Tree pests and diseases - Lake District National Park

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Author: Olivia Wass, Woodlands Officer at Lake District National Park

Overview

Tree pests and diseases are growing concerns and threaten a significant number of trees nationally, including in the Lake District National Park, resulting in the decline of key tree species, disruption to woodland habitats, and visible changes to the natural and cultural landscape. Introduced from overseas, many pests and diseases spread rapidly and unpredictably – a threat likely to be exacerbated by the effects of climate change. Building woodland resilience through diverse planting and taking steps to prevent the spread are now more important than ever – with everyone, from land managers to visitors, playing a role in reducing the transmission of harmful pests and diseases.

What can we do to prevent the spread?

The Lake District National Park Authority is committed to promoting best practices in biosecurity and tree disease management by:

Staying informed with latest pest and disease developments
Reporting sightings of pests and diseases to Forestry Commission via Tree Alert
Encouraging best practice biosecurity practices for staff and visitors, such as cleaning boots and tools before and after visits – for more details, visit GOV.UK
Conducting regular survey inspections to monitor tree safety across all our car parks and woodland sites
Sourcing trees for planting from local, disease-free areas
Responding promptly to Statutory Plant Health Notices

By following these practices, we aim to safeguard the long-term resilience of Lake District’s woodlands for future generations.

Current threats

Ash Dieback

Ash dieback, also known as Chalara, represents a major challenge to the management of our woodlands in the Lake District National Park. We have important ash woodlands as well as significant numbers of individual ash trees in our farmed landscapes.

As part of our efforts to manage ash dieback and safeguard ash trees and woodlands within the National Park, we are actively monitoring affected areas. Trees displaying signs of severe stress may need to be felled to reduce risks. However, trees with no symptoms or only mild symptoms will be left in place and carefully monitored to assess their ongoing health.

Learn more about Chalara ash dieback in the UK.

Phytophtora Ramorum

While ash dieback has received significant attention, it is only one of many challenges currently threatening the health of our trees and woodlands. Phytophthora ramorum, commonly known as ‘larch disease’, has already affected several larch plantations within the Lake District National Park. It infects bark and foliage causing wilt, blackened needles and needle drop. This infection can lead to the gradual death of branches and needles of infected trees. Where outbreaks occur, Forestry England may issue a Statutory Plant Health Notice (SPHN), requiring landowners by law to fell and remove affected trees to help contain the disease and reduce the risk of further spread.

P. ramorum affects a wide range of plant species, with larch trees being particularly vulnerable and heavily impacted in some of our woodlands. Rhododendron, also highly susceptible, can contribute to the spread of the disease – providing another important reason to eradicate it from our sites.

Phytophthora Pluvialis

Building on these concerns, Phytophthora pluvialis is another emerging tree disease now identified across Cumbria – first discovered in Oregon in 2013 and later detected in Cornwall in 2021. Although its symptoms are not dissimilar to those of P. ramorum, P. pluvialis primarily affects Douglas fir and Western hemlock in the UK. Infected trees may exhibit lesions on stems, branches, and roots, needle cast (where needles turn brown and fall off) and shoot dieback. We are monitoring its development across the landscape as we work to understand and manage its potential impact.

Useful links

Advice to people using our woodlands can change quickly. Please look at the following websites for the best information: