Skip to main content

Forest floor covered in rhododendron ponticum

Conservation – a fine balance

As the largest land managers in Scotland, we are responsible for managing the national forests and land on behalf of Scottish Ministers. We do this in line with the Scottish Government’s 50-year vision for economically sustainable forestry that conserves and enhances the environment, and that delivers benefits for people and nature.

We are leaders of Sustainable Forest Management in Scotland. Every woodland we manage holds UKWAS certification. This independent industry standard recognises that sometimes, for foresters to be able to do their work, they will need to use plant protection products (PPPs). More commonly known as 'pesticides', these PPPs help land managers – including us – to protect crops and habitats.

Why we use PPPs

As the climate changes, the conditions that support pests – and diseases – improve. So, for the health of our forests now and in the future, it’s vital that we manage these threats as best we can.

The products available to us are all approved for use in Scotland by the UK Health & Safety Executive. They are commonly used in the agricultural sector and in horticulture, as well as in amenity areas and home gardens. Far smaller amounts are used in forestry as well as more targeted application.

We use PPPs to control tree pests like large pine weevil (Hylobius abietis). We also use them in ancient and semi-natural woodlands, such as temperate rainforests, to reduce weed damage from plants like Rhododendron ponticum and Japanese knotweed. They are always used at the recommended quantities and with the techniques set by the UK Health & Safety Executive as being safe.

Protecting our temperate rainforests

We manage significant areas of temperate rainforest and are taking a ‘landscape-scale’ approach to restoring these vulnerable habitats. One of the main challenges we face is dealing with the threat from invasive non-native weed species, such as Rhododendron ponticum, which once established in a woodland reduces the quality and condition of the habitat so that many native species cannot thrive.

Hands wearing blue protective gloves drill into a Rhododendron ponticum stem.

Rhododendron is sometimes removed by hand – but only when the plants are very small seedlings. Once mature, effective control is only possible with herbicides to kill the stump and roots. However, by using techniques like stem treatment we reduce the quantity of PPP’s used and stop unwanted consequences on non-target species – which can happen when less targeted foliar spraying is used.

Without these PPPs we would not be able to save our rainforest from the inevitable expansion and damage caused by a range of weed species.

You can learn more about Rhododendron ponticum: the silent killer of Scotland's rainforest in our blog.

Read the blog

When to use PPPs

Choosing when to use PPPs can be difficult. Overall our aim is to find alternatives to their use where possible or, when their use is necessary, to limit and reduce their use. We take extreme care to minimise any potential environmental impact.

To find the best option for each situation, we take an Integrated Pest Management (IPM) approach that allows us to work through the choices. We use this approach when managing, for example, the tree pest Hylobius abietis (the large pine weevil). This pest is estimated to cause £5 million worth of direct losses across the UK each year. It significantly slows the re-establishment of future forest crops.

About weevil damage

Rows of stumps from felled treesAdult weevils lay their eggs in the stumps and roots of felled trees.

When the young beetles emerge, they feed on seedlings and young trees close to these stumps, damaging or even killing the trees they feed on, including conifers and many native broadleaved species. 

We monitor several pests and diseases. You can learn about these threats to our forests on our pests and diseases page.

Pests and diseases

Finding the best solution

By monitoring weevil populations, we know when an increase in numbers means that we need to act to reduce the impact of weevil damage. Our expertise as professional foresters, combined with both our detailed knowledge of local forest environments and the robust research that underpins the IPMS, allows us to determine the most appropriate solution for the situation.

These options include (in order of preference):

  • Delay replanting the trees to avoid the most damaging part of the weevil life cycle. 
    This avoids the need for PPPs, but it is not always possible or desirable. On some sites, waiting many years before replanting lets weeds take over. These weeds then need to be treated with other PPPs. With a limited amount of available land to grow productive trees on, we need to keep a certain amount of forest cover to meet future timber demand.

  • Using trees that have been pre-treated with insecticide in the nursery. 
    This concentrates the treatment where it is needed.

  • Targeted spraying on site. 
    If at a later stage – and within the first three years of growth – we must treat the tree again, we use a hand-held spray application. This contains the treatment to the individual trees.

Minimising the use of PPPs

As part of our ongoing effort to minimise the use of PPPs, we continue to work with partner land managers across British and Irish public and private sectors to find alternatives. Coillte, Scottish Enterprise, Highlands and Islands Enterprise, the Scottish Government, and the Scottish Funding Council are just some of the partner land managers we work with.

Through continued research, we hope to see the development of innovative, non-chemical and cost-effective ways of reducing the damage caused by pests in a way that could greatly improve the sustainable management of woodlands in Scotland. 

Find out more