Impact of Phytophthora diseases on trees

 

Summary

Phytophthora (Greek for ‘plant destroyer’) is one of the world’s most destructive genera of plant pathogens.  Probably the most notorious species of the genus is Phytophthora infestans, which causes a disease known as 'late blight of potatoes' that contributed to the potato famine in Ireland in the mid 1800’s.  Since the early 1990’s the profile of Phytophthoras in forests and natural ecosystems has risen markedly in Europe and diseases such as Phytophthora disease of alder and oak decline in the Iberian peninsula are now widespread and highly damaging in some countries.

Currently, the Phytophthora research programme is focussed on assessing the impact of two introduced, invasive Phytophthora species, P. ramorum and P. kernoviae, which were first discovered affecting trees in the UK in 2003. P. ramorum is also probably better known as the cause of Sudden Oak Death in the USA. 

Both P. ramorum and P. kernoviae have been found in woodlands and garden-parks in the south west of England, mainly infecting ornamental species such as rhododendron but also causing lethal stem cankers on a range of broadleaved tree species - most commonly beech (Fagus sylvatica) and red oak (Quercus rubra).  Both pathogens are subject to control measures intended to eradicate or contain disease outbreaks found in the natural environment, thus our research is aimed at gaining a better understanding of the biology of these Phytophthoras to improve the effectiveness of disease management and eradication.

Major research objectives

• Determine the extent and the severity of Phytophthora ramorum and P. kernoviae on trees in Britain.
• Through laboratory experiments, assess the susceptibility of woodland and ornamental tree species to P. ramorum and P. kernoviae, and therefore the potential risk these pathogens pose to our trees and woodlands.
• Obtain field data on the infection process and development of disease caused by these pathogens in relation to key variables (e.g. host availability, inoculum production and local climate).
• Determine how both pathogens spread in natural and semi-natural environments.
• Increase our understanding of the biology of P. ramorum and P. kernoviae to aid management decisions on containment and eradication.

Funders and partners

This research is funded by the Forestry Commission Phytophthora ramorum and P. kernoviae Programme, Defra and under the EU FP6 Project - Risk Analysis for Phytophthora ramorum (RAPRA).

Further information

Forestry Commission publications

Further information on Phytophthora diseases can be found in various Forestry Commission publications including:

• Phytophthora Pathogens of Trees: Their Rising Profile ^{(PDF - 2906K)}
  Forestry Commission Information Note 30.
• Phytophthora Disease of Alder ^{(PDF - 1350K)}
  Forestry Commission Information Note 6 (revised).
• Progress in Research on Phytophthora Diseases of Forest Trees
  Forest Research – IUFRO publication.

Forestry Commission pest and diseases pages

• Phytophthora kernoviae
• Phytophthora ramorum

Status

Research on Phytophthora diseases of trees has been a key part of the work of Forest Research for many years. The programme on Phytophthora ramorum and P. kernoviae started in 2003 and is on-going.

Contact

Dr Joan Webber
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH

Tel: 01420 22255
Tel direct: 01420 526246
Fax: 01420 23653
Email: joan.webber@forestry.gsi.gov.uk