The Bishop of Exeter received the following written answers on 19th June 2023:
The Lord Bishop of Exeter asked His Majesty’s Government what assessment they have made of acute oak decline in the UK; and what steps they are taking to minimise its impact.
Lord Benyon (Con): We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.
Acute oak decline is a complex disease of native species of oak (Quercus robur and Quercus petraea) that mostly affects mature trees aged over 50 years. It has been established in the UK for many years and does not meet the criteria for a regulated pest. The Pest Risk Analysis for Acute oak decline is attached to this answer and is available to view on the UK Plant Health Risk Register, together with the risk ratings and current mitigations for this disease. The disease has been prioritised for research, survey to monitor its distribution, and management by industry.
Defra has invested over £1 million in research to understand the causes, distribution and scale of acute oak decline in the UK. Forest Research has used this research to inform published distribution maps and management guidance for landowners. Research on acute oak decline is also supported by Action Oak, a pioneering new partnership launched in 2018, which is part of the Government’s response to concerns about the long-term future of our oak trees.
The Lord Bishop of Exeter asked what steps they are taking to prevent Asian and citrus longhorn beetles arriving in the UK.
Lord Benyon: We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.
Asian longhorn beetle (Anoplophora glabripennis) and citrus longhorn beetle (Anoplophora chinensis) are damaging pests of broadleaved trees including sycamore, maples, willow, birch and elm and are designated as priority, quarantine pests. They are not currently present in the UK. We have contingency plans in place and will take statutory action in the event of a finding.
Risk ratings and current mitigations for both pests are available to view on the UK Plant Health Risk Register. A common pathway for the spread of Asian longhorn beetle is wood packaging material such as pallets, and there are international standards in place for treating such material (International Standard for Phytosanitary Measures No. 15) to mitigate this risk. A common international pathway for the spread of citrus longhorn beetle is the movement of young trees for planting, particularly maples. The UK has general prohibitions in place on imports of all high-risk trees from outside of the EU, and further controls on other known hosts from countries where the pest is known to occur. All imports of trees must be pre-notified to government and are subject to an official inspection and surveillance programme.
The Lord Bishop of Exeter asked His Majesty’s Government what assessment they have made of the threat posed by bronze birch beetles to the UK’s forests.
Lord Benyon: We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses new and emerging threats to plant health and their potential impact on the UK.
Bronze birch borer (Agrilus anxius) is a priority, regulated pest with a surveillance programme and contingency plan in place. A pest risk analysis for this pest was carried out in 2011 for the whole of the Europe and Mediterranean Plant Protection region and is attached to this answer, with UK experts in pest risk analysis and forestry being part of the working group. This is available to view on the EPPO website (https://gd.eppo.int/(opens in a new tab)) and provided the basis for the inclusion of the pest on the UK Plant Health Risk Register.
Bronze birch borer is a specialist wood-boring beetle pest of birch trees. It is native to North America and absent from the UK. Specific import measures on birch material from third countries, including North America, are in place to mitigate against its entry into the UK and such materials are subject to pre-landing notification and inspection by the UK plant health authorities. Statutory action would be taken against any findings of this pest in the UK.
The Lord Bishop of Exeter asked His Majesty’s Government what assessment they have made of the elm zigzag sawfly in the UK; and what mitigating measures can be taken to slow its spread.
Lord Benyon: We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.
A comprehensive pest risk analysis for Elm zig-zag sawfly (Aproceros leucopoda) was conducted in 2016, before the pest was first reported in the UK. This is available to view on the published UK Plant Health Risk Register and is attached to this answer, it provides the basis for the inclusion of the pest on that national prioritisation tool.
The assessment concluded that there were no practical options to ensure continued exclusion or eradication from the UK due to its rapid expansion across Europe and the pest being a hitchhiker, which can be introduced on transport such as cars and trains. On that basis, statutory eradication action against findings in the wider environment when the pest was confirmed in the UK in 2017 were not technically justified.
The Forestry Commission conducts ongoing surveillance to monitor the distribution of Elm zig-zag sawfly and have published guidance for landowners to inform its management. Pest spread has also been recorded through citizen science, by the Observatree volunteer network.
The Lord Bishop of Exeter asked His Majesty’s Government what assessment they have made of the spread of European mountain ash ringspot-associated virus in the UK; and what mitigating measures can be taken to slow its spread.
Lord Benyon: We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.
A comprehensive Pest Risk Analysis for European mountain ash ring-spot-associated virus (EMARAV) was conducted in 2013. This is available to view on the published UK Plant Health Risk Register (https://planthealthportal.defra.gov.uk/(opens in a new tab)) and is attached to this answer. It provides the basis for the inclusion of the pest on that national prioritisation tool.
EMARAV is a virus of the genus Sorbus, commonly known as Rowan or European mountain ash. Evidence demonstrates the virus has a widespread presence in Scotland and previous findings in other parts of the UK. The virus has a limited impact and is considered to pose a low risk to the UK. Statutory action is not taken against this pathogen.
The Lord Bishop of Exeter asked His Majesty’s Government what assessment they have made of the damage caused by the eight-toothed spruce bark beetle to the UK’s forests.
Lord Benyon:
We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.
The eight-toothed spruce bark beetle, Ips typographus, is a serious pest on spruce in Europe and could cause significant damage to Britain’s forestry and timber industries. The beetle is primarily a secondary pest, preferring stressed or weakened trees. However, under the right environmental conditions, beetle numbers can increase enough to result in attacks on healthy trees.
Ips typographus is a priority, regulated pest with a surveillance programme and contingency plan in place. The pest risk analysis for Ips typographus that provided the basis for the current entry of the pest on the UK Plant Health Risk Register, is being updated and will be issued for consultation shortly.
In 2018 a breeding population of Ips typographus was first confirmed in Kent, as part of routine surveillance by the Forestry Commission. Further findings have been identified in the South-East of England in 2021-23. Evidence demonstrates that outbreaks have resulted from natural dispersal (blow over) of the pest from the continent. There is no evidence of within-UK spread, or of impacts on healthy spruce in the UK.
All outbreak sites are subject to robust eradication action, and a demarcated area is in place restricting the movement and felling of susceptible material. Monitoring of the 2018 outbreak indicates that eradication action on that site has been successful.
We continue to fund research into the impact and spread of Ips typographus. Over the longer term, the Forestry Commission is encouraging landowners to remove susceptible spruce from the South-East and replant with other species. Financial support is available for this through the Tree Health Pilot.
The Church of England in Parliament 
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