First found in Scottish plant nurseries in 2002 and in gardens/parks in 2007, Phytophthora ramorum (‘Ramorum’) is causing extensive damage and mortality to larch trees and other plants in (mainly) the wetter west of Scotland.
In 2010, it was found on Japanese larch at a site on the Craignish peninsula in western Scotland. In 2011, further sites of infection were detected on Mull and at several locations in Dumfries and Galloway.
Since then the disease has spread to a number of new, relatively localised sites with the exception of south west Scotland where particularly favourable weather conditions in 2012 led to a major surge in the scale and intensity of infection resulting in the designation of a Management Zone (see below).
In Great Britain, three larch risk zones (PDF 1.65MB) have been identified, with Zone 1 being at the greatest risk of infection and Zone 3 at least risk.
By the end of 2013, approximately 5000-6000 hectares of larch was thought to be infected within a core area – now designated as the 'Management Zone' – centred on south west Scotland.
Outside this core area, sporadic infections have continued to occur, each of which has been served with Statutory Plant Health Notices (SPHNs) requiring the felling of infected larch stands as well as all larch in a buffer area around them.
Relatively low numbers of new infections were found in the period from 2014 to 2017, with outliers being detected and dealt with mainly in areas across the West of Scotland.
The 2018 aerial surveillance programme and follow up field surveys have confirmed a significant increase in the number of areas of larch containing trees infected with Phytophthora ramorum. These recently symptomatic trees are largely in areas where infection has been confirmed before - Dumfriesshire & Ayrshire. It is likely that the favourable, damp conditions experienced in these areas during the summer to autumn 2017 period is the main driver for the observed increase in infections.
These new areas are on a scale that makes it impossible to fell all of the infected trees this year, so priority is being given to dealing with infections occurring furthest from the ‘P. ramorum Management zone’ in SW Scotland. Newly infected areas within 10km of the edge of the P. ramorum management zone will still be dealt with, but some may not be felled until 2019.
This policy will be reviewed once further aerial surveys are completed in late August and early September 2018.
The Phytopthora Ramorum map update (updated 9 December 2019) shows the disease's progression and is regularly updated.
Ramorum (on larch) action plan for Scotland (PDF 887KB), last updated in 2017.
Visiting woodlands in Scotland
The countryside remains very much open for visitors. Access to woodlands in Scotland is only likely to be restricted for safety reasons, such as at sites where active felling operations are underway. However, to help us limit the spread of the disease we need your help.
The most important thing you can do is clean up. Before visiting any forest, anywhere, just make sure you’ve cleaned your shoes, your bike and your dog. This will minimise the risk of introducing or spreading pests and diseases.
Remember: dirt carried on footwear, wheels and animals can spread tree diseases from one place to another.
Together we can help control the spread of forest diseases. To find out more, visit Keep it clean.