Plant disease in the New Forest

A further outbreak of the fungus-like plant disease Phytophthora ramorum has been confirmed on the Tall Trees Trail in the New Forest.

The infected Rhododendron plant was found during ongoing monitoring of the area by Fera (Food and Environment Research Agency), a few hundred metres from the initial infection site found earlier this year.

Phytophthora ramorum got its nickname ‘sudden oak death’ because it has killed significant numbers of tanoaks and native American oaks in America, which are not a true oak species at all.  However, Britain's two native oak species, sessile and pedunculate oak (Quercus petraea and Q. robur) have proved much less susceptible than their American cousins. British native oaks only become infected if they are standing very close to heavily infected shrubs such as Rhododendron ponticum. There is evidence that other species, suck as beech and Douglas Fir, are more susceptible. Therefore, minimising the risk of the infection spreading into the New Forests’s trees is a priority.

The infected plant will be cut and burned on-site, along with those Rhododendron bushes in close proximity. This will be followed by clearance of a buffer zone around the area (on advice from Fera). Only Rhododendron species are currently being cleared.

Rhododendron is the primary host for P. ramorum. By removing infected and non-infected Rhododendron bushes, the build-up of spores of the disease and the potential risk to trees of being infected are minimised.

P. ramorum produces a resting spore which can lie for years in leaf litter so it is unsurprising that further infection has been found following outbreaks earlier in the year. It is important to have a robust monitoring programme, which is currently in place, as removing the primary host reduces the potential for further infection.

The affected section of the waymarked ‘Tall Trees Trail’ will be closed off to the public and a diversion put in place, so that visitors can still enjoy a circular walk in the Rhinefield Drive area.  This may need to be in place for several months and therefore Forestry Commissionwe appeal to the public to help us in tackling this disease by observing diversion notices and keeping themselves and dogs away from the infected areas.

For media enquiries, please contact Libby Burke, Forestry Commission New Forest Communications Manager, tel 023 8028 3141.