An invasive pathogen causing bleeding cankers on beech tree trunks, necrosis on leaves of rhododendrons, pieris and magnolias, and extensive dieback of bilbery.
Discovery of the disease
While undertaking surveys in the southwest of England in November 2003, the new species Phytophthora kernoviae was discovered concurrently by Forest Research and Food and Environment Research Agency (Fera) scientists at different woodland sites. This organism, previously unknown to science, has now been described and officially named Phytophthora kernoviae, the name being derived from Kernow - the Cornish name for Cornwall.
Details of the pathogen are given in:
Phytophthora kernoviae sp. nov., an invasive pathogen (PDF-258K)
P. kernoviae was isolated initially from the trunk of a large beech tree (>1m diam.) with an aerial bleeding lesion (canker). It was also found infecting the leaves and shoots of Rhododendron ponticum at the same site.
It is now known that P. kernoviae is highly aggressive pathogen which attacks leaves, buds and shoots of understorey woodland rhododendrons and kills the inner bark of beech trees. Two native oak trees (Quercus robur) have also been found with the bark killing bleeding cankers caused by P. kernoviae. However, trees are only placed at risk from this pathogen if growing very close (usually within 0-2m) to a plant generating spores from infected leaves. Invariably, the infected plants that pose the risk to tree in woodlands are bushes of Rhododendron ponticum, growing as an understorey in woods and forests
In addition a number of popular garden ornamentals such as Magnolia and Pieris species are also affected with a leaf and shoot blight.
Most recently, P. kernoviae has been found to be capable of causing extensive damage to bilberry (Vaccinium myrtillus).
Poster describing the impact of p. kernoviae on bilberry (PDF-195K)
A full list of hosts found affected in the UK is given below.
| Common name | Latin name | Family | Symptom expression | Number of affected plants |
|---|---|---|---|---|
| European beech | Fagus sylvatica | Fagaceae | Bleeding canker | 50-1000 |
| English oak | Quercus robur | Fagaceae | Bleeding canker | Five or less |
| Tulip tree | Liriodendron tulipifera | Magnoliaceae | Bleeding canker and leaf necrosis | Single tree |
| Sweet chestnut | Castanea sativa | Fagaceae | Leaf necrosis | Five or less |
| Holm oak | Quercus ilex | Fagaceae | Leaf necrosis | 5-10 |
| Rhododendron | Rhododendron spp. | Ericaceae | Leaf necrosis and stem dieback | Thousands |
| Pieris | Pieris spp. | Ericaceae | Leaf necrosis and shoot dieback | Hundreds |
| Bilberry | Vaccinium myrtillus | Ericaceae | Leaf necrosis | Thousands |
| Magnolia | Magnolia spp. | Magnoliaceae | Leaf spots, bud blast, blossom blight | 10-50 |
| Michelia | Michelia doltsopa | Magnoliaceae | Leaf necrosis | Five or less |
| Drimys | Drimys winterii | Winteraceae | Leaf necrosis | 10-50 |
| Chilean hazelnut | Gevuina avellana | Proteaceae | Leaf necrosis | Single plant |
| Cherry laurel | Prunus laurocerasus | Rosaceae | Leaf necrosis and stem dieback | Five or less |
| Ivy | Hedera helix | Ariliaceae | Stem necrosis | Single plant |
| Podocarpus | Podocarpus salignus | Podocarpaceae | Leaf necrosis and shoot dieback | Five or less |
Further information about Phytophthora kernoviae
Contact
For further information contact:
Dr Joan Webber
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH
Tel: +44 (0) 1420 22255
Fax: +44 (0) 1420 23653
Email: joan.webber@forestry.gsi.gov.uk
or:
Dr Sandra Denman
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH
Tel: +44 (0) 1420 22255
Fax: +44 (0) 1420 23653
Email: sandra.denman@forestry.gsi.gov.uk
