Phytophthora ramorum: Updates, questions and answers

Update:  26 November 2023

Many thanks to all our visitors for your patience and understanding while Woodland Play and the surrounding areas of Middle Wood and Ellesmere Lake have been closed due to a plant disease.
 
Subject to some further minor works, we now have a timetable for when the affected areas should reopen:

• Friday 24 Nov: Ellesmere Lake perimeter walk reopens & Chinese Streamside Garden stream turned back on.
• Friday 1 Dec: Lower Middle Wood walks reopens
• Friday 15 Dec: Woodland Play reopens

Update:  4 October 2023: 

Due to the outbreak of a plant disease, the Woodland Play and the surrounding areas of Middle Wood and Ellesmere Lake are closed to all visitors until further notice. This is a plant pathogen posing no risk to humans or animals.

The disease is caused by the plant pathogen Phytophthora ramorum, which affects woody plants and trees. Because of the risk it poses to gardens and woodlands, the pathogen is regulated and ‘notifiable’, meaning fast action is taken to contain and eradicate it.
 
Led by our curator, Marcus Chilton-Jones, and supported by experts in the RHS Biosecurity and Plant Health teams, the Bridgewater garden team is working hard to minimise the further spread of this plant disease and limit its impact as much as possible to our garden, and heritage plant collections. This includes targeted and careful management of the outbreak in affected areas and monitoring all areas of the garden closely. 
 
We appreciate your understanding and patience. The rest of the garden remains open for all our visitors to enjoy and we will provide an update on access to the closed areas as soon as possible. 
 
For more information, including what you can do to help us manage the outbreak, please see below.
 
If you have any questions, please email [email protected]

Questions and answers

What is Phytophthora ramorum?

• Phytophthora ramorum is a fungus-like organism causing disease on plants
• It damages about 150 different species of trees and shrubs, including rhododendrons, magnolias, camellias, beech, ash and larch
• It can cause cankers on branches and stems, or lesions and dieback of foliage
• It is a ‘notifiable’ disease, as it could cause a significant threat to the environment, so sightings must be reported to the government
• There are no effective chemical treatments available to treat the disease, so it is controlled by removing infected plant material to minimise further spread and damage
• It poses no risk to human or animal health

Where does it come from and how does it spread?

• Phytophthora ramorum was first discovered in the UK in 2002 on an imported Viburnum plant
• It has now been found at hundreds of sites in England and Wales, as well as in Scotland, Northern Ireland and the Channel Islands
• Phytophthora ramorum spores spread via wind-driven rain, meaning plants and trees in wetter parts of the UK, including the North West, are particularly susceptible
• It can also be carried by infected plant material; in soil and compost; on footwear, tools, equipment and vehicle wheels (including bicycle wheels); and via other water sources like rivers and streams

What we’ve done at RHS Garden Bridgewater to manage the outbreak and help control the spread of the disease:

• Tested any plants that are symptomatic
• Removed and burnt (in situ) the main invasive host species for this disease - Rhododendron ponticum
• Protected our plant collection by pruning and raising the canopy of plants that are susceptible to Phytophthora ramorum, making conditions less favourable for infection
• Restricted access to and from areas where plants have tested positive for the disease
• Implemented a strict cleaning and sterilising regime for tools, machinery and footwear used by our garden staff working in these areas

How can you help? 

• Please keep on the main hard paths when you’re walking around the garden (don’t go off the paths or onto the bark pathways)
• Clean footwear and wheels: Before you come into the garden, please brush soil, mud and leaves off your shoes and buggy or wheelchair wheels. To help avoid further spread, clean these items at home before you go into your own garden or into another garden, park, woodland or similar site
• It's more important than ever, not to take any plant material from the garden, i.e. ‘cuttings’, leaves, pinecones, conkers, acorns etc.

How can you identify Phytophthora ramorum?

• You can see photos and further descriptions of the symptoms of Phytophthora ramorum infection on a range of different host plants in this Forest Research document >
• Phytophthora ramorum is classed as a ‘notifiable’ disease. If you spot it in your own garden, please report it immediately to the relevant plant health authority, whose contact details can be found on the UK Plant Health Information Portal >