methyl sulfanilylcarbamate) applied at 3.4 or 6.7 kg/ha to forest plantations in western Oregon effectively controlled western bracken [Pteridium aquilinum (L.) Kuhn var. pubescens Underw.] without damaging Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings. Asulam also did not damage noble fir (Abies procera Rehd.) seedlings if applied without a surfactant. The half-life of asulam in forest soils ranged from less than 7 to 18 days and vertical movement in the soil profile was minimal. No herbicide residues were found in runoff water from treated areas up to 208 days after application.

In addition to bracken, Pteridium aquilinum, and other ferns, only a restricted range of species among the natural flora suffer severe damage if sprayed with asulam in late summer. Of the plants associated with bracken in relatively well-drained situations those affected most by the herbicide include the three Ulex species, Rumex acetosella, young plants of Calluna vulgaris, some Compositae and grasses of the genera Poa, Holcus and Agrostis (though not A. setacea). In damp and wet upland habitats, Cirsium palustre, Juncus effusus, Glyceria fluitans and a few other species are moderately susceptible to asulam but the majority of plants appear to be resistant or only slightly damaged. Areas from which bracken has largely been removed tend to be invaded by such species as Deschampsia flexuosa, Holcus mollis, Chamaenerion augustifolium, Digitalis purpurea and Urtica dioica. If grazing pressure is low the absence of competition enables woody species to regenerate from seed. Colonization and subsequent spread of the perennial plants is influenced by what was present as ground flora before the bracken was killed and by the depth of bracken litter. Asulam is considered to be a useful aid to the management of nature reserves where encroachment by bracken needs to be checked. Its most widespread use for bracken control is likely to be on upland farms to clear bracken from marginal land with the aim of increasing and improving pasture. Adjoining woodland and moorland habitats may suffer from resulting changes in land management. Moreover, indiscriminate aerial spraying of asulam over large areas may affect local populations of plants, notably ferns, in the more open areas not protected by a canopy of bracken.

The initial effect on the underlying sward of spraying bracken with 4.5 kg ha−1 a.i. asulam or 2.0 kg ha−1 a.i. glyphosate was to cause some damage which was greater if glyphosate was used rather than asulam or if treatment was carried out in August rather than in July. Agrostis species were especially susceptible while Festuca species were resistant. The recolonization of areas of bare ground after spraying was primarily by Holcus moliis, Anthoxanthum odoratum, Galium hercynicum and Potentilla erecta, but the population of the latter two species decreased as Agrostis became reestablished. If Digitalis purpurea, Urtica dioica or Cirsium arvense were present originally, heavy infestations developed following the use of asulam, with a smaller increase after glyphosate spraying. In all cases, by the end of three years after treatment, grasses occupied a greater area of the sward in treated than in control plots.

Summary Early research demonstrated bracken fern, Pteridium esculentum, to be a significant weed responsible for suppression of growth in Pinus radiata plantations in the south-east of South Australia. However, treatments to control the fern failed to produce consistently good results. This paper presents results from more recent trials of various pre-plant treatments. The best results have been obtained with autumn applications of herbicides to dense stands of mature healthy fronds. This occurred when site preparation treatments such as windrowing and ploughing were undertaken at least six to seven months beforehand to give the bracken fronds sufficient time to regenerate. In general, glyphosate has been more effective than asulam, hexazinone, chlorsulfuron or metsulfuron-methyl. All warrant further research on factors effecting efficacy. Adjuvenants such as diesel plus emulsifier, Ulvapron and particularly Silwet have enhanced the herbicide effect on mature fronds. The current recommended treatment for ...

Asulam (methyl 4-aminobenzenesulfonyl carbamate) is a broadspectrum systemic herbicide active against broadleaf weeds such as dock (Rumex sp.) and bracken fern (Pteridium aquilinum) (SOPER et al., 1948; HOLROYD et al., 1970). These weeds are pests in pasture lands and reforestation areas, respectively. Asulam is registered throughout the world, as Asulox(R) herbicide for use in pastures and other non-crop uses and in the Caribbean for control of johnsongrass (Sorghum halepense) in sugarcane (TUCKETT and BALL, 1968). It is currently under experimentation in the United States for these same purposes.

