Community Tree Nurseries and biosecurity
Reducing and managing the risks...
Community Tree Nurseries (CTN) are a diverse group of small nurseries, growers and networks all gathering and growing trees from seed, usually from nearby areas. They provide an invaluable contribution to the UK tree supply chain and appear to be on the increase with large tree planting targets placing demands on commercial tree nurseries. Not only do they grow hundreds of thousands of trees for planting projects, but they also provide a host of additional benefits to the local community. These nurseries are incredibly diverse and range from learning new skills through City and Guilds qualifications, supporting local community organisations, and providing happy, meaningful community action for the health and wellbeing of volunteers.
What do we mean when we talk about biosecurity?
Biosecurity is a concept which means taking precautions to prevent both the introduction and spread of harmful organisms which could damage our treescapes. These organisms can be pests, such as insects, or pathogens like viruses, bacteria or fungi which can infect our trees. Our trees tolerate living with an array of pathogenic organisms by virtue of being part of the natural environment but are under threat from new and introduced pests and diseases. Globalisation and increased trade have increased the spread of new tree pathogens (see Figure 1) as a result of increased movements of trees, wood and soil around the globe although they can also arrive naturally e.g. on the wind.
The most prominent and publicly known tree disease at present is ash dieback (Hymenoscyphus fraxineus) which is currently infecting our beloved ash trees, Britain’s third most common tree species. We could lose up to 80% of them as a result. Major tree disease disasters are uncomfortably familiar, with Dutch Elm Disease wiping out tens of millions of our native elm trees since it was introduced in the 1960s. The huge impacts on our treescapes, and the emotional, environmental, and monetary impacts of outbreaks highlight the importance of bringing biosecurity into all stages of tree production, management and forest product movement. Indeed, it was the loss of so many of our elms in the 70s that spearheaded the creation of The Tree Council to champion our trees nationally.
This year Defra released The Plant Biosecurity Strategy for Great Britain (2023 to 2028) which outlines the vision “To protect Great Britain’s plants through a strong partnership of government, industry, and the public, working together to reduce and manage risks posed by plant pests and pathogens, and facilitate safe trade.”
To be 100% ‘biosecure’ is, in a literal sense, not a realistic proposition – nature has a habit of getting round our imposed obstacles – but we can behave in ways which aim to reduce the risks. And we must.
How is it relevant to CTNs?
Local provenance production, common to CTNs, can reduce some biosecurity risks. However, biosecurity is still important when dealing with locally sourced trees to prevent the spread of pests and diseases, which could still have dramatic impacts and spread to wider areas.
Biosecurity risks exist, even with local provenance trees. What if, for example, a CTN is accepting donations of saplings from the local community to grow on? How do we know those trees have been collected and handled in a way to minimise biosecurity risks? How are they treated once they arrive at the nursery? Are they quarantined? Are routine health checks put in place to monitor the presence and potential spread of pests and diseases?
Spending the autumn visiting multiple sites looking for next year’s seed stock can risk spreading pathogenic organisms in the environment, even if the risk of bringing problems back into the nursery is managed. Steps, such as boot washes and disinfection between sites, should be taken to avoid this and there is helpful guidance here from Kew UK National Tree Seed Project - seed collecting guide.
A good working knowledge of how to identify trees infected with pests and/or diseases can be invaluable in choosing which trees to collect seed or reproductive material from, and which to avoid. It is unreasonable to expect everyone to have an understanding of all pests and diseases of trees, and indeed, many are not serious. However an understanding of the key problems can reduce the spread of potentially devastating problems. There are useful materials available to help such as Observatree’s guide to priority pests and diseases. Community groups involved in seed collection should always check with a skilled individual if they are unsure about collecting seed from a particular tree. If anyone has any concerns about a particular tree, then they should report it to the Forest Research’s TreeAlert website.
Then there are the on-site activities which need to be considered. Good hygiene practices can be effective at managing these risks. The Shared Outcomes Fund Trees Outside Woodlands (SOF TOW) project has been exploring ways to enable CTNs to become more biosecurity savvy and has funded grants for equipment and case studies to help CTNs in this area (see Tree Growers Guide section 4 and resources section The Tree Growers Guide).
The Community Tree Nursery Collaborative, a peer-to-peer network supporting CTNs, has hosted webinars discussing biosecurity here.
The huge impact that adopting good, simple, routine plant hygiene practices can have on reducing the spread of pests and diseases must not be underplayed. The Tree Council is keen to champion those CTNs demonstrating good practice to share with others.
Plant Healthy certification
Going one step further, adopting the Plant Health Management Standard and achieving certification will help to manage the risk of pests and diseases. Certification is voluntary at present, but it is a requirement of some government funded tree planting schemes. It can be a challenge for CTNs to gain Plant Healthy certification because they have to pay for certification and audits. However there is work looking into how this can be addressed, such as a trial group accreditation scheme funded through the SOF TOW project.
Streamlining accreditation systems and providing clear, achievable, easy to follow biosecurity protocols must be prioritised. Training and upskilling people within or entering the sector, and championing the role of CTNs within our tree production systems nationally is also vital.
As signatories to Defra’s Plant Biosecurity Strategy, The Tree Council is championing the development of CTNs and all the necessary biosecurity practices required to help support a healthier tree population in the longer term.
Jackie Shallcross is The Tree Council's lead for the Shared Outcome Fund Trees Outside Woodlands project. If you’d like more information, please email jackie.shallcross@treecouncil.org.uk. Find out more about The Tree Council at treecouncil.org.uk
Further reading
The Shared Outcomes Fund Trees Outside Woodland programme is developing innovative and sustainable new ways to increase tree cover to address both the climate and ecological emergencies. The £4.8m, five-year programme is funded by HM Government and delivered in partnership by The Tree Council, Natural England, the Department for Environment, Food & Rural Affairs with five local councils.
The University of Coventry’s Growing Connections project is exploring the CTN sector and biosecurity.
Defra’s Tree Health Resilience Strategy outlines Defra’s plan for a healthy treescape.