Research in our Spotlight on the Forestry Market indicates that there were only two new cases in the 1980s and 1990s, which increased to seven in the 2000s and 11 in the 2010s.
In recent decades, new tree pests and diseases have increased in the UK.
New threats to UK forestry continue to emerge; however, five significant threats have been prevented from reaching the UK. National biosecurity measures are helping to control imports and safeguard the UK's forests.
1. Pine processionary moth
The risk from pine processionary moth is more to people than trees. Trees will suffer from repeated defoliation, weakening them and making them more prone to other pests and diseases. Humans are at risk of a bad reaction from exposure to the irritating hairs of the moth larvae. Just as oak processionary moth has done, this could compromise the social value offered by woodland.
2. Emerald ash borer
The larvae of the emerald ash borer bore into the bark of the ash tree, disrupting the tree's ability to transport water and nutrients, which can lead to the tree's death. This pest has killed billions of ash trees in the United States. Imports of ash wood and wood products, including firewood, are regulated to prevent the introduction of the emerald ash borer into the UK. Stronger import controls to countries within 100km of confirmed outbreak areas were introduced in 2020. Even if the introduction of the emerald ash borer is avoided, ash faces a tough future in the face of the continuing prevalence of ash dieback, which was first confirmed in the UK in 2012.
3. Asian longhorn beetle
The Asian longhorn beetle is known to damage trees such as maple, birch, and oak. The larvae bore into the wood of living trees, creating tunnels that can eventually kill the tree. In 2012, an outbreak of this beetle was discovered in Kent, leading to the felling of over 2,000 trees but eradicating the outbreak. Legislation now requires the monitoring of wooden packaging material from China to reduce the risk of entry.
4. Plane wilt
Plane wilt is a fungal disease affecting plane trees, common in British towns and cities. The pathogen enters the tree through existing cuts and damage, obstructs the water transport system and can cause death. This pathogen was accidentally introduced from the United States to southern Europe during World War II. It has since spread northwards through Europe. In certain urban locations, the widespread prevalence of plane trees provides significant benefits in mitigating air and noise pollution and intercepting rain to reduce the prevalence of run-off. The impact of losing these trees would therefore be devastating and hard to mitigate.
5. Xylella fastidiosa
The Xylella bacterium does not impact a single species of tree, nor is it limited solely to trees. The bacterium can infect more than 650 different plant species, including oak, elm and plane, as well as grapes, blueberries and many herbaceous plant species. The bacterium is transmitted between plants via insects. In 2013, it was identified as the cause of death of olive trees in southern Italy. There are now major outbreaks on ornamental plants in southern France (including Corsica), the Balearic Islands (Ibiza, Mallorca and Menorca), southern Spain and most recently in Portugal. The bacterium causes a variety of symptoms which can include leaf scorch, wilt, dieback and even death.
Awareness, vigilance and action
Even if pests and diseases arrive in the UK, measures can still be taken to mitigate the spread. The Asian beetle serves as an example where proactive measures successfully eradicated an early-stage infestation. Where eradication is not possible, management may still be. The spruce bark beetle is a well-established pest in the UK. Efforts are underway to manage the pest with ‘classical’ biological control, introducing a predatory beetle that exists within the same environment as the spruce bark beetle. The predatory beetle can detect chemical signals from prey, giving it the ability to locate its prey even when there are only a few infested trees in the area. Whatever the stage of infestation and prevalence, maintaining awareness, practicing vigilance, and taking action are the best ways to protect UK forests from future harm.
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
