Conker crisis as blight and moths destroy trees

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For years, it has been a favourite playground game, requiring skill, cunning, and, above all, a plentiful supply of conkers.

But this autumn the sport is under threat from a string of hungry pests and deadly diseases.

The spread of a grisly disease known as bleeding canker and a midge-sized moth with a voracious appetite could make this year the worst ever for conkers.

Up to 50,000 of the country's horse chestnut trees - one tenth of the national stock - has already been infected by bleeding canker - and experts are at a loss how to stop its spread.

The disease causes black gum to ooze from weeping sores in the bark. If the ulcers encircle the trunk, the result is rapid death.

In other cases, the tree is weakened so much that it has to be felled for safety reasons.

Until recently, rates of the disease, caused by two fungi, were low. But around five years ago, the disease started to take hold around the UK, and no one knows why.

Tests show the culprit is not the fungi that has caused a problem in the past, and until the predator is identified, there is no treatment or cure.

Our horse chestnuts are also under attack by the grubs of a foreign moth.

These devour its leaves, causing them to turn brown and fall off earlier than usual - and can lead to the trees producing fewer, and smaller conkers.

First spotted in the UK in a London back garden four years ago, the leaf miner moth, or Cameraria ohridella, has spread its wings across the southern half of England.

A Forestry Commission spokesman said: "The first report was in Wimbledon in July 2002.

"Since then it has spread throughout South-East England, from Margate and Folkestone in the east, to places as far west as Oxford and Bournemouth, and as far north as Norfolk and the Midlands."

There as even been an outbreak in Newport, Wales - thought to be caused by leaf miners who hitched a ride in a passing car.

In the grounds of London's Alexandra Palace, it looks as if autumn has come early.

There, horse chestnut leaves blighted by the leaf miner moth have turned golden brown and are growing sparser by the day.

The destruction is caused by the larvae - laid as eggs inside the leaves - munching or 'mining' their way to the outside.

With a single leaf holding up to 700 eggs, the leaves quickly turn brown and can be shed as early as August.

First seen in Macedonia in the 1970s, though it may have originated in Asia, the leaf miner moth has now spread across much of Europe.

Experts believe it is inevitable the moth, aided by gusts of wind and passing motorists, will eventually become widespread across the whole of the UK.

With no natural predator, its control is limited. There are also fears that infestation with the moth may speed up the death of trees already struggling to fight off canker.

While gardeners can keep the grubs at bay by sweeping up leaves and composting or burning them, such techniques are less practical in larger areas such as parks and woodland.

If the twin-pronged attack were not enough, horse chestnut trees are also under siege from a third pest - a fungus which causes yellow-bordered brown blotches on the leaves.

Last night, the Forestry Commission urged gardeners not to panic if they see their prize horse chestnut tree ailing.

While the canker may be fatal, moth infection and leaf blotch are often not as bad as they look, and expert opinion should be sought before trees are felled.

Despite the spread of disease, this year's World Conker Championships, held annually in Northamptonshire, will go ahead as planned.

Organisers have already collected more than half of the 2,000 conkers needed for the October 8 contest.

 

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