Forestry Commission Scotland’s annual early summer tree health aerial surveys have detected new outbreaks of ramorum blight at 24 sites across Scotland. Although the majority of new findings are near sites of previously known infections, seven sites are in Angus and Perthshire – an area out-with the most suitable climatic area for this disease – and some are over 10km away from known existing infections. All appear to be highly localised in extent.
Ramorum blight is caused by the fungus-like pathogen Phytophthora ramorum. It infects rhododendron and viburnum and causes Sudden Oak Death disease in oaks. It also affects larch and the FCS have a programme of monitoring the spread. Infected trees outside a management zone in Dumfries and Galloway must be felled and there are restrictions on the movement of timber within the zone. Symptoms of the disease on larch trees include dieback of the tree’s crown and branches, and a distinctive yellowing or ginger colour beneath the bark.
“Our helicopter surveillance & monitoring programme has ensured early detection and action is already underway via statutory measures.
“Furthermore, our system for managing disease outbreaks, including handling of statutory measures and impact arising from increased harvesting of infected trees, is well embedded and understood by the sector.
The recent detections might be an early indication that the wet and windy conditions experienced during summer/early autumn 2015 might have led to a jump of the disease into areas normally less favourable for ramorum blight. Further aerial surveillance currently underway will help to determine whether there is a new trend of spread rather than the sort of isolated occurrences previously seen.
The detection of P.ramorum in lower risk areas also highlights the importance of all woodland owners remaining vigilant and implementing the good biosecurity practices recommended in Forestry Commission Scotland’s Keep it Clean campaign.
“For the health of our woodlands and forests, it is important to help prevent the spread of tree pests and diseases, and that means that everyone adopts good biosecurity practice.