National Plant Health Week special – Protecting Scotland’s trees and forests

Scottish Forestry wants to see Scotland’s forests and trees flourish. 

As part of that vision, we aim to minimise the spread or impact, where possible of significant tree pests and diseases and to search for new tree health issues so that they can ideally be eradicated before they become a problem.

What are we already dealing with? 

There are plenty of existing organisms affecting tree health across Scotland. 

Some for example, ash dieback, we can look out for and report trees that appear tolerant. 

Another example is Dutch elm disease (discussed in our recent blog ‘Working to protect the elms’).

For some pests and diseases we can influence their impacts.

Our annual aerial surveillance programme spots symptoms of Phytophthora ramorum (a pathogen carried in water seriously damaging to larch and many other trees) and Dendroctonus micans (a beetle that can attack and kill spruce trees).

Quickly spotting symptoms of P. ramorum in larch and rapidly removing affected trees reduces the likelihood of wet weather spreading the disease to other nearby larch. With D. micans, there is a specific beetle predator, Rhizophagus grandis (Forest Research website).

The earlier we find outbreaks of the beetle the sooner Forest Research can release R. grandis reducing local populations and levels of tree damage.

We want to avoid new tree pests and diseases becoming established in Scotland and look for signs of them in various ways and collaborations.

Following up aerial surveillance data and TreeAlert reports, we undertake surveys for potential exotic pest and activity.

There are also a wide range of insect trapping networks at ports and processing sites (managed on our behalf by Forestry Commission), annual insect trapping in both broadleaf and coniferous woodlands around the country in collaboration with Forest Research, and a network of insect traps (also managed on our behalf by Forestry Commission) targeting the serious bark beetle Ips typographus and a close relative in pine and spruce forests across Scotland.

Because two Ips typographus were caught in traps near Grangemouth in 2023, we also installed a network of traps around that area (and positively, there has been no evidence of a breeding population).

We are also looking specifically within our pine forests supplementing surveys already undertaken for Dothistroma needle blight, developing a surveillance and sampling regime for other potential and existing pests and diseases of pines (including Curreya pitiophila) this year, expanding further in 2026.

Phytophthora threats are also in our sights, and beyond site surveillance (often in collaboration with Horticulture and Marketing Unit inspectors), we will be looking for new and existing species from DNA samples from forest soil and floating water bait “traps”. This evidence will help target future ground surveillance.

We could not achieve these results without the outstanding work from our own contractors, Forest Research scientists and Field Data Services, and the watchful eyes of Tree Health Champions in Scottish Forestry and Forest and Land Scotland, and numerous other groups such as Observatree volunteers.

Woodland owners or managers

Follow Forest Research’s Biosecurity Action Plan. Research into pests and diseases and their symptoms that could affect your location’s tree species, and consider and manage potential pathways for new pests and diseases arriving at your site.

Forestry and arboricultural workers

Familiarise yourself with tree pests and disease symptoms you might come across on the tree species you work with (there are great visual resources online such as Observatree and Forest Research), and report if you find any symptoms.

If working on an obviously unhealthy tree, make sure you undertake simple biosecurity measures on your equipment before proceeding to work on healthy trees (many tree diseases can be accidentally introduced through contaminated equipment).

Everyone can help

You can all undertake some simple personal biosecurity measures measures before visiting woodlands – if the soles of your boots or shoes are visually clean, you are unlikely to be bringing hitch-hiking tree pests and diseases or Invasive non-native plants (GB non-native species secretariat website) or invertebrates with you.