Horticulture
Scotland is renowned for the quality of its private and public horticultural collections, and its rich cultural history of plant collecting, allotments and gardening. Horticultural plantings are of significant economic value, as well as providing amenity, health and well-being, cultural and conservation resources. However, pest and pathogens represent a major threat to this highly diverse set of plantings.
Horticultural plantings provide amenity value in public spaces, form structural components of landscaping projects, represent a significant component of urban biodiversity and are central to private, public and heritage gardens. Given the diversity of plants involved in horticulture, there is a corresponding diversity of pests and pathogens of concern, and a particular challenge is the extensive network of plant movement at a range of scales from industrial supply to movement of individual plants between gardens. This results in a highly distributed network of pest and disease vectors. The role of the public is of particular importance for horticulture, in terms of both the ownership of plants in private gardens, and as being a major source of plant movement.
Knowledge Bank
Projects
• Expert visitation of sites to seek evidence of problems with alder health, gain some understanding as to possible causes, and identify key dimensions of a thorough study should this prove warranted. Lab work to confirm field diagnoses.
• Preliminary citizen science request inviting site-specific records of concern over alder health (potentially via the trained Observatree volunteer network to gather data), with analysis to identify any geographic clustering.
• Produce recommendations for further work including; refined survey methodologies for widespread application by interested organisations; identification of potential candidate sites for detailed study over time, and; a discussion document on risks to existing alder of expansion of riparian woodland.
Drawing upon and summarise existing literature, in addition to engagement with experts and practitioners with knowledge of existing sectoral practices in Scotland, UK and internationally, as well as gap analysis, the project will generate a better understanding of the rationale for taking precautions and an improved evidence base with which to justify taking action, answering four main questions:
• What are the current barriers to adopting precautionary measures?
• How can barriers be reduced?
• What are the limitations of the current risk assessment process?, and
• What are the priority areas for action and further research?
This work will examine and define the extent to which current UK and Scottish regulations and voluntary schemes control the way growing medium constituents must be treated prior to their inclusion in growing media, to generate an understanding around mitigating risks of spread of plant pathogens. Workshops with stakeholders will improve understanding of current practices and perceptions of alternative ‘best practice’ options for nurseries managing waste materials and for biosecurity risks of using reduced peat and peat-free growing media. A concurrent diagnostic study will identify Phytophthora species present in waste heaps from nurseries located in Scotland and the potential for these pathogens to spread into healthy plant stock either aerially or via water run-off and soil transfer.
Findings will be combined with a comprehensive desk-based study and feed into follow-up workshops on the development and introduction of ‘best practice’ guidance on the most appropriate and safest ways to manage waste growing media and plant material, to be built into the Plant Health Management Standard.
• How can important plant species in botanic collections and historic gardens be protected from inadvertent disease introduction on the footwear, etc. of visitors?
• What is the risk of further inadvertent spread from gardens into the natural environment?
• How can gardens, nurseries, farms and the natural environment be protected from pest and disease spread through the movement of large machinery (e.g., tree harvesting machines)?
Through a desk based study that incudes literature review, contact with plant health authorities, semi-structured interviews with landowners and expert practitioners from other sectors, the project will; determine what official biosecurity advice already exists and procedures are in place in Scotland; explore other sectors which provide additional novel approaches to biosecurity; and carry out a thorough assessment of what procedures are in place, or being considered and developed, in different countries/regions to address these specific biosecurity risks.
1. What is the overall goal and vision for PHC and how do we articulate this for different groups and sectors?
2. What do we want to communicate, when and to whom?
3. How do we want to communicate to different audiences and for these different purposes?
4. How do we optimise budget and human resource in communicating about plant health?
Impact: The outcome of this project will be a Communication Strategy outlining the goal of communication, roles and responsibilities and a process, including an annual cycle of reflection to permit update or modification on a regular basis and linking to the communication matrix.
Impact: The outcomes of this project to provide guidance to both policy and industry on the most effective ways to reduce spread of PCN.
Impact: Keep plant health and biosecurity at the forefront of our stakeholders’ minds, and a high priority for them, raising stakeholder awareness about the risks from plant pests and pathogens and the solutions available for their management and control, and raising the profile of the Plant Health Centre and our online resources.
Impact: Deliver recommendations as to the suitability of vector trapping methods and eradication strategies, if deployed in Scotland.
