‘Unprecedented threat’ for UK trees
- 31st August 2012
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UK trees are facing an “unprecedented level of threat” from pests and diseases, the Forestry Commission has warned.
All species are vulnerable to potential attacks – from ecologically vital oaks to non-native ornamental species, such as lawson cypresses.
The biggest risk, it warns, comes from non-native organisms, which – in their natural range – are kept in check by natural predators and environmental conditions.
However, if they are able to become established in the UK’s natural environment then there are often no natural controls to curb their spread, resulting in a potentially devastating impact on the landscape.
In October 2011, UK Environment Secretary Caroline Spelman launched the Tree Health and Plant Biosecurity Action Plan, warning that millions of trees could be lost in the next few years unless urgent action was taken.
The Commission recently published biosecurity guidance, offering advice on steps that can be taken to avoid accidentally spreading damaging organisms on clothes, footwear, vehicles, etc.
“The fact that we are an island has helped us, because we are fairly impoverished compared with the European mainland,” explained Hugh Evans, head of Forest Research in Wales.
“So even the 20 miles of water is enough to protect us from the pests that are quite dangerous on the mainland.”
But our relative isolation has come at a cost, he warned.
“If pests do get through, then they arrive without the spectrum of natural enemies and that is one element that can make the effect within the arrival country much worse than in the country of origin.”
Richard McIntosh from Food and Environment Research Agency (Fera) says the growing volume of international trade is one reason for concern.
“Trade is becoming increasingly global, and there is an ever-widening diversity of plants and plant material being traded around the world,” he told BBC News.
“There are examples of where pests or pathogens have been introduced, and it is very difficult to respond to them once they are within the EU.
“Prevention is much better than cure but identifying all of the risks is not always the easiest thing to do.”
Probably the most widely publicised pathogen is Phytophthora ramorum, a fungal organism which was suspected of being introduced to these shores via the plant trade. There is no treatment; infected trees have to be felled and removed from the natural environment.
Although it had been present at low levels in the UK for a number of years, in 2009 there was a sudden change in the pathogen’s behaviour. It was recorded infecting and killing the commercially important Japanese larch trees in South-West England.
It was the first time in the world that P. ramorumhad been found on a species of conifer. It has since been recorded affecting larch trees at sites in all four UK nations.
Source: BBC News