Blooming Glorious

24th April 2009

The Horse Chestnut, loved for its spring blossom, and by generations of children for its conker nuts, is in trouble, threatened by a newly discovered form of bleeding canker. Could it go the way of the Elms?).

Jack Watkins investigates.

It’s a tree bursting with nostalgic associations. From school trips in spring to Hampton Court, when its pink and white ‘candles’ are in full astounding bloom on the lawns near the Palace, to picking up the fallen conker nuts for games in the playground, the Horse Chestnut conjures up fond memories of childhood. Added to this, its high visibility (it’s frequently planted on village greens, roadsides or roundabouts – anywhere, in fact, where its spreading canopy can be seen to maximum effect) means it’s the one species that even those who care not a jot about trees can usually name.

There are highbrow types who furrow their brows at this. The doyen of countryside historians, Dr Oliver Rackham, with characteristic astringency, describes it as a ‘sad example of a once glamorous species, associated with oriental romance, being deprived of its meaning though being made the universal tree of bus stations.’ There is, you see, a certain irony that the British, with their great heritage of native broadleaved trees, should yet take one that is actually a foreigner so closely to their hearts, planting it on their streets and in their municipal parks.

Aesculus hippocastanum – Horse Chestnut – didn’t actually arrive here until the 16th century. Its native lands are the Balkans and parts of Asia. The name may have emanated from Turkey, where the flour from the conkers, mixed with oats, is used as a medicinal for broken-winded horses. Seeds were not brought to western Europe until the late 16th century, but within a few decades the Jacobean plantsman John Tradescant was growing them.
It was Sir Christopher Wren who designed the majestic, mile long avenue of the trees at Bushy Park, in the Hampton Court palace grounds. People have long marvelled at their colourful spring flowerings and their precocious foliage, but their early leafing has always left them vulnerable to wilting in our late frosts, while native British trees like oak and ash sagely bide their time. By the 1890s, Chestnut Sunday in early May was one of the most popular festivals in London, the locals delighting in picknicking under the spreading shade.

There was much cause for dismay, therefore, when, a couple of year ago, reports began circulating in the press about a new form of bleeding canker (looking like a running sore or an area of dying bark on the tree’s trunk or branches, oozing or ‘bleeding’ liquid), that was spreading and killing off the trees. In 2006, it was reported that the canker had killed off nearly 3,000 of them. Last spring, more detailed fieldwork by the Forestry Commission’s research arm, Forest Research, found symptoms which were thought ‘might’ indicate bleeding canker in 49% of the trees inspected in a sample survey. So is the country facing the prospect of another Dutch Elm type scenario sweeping through our tree’d landscape?

No, is the short answer. Unlike the Sweet Chestnut (Castanea sativa), another non-native, introduced here by the Romans, but one which took readily to our soils and became a tree beloved by woodsmen, the Horse Chestnut has never truly naturalised (though you may see the occasional one that has sprung up wild in a hedgerow). It has a low timber utility, so its planting here has generally been for visual impact. There are, therefore, estimated to be fewer than two million Horse Chestnuts, in comparison to the millions of Elms that we once had, according to Forest Research figures.

According to one of Forest Research’s spokesmen, the Horse Chestnut canker is also less virulent: “The Dutch Elm disease fungus is spread very rapidly by elm bark beetles flying from infected trees to healthy ones to feed.” Added to the ability of Dutch Elm to spread along the root systems that Elms, particularly in hedgerows, often share, it’s probable we have lost 30 million of them in three decades.

Bleeding canker, by contrast, needn’t be a Horse Chestnut’s death warrant. “Some trees with trunk infections retain healthy-looking crowns and might not deteriorate further,” said the spokesman. “In some, the disease progression can be very slow, or even cease, with the trees showing signs of recovery. Some trees survive, some die, and some have to be felled for public safety reasons when the condition weakens the trunk or a branch to a point where it is in danger of falling.”

Taking a pessimistic view, one can easily imagine the knee-jerk reaction of many a health-and-safety-spooked local authority on this matter. Many trees could be needlessly felled, and locals will need to be vigilant because too many of their locally elected representatives still live in the Dark Ages in terms of understanding trees. More understandable, perhaps, may be a tendency to veer away from planting young Horse Chestnuts which could replace older specimens as they pass maturity. Horse Chestnuts are not a long-lived species. The message must be to enjoy them while we can. We may be among the last generations to be readily able to savour their beauty.

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