Phytophthora: destructive parasitic fungi causing brown rot in plants.
There are currently two phytophthoras causing concerns over their possible impact on trees in Britain.
Phytophthora ramorum has caused extensive damage to trees and native plants in parts of the USA. It has also been found in a number of European countries, mostly on plants and shrubs. The first case in trees in Britain, in a Southern Red Oak in Sussex, was confirmed in November 2003 and further cases were confirmed weeks later in trees in the south west of England.
Phytophthora kernoviae is a more recent discovery. So far it has only been found in Britain and only in a very few cases on trees. It has been found to cause damage to a number of trees species including beech and English oak.
This research information note outlines the biology and ecology of the Phytophthora pathogen.
BEST PRACTICE NOTE NUMBER 01 (Revised December 2006)
Scope
To advise on best practice when forestry operations are taking place in woodlands which have been confirmed as having either Phytophthora ramorum and/or P. kernoviae. Best practice should incorporate general hygiene precautions and applies to not only to minimising the spread of either of these two pathogens but also any other potentially damaging pests and diseases.
.
Background
Phytophthora ramorum is a fungus-like pathogen, which has been identified as the causal agent for the condition known in the USA as Sudden Oak Death. The first evidence of it in Britain was found during April 2002 on a viburnum but since then it has been found mainly on rhododendrons in nurseries and garden centres. In November 2003 the first evidence of an established tree having the disease was confirmed in Sussex. Further infections were subsequently confirmed on trees in historic gardens in Cornwall. To date (December 2006) a total of 62 trees in Britain have been recorded as infected by P ramorum (44 with leaf infection and 18 with inner bark infection). Rhododendrons were present on all of these sites.
During the latter part of 2004, a second and previously unknown Phytophthora, now formally named P. kernoviae, was discovered in Cornwall, affecting rhododendron and some trees. A Management Zone was set up to contain the disease and this is defined in the Plant Health (Phytophthora kernoviią Management Zone) (England) Order 2004.
ąPrior to formal naming, Phytophthora kernoviae was referred to both as P. kernoivii and P. Taxon C
A smaller outbreak in South Wales is subject to containment and eradication measures and an infected nursery was also identified in Cheshire although this outbreak was eradicated. During 2005 as a result of intensive surveys by Plant Health & Seed Inspectorate (PHSI) of Defra further outbreaks of both P ramorum and P. kernoviae, were discovered in Cornwall. In 2006 P. kernoviae was found on a single 150-year old Rhododendron ponticum in a historic garden in Cumbria. The infected rhododendron has now been destroyed. To date (December 2006) a total of 79 trees have been recorded as being Infected with P kernoviae ( 17 with leaf infection, 57 with bleeding canker), all in Cornwall. Rhododendrons were also present on all of these sites.
These are potentially very damaging diseases to the trees and shrubs in Britain with serious commercial and landscape consequences. Defra, SEERAD, NAWAD and the Forestry Commission are operating a strategy to control the spread of these diseases and prevent them becoming a common occurrence in Britain. Scientific evidence suggests that rhododendron acts as a reservoir for the disease to move into trees. Therefore the Plant Health Service is recommending that the following best practice when working with or woodlands with infected rhododendron.
Best Practice
1. All staff should be made aware of this best practice note
2. Any operator, who during the course of any forest operation, comes into
contact with infected rhododendron should ensure:
that before leaving the site, footwear, tools, equipment, plant and machinery are free from any soil and plant debris. As this is common practice when moving machinery from site to site via main roads it is suggested this is extended to all movement of plant, machinery tools and equipment within the forest boundary. This should be achieved by simple brushing to remove as much soil and plant debris as is reasonably practicable.
in areas where either P ramorum or P kernoviae is detected, measures will be imposed by the serving of a Statutory Notice and these will include, in addition to the above measures, disinfecting with an appropriate fungicide.
.
Review
The content of this Best Practice Note will be kept under review and will be
updated as necessary in the light of new information about the pathogen and the way that it may be spread.
Further Information
For further in formation on this Best Practice note and P ramorum please contact:
Dave Tracy - 01546 602832 - Operations Support Officer
Roddie Burgess - 0131 314 6401 Head of Plant Health Service