Following a Ministerial round table meeting on PCN in June 2020, the PHC were asked by the OCPHOS to form a working group to identify a clear strategy for dealing with the PCN crisis.
Publications
Potential of biocontrol for the sustainable management of plant diseases in Scotland: opportunities and barriers
Previous PHC projects identified biocontrol as a major element of Integrated Pest Management (IPM) with a role to play in mitigating pesticide withdrawals. However, it is currently unclear how practical biocontrol is as a suitable alternative to pesticides in Scotland, what the opportunities are for deployment across different sectors and what barriers exist to uptake (including regulatory).
Action Research to gain a deeper understanding of large-scale biosecurity risks to Scotland
This project has developed a systems approach, in the context of plant health biosecurity risks in the retail, infrastructure landscaping and planting in the natural environment, to facilitate further understanding of key organisations and identify general and specific leverage points at which interventions could have a significant effect on the system.
A targeted analysis of the impact of insecticide withdrawals in Scotland, in the context of alternative control options
Insecticides are commonly used in Scottish agricultural, horticultural, forestry production, and for amenity and natural environment management purposes. Over the last 10 years, approximately 50% of UK insecticide active substances have been withdrawn due to increasing concern over human health and environmental impacts. Some of these losses will be mitigated by using alternatives but their practicality and cost under Scottish conditions is unknown. This project analysed current crop production patterns and insecticide use in combination with how likely different insecticides are to be withdrawn and provided stakeholder views on the impacts of any such losses on their industry, including other control methods that may be adopted.
PHC Annual Report 2022-2023
The Plant Health Centre works with Scottish Government, public bodies and stakeholders to provide scientific evidence to help them make important decisions about pests and pathogens that threaten Scotland the most. Over the past 12 months we have delivered a consistent programme of stakeholder engagement and project commissioning, which are detailed in our annual report.
Biosecurity practices to support plant health: a review of knowledge and practice
This research investigated plant biosecurity risks from site visitors, tools & equipment, and large machinery. In addition to reviewing published guidance, UK businesses and organisations were engaged via questionnaires and interviews to explore how these aspects of biosecurity are understood and what procedures may be in place to address them.
Identifying the plant health risks associated with plant waste disposal and peat-free growing media and developing best practice guidance for waste disposal and composting across sectors
This research focussed on two areas of biosecurity that provide significant risk to plant businesses and the wider environment in Scotland, i) plant waste management, and ii) the constituents of reduced-peat and peat-free growing media.
Enhancing the Plant Health Centre’s communication with stakeholders
This project was commissioned to implement a selection of the recommendations made in the PHC stakeholder engagement strategy and communication plan. The team developed strategies to manage time and resources of the Plant Health Centre more efficiently regarding communication of outputs, general information on activities, aims and current issues related to plant health.
Perceptions of pest risk and differences in IPM uptake by arable farmers and agronomists in Scotland
Pesticide use remains an important tool in managing pest, weed and disease risks to crops and maintaining profitable production. There are several drivers for reducing reliance on pesticides and promoting the uptake of more sustainable practices through integrated pest management (IPM). By identifying IPM information networks it may be possible to improve the flow of information to farmers by targeting their preferred information sources. Better informed farmers and agronomists can make better IPM decisions. Therefore, this project undertook a telephone survey to collect information on currently perceived invertebrate pest and disease threats in Scotland, the level of IPM uptake, and the information sources they relied upon.
Improving knowledge of Xylella fastidiosa vector ecology: modelling vector occurrence and abundance in the wider landscape in Scotland
If introduced to the UK, the insect-vectored, bacterial plant pathogen Xylella fastidiosa could be a serious threat to trees and other plants. There is a lack of knowledge about the ecology and distributions of Xylella vectors in Scotland and the potential effects of this on any outbreak of the disease, which this project aimed to address.
A review of gene editing for the benefit of plant health
This report is the output of a call-down project that assesses the type of plant health problems in Scotland that GE could address, with potential benefits, barriers to deployment and dis-benefits noted.
Assessment of large-scale biosecurity risks to Scotland
PHC commissioned an assessment of large-scale biosecurity risks with a focus on three areas of concern:
- non-specialist and online horticulture sales;
- landscaping and infrastructure;
- planting for environmental benefits.
An additional area was the potential for modelling to support decision making across these areas of concern. This policy report summaries each report and highlights the key findings and suggested actions.
