Hannah Gray meets a man doing his best for these beleaguered trees.

IT seems perverse that a tiny, flying beetle can be responsible for killing a single strapping, 65-ft tall tree, let alone millions of them, but that is precisely what happened in the late 1970s and 1980s to the elm population in this country.

There had been a form of Dutch elm disease in the UK since the beginning of the 20th Century, but in the late 1960s, a far more virulent strain reached our shores from North America, brought in by the elm bark beetle, which arrived on a shipment of logs.

As it nibbles on the young bark of elm trees, the beetle inadvertently drops fungal spores. In turn, these spores can be deadly to the trees the beetles feed on.

This North American strain of Dutch elm disease can kill a tree in about a week, and it quickly spread around the country.

Over the next few years, around 20 million elms were wiped out, and by 1995, there were estimated to be just five million left in the country, from a population of 30 million.

Elms continue to be infected by the disease to this day, but there are pockets of the trees, and even some mature ones, which have survived numerous attacks.

Four such trees survive at the entrance to Ferry Meadows in Peterborough, where they are lovingly checked, tended and even nursed by park ranger Ashley Wheal.

It is an ongoing task, and a labour of love.

Because not only are these trees elderly statesmen of the plant world – they are thought to be nearly 140 years old – but they are also a vital habitat for the white letter hairstreak butterfly, which, as the elms have declined, has become a rare species.

The butterfly lava eat the foliage of the elms and so the survival of the trees is vital for the continuation of this butterfly.

Such is the responsibility resting on the shoulders of Ashley, who has worked for Nene Park Trust for 19 years.

Shortly after he started work, he became interested in trees, studied for two qualifications and became a qualified tree surgeon.

Today he has his work very much cut out. Virtually every day from June until mid-October, Ashley has to inspect and care for his trees.

The first signs of infection of Dutch elm disease usually start at the top of the tree, with leaves turning yellow and then brown.

Sometimes it is possible to remove limbs of trees to prevent the disease from spreading, which sees Ashley, helped by his colleagues, donning a harness and climbing to great heights, chainsaw in hand.

He also goes to the rather unusual length of injecting his trees with fungicide to treat them.

This method was widely used in the 1970s and 1980s, but is now generally overlooked.

Ashley drills holes in the side of infected trees and injects fungicide into the trunk, so that it is drawn up through the tree's xylem cells.

He said: "What I found was that most people had almost given up trying to do anything, they'd lost so many, but some people had had a go at injecting almost as a last ditch attempt to save them. I found a contractor that had the knowledge and the equipment and I got him to train me up."