Phytophthora: destructive parasitic fungi causing brown rot in plants.
Phytophthora are a large goup of pathogens that cause diseases in plants, including many species of tree. The name is derived from Greek and literally means 'plant destroyer' from phyto (plant) and phthora (destroyer).
Videos - the threat to trees, woods and forest plants from Phytophthora ramorum and Phytophthora kernoviae and how their spread can be prevented.
Phytophthora alni is highly specific to alder trees, species commonly found on riverbanks thanks to their preference for cool, damp sites. It was first identified in Britain in 1993, and has been the cause of mortality in many thousands of alder trees throughout England, Scotland and Wales.
Phytophthora austrocedri is a rare form of phytophthora that was in 2011 confirmed by Forest Research scientists as the cause of dieback and mortality in juniper bushes in the Moor House - Upper Teesdale Natural Nature Reserve in the North Pennines of England. It had previously mostly only been associated with decline of Chilean cedars (Austrocedrus chilensis) in the Patagonia region of Chile and Argentina.
Phytophthora kernoviae is a more recent discovery that so far has only been found in Britain, Ireland and New Zealand. It has been found to cause damage to some tree species, including beech and pedunculate or 'English' oak (Quercus robur), although so far it has affected very few trees in Britain.
Phytophthora lateralis was first identified in Great Britain in 2010. It particularly affects Lawson cypress trees (Chamaecyparis lawsoniana), and kills most of those that it infects. It is the main cause of mortality in Lawson cypress in its native range in south-western Oregon and north-western California.
Phytophthora ramorum has caused extensive damage to native trees and plants in parts of the USA. It has also been found in European countries, including the United Kingdom, but mostly on plants and shrubs such as rhododendron and bilberry. Few trees in Britain were affected until 2009, when it was found infecting, and sporulating (producing reproductive spores) on, large numbers of Japanese larch trees in South West England, and in 2010 on Japanese larches in Wales, Northern Ireland and Scotland.