Complete Reducibility in Good Characteristic

Let $G$ be a simple algebraic group of exceptional type, over an algebraically closed field of characteristic $p \ge 0$. A closed subgroup $H$ of $G$ is called $G$-completely reducible ($G$-cr) if whenever $H$ is contained in a parabolic subgroup $P$ of $G$, it is contained in a Levi subgroup of $P$. In this paper we determine the $G$-conjugacy classes of non-$G$-cr simple connected subgroups of $G$ when $p$ is good for $G$. For each such subgroup $X$, we determine the action of $X$ on the adjoint module $L(G)$ and the connected centraliser of $X$ in $G$. As a consequence we classify all non-$G$-cr connected reductive subgroups of $G$, and determine their connected centralisers. We also classify the subgroups of $G$ which are maximal among connected reductive subgroups, but not maximal among all connected subgroups.Comment: 66 pages. To appear in Trans. Amer. Math. So

Crop protection in organic agriculture - a simple matter?

This report was presented at the UK Organic Research 2002 Conference. Crop protection strategies in organic agriculture and horticulture aim to prevent pest, disease and weed problems through optimisation of the cropping system as a whole. Choice of crops and varieties within the rotation and use of appropriate husbandry practices are critical to the success of the system and direct curative action against pests and diseases is rarely necessary. Research is urgently needed to determine strategies for control of key pests and diseases in organic systems if UK organic agriculture is to expand to meet increasing consumer demand. This paper describes current prevention and control strategies for pests, diseases and weeds in UK organic agriculture and identifies problems that are currently limiting expansion of the industry

An investigation into the relationship between preceding break crops and weed populations in barley crops in organic ley/arable rotations

This report was presented at the UK Organic Research 2002 Conference. The relationship between weed populations and cereal crops following nine organic break crops was investigated in field trials in Warwickshire, Aberdeenshire and Ceredigion in 2001. Weed biodiversity was high on all sites and varied between sites in terms of species present. Severity of weed infestation differed significantly between sites and between cereals following different break crops. The impact of break crop species on the incidence and severity of the weed burden in the following cereal is discussed in relation to the field trials at the three sites

Effects of composting manures and other organic wastes on soil processes and pest and disease interactions

Introduction Composts and manures are of major importance in providing fertility in organic farming systems, since synthetic fertilisers are prohibited. It is understood that composts have radically different nutrient release characteristics to those of uncomposted materials and manures, and it is believed that composting increases the beneficial effects of organic materials on soil health, soil quality, soil fertility and nutrient use efficiency. It has also been shown that some plant pests and diseases are suppressed through the application of composts and compost extracts to soils. There is considerable potential to use a wider range of feedstocks from on and off-farm sources and to improve the composting process and compost/manure application techniques. This review of scientific work to date was urgently required to help determine key research priorities to achieve this potential (Defra project OF0313). Project aims 1.To document the current standards, regulations and legislation relevant to recycling, compost/manure preparation and application and to review common UK practices relating to the preparation and application of uncomposted materials, manures, composts and compost extracts. 2. To review current scientific knowledge (from the literature) of the effects of different composting processes on chemical and biological parameters in the finished compost or compost extract. 3. To review (from the literature) the effects of uncomposted materials, manures and composts on soil health and quality, soil fertility and crop development and nutrition. 4. To review (from the literature) the effects of uncomposted materials, manures, composts and compost extracts on pest and disease incidence and severity in agricultural and horticultural crops. 5. To outline a proposed strategy for research which seeks to develop composting systems and compost/manure application protocols with a view to optimising soil fertility management and pest and disease control in organic agriculture and horticulture. Objective 1 - The current standards, regulations and legislation relevant to recycling, compost/manure preparation and application are documented in detail in the full report on Objective 1 (Appendix 2). Manures and uncomposted plant materials (e.g. green manures) are commonly used on UK organic farms. True composts (defined in the glossary, Appendix 1) are rarely prepared on UK organic farms, although there is increasing interest in their use, particularly on farms producing high value horticultural crops. An increasing number of companies are producing (or are interested in producing) composts suitable for use on organic farms as soil amendments or growing media. Objective 2 - The effects of different composting processes on chemical and biological parameters in the finished compost or compost extract are reviewed in detail in the full report on Objective 2 (Appendix 3). A short version of this review appears on pages 7-10 of this report. Objective 3 - The effects of uncomposted materials, manures and composts on soil health and quality, soil fertility and crop development and nutrition are reviewed in detail in the full report on Objective 3 (Appendix 4). A short version of this review appears on pages 10-13 of this report. Objective 4 - The effects of uncomposted materials, manures, composts and compost extracts on pest and disease incidence and severity in agricultural and horticultural crops are reviewed in detail in the full report on Objective 4 (Appendix 5). A short version of this review appears on pages 13-17 of this report. Objective 5 - A proposed strategy for research was outlined which seeks to develop composting systems and compost/manure application protocols with a view to optimising soil fertility management and pest/disease control in organic agriculture/horticulture Organic farming systems are by nature holistic. In other words, they function as a whole and all aspects of the system are interdependent on many other aspects of the system. It is essential therefore that research which is carried out to optimise the use of uncomposted plant residues, composts, manures and compost extracts is interdisciplinary; that is it must be carried out with reference to the organic farming system as a whole and not just a single aspect of it. Technology transfer and knowledge transfer are key elements to the proposed strategy for research. Seminars and conferences, farm walks, demonstration farms and a wide range of publishing formats must be used to ensure that end users have full access to the results of research carried out in the UK and abroad. The amount of information which is available for dissemination to those who wish to make or use composts will naturally depend on the amount of relevant research and development work which is going on in the UK, Europe and worldwide

