Dothistroma needle blight (DNB) is the most recent disease to threaten Irish trees and forests. It was detected for the first time in Northern Ireland in 2011. The disease, also referred to as red band needle blight, was thought to be of minor importance as it seemed to be confined to isolated stands of Corsican pine.

However, it was discovered in the Republic for the first time last September and worryingly was identified by the Forest Service on Scots pine trees in two privately owned forests in counties Limerick and Cork.

DNB is caused by one of two fungal pathogens – Dothistroma septosporum and D. Septosporum. The disease is regulated under the EU Plant Health Directive 2000/29/EC.

“Where the disease is found, member states are required to take measures to eradicate, or where that is impossible, to inhibit the spread of this harmful organism,” said a Department spokesperson.

“The disease is windborne and has a number of potential conifer hosts, many of which are only slightly susceptible, but a number of pine species are known to be particularly prone,” he said. “Until recently the disease was considered to be mainly a problem of the southern hemisphere, especially in plantations of Monterey pine.”

However, since the 1990s a notable expansion in the range of the disease globally has been observed.

In Britain, both Corsican and lodgepole pine have been severely affected, while to date Scots pine has been less severely affected.

Pine trees with DNB shed the previous season’s needles which continues yearly and as a result timber yields are reduced and trees can eventually die.

“Generally the disease will only cause mortality where the infection levels are high for successive years,” according to the spokesperson.

In addition to the existing national forest health surveys, the Department commenced targeted surveys for the presence of DNB in forests with pine close to the infected trees. This was followed by a systematic survey nationally in other selected forests, concentrating on crops where ill-health in pine has been reported.

While the initial actions required of national authorities in relation to a first finding of DNB on their territories are prescribed by the EU Plant Health Directive, longer-term policy and strategies for the management of DNB in Ireland will only be fully determined once targeted and systematic surveys are completed and the likely extent and severity of the disease is known.

Increase in tree diseases a worrying trend since 2010

Ireland’s claim to have the healthiest forests in Europe is under threat as Dothistroma needle blight (DNB) is just the latest disease to threaten the forest resource. Ash dieback, caused by the fungal pathogen Hymenoscyphus fraxineus – previously known as Chalara fraxinea – continues to attack ash trees and woodlands while Phytophthora ramorum is ever present in Japanese larch.

The latest information on ash dieback shows that the disease continues to spread. Early last year, 449 confirmed cases had been reported since the first outbreak in 2012. The disease has been detected in forest, roadside and hedgerow trees throughout Ireland. Up to September 30 last year, findings of the disease have been confirmed in a further 140 forestry plantations, which brings the current total for forestry plantations to 255.

“Taken together, the new findings in 2016 indicate a continual widening of the general geographic distribution of the disease and that the disease is present, to a greater or lesser extent, in all 26 counties in Ireland,” a Department spokesperson said.

As a result of the seriousness of ash dieback and P. ramorum, both ash and Japanese larch are precluded from the afforestation programme. Where both diseases are present, not only are the infected trees felled but the stand or compartment is also clearfelled.

This approach is likely to be reviewed, especially where ash dieback is present on mature or semi-mature crops. While infected trees should be removed and vegetation destroyed, nearby healthy trees should be retained as many of these may grow on to produce hurleys and commercial timber lengths. This practice would also provide valuable information on the timescale of disease spread and the possibility of some trees resisting the disease.

This approach may also be worthwhile in the case of P. ramorum although this disease is further complicated because it spreads to other species. Originally found on Rhododendron (R. Ponticum) in 2009, it spread not only to Japanese larch in 2010 but has also been detected in noble fir, beech and Spanish (or sweet) chestnut growing in close proximity to the infected larch.

We don’t know to what extent the various fungal pathogens might infect other species including Sitka spruce, which “is deemed to have a low susceptibility to the disease,” according to the Department of Agriculture, Food and the Marine.

Consultation around best practice in dealing with the diseases is undertaken with other EU member states’ plant health authorities.

During the past five years, the introduction of three new diseases threatens the future of ash and Japanese larch while Scots and Corsican pine along with noble fir, beech and sweet chestnut have also suffered damage. It is now clear that the EU plant health regulations along with import controls are not working.

Forest protection is now a major issue in Ireland. A spokesperson for the Society of Irish Foresters said the worrying increase of forest diseases underscores the need for a forest research institute before other important tree species are threatened.

Forest owners, nursery staff, and members of the public are asked to be vigilant in relation to disease infection and report (with photographs, if possible) any sites where there are concerns about possible disease symptoms to the Forest Service, Department of Agriculture, Food & the Marine by post, phone (01-607 2651), e-mail (forestprotection@agriculture.gov.ie) or by using the Treecheck App.

IN BRIEF

MINISTER DOYLE ANNOUNCES FIRST TRANCHE OF TAX FREE FOREST PREMIUMS FOR 2017

Andrew Doyle, Minister of State with responsibility for forestry has announced the first tranche of annual tax-free forestry premium payments for 2017. The payments are currently being issued to those forest owners who applied on-line through the Department’s online services portal www.agfood.ie.

“A total of €26.80 million is being paid in this bulk payment run in respect of some 6,900 forest premium applications,” he said. “We will continue to process on-line applications for 2017 forest premiums as they are received, with payments being issued on a weekly basis,” he said.”I would encourage forest owners to avail of the on-line facility because of the obvious benefits for them in terms of early premium payment.” Application forms for the paper based system will issue in February 2017.

Pic of Minister Doyle Minister of State from archives

TEAGASC NATIONWIDE FORESTRY CLINICS

Teagasc nationwide series of Forestry Advisory Clinics are now underway to facilitate as many farmers and other landowners with forests or considering the forestry option. For newcomers, the 2017 Teagasc Forestry Clinics are an ideal opportunity to flesh out the details of how forestry might work for you. If you are already a forest owner, you are also welcome to come along to discuss forest management issues. A one-to-one forestry appointment with a Teagasc forestry adviser will provide private landowners with free, independent and objective advice. Contact your local Teagasc office for further details.