Assessment of large-scale plant biosecurity risks to Scotland from non-specialist and online horticultural sales
This project focused on an initial exploration of tree and plant biosecurity risks to Scotland arising from large-scale movement of plants via non-specialist (those for which plants are not their primary product type, e.g., supermarkets, DIY and lifestyle stores) and online plant retailers. By better understanding the characteristics of these retailer types, the plant health behaviours they undertake, and the challenges they face, potential avenues were offered for greater engagement and collaboration on biosecurity with this important, but understudied and hard to reach sector.
Assessment of plant biosecurity risks to Scotland from large scale plantings for landscaping and infra-structure projects
Planting for large-scale landscaping and infrastructure can typically involve tens of thousands of individual plants, potentially threatening plant health in Scotland due to the biosecurity risks of imports and widespread planting of infested or diseased plants. This project aimed to understand the extent and means to mitigate against such plant biosecurity risks with a focus on mapping the pathways from plant specification through to planting and establishment and highlight different biosecurity awareness for actors, in decision-making and procurement processes.
Assessment of plant biosecurity risks to Scotland from large scale tree plantings for environmental benefits
This report features five case studies from across Scotland and examines risks associated with large scale tree planting schemes, levels of awareness around pests and diseases, and how the decisions and actions of those involved can serve to reduce or exacerbate pest and disease related threats and long-term tree health. Each case study was unique in respect to their combination of location, site conditions, ownership, management objectives, species choice, supply chains and management activities. By highlighting best practice and lessons learned, it was hoped to ensure that future planting schemes can be successful and, importantly, reduce the likelihood of pests and diseases being introduced and spread into the wider environment.
The potential of ecological and epidemiological models to inform assessment and mitigation of biosecurity risks arising from large scale planting
Large scale planting projects linked to infra-structure such as transport networks and major housing projects or to planting for environmental benefits (e.g., urban greening, woodland restoration) pose high biosecurity risks due to the high number and types of plants involved. This report focusses on whether and how ecological and epidemiological model frameworks can inform assessment and mitigation of biosecurity risks from large scale planting using a combination of literature review and stakeholder engagement. The project aimed to identify priority steps to develop more useful models and tools for assessing biosecurity risks from planting in the future.
A stakeholder engagement strategy and communication plan for Scotland’s Plant Health Centre
The aim of this project was to develop an operational communication plan from existing stakeholder engagement principles, communication theories and knowledge banks, identifying and summarising actions for the PHC.
Metabarcoding analysis of Phytophthora diversity in spore traps and implications for disease forecasting in the P. ramorum management zone
Surveillance and monitoring of airborne pathogens is a key tool in the management of healthy forests and controlling disease outbreaks. A Scottish Forestry-funded project was carried out in autumn 2019 to validate different spore-trapping techniques for monitoring airborne P. ramorum inoculum using a species-specific qPCR assay. This project aimed to add further value to the Scottish Forestry project by investigating the suitability of DNA metabarcoding for screening spore trap samples for P. ramorum and other Phytophthora species, seeking early data for aerially dispersed Phytophthora species that may become problematic in UK forests. The study highlighted the value of both monitoring P. ramorum dispersal and detecting other Phytophthora species, to predict and understand changes in disease severity in UK tree host species. Recommendations included that the use of both rain and wind-borne inoculum capture methods might be advantageous due to the variety of weather conditions under which inoculum can disperse. Lineage testing in Southwest Scotland should be carried out to look at the prevalence of lineage EU1 in the EU2 area and to monitor for presence of North American lineages. Development of a new DNA barcode more specific to Phytophthora would be beneficial.
Monitoring for BMSB in Scotland - Final Report and Policy Summary
The increase in global trade brings with it the risk of spread of new pests and diseases into Scotland. Halyomorpha halys, Brown Marmorated Stinkbug (BMSB) is an invasive pest that has already become established in North America and several European countries. The insect aggregates inside houses over winter and can cause problems as an urban nuisance pest in homes as well as being a pest of agriculture. In this project, co-ordinated monitoring for the presence of BMSB was undertaken by teams at SASA and the James Hutton Institute. A reference collection of voucher specimens of common UK stinkbug species was established, including DNA barcoding. A process-oriented climate-based niche model was used by a team at SRUC to determine the areas in Scotland that are suitable for the establishment of BMSB under current and future climates.
Recommendations and suggested 'next steps', including encouraging further surveillance, are detailed in the report and policy summary documents.
