IT is a unique canopy that was planted more than 100 years ago to provide a rich autumn colour and more light in the winter.

But the felling of 900 Japanese larches has begun at one of Scotland’s best-loved gardens after the highly contagious tree disease called sudden oak death was discovered in one of the specimens.

The move is the latest step in The National Trust for Scotland’s plan to manage the outbreak of Phytophthora ramorum, which has affected a number of forests across Scotland, after it was first discovered at Arduaine Garden on the Argyll coast.

The conservation charity, which owns the 20-acre garden, started the felling process in autumn and said hundreds of trees will be axed to stop the problem spreading.

Now moving into full-scale operation, the felling is part of a four-year plan to protect one of Scotland’s most remarkable gardens, while boosting its biodiversity and resilience.

Making up much of the “shelterbelt”, which enables Arduaine Garden to grow its unique mix of plants, the larch species is particularly prone to disease.

In 2007, several of the garden’s Japanese larches were diagnosed with the first cases of Phytophthora ramorum in Scotland and were earmarked for removal.

As a result, the Trust is required to fell surrounding larches to prevent the disease affecting an area where there are large commercial forest plantations, which would be susceptible.

This poses a considerable problem in the hillside garden where there are no access roads and where important, rare shrubs grow underneath the tree canopy.

The disease is a fungus that kills trees and shrubs, and had been previously found in the garden’s shrubs, particularly rhododendrons for which Arduaine is famous. It spread and in 2016 a statutory notice for the trees’ removal was issued.

Trust arborists and horticultural experts are now uprooting the trees before milling them on site.

This will kill disease in the wood, allowing it to be recycled and transported for other purposes without fear of spreading infection.

Simon Jones, gardens and designed landscapes manager at the National Trust for Scotland, said: “We’re doing what is scientifically and morally right for the state of plant health in Arduaine Garden and beyond. While we can’t be definitive about removing disease from the property altogether, this innovative approach will go some way towards helping us protect this historic garden from future outbreaks of sudden oak death, by creating a more diverse and resilient arboretum.

“These are the first steps in what will be a long and thorough process – it’s important that we get this right for the future of the garden.”

First established in 1898 by James Arthur Campbell and continued by two succeeding generations of his family, Arduaine, which lies on a promontory between Lochgilphead and Oban, is home to a host of tree and plant species that are rarely seen in Scotland.

The collection includes species from as far away as East Asia and South America, including that renowned selection of rhododendrons. The entire canopy at Arduaine, which was planted in 1898, is Japanese larch which allows more light in winter and lovely spring and autumn colour.

Now among a variety of uses for the felled wood will be the creation of an organic, Queensferry Crossing-inspired windbreak to replace the larch shelterbelt. Phytophthora ramorum has been spreading up the west coast of Britain for some years, as a result of the climate becoming warmer and wetter, and has affected larches in Cornwall and Wales.

HeraldScotland:

It is a pathogen better known as sudden oak death or Ramorum dieback and can also infest other types of trees, but is often referred to in Britain as larch tree disease because larch trees are particularly susceptible.

It has also been found on juniper trees in the north of England, causing fear it could spread north to what is an important native species in Scotland.

The £250,000 project at Arduaine is part of NTS’s programme to invest almost £60 million over the next five years.

But NTS had planned to close Arduaine and 10 other properties in 2009 as a result of a financial shortfall.

That galvanised a public campaign that led to a rethink and eventually an overhaul of the way the Trust is run.

NTS announced the future of the garden was secure thanks to donations amounting to £1.9m and a partnership with the neighbouring Loch Melfort Hotel.

Mr Jones added: “It’s another example of how we’re investing significantly in Scotland’s natural heritage, to maintain and enhance the way we celebrate its history and culture for current and future generations.”