Walkers have been warned to clean their boots after venturing into woodlands to prevent the spread of killer tree diseases around Scotland.
Forestry Commission Scotland said that tree pests and diseases could be carried from one location to another in mud and forest debris including on boots, bike wheels, dogs’ paws, horses’ hooves and tools.
In Scotland, the biggest threat is from Phytophthora ramorum, which affects larch trees and other plants. Other tree diseases that could be spread unwittingly include Chalara dieback of ash and Dothistroma needle blight.
The commission’s Keep it Clean biosecurity campaign aims to help to prevent the spread, particularly after the recent spate of wet weather.
Anna Brown, the commission’s head of tree health, said: “It’s great to know that even in this foul weather there are some hardy souls prepared to venture out and enjoy Scotland’s forests.
“However, they will be faced with some pretty tough conditions. There will be some trails that will be flooded or washed out and others that will in part be very muddy —and that’s why we’re reminding people to ‘keep it clean’.”
Dr Brown added: “There’ll be no avoiding the mud but don’t take it from one place to another.
“All we’re asking is that when people get home, they take the time to make sure that their footwear, bike tyres, kit, shoes and walking poles, even their dog’s paws, are cleaned and mud free before venturing out to another location.
“It’s a small thing to do but it could have a big impact on the health of your local forest or woodland, and those across Scotland.”
Forestry Commission Scotland says that the threat to the country’s trees is rising because of increased global travel, more introduced species and the effects of climate change.
As people travel, so do more species and diseases. They hitch a ride to new environments on the wind, on goods, animals, foods and people.
When they arrive, pests and diseases can spread rapidly and can cause significant problems to the health of trees.
The biggest threat at present is from Phytophthora ramorum, which was first found in Scottish plant nurseries in 2002 and in gardens and parks in 2007, and causes extensive damage and mortality to larch trees and other plants in mainly the wetter west of Scotland.
By the end of 2013, approximately 5,000 to 6,000 hectares of larch was thought to be infected within a core area centred on southwest Scotland.
Chalara dieback of ash is a serious disease of ash trees caused by a fungus called Hymenoscyphus fraxinea. The disease causes leaf loss and crown dieback in affected trees and is usually fatal.
Dothistroma needle blight, caused by the fungus Dothistroma septosporum, is present throughout Scotland, with the greatest impact in the north and northeast. The disease affects a large range of conifers but especially pine. The fungus affects the needles of the infected tree, which eventually shed. This can continue year on year and gradually weaken the tree, significantly reducing timber yields. It can also eventually lead to mortality.