SUMMARY The performance of asulam was assessed from a field experiment in which bracken (Pteridium aquilinum) was subjected to a variety of cutting pre-treatments prior to spraying with the herbicide. Both cutting bracken twice in the year prior to asulam application, and spraying frond regrowth 10 wk after a single mid-June cut, improved the performance of asulam. Summer cutting removes nutrients and dry matter from the system and reduces frond height, but increases frond density and the number of active buds on the rhizome system. The enhanced efficiency of asulam on pre-cut plots may be due to any one of these factors, or a complex interaction between some (or all) of them. In areas of tall bracken a cutting pre-treatment has the important practical advantage of reducing the height of the canopy, making the subsequent use of ground spraying equipment easier.

The outcome of spraying two bracken-infested hill sites in July with asulam at the commercial rate of 4·5 kg a.i. per ha was a 98% reduction in frond numbers which persisted for the following 3 years. Broad-leaved grasses, Agrostis tenuis, Agrostis canina and Poa pratensis, were susceptible to asulam and were severely reduced at both sites while fine-leaved grasses, Festuca ovina and Deschampsia flexuosa, were resistant. Over a period of 3 years after spray application the original bare ground under the bracken canopy and that produced by the effects of asulam was recolonized by the recovery of the broad-leaved grasses and an increase in the cover of herbs. The latter also increased on the unsprayed control areas. A favourable aspect and an abundance of the productive broad-leaved grasses appeared to be the main factors which determined the amount of increase in herbage yield observed following spray treatment. One such area gave a herbage DM yield of 3039 kg ha-1 during the growing season which was 47% greater than the control while an area with a less favourable aspect and dominated by the less productive fine-leaved grasses gave a herbage yield of 2069 kg ha-1 which was only 18% greater than the control.

The metabolism of [ring-14C]asulam, a systemic herbicide highly effective against bracken, has been studied in rats. Most of the radioactivity (76-100% dose) administered orally or intravenously is excreted in the urine in 24 h as unchanged asulam (61-74% dose), N4-acetylasulam (8-14%) and N4-acetylsulphanilamide (0.1-2.6%). Small amounts of radioactivity (0.3-7.4% dose) were present in the faeces, only traces (0.2-0.3%) were excreted in the bile, and no significant 14CO2 was detected. Perfusion of rat liver with 14C-asulam resulted in more extensive metabolism. Total amounts present in perfusate (81% total), bile (1%) plus liver (14%) were 23.1% for unchanged asulam, 25.7% for acetylasulam, less than 1% for acetylsulphanilamide, and 4.5% as conjugates of asulam and acetylasulam, together with several other unidentified metabolites. Asulam is acetylated more readily than sulphanilamide, by rat-liver homogenate, and the highest enzyme activity was associated with the mitochondrial fraction (2.4 pmol/mg protein per min). Although not hydroxylated by rats in vivo, evidence was obtained for the hydroxylation of asulam by rat-liver microsomal preparations in vitro.

The effects of ethephon and 2,4-D on the absorption, translocation and biochemical action of asulam were examined in field- and pot-grown bracken (Pteridium aquilinum (L.) Kuhn). In pot plants, asulam was observed to translocate basipetally to the rhizome system, greater accumulation being evident in the buds and apices compared to the rhizome per se. Although 2,4-D increased absorption of 14C-asulam, neither 2,4-D nor ethephon significantly affected total basipetal translocation. Ethephon was found to reduce accumulation of 14C-asulam within the target meristematic tissues of the rhizome system; this may account for the reduction in bracken control with asulam (4.40 kg a.i. ha−1) + ethephon (0.33 kg a.i. ha−1) compared to asulam alone (65 and 81% control, respectively). September application of asulam (4.40 kg a.i. ha−1) significantly reduced frond density in the following season. The incorporation of 14C-leucine into protein, and the folate levels were reduced in buds and apices treated with asulam. Simultaneous application of 2,4-D (0.33 kg a.i. ha−1) had no significant effect on the activity of asulam (4.40 kg a.i. ha−1) with respect to frond density and the reduction of folate levels, although there was evidence of antagonism with respect to protein synthesis. Free folate levels in rhizome apices treated with asulam + ethephon were greater than in those treated with asulam alone.Key words: Bracken, asulam, absorption, translocation, biochemical action

