Sibbaldia: the International Journal of Botanic Garden Horticulture 2020-03-31T14:05:58+01:00 Kate Hughes Open Journal Systems <p><em>Sibbaldia</em> exists to give horticulturists and managers a voice and to bring the work they do to a worldwide audience. It is for horticulturists, managers and students of botanical, heritage and conservation landscapes. The Editor particularly welcomes articles on horticultural techniques, cultivation of species and the application of horticulture for conservation practice. Articles on the curation, plant science, health and heritage of plant collections and species are also welcomed.</p> Foreword 2020-03-30T14:00:43+01:00 Kate Hughes Katherine Hayden <p>Not applicable</p> 2020-02-21T00:00:00+00:00 Copyright (c) 2020 Kate Hughes; Katherine Hayden Guest Essay Global hosts and global pathogens: a perspective 2020-03-31T14:05:43+01:00 Janis Antonovics Katherine Hayden <p>Plant species are assailed by a remarkable diversity of pathogens, and these and other pests pose a serious direct risk to collections in botanic gardens as well as a potential source of pathogen escape. The high diversity of species in gardens combined with low population numbers minimises the likelihood of disease spread of specialist pathogens, but importation of novel pathogens is a constant concern. In parallel with natural systems, there is little data on pathogen loads in botanic gardens, on what accession policies minimise these and if such loads are likely to differ by country of origin or plant life form. Nevertheless, commonsense measures such as prohibiting the importation of plants in soil, shifting to seed and in vitro propagation, and inspection and quarantine on receiving and transferring plants should be implemented.<br>This edition of <em>Sibbaldia</em> explores a variety of directions for improving our ability to develop strategies for dealing not just with pathogen threats, but with a more rational approach to pests and to microbial interactions that are a natural part of a plant’s heritage.</p> 2020-02-21T14:29:26+00:00 Copyright (c) 2020 Katherine Hayden; Janis Antonovics Botanic Garden Profile Inverewe: gardening on the edge 2020-03-31T14:05:36+01:00 Kevin Frediani <p>Set in the heart of the Scottish Highlands, Inverewe is one of the most spectacular garden locations in the UK. Situated beside the A382 on the North Coast 500 tourist route, the property receives over 100,000 visitors each year, drawn to see a diversity of plants and to enjoy the breathtaking backdrop of mountains and seascape it affords. Since its first plantings in 1864, the property has been a centre for experimental approaches to establishing and growing tender woody and herbaceous perennials, while a diaspora of alumni have gone on to fulfil prominent roles in the horticultural industry over the years. The garden today covers approximately 22 ha of mainly woodland gardens, renowned for the diversity of their designed elements and whose conservation management is based on a thorough understanding, appreciation and analysis of the garden’s historical development and its significance in local, regional and national contexts.<br>In recent years, Inverewe has faced a number of challenges related to the growing impact of global change, with increased occurrences of extreme weather events, and emergent pest and disease incidents associated with climate change and the movement of plants and their vectors, which include human-aided transport of problems between sites. In this context, this article provides a lens on the drivers of change that the plant collection is facing in the early decades of the 21st century. After an introduction to the garden, its evolved collections and management approach, three case studies are highlighted as examples of emerging threats to Inverewe as a garden and work of art. Inverewe is presented as a landscape that endures through adaptation to social, economic and, increasingly, environmental challenges that shape the direction it takes as a garden and plant collection growing on the edge.</p> 2020-02-21T14:31:42+00:00 Copyright (c) 2020 Kevin Frediani Student Project Environmental influences on box blight epidemics 2020-03-30T14:00:36+01:00 Lizzie Sharp Clare Hurst Jassy Draculic Matthew Cromey <p><em>Calonectria pseudonaviculata</em> and <em>C. henricotiae</em> are two recently differentiated fungal species responsible for box blight, a disease that threatens the <em>Buxus</em> genus. Infection can be introduced to gardens on new plants and is spread through the use of tools. The fungus survives on stem lesions and fallen leaves when spores are dispersed by rainsplash. In this study, 195 <em>Calonectria</em> UK isolates collected by the Royal Horticultural Society (RHS) Advisory Service were identified to species level. Detached stem assays were performed to assess how long stem and leaf lesions remain infectious, and their sensitivity to fungicides. A survey was also carried out at three National Trust properties on the effect of clipping on box blight distribution and severity. It was found that <em>C. henricotiae</em> was only present in and after 2011. <em>C. henricotiae</em> is more thermotolerant, and the increase in prevalence may be a result of increasing temperature and longer dry spells in the UK. Sporulation could occur multiple times on both stem and leaf lesions in humid conditions, although spore production dropped markedly after six sporulation events. Fungicides were effective at preventing spore production on stem lesions. Long dry spells may also reduce <em>Calonectria</em>’s ability to sporulate, leading to limited box blight spread between plants.