A plant disease caused by a fungus-like pathogen known as Phytophthora ramorum (P.ramorum), has been diagnosed in Oak and Japanese larch.
If this disease can make the spices jump from a hardwood like Oak to the conifer Larch, there is no reason it could not jump to other conifers like Douglas and Spruce. 'IF' that were to happen, it could destroy large areas of the UK's woodland. (Sometimes calledl 'Sudden Oak Death)
The pathogen P. ramorum has potential to attack a wide range of woody plants and could cause significant damage to woodland and other habitat. It can be spread on footwear, vehicle wheels, tools and machinery, by the movement of infected plants and in rain, mists and air currents. The disease has been recently confirmed in Japanese larch woodland in England, Wales and the south of Ireland.
In Europe, including the UK, P. ramorum has been found mainly on container-grown Rhododendron, Viburnum and Camellia plants in nurseries. It was first detected in the UK in 2002, when emergency measures were introduced. The initial measures included destruction of infected plants, a ban on imports of susceptible material from affected areas of the USA, and notification of movements of susceptible nursery stock. These measures were notified to the EU Standing Committee on Plant Health, which agreed EU-wide emergency measures in November 2002, based largely on the UK's action. Those measures are still in place.
In January 2009 the first finding in the wild of P. ramorum on the heathland plant Vaccinium myrtillus (bilberry) was confirmed at a site in Staffordshire. Most recently, in August 2009, the pathogen was identified on Japanese larch trees at sites in Somerset, Devon and Cornwall.
The first indication of the disease on Japanese larch trees, is a visible wilting of young shoots and foliage, or later in the growing season, withered shoot tips with yellowing needles which then become blackened. The infected shoots shed their needles prematurely. Trees may also have bleeding cankers on their upper trunks.
What to do if P. ramorum or P. kernoviae is suspected
Check symptoms carefully and if you suspect disease is present, notify Defra PHSI (or your relevant
Plant Health Authority) immediately. In woodland situations, notify the Forestry Commission (Plant
Health Service). This is a legal requirement. If confirmed, a Statutory Notice will be issued specifying
required actions. In the meantime:
• Cordon off the area concerned and restrict public access.
• Do not handle or move the plants.
• Inspect other susceptible plants for symptoms and keep under review. Include the perimeters
of sites containing trees or likely hosts such as ‘wild’ Rhododendron.
• Do not apply anti-Phytophthora fungicides to plants where infection is suspected.
Such fungicides are likely to suppress but not eradicate the pathogens.
• Restrict or, where practical, avoid the use of overhead watering with plants known or
thought to be infected.
• Provide the authorities concerned with all necessary documentation and records including,
where appropriate, plant passport information.
What to do if P. ramorum or P. kernoviae is confirmed
If either disease is confirmed, a Statutory Notice will be issued detailing the eradication and
containment actions required (see eradication and containment policy at 10.3). Ensure all the
required actions including any stipulated removal and destruction of plant material, containers and
associated soil or growing media are implemented as soon as possible within the timeframe laid
out in the Statutory Notice. The following actions may be specified:
• Removal of plant debris and surrounding leaf litter.
• Prevention/removal of re-growth.
• Excision of infected bark and wood on trees with bleeding cankers.
• Prohibition on the movement of infected plants and use of infected material
(e.g. propagation/foliage display purposes).
• Prohibition on the use of anti-Phytophthora fungicides on any plants held under Statutory
The Notice will also require appropriate measures to be taken to prevent re-infection of the site.
These measures may include:
• Restricting public access (e.g. appropriate signage, cordoning off).
• Not planting susceptible plants within a four metre radius of where infected plants were for a
period of three years or,
• The removal and deep burial of soil.
As you can gather, if this disease takes a real hold in the UK, the results for the countryside, landowners, farmers and people like the NT and Woodland Trusts would be catastrphic and could mean the deforestation of vast areas of the UK's woodland.
More info :- http://www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/phytophthora/pRamorum/
With thanks in part to DARD and DEFRA