SUMMARY The effects of cutting and the herbicide asulam for the control of a dense uniform stand of bracken Preridium aquilinum were investigated experimentally over a 6 —yr period in Norfolk, England. Bracken is a particularly difficult species to control by either mechanical or herbicidal means because of its extensive and complex rhizome network, containing large reserves of dry matter and a large number of frond buds. Cutting bracken in the summer removed dry matter from the system and reduced frond vigour but did not reduce the number of frond buds to a critical level. Whereas the first few cuts substantially reduced the standing crop of fronds, relatively stable standing crops of fronds were observed in future years despite continued cutting. Asulam caused a 99% reduction in the standing crop of fronds in the year after spraying, but in the absence of further treatment, fronds recovered to pre-spray levels after 6 yr. Asulam caused severe localised damage to frond buds and rhizome apices, but otherwise the rhizome network remained intact. New sections of frond bearing rhizome (short shoots) developed on storage rhizome (long shoots) deep in the soil of both the asulam plots and those cut.

Mechanical methods of bracken control are now being replaced by the use of chemicals. Trials indicate the value of asulam and glyphosate in reducing frond numbers of bracken when sprayed in late July or early August in the west of Scotland. There is still a need to find a bracken eradicant chemical rather than a control chemical. Research is also required to investigate the results of removing the bracken cover on the ecology of the treated areas. The effects of sudden exposure of the hitherto protected grass to extremes of climate are not known.

Summary: Asulam was tested for the control of bracken in non-arable pasture on the North Coast of New South Wales between 1971 and 1976. Satisfactory results were obtained with applications between April and early July, providing treated fronds were mature. The degree of control varied between years and sites. Rates of 4–8 kg a.i./ha reduced frond numbers from 70 to 100% after 6 months but recovery commenced as early as 9–12 months after application. Whole plants and sections of rhizome were excavated 4, 6 and 9 months after treatment and a sequence of events is described for the effect of asulam on bracken. The effects of frond maturity, frond density and frost are discussed in relation to herbicide effectiveness and ecological implications of the results are discussed in relation to increasing productivity of bracken-infested pasture. Resume: Emploi d'asulame en pâture contre fougere (Pteridium esculentum G. Forst (Cockayne)) L'asulame a eteeprouve contre la fougere en pâture non labourable sur la cote Nord de la Nouvelle Galles du Sud de 1971 a 1976. d'assez bons resultats ont ete obtenus par des applications entre avril et debut juillet, a condition que les frondes traitees fussent adultes. La qualite du desherbage variait d'une annee et d'un site a l'autre. Des doses de 4 a 8 kg/ha m.a. ont reduit de 70 a 100% le nombre des frondes au bout de 6 mois, mais le retablissement a commence des le 9eme ou le 12eme mois apres l'application. Des plantes entieres et des sections de rhizome ont ete deterrees 4, 6 et 9 mois apres traitement, et une suite d'evenements est decrite quant a l'effet de l'asulame sur fougere. Les incidences de la maturite des frondes, de leur densite et de la gelee sont discutees en relation avec l'efficacite de l'herbicide; les consequences ecologiques de ces resultats sont evoquees dans la perspective d'accroitre la productivite de pâtures infestees de fougeres. Zusammenfassung Die Bekampfung von Adlerfarn (Pteridium esculentum G. Forst (Cockayne)) in Grunland mit Asulam Zur Bekampfung des Adlerfarns in Dauergrunland wurde Asulam zwischen 1971 und 1976 an der Nordkuste von Neu-Sud-Wales gepruft. Befriedigende Ergebnisse wurden erzielt, wenn die Behandlungen zwischen April und Anfang Juli durchgefuhrt wurden, vorausgesetzt, dass die Wedel ausgewachsen waren. Der Bekampfungsgrad schwankte mit den Jahren und den Versuchsorten. Sechs Monate nach der Behandlung war bei Aufwandmengen von 4 bis 8 kg A.S./ha die Wedelzahl von 70 bis 1OO% verringert. Die Pflanzen begannen sich aber bereits 9 bis 12 Monate nach der Behandlung wieder zu erholen. Es wurden 4, 6 und 9 Monate nach der Behandlung ganze Pflanzen und Rhizomabschnitte ausgegraben und anhand einer Reihe von Beobachtungen die Wirkung von Asulam auf Adlerfarn beschrieben. Die Wirkung der Wedelreife, Wedeldichte und von Frost werden in Beziehung zur Wirksamkeit des Herbizids diskutiert und die okologischen Auswirkungen der Ergebnisse im Zusammenhang mit der steigenden Produktivitat von mit Adlerfarn verseuchten Grunland diskutiert.

