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BIOSECURITY– Protecting our Trees

What is biosecurity?

Biosecurity refers to any measures or precautions that aim to prevent the spread and/or introduction of tree pests, diseases, and invasive non-native species.

Pests and diseases are a natural part of any ecosystem, and in their natural range, plants and animals have evolved to develop a level of tolerance for them. This forms a natural balance.

However, the introduction of new and exotic pests and diseases poses a grave threat to our trees, plants, and crops. This is primarily due to global travel, trade and free movement of goods, which provide potential pathways for pests and diseases to spread from one area, country, or continent to another in a matter of days.


When a new or exotic pathogen (an organism that can cause a disease) is suddenly introduced to an environment or to trees that have not evolved with it, it can have devastating consequences. It can result in economic loss, but more importantly, it can have significant impacts on our natural landscape, biodiversity, and tree collections.

Examples of this include Dutch Elm Disease, which decimated our elm population in the 70s and 80s, and Ash Dieback, a fungus that was likely accidentally imported into Ireland and is now affecting Ash trees.

The Horse Chestnut Tree is also facing significant challenges, as its foliage has been affected by different pathogens, causing damage to this, one of our more common landscape trees. Additionally, the Oak Processionary Moth, which if established, could threaten one of our more iconic trees, the Oak. It is a pathogen we should be on the lookout for. With this particular pathogen, there is also the added threat to human health, as the irritating hairs from the caterpillars can result in skin irritation and allergic reactions.

But all is not lost...

It is important to remember that not all hope is lost when it comes to trees. In any population, there is usually a certain level of tolerance, and some trees can survive even in adverse conditions. Therefore, it's crucial not to cut down trees just because they belong to a particular species, might be prone to disease or might die in the future.


If a tree shows tolerance to a disease, it can be a valuable genetic resource. It's highly recommended to retain such trees wherever possible and safe to do so. These trees can pass on their genetic tolerance when they cross-pollinate with other trees, ensuring a more resilient population of trees for the future.

What can we do?

It is important to be aware of how easily pests and diseases can arrive in the country and spread once here. Biosecurity measures must be taken to prevent the spread of pathogens, pests, and diseases.

These precautions include being cautious when transporting soil, plant material, packaging, or vehicles and being mindful of wind-carrying fungal spores and microorganisms being transferred by rain splash or wet ground conditions.


When purchasing trees, it is recommended to source them from a local nursery that ideally grows them locally. If that is not possible, then trees that have spent at least one growing season in the area can be chosen.


It is important to ensure that the nursery is registered with DAFM (Department of Agriculture, Forestry & the Marine) as a 'Professional Operator', which means they are part of the government's biosecurity program.


And avoid bringing trees or plants home from holidays abroad to prevent the introduction of new pests and diseases into the country.

The Department of Agriculture Food & Marine (DAFM) are responsible for monitoring plant health in Ireland.

If you know of or suspect the presence of an exotic or damaging pest or disease, then you should contact them at:

Or use Tree Check, a web-based App which allows you to report details and send photographs of suspected pests or diseases to DAFM. 

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