argyll and bute, ash trees fungus, Chalara fraxinea, Forestry Commission, japanese knotweed, rhododendron ponticum
The British are known for their love of plants. Our thirst for acquiring the exotic and unusual started in the 18th century when trade routes and the Empire were expanding. Plant hunters would send back plants from across the globe to satisfy the demand from the rich with vast estates. Our temperate climate meant that we were able to grow a wide variety of plants and our relatively small number of native species fuelled an interest in plant collection. As plants were imported in greater numbers they became cheaper to buy, so much so, that plants which only fifty to a hundred years ago were rare and prized could now be found in parks and homes across the country and were no longer the preserve of the rich.
It’s hard to imagine not having rhododendrons, magnolias, acers, rudbeckias and tulips, for instance. The list of plants that we now take for granted but that were introduced here is vast. Britain would certainly be a much less colourful and interesting place horticulturally. However, the import of plants from abroad has brought its problems. Rhododendron ponticum has become the dominant species in many places, out-competing pretty much every other species in the area. And, if that wasn’t enough, it’s also the host for a plant disease which kills trees. In Argyll and Bute, in Scotland, the problem is so bad that it was decided to remove vast areas of the rhododendron at an estimated cost of nearly £10 million.
And of course, there is Japanese knotweed. Introduced by the Victorians because they thought it an attractive and unusual plant, it is wreaking havoc in the countryside. It can reproduce from the tiniest piece of root, grows quickly, creating dense shade and excluding smaller, native species and can push up through tarmac, paving and damage infrastructure. This plant has something of the Triffid about it. Complete eradication would be impossible when it comes to Japanese knotweed, so control is the only option, although the cost of this is estimated to be in the billions.
And now we’re faced with another problem. Chalara fraxinea is a fungus that attacks ash trees. It has been a problem on mainland Europe for a while now, particularly in Poland where it was first discovered in 1992. In Denmark where it was first spotted in 2003 it has killed between 60% and 90% of ash trees. When it was announced last week that the fungus had been found on mature trees in East Anglia alarms bells started to ring. With some 30% of trees in the UK being ash this discovery could have a dreadful impact, not just on our countryside, but also on our parks and urban areas. Reminiscent of the impact Dutch elm disease had in the 1970s, when an estimated 20 million of the 30 million elms in the UK were wiped out.
According to the Forestry Commission, Chalara fraxinea has been found in a number of location in England since February of this year. All of these were on newly planted trees imported from Holland. It does seem strange that when the first imports were found to be contaminated, imports weren’t banned. Apparently, the mechanisms involved with plant biosecurity don’t work as quickly as with, say, animal disease and I can appreciate the levels of bureaucracy involved probably do create an unwieldy infrastructure that cannot respond rapidly to such problems. But, it’s not as if this is a problem that has just been sprung upon us.
As trees go ash isn’t one of my favourites. There was an ash tree at the bottom of a neighbour’s garden which was so close to the fence that most of the tree was in fact in our garden. It wasn’t especially attractive with it’s strangely fat black buds, seed pods that used to shed in vast quantities all over the garden and its ability to self seed so prolifically. It didn’t even redeem itself in autumn with a spectacular show of colour. The leaves turned a bit yellowy, as if the tree was a bit sickly, and then dropped. The tree was removed last year when new people bought the house. I didn’t like the sudden appearance of my neighbours’ houses that had been, up until that point, hidden by the ash tree but I wasn’t sad like I was when our beautiful birch was removed.
Ash, in my opinion, don’t make great garden trees because of their lack of ornamental interest but that doesn’t mean that I want to see them wiped out in our woodlands, hedgerows and parks. They are a native tree that fits with our landscape and climate. According to the Guardian, 60 of this country’s rarest insects would suffer dramatically from any serious loss of ash trees. They also provide important sites for tree roosting bats such as the Noctule bat and what about the lichens and mosses, so often forgotten about but vital to biodiversity, that would no longer have somewhere to live.
Perhaps the most surprising element of this whole story for me though, is why on earth are we importing sapling ash trees from Holland? Ash is notorious for its ability to self seed and trees generally don’t need much care to get them to a sapling stage. I find it hard to believe we can’t grow them ourselves, here in the UK.
Hopefully, the worst won’t happen. Maybe our native trees will have a natural immunity to the infection, possibly the spread can be controlled. Whatever the outcome for our ash trees this surely must be the time to reflect on how European plant bio-security regulations are not working and perhaps on a more basic level we, as gardeners and growers, need to look a little more closely into where our plants are coming from.
For more information about the ash tree fungus, how to spot the signs and what to do, these websites should help. www.forestry.gov.uk and www.woodlandtrust.org.uk