SynopsisThe biology of bracken (Pteridium aquilinum L. Kuhn) is reviewed with particular reference to its importance as a troublesome weed of upland grasslands. The problem of control is discussed, particularly with regard to the role of the rhizome system and its associated buds. The modes of action of glyphosate and asulam are described with particular reference to their foliage-absorption, translocation, and the nature of activity in the buds, the ultimate target sites.

Summary: The effect of asulam (methyl (4-aminobenzenesulphonyl) carbamate) on the synthesis of RNA and protein was investigated in bracken sporeling plants and excised rhizome bud tissue. Foliage application of asulam (4.4 kg/ha) reduced the RNA levels in frond buds and young fronds within 3 days, while protein levels were significantly reduced after 14 days. A significant reduction in respiratory activity of buds was observed after 2 weeks, the level of inhibition being 54% after 8 weeks. During a 3-h incubation period, O2 uptake by excised bud issue was stimulated by 5 and 10 ppm asulam and inhibited by higher concentrations; 32P uptake was inhibited at all concentrations. Asulam (5 ppm and above) inhibited bud growth and reduced RNA and protein levels in incubated buds (20 h at 30°C), and the incorporation of [14C]orotic acid into RNA and [14C]leucine into protein. Reduction of RNA levels and inhibition of [14C]ladenine incorporation into RNA in buds occurred entirely in the ribosomal and supernatant fractions of the cellular extract. Inhibition of RNA synthesis by asulam (50 ppm) as measured by [14C] orotic acid incorporation into RNA was completely antagonized by CEPA (3-chloroethylphosphonic acid) (50 ppm) and partially by 2,4-D (2,4-dichlorophenoxyacetic acid) (50 ppm) and GA (Gibberellic acid) (50 ppm). These results suggest that the interference of asulam with RNA and protein synthesis at the metabolically active sinks (rhizome buds) could be one of its major mechanisms of action in bracken. Resume: Recherches sur le mode d'action de l'asulame sur la fougere (Pteridium aquilinum L. Kuhn) II. Activite biochimique dans les bourgeons des rhizomes. L'effet de l'asulame (amino-4 benzenesulfonyl) carbamate de methyle) sur la synthese de I'ARN et des proteines, a eteetudie sur des plantes sporulees de fougeres et des tissus de bourgeons de rhizome excises. Une application foliaire d'asulame (4,4 kg/ha) a reduit dans les 3 jours les teneurs en ARN dans les bourgeons de frondes et dans les jeunes frondes, cependant que les teneurs en proteines ont ete reduites significativement apres 14 jours. Une reduction significative de l'activite respiratoire des bourgeons a ete observee apres 2 semaines, le niveau d'inhibition atteignant 54%. Durant une periode d'incubation de 3 heures, l'absorption de O2 par des tissus des bourgeons excises a ete stimulee par 5 et 10 ppm d'asulame et inhibee par des concentrations plus elevees; l'absorption de 32P a ete inhibee a toutes les concentrations. l'asulame (a 5 ppm et au-dessus) a inhibe la croissance des bourgeons et reeduit les teneur s en ARN et en proteines dans des bourgeons soumis a une incubation de 20 heures a 30°C, ainsi que l'incorporation de l'acide [14C]orotique dans l'ARN et de la [14C]leucine dans la fraction proteique. La reduction des teneurs en ARN et l'inhibition de l'incorporation de la [14C]adenine dans l'ARN des bourgeons se sont