Over 100,000 trees will have to be felled to curb the spread of a virulent disease through forests on the Antrim Plateau.
Forest Service has confirmed that it will cost an estimated £12,000 to fell around 40,000 immature Japanese larch and 63,000 mature trees after an outbreak of the aggressive fungus Phytophthora ramorum in three forests.
The disease may have been present this time last year but it was only after extensive defoliation this summer that samples were taken and disease confirmed.
Phytophthora ramorum is the same pathogen that causes Sudden Oak Death in the USA and has sparked 34 outbreaks in Northern Ireland in species such as cotoneaster and rhododendron — but this is the first time it has appeared in Japanese larch in Northern Ireland.
Forest Service has embarked on a major tree felling programme to eradicate the disease in 200 hectares of woodland at Ballyboley and Woodburn Forests — 8% of the Japanese larch crop in Northern Ireland and 0.3% of the total Forest Service plantation.
Co Antrim landowner Lord Rathcavan revealed that it has cost £35,000 to fell a three hectare 65-year-old larch wood after he found the trees were infected.
The Broughshane landowner said the disease was well established in nearby Forest Service plantations at Ballyboley and could only have reached such levels as a result of being allowed to go unchecked for at least a year.
“I am profoundly concerned that the PR disease has been allowed to take hold in Northern Ireland Forest Service managed woodlands,” he said.
“I regrettably have had to fell the larch wood and burn the tops, branches and bark as advised by the GB Forestry Commission but one can’t expect this to contain the disease when only seven miles away the NIFS woods are allowed to go untreated.”
Stuart Morwood, of Forest Service, said 13% of the forestry in Ballyboley and Woodburn forests will have to be felled over winter.
“We were aware of defoliation in these areas towards late summer and early autumn last year. It was inspected at that stage, but there could have been a variety of reasons to account for that, which would have included weather and site conditions and endemic pathogens of larch,” he said.
“It wasn’t until early summer this year when the defoliation became quite severe and we had reports from other areas that we were aware this was a problem that was not easily explained by these factors.
“We set in progress a programme of sampling and having molecular and isolation tests done on the samples. At the minute we are focusing on the outbreak areas and the immediate surroundings and we will do all we can to minimise the spread.”
Japanese larch is a commercial crop supplying the stake and fencing market.
While the 40,000 immature trees have been written off, around 63,000 infected mature trees will be processed under stringent biosecurity measures. That timber will require a movement licence to be transferred from the plantation to the mill.
Any bark that remains after processing will be destroyed.
Forest Service is appealing to visitors using Ballyboley and Woodburn Forests to stay on roads, not bring forest material home and clean anything in contact with the forest before visiting any other forests.
There were 34 previous outbreaks of Phytophthora ramorum in Northern Ireland before, many affecting rhododendron. All were brought under control.