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

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

Rapid Evidence Assessment of the Alternatives to Horticultural Peat in Scotland

The Scottish Government has a commitment to restore Scotland’s peatlands. An element of this is to phase out the use of peat in horticulture. This Rapid Evidence Assessment looks at the current state of knowledge on the role of peat in UK growing media, and the potential for alternative growing media constituents

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

Risk assessments for quality-assured, source-segregated composts and anaerobic digestates for a circular bioeconomy in the UK

A circular economy relies on demonstrating the quality and environmental safety of wastes that are recovered and reused as products. Policy-level risk assessments, using generalised exposure scenarios, and informed by stakeholder communities have been used to appraise the acceptability of necessary changes to legislation, allowing wastes to be valued, reused and marketed. Through an extensive risk assessment exercise, summarised in this paper, we explore the burden of proof required to offer safety assurance to consumer and brand-sensitive food sectors in light of attempts to declassify, as wastes, quality-assured, source-segregated compost and anaerobic digestate products in the United Kingdom. We report the residual microbiological and chemical risks estimated for both products in land application scenarios and discuss these in the context of an emerging UK bioeconomy worth £52bn per annum. Using plausible worst case assumptions, as demanded by the quality food sector, risk estimates and hazard quotients were estimated to be low or negligible. For example, the human health risk of E. coli 0157 illness from exposure to microbial residuals in quality-assured composts, through a ready-to-eat vegetable consumption exposure route, was estimated at ~10-8 per person per annum. For anaerobic digestion residues, 7 x10-3 cases of E. coli 0157 were estimated per annum, a potential contribution of 0.0007 percent of total UK cases. Hazard quotients for potential chemical contaminants in both products were insufficient in magnitude to merit detailed quantitative risk assessments. Stakeholder engagement and expert review was also a substantive feature of this study. We conclude that quality assured, source-segregated products applied to land, under UK quality protocols and waste processing standards, pose negligible risks to human, animal, environmental and crop receptors, providing that risk management controls set within the standards and protocols are adhered to

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

ABSTRACT 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 Ascorbic Acid, Glutathione, Thiocyanate, and Iodide on Antimicrobial Activity of Acidified Nitrite

It has been hypothesized that dietary nitrite augments the antimicrobial activity of gastric acid after conversion to nitric oxide and other reactive nitrogen intermediates, thus resulting in increased resistance against gastrointestinal infection. In this study, we showed that the reducing agents ascorbic acid and glutathione reduced the activity of acidified nitrite against Yersinia enterocolitica (P < 0.001). In contrast, iodide and thiocyanate increased the antimicrobial activity (P < 0.001), whereas hydroxyacids (citrate, lactate, and tartarate) had no measurable effects