A SERIOUS outbreak of disease in larch trees will mean that many hundreds of trees will have to be felled this winter as an emergency method of controlling the spread of the fungus to other varieties such as rhododendron and blueberry.
The disease has now been officially confirmed after it was initially discovered in the plantations close to Ballaugh village, with the Department of Agriculture taking the decision to close Colden plantation and to restrict access to Ballaugh plantation.
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DEFA staff are currently involved in investigations into other suspected sites identified by aerial surveys. The Department has also called a public meeting for next week to discuss the potential threat to the Island’s trees and shrubs. It will be held at the Glen Helen Hotel on Thursday, November 10th at 7.30pm.
The disease is officially known as ‘phytophthora ramorum’ which is also occasionally referred to as ‘Sudden Oak Death’, although this is misleading in the UK as to date native oaks have shown little susceptibility to this disease. However, this has not been the case in the USA where oaks have suffered, hence the name.
Phytophthora ramorum is a fungus-like pathogen which is serious in Japanese larch (Larix kaempferi) trees and rhododendron (Rhododendron ponticum), both of which produce large numbers of infective spores. Larch and rhododendron are widespread throughout the Isle of Man.
It kills larch trees very quickly and is a recent appearance in Britain. The trees produce large quantities of the spores that spread the disease, which can infect a wide range of trees and plant species. The only available disease control treatment is to fell the trees, preferably before the next spore release, which current information indicates occurs in the autumn.
To control the disease, DEFA said in a statement today that it will fell areas within both Ballaugh and Colden plantations, amounting to around 9,000 cubic metres of timber covering an area of 30 hectares (74 acres).
The statement said, “Whilst the Department carries out the necessary sanitation felling of infected areas, the decision has been taken to close Colden Plantation to the public and restrict access to Ballaugh Plantation.
“The Department therefore asks members of the public to respect and observe all site signage and information notices to help prevent the risk of the disease spreading not only to other plantations but also to plants in the uplands and private gardens.”
The outbreak follows similar recent findings in Cumbria and Lancashire, following its original UK discovery in the south west of England, where the disease has caused the premature felling of hundreds of thousands of larch trees.
The outbreak was first suspected during aerial surveys to look for signs of the disease which was undertaken by the Forestry Commission, in conjunction with the UK Food & Environment Research Agency (F.E.R.A).
Experts followed-up with ground inspections and laboratory analysis of samples taken from trees which showed possible symptoms of the disease. Other larch woodland in surrounding areas is being inspected from the ground to check whether the disease is more widely present.
Dr. John Morgan, Head of the Forestry Commission’s Plant Health Service, said, “Overall, the number and area of outbreaks on larch that we are finding this year are down on the previous two years, and most are close to, or contiguous with, previously infected sites. However, these outbreaks in new regions demonstrate that the threat posed by this disease is still serious.
“We are therefore continuing to urge everyone who manages, works in or visits trees and woodland to keep a close watch for signs of the disease, not only in larch trees, but also in other susceptible plants, particularly rhododendron and bilberry. Anyone who suspects they have seen its symptoms should report it without delay.”
Symptoms of the disease vary from species to species, but is in general evident by rapid blackening and wilting of foliage. Detailed information about P. ramorum, and a symptom recognition guide, is available from the Department of Environment, Food and Agriculture.
For further information contact: www.forestry.gov.uk/pramorum.