Dieback of birch

 

Summary

As a major component of native woodlands throughout Scotland, birch is valued increasingly as a resource for conservation, habitat and landscape purposes. Both silver birch (Betula pendula) and downy birch (B. pubescens) are two of the more important broadleaved species in new native woodland planting and natural regeneration schemes in Scotland, of which 50,000 ha were created during the 1990’s. However, widespread dieback of young birch has been reported recently in at least 20 new native woodland plantations in Scotland.

This project aims to investigate the role of shoot fungi as causal agents of crown dieback of birch. The primary pathogens on birch shoots will be determined, and their distribution and impact on birch evaluated. The project will then investigate the biology and ecology of infection of birch by these fungi and identify factors which may influence the susceptibility of birch to infection.

Research objectives

The main objectives of this project are to:

• Investigate the fungi infecting birch shoots in Scotland
• Identify the primary pathogens
• Determine the impact of these fungi on the national woodland resource
• Establish recommendations for managing the problem.

Surveys were carried out in 2002 at a number of new native woodland schemes in Scotland to describe the fungi colonising young shoots of birch. The pathogenicity of the most frequently occurring fungi was then evaluated on young birch trees in inoculation studies. Two fungal pathogens have now been identified as causal agents of shoot dieback of birch; these are Anisogramma virgultorum and Marssonina betulae.

Current work is focusing on the distribution, impact and long term infection cycles of A. virgultorum and M. betulae at nine new native woodland schemes and six birch provenance trials planted in Scotland. Other studies are also being conducted to investigate the infection biology and life cycles of these two fungi, and to test further the susceptibility of different provenances of silver and downy birch.

Funders and partners

This research is funded by the Forestry Commission Dieback of birch programme.

The Scottish Foresty Trust is funding a 3-year PhD studentship on the distribution, impact and biology of Anisogramma virgultorum. The student, Ms Heike de Silva, commenced this programme in May 2004, and is co-supervised by Dr Steve Woodward at the University of Aberdeen.

Forestry Commission policy

UK forestry policy has two main aims: the sustainable management of existing forests and woods and a steady expansion of woodland area to provide benefits for society and the environment. This project will significantly increase our knowledge of the pathology of an important native broadleaved species and factors leading to dieback, enabling future plantations to be managed more effectively to reduce the impacts of disease.

Status

The programme commenced in 2002 and will be reviewed in 2006.

Contact

Sarah Green
Forest Research
Northern Research Station
Roslin
Midlothian
Scotland EH25 9SY

Tel: +44 (0)131 445 2176
Tel (direct): +44 (0)131 445 6942
Fax: +44 (0)131 445 5124
Email: sarah.green@forestry.gsi.gov.uk