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Countryfile on tree health

15th Nov 2018

We eagerly watched the recent episode of Countryfile in which the problem of imported tree pests and diseases was discussed. Biosecurity is high on our agenda at Chew Valley Trees, and has been for a long time.

One of the problems raised in the show was that sometimes trees are labelled with a Union Jack when in fact they may have spent time abroad at some point in their production. We would like to point out that where you see the British Grown label on our website, it means those trees or shrubs have been fully produced in the UK, right from propagation. We can apply this label to over 98% of our stock.

The main benefits of buying British Grown are that you can be confident you are supporting British growers, and that they have not been brought in from another country, harbouring any pests or diseases not already present in the UK. It's a sad fact that oak processionary moth, as shown on Countryfile, was introduced on imported trees, and now poses a serious threat to our oak population. In addition, its caterpillars are a health hazard. Fortunately, this pest has not made it down here to Somerset, and long may it stay that way.

In the BBC programme, two proposals were suggested to combat the bringing in of pests and disease: banning imports or keeping them for 12 months before they can go out for planting. Limits on movement of some high risk trees, such as olives, have recently been put in place by Defra to reduce the risk of bringing in Xylella fastidiosa, while Ash Dieback has resulted in rules banning the movement of this beautiful tree, which are unlikely to be lifted anytime soon.

With imports, the worst risk comes from those that are brought in to the country for planting straight out in the landscape, bypassing the obligatory checks that are required at nurseries like Chew Valley Trees. It is well worth noting, however, that the threat isn't just from importing live trees. Signs of Asian longhorn beetle, which has killed millions of trees in its home continent, were found on Ai Weiwei's tree stump art installation at the Royal Academy in London (which was subsequently fumigated).

The beetle's exit holes were spotted by the government's chief plant health officer, Prof. Nicola Spence, who happened to be visiting. In a recent speech, she also noted that pests and disease can be brought in on anything from Christmas wreaths to furniture. A trendy potato-like vegetable from the Andes, featured on Masterchef, has even been found to pose a threat to our homegrown potatoes thanks to a virus it hosts.

The first outbreak of Asian longhorn beetle in the UK, in Kent in 2012, was thought to come from infested packaging on Chinese stone imports. So far, the pest hasn't gained a foothold here. Dutch Elm Disease, though, absolutely has. The epidemic which decimated swathes of our elms in the 1970s-80s came in via infected timber from Canada.

The trees we import at Chew Valley Trees - a tiny proportion of those we sell - are sourced from reputable nurseries in the EU, where they undergo inspections by both trained people at the export nursery and the relevant plant health authority there. Once in this country, they undergo further checks by both our nursery staff and the Defra Plant Health Authority. Chew Valley Trees is committed to maintaining tree health here in the nursery and in the wider landscape, and fully support measures that contribute to this aim, such as plant passports the plant health assurance scheme currently under development.

We also urge our customers to be vigilant when it comes to protecting our trees: please don't buy anything imported that isn't part of the plant passporting scheme (which offers traceability and checks). More information about tree pests and diseases is available from the Forestry Commission and Animal & Plant Health Agency.

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