Defra's "Tree Health Resilience Strategy", published last month (May), calls for concerted action between tree managers, charities, the public and Government to strengthen resilience against pest and disease threats to Britain's trees.
The Arboricultural Association is among those that called for the strategy to develop biosecurity guidance for the industry, and indeed a launch event for its Biosecurity in Arboriculture guidance note is already planned for later this summer. This will go into greater detail than its original position statement, published two years ago, giving biosecurity best practice guidance for arborists at all levels in the industry.
The association’s former technical officer Simon Cox, now an independent environmental consultant, helped draft both documents.
"It’s good that Defra has produced this so quickly [after the launch of the 25-year environment plan],"
He tells Horticulture Week.
"The strategy says ‘some of this is happening, but we need industry to do such-and-such’, and the Arboricultural Association has a role in that, which we are already working on."
"The ball has to keep rolling on this. The plan is for our new guidance note to then be broken down into tailored advice for practical arborists, or those in the plant trade, or for tree managers looking to build resilience into the tree population."
He says the response to the original position statement was
"fantastic, partly because it already had Defra, ICF [Institute of Chartered Foresters] and Forestry Commission backing, and it quickly established a lot of support".
"We said companies should have biosecurity policies — they should consider it just as they would any other risk to their business. We gave them the tools and templates to do things like risk assessments."
Since then the Forestry Commission has published Biosecurity for Arborists guidance as part of its "Keep It Clean" campaign, and biosecurity was then the theme of last year’s Arboricultural Association conference, at which Prince Charles expressed his concern on the issue in his opening address.
Meanwhile, the Trees & Design Action Group’s forthcoming Species Selection for Green Infrastructure is "another piece of the puzzle", adds Cox.
Areas to tackle
But he says there is still bad practice to address.
"Companies will ring up whoever and say ‘get this tree to me in two days’ time’. They may be told, ‘you can’t import London plane’, so they’ll say, ‘well what else can you get?’ That’s how oak processionary moth (OPM) probably got in — someone didn’t think properly or the person planting the tree didn’t realise that nest was an issue. There are many building blocks we have to put together."
"Why aren’t we producing more trees ourselves, not just nationally but locally, rather than rely on people growing them hundreds or even thousands of miles away? The number of UK nurseries has decreased over the last 20 years — the land has been sold and no one is stepping in to replace them. Other countries have support for these kind of rural industries. Meanwhile, it’s so easy to bring things in from wherever."
For the UK to now find itself better able to address this at official level" is one advantage of Brexit", says Cox.
"It’s an opportunity, if there’s the will and the training."
The Woodland Trust, a member of the Government’s Tree Health Policy Group, wants biosecurity measures including quarantines already used by some horticultural businesses to be extended, and says:
"Once we leave the EU we will have the chance to tighten biosecurity measures further and take swifter, more targeted action against serious threats like Xylella."
Its senior conservation officer Nick Atkinson adds:
"There needs to be greater Government monitoring at points of entry to ensure that what is brought in is properly certified, and quarantined where necessary."
He says the amount spent on this
"should be proportionate to the potential costs of an outbreak"
"There is a cost to keeping pests and diseases at bay, but compared to the cost of not taking action, it’s a no-brainer. We calculated the cost to society of ash dieback (ADB) will be at least £15bn, if you take in the loss of the services the trees provide, and the cost of felling and replacing them."
But he adds:
"Right now those costs aren’t being borne equitably. The horticultural industry, for one, needs to take responsibility, although all biologically active material that is traded internationally, including woodchip and firewood, is a risk."
From the charity’s own point of view, he notes:
"Our focus is on the semi-natural landscape, and we want that to be resilient, with a diversity of trees both in terms of species and genetic stock — issues which have been overlooked in the past. Do we need to re-evaluate producing trees clonally?"
The Woodland Trust already has its own "UK sourced and grown" assurance scheme for tree nurseries, described by Atkinson as "the gold standard" for assured provenance.
"Not only do you avoid importing pests and diseases from overseas, you have stock that’s best adapted to local conditions,"
But for the typically non-native species demanded in urban areas,
"it’s a question of balancing risks, and we haven’t yet got that balance right"
"They should only be brought in through a traceable route. One silver lining from ADB, OPM and now Xylella is they have raised the flag on this."
Tree health strategy: key tasks
- Consultation with industry to ensure a swift and effective response should new pests and diseases enter the UK.
- Raising of biosecurity standards in the horticultural industry through assurance and safe sourcing, and adoption of this in public procurement.
- Stronger monitoring and protection, specifically against Xylella.
- Launch of "Don’t Risk It" campaign this summer to raise awareness of the risks of bringing back plant material from abroad, and possible banning of regulated plant material in passenger baggage.
Read in HortWeek