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C Hawes

Publications and source records attributed to C Hawes.

At least 19 recordsLinked to original sources
PubMed2006

Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops.

The Farm Scale Evaluations (FSEs) showed that genetically modified herbicide-tolerant (GMHT) cropping systems could influence farmland biodiversity because of their effects on weed biomass and seed production. Recently published results for winter oilseed rape showed that a switch to GMHT crops significantly affected weed seedbanks for at least 2 years after the crops were sown, potentially causing longer-term effects on other taxa. Here, we seek evidence for similar medium-term effects on weed seedbanks following spring-sown GMHT crops, using newly available data from the FSEs. Weed seedbanks following GMHT maize were significantly higher than following conventional varieties for both the first and second years, while by contrast, seedbanks following GMHT spring oilseed rape were significantly lower over this period. Seedbanks following GMHT beet were smaller than following conventional crops in the first year after the crops had been sown, but this difference was much reduced by the second year for reasons that are not clear. These new data provide important empirical evidence for longer-term effects of GMHT cropping on farmland biodiversity.

Agriculture↗
PubMed2004

Ban on triazine herbicides likely to reduce but not negate relative benefits of GMHT maize cropping.

The UK Farm-Scale Evaluations (FSE) compared the effects on biodiversity of management of genetically modified herbicide-tolerant (GMHT) spring-sown crops with conventional crop management. The FSE reported larger weed abundance under GMHT management for fodder maize, one of three crops studied. Increased seed production may be important for the long-term persistence of these arable weeds and may benefit invertebrates, small mammals and seed-eating birds. In three-quarters of FSE maize fields, growers used atrazine on the conventionally managed half, reflecting contemporary commercial practice. Withdrawal of the triazine herbicides atrazine, simazine and cyanazine from approved lists of EU chemicals could therefore reduce or even reverse the reported benefits of GMHT maize. Here we analyse effects of applications of triazine herbicides in conventional maize regimes on key indicators, using FSE data. Weed abundances were decreased greatly relative to all other regimes whenever atrazine was applied before weeds emerged. Here, we forecast weed abundances in post-triazine herbicide regimes. We predict weed abundances under future conventional herbicide management to be considerably larger than that for atrazine used before weeds emerged, but still smaller than for the four FSE sites analysed that used only non-triazine herbicides. Our overall conclusion is that the comparative benefits for arable biodiversity of GMHT maize cropping would be reduced, but not eliminated, by the withdrawal of triazines from conventional maize cropping.

Atrazine↗
PubMed2003

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. II. Effects on individual species.

We compared the effects of the management of genetically modified herbicide-tolerant (GMHT) and conventional beet, maize and spring oilseed rape on 12 weed species. We sampled the seedbank before and after cropping. During the season we counted plants and measured seed rain and biomass. Ratios of densities were used to calculate emergence, survival, reproduction and seedbank change. Treatments significantly affected the biomass of six species in beet, eight in maize and five in spring oilseed rape. The effects were generally consistent, with biomass lower in GMHT beet and spring oilseed rape and higher in GMHT maize. With few exceptions, emergence was higher in GMHT crops. Subsequent survival was significantly lowered for eight species in beet and six in spring oilseed rape in the GMHT treatments. It was increased for five species in maize and one in spring oilseed rape. Significant effects on seedbank change were found for four species. However, for many species in beet and spring oilseed rape (19 out of 24 cases), seed densities were lower in the seedbank after GMHT cropping. These differences compounded over time would result in large decreases in population densities of arable weeds. In maize, populations may increase.

Agriculture↗
PubMed2003

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. I. Effects on abundance and diversity.

We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide-tolerant (GMHT) variety, with weeds controlled by a broad-spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one-fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad-spectrum herbicide, so that late-season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one-third and one-sixth of those in conventional treatments. The effects of differing weed-seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20% lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late-season biomass was 82% higher and seed rain was 87% higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.

Agriculture↗
PubMed2003

On the rationale and interpretation of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

Farmland biodiversity and food webs were compared in conventional and genetically modified herbicide-tolerant (GMHT) crops of beet (Beta vulgaris L.), maize (Zea mays L.) and both spring and winter oilseed rape (Brassica napus L.). GMHT and conventional varieties were sown in a split-field experimental design, at 60-70 sites for each crop, spread over three starting years beginning in 2000. This paper provides a background to the study and the rationale for its design and interpretation. It shows how data on environment, field management and the biota are used to assess the current state of the ecosystem, to define the typical arable field and to devise criteria for selecting, sampling and auditing experimental sites in the Farm Scale Evaluations. The main functional and taxonomic groups in the habitat are ranked according to their likely sensitivity to GMHT cropping, and the most responsive target organisms are defined. The value of the seedbank as a baseline and as an indicator of historical trends is proposed. Evidence from experiments during the twentieth century is analysed to show that large changes in field management have affected sensitive groups in the biota by ca. 50% during a year or short run of years--a figure against which to assess any positive or negative effects of GMHT cropping. The analysis leads to a summary of factors that were, and were not, examined in the first 3 years of the study and points to where modelling can be used to extrapolate the effects to the landscape and the agricultural region.