</p> 2020-02-21T00:00:00+00:00 Copyright (c) 2020 Lizzie Sharp, Clare Hurst, Jassy Draculic, Matthew Cromey Phytophthora pathogens threaten rare habitats and conservation plantings 2020-03-31T14:05:29+01:00 Susan J. Frankel Janice Alexander Diana Benner Janell Hillman Alisa Shor <p>Phytophthora pathogens are damaging native wildland vegetation including plants in restoration areas and botanic gardens. The infestations threaten some plants already designated as endangered and degrade high-value habitats. Pathogens are being introduced primarily via container plant nursery stock and, once established, they can spread to adjacent areas where plant species not previously exposed to pathogens may become infected. We review epidemics in California – caused by the sudden oak death pathogen <em>Phytophthora</em><br><em>ramorum</em> Werres, De Cock &amp; Man in ‘t Veld and the first USA detections of <em>P. tentaculata</em> Kröber &amp; Marwitz, which occurred in native plant nurseries and restoration areas – as examples to illustrate these threats to conservation plantings.</p> 2020-02-21T15:09:26+00:00 Copyright (c) 2020 Susan J. Frankel Diversity of woody-host infecting Phytophthora species in public parks and botanic gardens as revealed by metabarcoding, and opportunities for mitigation through best practice 2020-03-31T14:05:58+01:00 Sarah Green Carolyn E. Riddell Debbie Frederickson-Matika April Armstrong Matt Elliot Jack Forster Pete E. Hedley Jenny Morris Peter Thorpe David E.L. Cooke Paul M. Sharp Leighton Pritchard <p>The diversity of <em>Phytophthora</em> species in soils collected from 14 highly disturbed sites in northern Britain, including botanic gardens, arboreta, public parks and other amenity woodland sites, was analysed using a molecular technique known as DNA metabarcoding. This technique enables the identification of multiple species present in a single environmental sample based on a DNA ‘barcode’ unique to each species. The genus <em>Phytophthora</em> was targeted in this study due to its increasing impact on Britain’s forests and woodlands over the<br>last 20 years. The introduction and spread of new Phytophthora species into Britain has been strongly associated with the movement of traded containerised plants, with a number of <em>Phytophthora</em> outbreaks reported on host trees located in public gardens and parks that had recently undergone planting or landscape regeneration schemes. This study was undertaken to assess the extent to which these highly disturbed sites with extensive planting regimes act as harbours for woody-host infecting <em>Phytophthora</em> species. A total of 23 <em>Phytophthora</em> species, the majority of which are known to be pathogens of woody hosts, were detected across the 14 sites sampled. These included four quarantine-regulated pathogens and four species not<br>previously recorded in Britain. Also detected were three as-yet undescribed <em>Phytophthora </em>species and nine oomycete sequences with no clear match to any known genus. There was no effect of geographical location, elevation, underlying soil type, host family or host health status on the <em>Phytophthora</em> assemblages at each site, suggesting that the <em>Phytophthora </em>communities detected are likely to comprise introduced species associated with planting programmes. <em>P. austrocedri</em> and <em>P. pseudosyringae</em> were two of the most abundant <em>Phytophthora</em><br>species detected, both of which cause serious damage to trees and are regarded as fairly recent introductions to Britain. The practical implications of the findings in terms of mitigating <em>Phytophthora</em> introduction, spread and impact at botanic gardens, arboreta and urban parks are discussed.</p> 2020-02-21T00:00:00+00:00 Copyright (c) 2020 Sarah Green Phytophthora root rot: its impact in botanic gardens and on threatened species conservation 2020-03-31T14:05:22+01:00 Brett Summerell Edward Liew <p>Phytophthora root rot is one of the most devastating diseases of perennial plants worldwide, affecting plants in food production, amenity plantings and in natural ecosystems. The impact of these diseases in botanic gardens can be substantial and can affect how a site may be used for months and years ahead. Management is critically dependent on avoidance of the introduction of the pathogen and effective hygiene protocols are key to achieving this. Additionally, botanic gardens have a key role to play in protecting plants and enhancing conservation outcomes through surveillance, education and ex situ conservation programmes, as well as through the recognition that they can be critical as sentinel sites to detect new incursions of pests and<br>diseases. The impact of several Phytophthora species on the in situ and ex situ management of the critically endangered <em>Wollemia nobilis</em> (Wollemi pine), which is highly susceptible to phytophthora root rot, is used to highlight the need to ensure management of these pathogens is a critical component of threatened species recovery and management.