Published: 21 June 2012
Phytophthora ramorum
We have seen and heard in the media that the countryside, and our gardens are once again under threat from all sorts dangers of both manmade and natural causes.


A hillside in California devastated by the disease.
At present a disease called Phytophthora ramorum is spreading across the UK and is causing major damage to both commercial crops and ornamental species.
The high level of concern has prompted The Food and Environment Research Agency [FERA] to raise the awareness, and seriousness of this latest outbreak to as wide an audience as possible.
Everyone who spends time out in the countryside, visiting open gardens or working in their gardens can play their part in helping to monitor the spread of this highly contagious pathogen.

What is it?

This is a fungus like organism that causes the disease. All stages of the pathogens life cycle are of concern including the active reproductive stages and the relatively long lived spores that can survive in the soil and plant debris. The longevity of viable spores could also lead to greater genetic variability as time goes on.


Where it can be found

The disease has been found in historic gardens, public parks, woodland and heathland environments, plant nurseries and garden centres. The symptoms appearing mainly on shrubs such as Rhododendron, Camellias and Viburnum while the trees showing symptoms include Beech, Horse chestnut, Larch and Magnolia. This list indicates those species known at present, it is feared more plant types will also succumb.


Infection at a site in the UK. Image Credit: Henry Nicholls: Stopping the Rot. PLoS Biol 2/7/2004: e213

What are the symptoms?

These vary slightly between plant groups.  Shrubs can show blackening of leaves around the midrib and the tips and/or wilting and dieback of their younger shoots. Trees can show black lesions on the bark which can ‘bleed’ black sap. Heathland plants can suffer severe dieback of the entire plant.


How does it spread?

The microscopic spores produced on infected plants are spread in water splashing onto uninfected leaves and in surface water runoff caused by rain or irrigation. Also on any soil picked up on footwear or the feet of animals walking through infected areas. Taking cuttings or moving infected plants and infected material is also a method of spreading the disease to new areas.

We can all help to reduce the risk of spreading this disease by following good practice every time we are involved in the outdoor environment. The Food and Environment Research Agency are encouraging us all to follow these guidelines –


Monitor the health of the plants in your garden, familiarise yourself with the symptoms of Phytophthora and report any suspected findings. See contact information below.
Avoid propagation from any infected plants and do not introduce infected material into your own garden.
Keep to marked paths to reduce the risk of picking up contaminated soil and plant debris on your footwear
Pay attention to any site information notices informing us of contaminated areas
Clean footwear by removing soil and plant debris after each visit
Clean the tyres of vehicles, including bikes after off road trips

What can be done?

Visit the Food and Environment Research Agency website to see more images of the disease and further details of those plants being affected by Phytophthora. 
If you suspect any outbreak you can report the details to FERA via their website (linked below) , emailing:  or  calling 01904 465 625.  It would be helpful to pass on the details of the infected location and possible email a photograph of the infected plants. It is important not to touch the suspect plants or send samples of infected material as this could inadvertently cause the disease to spread further.
We can all play our part in reducing the spread of pests and diseases, The Gardening will keep readers up to date with developments relating to this particular disease plus any recommendations we can take to strengthen our bio-security at all levels.
Reported by Chris Allen  

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