Agriculture↗
PubMed2003

Invertebrates and vegetation of field margins adjacent to crops subject to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

The effects of management of genetically modified herbicide-tolerant (GMHT) crops on adjacent field margins were assessed for 59 maize, 66 beet and 67 spring oilseed rape sites. Fields were split into halves, one being sown with a GMHT crop and the other with the equivalent conventional non-GMHT crop. Margin vegetation was recorded in three components of the field margins. Most differences were in the tilled area, with fewer smaller effects mirroring them in the verge and boundary. In spring oilseed rape fields, the cover, flowering and seeding of plants were 25%, 44% and 39% lower, respectively, in the GMHT uncropped tilled margins. Similarly, for beet, flowering and seeding were 34% and 39% lower, respectively, in the GMHT margins. For maize, the effect was reversed, with plant cover and flowering 28% and 67% greater, respectively, in the GMHT half. Effects on butterflies mirrored these vegetation effects, with 24% fewer butterflies in margins of GMHT spring oilseed rape. The likely cause is the lower nectar supply in GMHT tilled margins and crop edges. Few large treatment differences were found for bees, gastropods or other invertebrates. Scorching of vegetation by herbicide-spray drift was on average 1.6% on verges beside conventional crops and 3.7% beside GMHT crops, the difference being significant for all three crops.

Agriculture↗
PubMed2003

Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

The Farm Scale Evaluations of genetically modified herbicide-tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide-application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.

Agriculture↗
PubMed2003

Responses of plants and invertebrate trophic groups to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

Effects of genetically modified herbicide-tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10-fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock-on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.

Agriculture↗
PubMed2003

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. I. Soil-surface-active invertebrates.

The effects of herbicide management of genetically modified herbicide-tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil-surface-active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface-active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.

Agriculture↗
PubMed2003

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. II. Within-field epigeal and aerial arthropods.

The effects of the management of genetically modified herbicide-tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long-term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.

Agriculture↗
PubMed2001

Cytoplasmic illuminations: in planta targeting of fluorescent proteins to cellular organelles.

Use of the jellyfish green-fluorescent protein as an in vivo reporter is in the process of revolutionising plant cell biology. By fusing the protein to specific targeting peptides or to sequences of complete proteins, it is now possible to observe the location, structure, and dynamics of a number of intracellular organelles over extended periods of time. In this review we discuss the most recent developments and unexpected results originating from the targeting of this unique protein and its derivatives to elements of the cytoskeleton and to membrane-bounded organelles in a range of plant cell types.

Arabidopsis↗
PubMed2000

Introduction

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

A rab1 GTPase is required for transport between the endoplasmic reticulum and golgi apparatus and for normal golgi movement in plants.

We describe a green fluorescent protein (GFP)-based assay for investigating membrane traffic on the secretory pathway in plants. Expression of AtRab1b(N121I), predicted to be a dominant inhibitory mutant of the Arabidopsis Rab GTPase AtRab1b, resulted in accumulation of a secreted GFP marker in an intracellular reticulate compartment reminiscent of the endoplasmic reticulum. This accumulation was alleviated by coexpressing wild-type AtRab1b but not AtRab8c. When a Golgi-targeted and N-glycosylated variant of GFP was coexpressed with AtRab1b(N121I), the variant also accumulated in a reticulate network and an endoglycosidase H-sensitive population appeared. Unexpectedly, expression of AtRab1b(N121I), but not of the wild-type AtRab1b, resulted in a reduction or cessation of vectorial Golgi movement, an effect that was reversed by coexpression of the wild type. We conclude that AtRab1b function is required for transport from the endoplasmic reticulum to the Golgi apparatus and suggest that this process may be coupled to the control of Golgi movement.

Arabidopsis↗
PubMed2000

Use of physical restraints and psychotropic medications in Alzheimer special care units in nursing homes.

OBJECTIVES: This study analyzed the use of mechanical restraints and psychotropic medication in Alzheimer special care units (SCUs) in nursing homes. METHODS: We analyzed 1993 data for more than 71,000 nursing home residents in 4 states, including more than 1,100 residents in 48 SCUs. The dependent variable in multinomial logistic regression was use of physical restraints or psychotropic medication. Models contained covariates representing facility and resident characteristics, and multivariate matching strategies were used to protect against selection bias. RESULTS: Residents in SCUs did not differ from similar residents in traditional units in their likelihood of being physically restrained. Residents in SCUs were more likely to receive psychotropic medication. CONCLUSIONS: With regard to the measures used in this research, the findings indicate that residents in the SCUs in the 4 study states did not receive quality of care superior to that provided to similar residents in traditional units. In fact, the results related to drug use raise the question of whether some may have received poorer care.

Aged↗