</p> 2020-02-21T15:20:46+00:00 Copyright (c) 2020 Brett Summerell The International Plant Sentinel Network: an update on phase 2 2020-03-31T14:05:14+01:00 Kate Marfleet Suzanne Sharrock <p>Invasive plant pests and pathogens pose a considerable threat to plant health worldwide. With increasing globalisation of trade in plants and plant material, and the effects of climate change, this threat is predicted to continue to rise. In recent years, there has been a sharp increase in the number of these harmful invasive organisms which cause large-scale environmental and economic damage. A significant issue in managing this threat is predicting which organisms will pose a threat in the future. Sentinel plants are individuals found outside their native ranges that can be surveyed for damage by organisms they would not otherwise encounter. Monitoring plant sentinels can build knowledge and understanding of pest/host relationships to support the development of management plans and risk assessments. Botanic gardens and arboreta, whose collections are estimated to include 30–40 per cent of all known plant species, many of which are exotic, are unique and under-utilised resources that can support sentinel research. The International Plant Sentinel Network (IPSN) consists of botanic gardens and arboreta, National Plant Protection Organisations (NPPOs) and plant health scientists who collaborate to provide an early-warning system for new and emerging plant pests and pathogens. Members provide scientific evidence to NPPOs to inform plant health activities and thus help safeguard susceptible plant species. In the UK, the IPSN conducts research activities prioritised by a Research and Development committee and preliminary findings of recent research activities are outlined in this paper. The IPSN also focuses on increasing knowledge and awareness, seeking best practice, developing standardised<br>approaches and providing training materials and methodologies for monitoring and surveying to enable gardens to contribute to sentinel research. Through multi-disciplinary collaboration and information sharing the IPSN aims to reduce the risk that alien invasive pests and pathogens pose to global plant health.</p> 2020-02-21T15:26:09+00:00 Copyright (c) 2020 Kate Marfleet Biological controls in botanic gardens 2020-03-31T14:05:07+01:00 Julian Ives <p>Biological control of insect pests in horticulture is evolving rapidly but use in botanic gardens can be difficult due to the variety and extent of the plant collections held at these gardens. This paper describes examples of successful biological control of mealybug species at the Cambridge University Botanic Garden and Royal Botanic Garden Edinburgh and looks at some of the challenges to extending the use of such controls in all environments.</p> 2020-02-21T15:32:13+00:00 Copyright (c) 2020 Julian Ives Botanic gardens and plant pathogens: a risk-based approach at the Royal Botanic Garden Edinburgh 2020-03-31T14:05:00+01:00 Katherine Hayden <p>Introduced and emerging plant diseases as a result of live plant movements are increasingly recognised as a global environmental and economic threat. This presents a fundamental challenge to botanic gardens and other ex situ plant conservation organisations: how to continue this important work while recognising and mitigating the plant health risks. The approach taken by the Royal Botanic Garden Edinburgh is presented as a case study, showing how we have reduced ecological and evolutionary opportunities for pests in <em>ex situ </em>conservation and are monitoring the success of these efforts. We have developed protocols in quarantine and horticultural practice, expanded visitor engagement and public education, and taken a precautionary approach towards plant distribution supported by in-house diagnostics and working closely with statutory authorities. We hope that by sharing activities as well as difficulties, botanic gardens can acknowledge and address the new biosecurity landscape.</p> 2020-02-21T15:37:03+00:00 Copyright (c) 2020 Katherine Hayden An integrated approach to meet future plant health challenges in Scotland 2020-03-31T14:05:51+01:00 Gerry Saddler <p>Plants are a vital component for the maintenance of life on Earth and serve as the feedstock for many industries on which large parts of the world rely. Like all other forms of life, they are susceptible to disease and attack, sometimes with disastrous consequences for habitats and economies. Safeguarding plant health is therefore rightly recognised as one of the major objectives for the Scottish Government, and the reason for which the Government launched its Plant Health Strategy in 2016. This paper describes the drivers and aims for this Strategy and some of the industry-led initiatives which are enabling its implementation.</p> 2020-02-21T00:00:00+00:00 Copyright (c) 2020 Gerry Saddler