A rigid triple of conjugacy classes in G 2

We produce a rigid triple of classes in the algebraic group G 2 in characteristic 5, and use it to show that the finite groups G 2(5 n ) are not (2, 5, 5)-generate

Control strategies for late blight in organic potato production

This report was presented at the UK Organic Research 2002 Conference. Protective copper fungicides are currently used to control late blight in most organic production systems, but approval for their use in organic farming will be revoked in 2002. Evidence suggests that organic potato production will not be reliably economic in the absence of Cu. Current controls for late blight are reviewed including: variety selection/breeding for blight resistance, diversification strategies, agronomic strategies for the management of late blight, and alternative treatments to Cu-fungicides

At Home He's a Tourist: New Zealand's Architectural Culture in the Eighties

I will discuss how architecture was presented and received during the 1980s in the non-specialist print media: magazines and books intended for the general public. During the decade, both the magazine and book publishing industries enjoyed unprecedented growth. The magazine sector saw the dominance of the New Zealand Listener challenged by new titles. Of these, Auckland Metro is the most interesting for architectural culture, since it published regular critiques (by the likes of Peter Shaw, Hamish Keith, David Mitchell and Pip Cheshire) of buildings and of town planning in Auckland. It also documented the rise and fall of the property developers, while arguing for the protection of historic buildings. Equally remarkable, though, is how Metro's interest in the civic aspects of architecture waned during the middle of the decade, as it became less concerned with politics and more with "lifestyle." Its emphasis shifts from public buildings to private houses, and discussion of these houses is centred more on the client than the architect. At the same time, individual architects are pictured as men (and sometimes women) of style, alongside fashion designers and hairdressers. This movement towards lifestyle can be found in other publications of the period and represents a withdrawal from the public square to the private space. Architecture is represented less as a public concern and more as a personal desire - about finding the ideal home. This acquisitive and aspirational interest in architecture is represented most clearly in the Trends family of publications, but also in books of the period. A contiguous development was a growing interest in historic buildings. These are shown both as desirable places to live, but also as representations of New Zealand identity. Old buildings also became an important aspect of New Zealand's tourist industry. One important part of this representation is in the work of art photographers, such as Robin Morrison and Laurence Aberhart. Parallels obviously can be made with the political climate of the decade, with its emphasis on personal gain and the dismantling of the public sphere by privatisation and de-regulation. Equally apparent is the contradiction of New Zealand discovering its heritage at a time when the historic buildings of its cities were being demolished. During the decade, buildings, architects and architecture become totems of larger forces in New Zealand society: of a nostalgia for the recent past, of progress to a brighter future and of a rediscovery of collective identity

An Investigation Into the Epidemiology and Control of Rhizoctonia spp. on Calluna vulgaris and Erica spp

Rhizoctonia spp. were isolated from 22% of cuttings and 10% of rooted plants of C. vulgaris and Erica spp., collected from UK nurseries, which showed browning of the foliage. Rhizoctonia spp. were most often isolated from cutting bases at compost level and from stem-base and foliage at compost level on rooted plants. Thirty two per cent of Rhizoctonia spp. isolates obtained from nursery stock species possessed multinucleate hyphal cells and were designated R. solani Kuhn. The remaining 68% which had two nuclei in each cell were termed binucleate Rhizoctonia spp. Rhizoctonia spp. were isolated from between 3% and 13% of samples of used nursery materials including cutting trays, capillary matting, polythene and composts collected from UK nurseries. They were not isolated from any samples of new, unused materials or composts. Spread of Rhizoctonia spp. and subsequent disease development was initiated from contaminated plastic trays, polythene, capillary matting, gravel, sand, compost and infected cuttings. Root development and the level of foliar browning due to disease caused by Rhizoctonia spp. on cuttings of C. vulgaris and Erica spp. , varied significantly depending on isolate. There was evidence of a relationship between number of nuclei and the level of both foliar browning and root development. The susceptibility of cuttings of E. cinerea and C. vulgaris, to disease caused by binucleate Rhizoctonia spp. differed significantly depending on both cultivar and environment. The susceptibility of C. vulgaris cvs Cuprea and Silver Queen cuttings to disease caused by binucleate Rhizoctonia sp. isolate D1, also varied depending on the environment in which stock plants were kept, and on whether cuttings were taken from shoot-tips or shoot-bases. The level of disease caused by binucleate Rhizoctonia sp. isolate 48 on C. vulgaris and E. vagans cuttings was related to the quantity of inoculum present in the compost. Disease development was most severe when inoculum of binucleate Rhizoctonia sp. isolate D1 was spread on the surface, and least severe when it was spread on the base of cutting trays 5 cm below the compost surface. The optimum pH for growth of isolates of R. solani and binucleate Rhizoctonia spp. in vitro lay between 5.4 and 7.4, and differed significantly depending on isolate. Disease development on C. vulgaris cuttings grown in compost amended with binucleate Rhizoctonia sp. isolate D1, was significantly lower in unlimed propagation compost (pH 3. 8) than in composts limed to pH values ranging from 4.9 to 6.0. The optimum temperature for growth of Rhizoctonia spp. in vitro was either 20 or 2