PHC2020/09: Economic Impact of Pesticide Withdrawals to Scotland, with Case Studies
Chemical forms of plant protection are widely used in Scottish agricultural, horticultural and forestry production plus for amenity and natural environment management purposes. The availability and use of active substances in pesticides are closely regulated and increasing concern over human health and environmental impacts has led to a greater likelihood that some existing approvals will be withdrawn and/or that approvals for new products will not be granted. Potential impacts from withdrawal of these pesticides are of policy interest and this summary report builds on the data and results from project PHC2018/15 (Potential impacts arising from pesticide withdrawals to Scotland’s plant health) and uses case studies to understand the likely magnitude and distribution of potential impacts and how they may be mitigated.
PHC2018/15: Potential Impacts Arising from Pesticide Withdrawals to Scotland’s Plant Health
The use of pesticides to manage plant pests and diseases is a key management intervention across plant health sectors, particularly in agriculture, horticulture and commercial forestry production. Pesticide withdrawals through legislation, coupled with resistance development and their impact on plant health, have emerged as key concerns for Scottish plant health stakeholders. This project quantifies the impacts on Scottish plant health that will arise from pesticide withdrawal scenarios and sets this in the context and time frame of alternative management tools.
Impact of climate change on the spread of pests and diseases in Scotland
This project constructed a modelling framework which combined epidemiological and economic modelling. The modelling framework was used to study predictions of spread and economic impact of pests which are not currently in the UK, including Xylella fastidiosa, Candidatus Liberibacter solanacearum (Zebra chip) and Ips typographus (Eight toothed Spruce Bark Beetle).
Impact: A web/desktop application is available to the PHC and Scottish Government to analyse the effects of climate change on the spread and economic impact of new threats.
Expansion of PHC Online Plant Health Resources
This project has expanded the PHC online Resource Bank for plant health threats to the Natural Environment sector in Scotland to include information sources for the remaining three sectors (Forestry, Agriculture and Horticulture). Information sources for Forestry, Agriculture and Horticulture were compiled and evaluated, and a Knowledge Bank relevant to each sector is now online at the PHC website, creating a comprehensive and unique signposting resource for plant health information with relevance to Scotland.
18-Month Review Summary Leaflet
The Plant Health Centre completed an in-depth review of its first 18-months of activity for our funder (the Scottish Government through RESAS) in September 2019. While the full report is not yet available to the public, we have created a summary leaflet that outlines out achievements over this period.
Threat: Candidatus Liberibacter solanacearum (Lso)
Status, Scottish specific issues, Plant Health Centre perspective and Key priorities and recommendations concerning the threat from Candidatus Liberibacter solanacearum to Scotland
Threat: Xylella fastidiosa
Status, Scottish specific issues, Plant Health Centre perspective and Key priorities and recommendations concerning the threat from Xylella fastidiosa to Scotland
The use of mobile technology to enhance plant health monitoring and awareness in Scotland
The aim of the project was to review existing websites and smartphone apps currently available and applied in the plant health sector and to assemble a detailed overview covering the following points:
- What options are available in terms of mobile software applications for plant health?
- What is their primary purpose?
- Who is the target audience (growers, plant health professionals, citizen science, …)?
- Which plant health sectors do they cover?
- Are they reliable and accurate?
- Is information submitted to a central database? If so, how is this information used?
- Could they be used globally, or are they limited to certain geographic regions?
Impact on Scottish crops if the molluscicide metaldehyde is withdrawn
This report sets out estimates for the crop loss and value to Scottish crop production should the molluscicide metaldehyde be withdrawn. This would leave ferric phosphate as the only available chemical control option. Short term losses are negligible as the substitution of ferric phosphate carries no additional treatment costs and has equivalent efficacy. Longer term there is some risk should resistance arise to this single site mode of action active, and ferric phosphate (although of lower mammalian toxicity to metaldehyde) has some environmental impacts of its own.
Difficult choices to protect gardens and the environment
Heritage gardens play an important role in plant conservation. They house collections gathered over decades or even hundreds of years, including varieties of plants that may be overlooked elsewhere, fostering heirloom varieties and preserving biological diversity that is the raw material of adaptation. As well as being beautiful and tranquil sites of cultural heritage, these ex-situ resources are treasure troves of biological diversity. Arduaine Gardens shows us that tough choices can be necessary and important to preserve these collections and the surrounding environment.