An invasive pathogen causing bleeding cankers on beech tree trunks and necrosis on leaves of rhododendrons, pieris and magnolias in the UK.
Discovery of the disease
Whlie undertaking surveys in the southwest of England in November 2003, Phytophthora kernoviae sp. nov. was discovered concurrently by Forest Research and Central Science Laboratory 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 old 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) [Photo 1]. It was also found infecting the leaves and shoots of Rhododendron ponticum at the same site [Photo 2].
Photo 1
First beech tree discovered with P. kernoviae bleeding canker,
Cornwall, UK, 13 Nov 2003
Photo 2
First Rhododendron ponticum leaf positive for P. kernoviae,
Cornwall, UK, 13 Nov 2003
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. In addition a number of popular garden ornamentals such as Magnolia and Pieris species are also affected with a leaf and shoot blight. 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 | Between 50-100 |
| English oak | Quercus robur | Fagaceae | Bleeding canker | Five or less |
| Holm oak | Quercus ilex | Fagaceae | Leaf necrosis | Five or less |
| Tulip tree | Liriodendron tulipifera | Magnoliaceae | Bleeding canker and leaf necrosis | Single plant |
| Rhododendron | Rhododendron spp. | Ericaceae | Leaf necrosis and stem dieback | More than 1,000 |
| Pieris | Pieris spp. | Ericaceae | Leaf necrosis and stem dieback | More than 100 |
| Bilberry | Vaccinium myrtillus | Ericace | Leaf necrosis | Between 5-10 |
| Magnolia | Magnolia spp. | Magnoliaceae | Leaf spots, bud blast, blossom blight | Between 10-50 |
| Michelia | Michelia doltsopa | Magnoliaceae | Leaf necrosis | Five or less |
| Drimys | Drimys winterii | Winteraceae | Leaf necrosis | Between 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 |
| Holly | Ilex aquifolium ‘Variegata’ | Aquifoliaceae | Leaf necrosis | Single plant |
| Podocarpus | Podocarpus salignus | Podocarpaceae | Leaf necrosis and shoot tip dieback | Single plant |
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