produites entierement dans les fractions ribosomiale et surnageante de l'extrait cellulaire. l'inhibition de la synthese de l'ARN par l'asulame (50 ppm) mesuree au moyen de l'incorporation de l'acide [14C]orotique dans l'ARN a ete comple tement supprimee par l'ACEP (acide 3-chloro-ethylphosphonique) (50 ppm) et partiellement par le 2,4-D (acide 2,4-dichloro-phenoxyacetique) (50 ppm). Ces resultats suggeerent que l'interference de l'asulame avec la synthese de l'ARN et des proteines dans dessites d'activite metabolique (bourgeons de rhizomes) pourrait etre l'un des principaux mecanismes de son action sur la fougere. Zusammenfassung Untersuchungen zum Wirkungsmechanismus von Asulam in Adlerfarn (Pteridium aquilinum L. Kuhn) II. Biochemische Wirkung in den Rhizomknospen Es wurde die Wirkung von Asulam [Methyl-(4-aminobenzosulfonyl)-carbamat] auf die RNS- und Proteinsynthese von sporulierenden Pflanzen und Knospengewebe abgeschnittener Rhizome des Adlerfarn untersucht. Blattapplikation von Asulam (4.4 kg/ha) verminderte den RNS-Gehalt innerhalb von drei Tagen in den Wedeln und den Wedelknospen; der Proteingehalt war nach 14 Tagen signifikant erniedrigt. Nach zwei Wochen wurde eine signifikant erniedrigte Atmungsaktivitat festgestellt; nach acht Wochen betrug die Hemmung 54%. Bei dreistundiger Inkubation wurde die O2-Aufnahme von isoliertem Knospengewebe durch 5 und 10 ppm Asulam stimuliert, durch hohere Konzentrationen gehemmt; die 32P-Aufnahme war bei allen Konzentrationen gemindert. Asulam (5 ppm und hoher) hemmte das Wachstum inkubierter Knospen und senkte den RNS- und Protein-gehalt (20 h bei 30°C); der Einbau von 14C-Orotsaure in RNS, und 14C-Leucin in Protein wurde gehemmt. Reduktion des RNS Gehalts und Hemmung des 14C-Adenineinbaus in RNS war ausschliesslich in der Ribosomalfraktion und im Uberstand des Zellextrakts festzustellen. Die Hemmung der RNS-Synthese durch 50 ppm Asulam, gemessen anhand des Einbaus von 14C-Orotsaure in die RNS, wurde durch 50 ppm CEPA (3-Chlorathylphosphonsaure) vollstandig. und durch 2,4-D (50 ppm), sowie durch Gibberellinsaure (50 ppm), teilweise aufgehoben. Diese Ergebnisse lassen vermuten, dass eine der Hauptwirkungen von Asulam bei Adlerfarn das Eingreifen in die RNS- und Proteinsynthese in den stoffwechselaktiven Sinks (Rhizomknospen) sein konnte.

SynopsisBracken is not a major weed problem on hill land in the north of Scotland, being restricted by environmental factors to the lower slopes of sheltered glens. There is no evidence of widespread stock poisoning by bracken in the area.Ploughing and reclamation, forestry planting and spraying with the selective herbicide asulam have considerably reduced infestations of bracken on land worthy of improvement. At the present time there is little scope for further economic control of bracken.Field experiments have defined full frond emergence from mid July to mid August as the most effective time for application of asulam. Reinfestation in about five years has been shown to follow incomplete control on small plots but an area sprayed by helicopter in 1972, where a very high degree of initial control was achieved, remained almost free of bracken in 1980.Easier handling of stock and increased availability of summer grazing are reported following bracken control. An increase in herbage production has been measured experimentally in the second year after removal of the bracken by spraying.