Dothistroma Needle Blight (DNB)
Dothistroma Needle Blight (previously referred to as Red Band Needle Blight) is a disease that can be caused by the two fungal pathogens, Dothistroma septosporum and Dothistroma pini. The disease has been present in Great Britain since the 1950s and is now a very significant disease of pine species there. The disease was found in Northern Ireland in 2011 on Corsican pine (Pinus nigra Arn. ssp laricio). The disease is present in most other EU Member States and in many other countries outside the EU (See world map below).
Pine tree species are the primary host of DNB. In Britain, Corsican pine has been the most severely affected pine species but severe damage to lodgepole pine has also been reported. To date Scots pine has been less severely affected in Britain. There are other less susceptible conifer hosts.
In September 2016 DNB was found in Ireland for the first time. It was identified as being present on Scots pine trees at two privately owned (grant aided) forests, one in southwest Limerick and one in northwest Cork. Samples taken from Scots pine trees at the two forests in early August were analysed and laboratory results confirmed the presence of D. septosporum in early September.
Pine trees with DNB shed the previous season’s needles (retaining the current year’s needles). The defoliation of previous season’s needles continues yearly, with the effect of reducing timber yields and weakening the tree which predisposes the forest to increased tree mortality. Generally the disease will only cause mortality where the infections levels are high for successive years.
There can be a significant economic impact on severely infected forests due to this reduction in timber yield.
In the UK where the disease is present in forests there is a policy of managing the pine to minimise infection in existing forests, inter alia by encouraging managers to ensure all pine stands are kept well thinned to facilitate air movement and lower humidity in the canopy and thus reduce the potential inoculum load and the risk of spread within their own forests or to neighbouring forest properties.
In Ireland approximately 10% of the forests are pine, mostly lodgepole pine with the remainder being made up of Scots pine, Monterey pine and Corsican pine. Sitka spruce the most common species in commercial forests in Ireland is deemed to have a low susceptibility to the disease.
Dothistroma septosporum tree disease is listed as a quarantined pest and is regulated under the EU Plant Health Directive - Council Directive 2000/29/EC, which requires Member States to take all necessary measures to eradicate, or where that is impossible, to inhibit the spread of the harmful organism. In accordance with Council Directive 2000/29/EC, Article 16(1), and Implementing Decision 2014/917/EU, Article 2(1), paragraph 1, a preliminary official notification report of the confirmed presence of DNB has been forwarded to the EU Standing Committee on Plants, Animals, Food and Feed.
In the EU, the movement of plants for planting is regulated through the plant passport system. In Ireland therefore there are regular inspections of nurseries each year. The Department will only grant authorisation to issue a plant passport if a place of production and its immediate vicinity is free of the relevant harmful organisms.
- Forests with DNB present: The Forest Service is liaising with the forest owners where DNB has been found and requesting that activities within these forests are suspended until further notice.
- Traceback / traceforward: Given the possibility that plants were supplied with the disease present the Provenance certificates associated with the infected sites are being examined and appropriate trace forward and trace back work is being carried out.
- Holding notices: Pending laboratory results, holding notices to cease the movement of pine species have been issued to those nurseries that supplied the Scots pine plants to the infected forests.
- The Forest Service is surveying for DNB presence within pine forests, focussing initially on pine forests located near the two confirmed DNB forest locations.
- Horticulture and Plant Health Division and the Forest Service are initiating a survey for DNB in pine producing nurseries and in pine forests near pine producing nurseries.
- Policy: Within the context of the requirements of the EU Plant Health Directive, disease management policy will be determined following the outcome of further surveys to confirm the extent of the disease and consultation around best practice in dealing with this disease.
Dothistroma needle blight was previously referred to as red band needle blight because of the red and colourful bands displayed across the infected needles. Trees with severe DNB infection will appear with mostly just the current years foliage intact. Due to the loss of previous season’s needles, a bottle brush appearance to the trees can result. The lower branches closer to the ground are often more affected. For further information on symptoms of the disease and other information the following web pages are recommended:
The national forest estate comprises ca. 732,000 ha. Pine species, primarily lodgepole pine (Pinus contorta) occupy ca 11% of the estate. 1.3 % of the forests estate is Scots pine.
The total standing growing stock of Irish Forests is estimated at ca 97 million cubic metres. Pine species represents almost 11 % of this volume. Scots pine representing 1.1% of the volume of timber in our forests, the remainder is mostly lodgepole pine.
Currently there is very little pine being planted under the Departments forestry grant schemes. Pine species accounted for 1.5% of species grant aided in 2015. Most of this was Scots pine.
Forest owners, forest nursery staff, and members of the public are asked to be vigilant for the disease and report (with photographs, if possible) any sites where there are concerns about possible DNB symptoms in pine, to the Forest Service, Department of Agriculture, Food & the Marine, by e-mail email@example.com or by phoning 01-607 2651.
Nursery stock producers should direct queries to your local Plant Health Inspector immediately. Alternatively, queries can be sent by e-mail to firstname.lastname@example.org, or by contacting the Department’s Offices on 01-505 8885. Reports will be followed up by relevant staff from the Department.
TreeCheck, an All Ireland smartphone App, may also be used to report suspect findings. Using a GPS-enabled smartphone the location of the suspect tree can be recorded by the app to allow a follow-up field visit by Inspectors in the relevant jurisdiction if required. All reports received will be acknowledged and examined and those of particular concern taken forward for follow up by specialist plant health inspectors.
To access the TreeCheck App scan the attached QR with your smart phone or type the address https://www.treecheck.net into your mobile web browser. (It is not available in the App store.) You will be presented with the App and the option to save a link to your home screen. Follow the directions for your phone. Please note if you have a GPS enabled phone you may be asked to “Share Location”. Choosing to share your location enables us to have accurate geo-location data to assist our Inspectors in the event we need to investigate your report further.