A RAMPANT disease that has devastated North America's oak trees is now threatening to spread through Scotland.
When Sudden Oak Death strikes it can kill within weeks. Cankers develop on oak trees and they appear to "bleed" to death as red sap spills down their trunks.
Already thousands of oaks in the United States have died and there are now fears Sco
tland's plants and trees are under threat, after the disease was discovered in a public garden for the first time.
Although no trees have yet been infected in Scotland, rhododendrons, viburnums and other shrub species have fallen victim.
The fungus, Phytophthora ramorum, could be spread on the shoes of visitors to public gardens, and eventually find its way into the wild.
Now the Royal Botanic Garden Edinburgh has put footbaths at the entrances of its four gardens in Scotland, so that visitors can clean their shoes before entering.
Dr Stephan Helser, senior plant pathologist at the Royal Botanic Gardens Edinburgh, said: "It is a disease that has come from the United States and has caused a very widespread death of oak there.
"It seems to be a pathogen that affects a range of different hosts. In Europe it has mainly affected plants like rhododendron and conifers such as yew trees.
"It seems to have a mechanism of attack which is broad so it attacks a wide range of shrubby plants.
"I think it lives on common plant substances and produces a reaction in the plant."
The disease first struck in the south of England about five years ago after arriving from the US, and has since arrived in Scotland.
The first case was recorded in Arduaine Garden in Argyll in October and soon after it was identified in Inverewe in the Highlands.
So far the disease has been kept under control but as the summer months arrive the risk increases as more visitors start flocking to public gardens.
Dr Helser said: "We decided when it had been discovered in the public gardens that it was time for us to put in some measure of hopefully controlling the fungus coming in. That's our main aim.
"We don't want to be alarmist of course and we don't want to discourage people from coming to see the gardens, but we also want to be prudent in making sure it doesn't come in."
Dr Helser said he hoped the tactics would work.
"I don't know whether it will be effective.
"If people dig with their hands in the soil and then come here and dig with their hands, then the footbath will be totally ineffective."
When the disease has been found, infected plants are removed and an area 3km around each site is monitored to make sure it is eradicated.
Sarah Cuthbert-Kerr, spokeswoman for National Trust Scotland, said so far the disease has been kept under control in the infected gardens.
But she added: "It's a potentially devastating disease. I don't think that's overstating it.
"Having it in public gardens is one issue but one of the main reasons people are working so hard to keep it under control is to stop if from getting into the wild."
