Nicola Spence, England’s first chief plant health officer, is set to retire this week after more than a decade leading efforts to protect the United Kingdom from imported plant diseases and pests. Since her appointment in 2014, Spence has overseen significant growth in the country’s biosecurity infrastructure, expanding inspection teams and broadening the national risk register to address an increasing number of threats.
Spence’s role has been central in guarding against pathogens such as Xylella fastidiosa, a bacterium that has devastated olive groves in Italy and poses a serious risk to British agriculture and native trees like oaks and elms. Although Xylella has not yet been detected in the UK, the Royal Horticultural Society (RHS) has banned certain plant imports, including lavender, from the Chelsea Flower Show due to their potential to harbor the disease. Vigilant inspections are now routine at major horticultural events; for example, in the lead-up to the Chelsea show, officials conduct thorough checks alongside RHS biosecurity teams.
The biosecurity frontline includes locations such as Provender Nurseries in Kent, where the Animal and Plant Health Agency (Apha) operates inspection points. Plants arriving from UK Channel ports are unloaded in secure, sterilized warehouses to allow officers to examine them for invasive pests and diseases. Such measures reflect growing recognition in the UK that plant health is a key component of national security, beyond traditional concerns over human or animal health.
Historical outbreaks underscore the stakes: Phytophthora infestans, the pathogen responsible for the 19th-century Irish potato famine, serves as a lasting reminder of the devastation plant diseases can cause. More recently, unintended introductions continue to disrupt ecosystems, as illustrated by Pseudogymnoascus destructans, a fungus accidentally brought to North America from Ukraine that has decimated bat populations and indirectly increased pesticide use in agriculture.
Authorities also remain alert to the possibility of deliberate introductions of pathogens as a form of agroterrorism. Last year, a couple was arrested in the United States for allegedly smuggling a wheat-destroying fungus, described by prosecutors as a “potential agroterrorism weapon.” While such incidents have not been reported in the UK, Spence notes that counterterrorism networks consider plant products a potential risk vector. Unsolicited seed packets mailed to UK households in the past year, though found to be harmless, highlight how easily novel pathways for disease could emerge.
Climate change is contributing to an expanding threat landscape by allowing more pests and diseases to survive and establish in the UK. Warmer, wetter winters facilitate the persistence of organisms that would previously have died. Other common vectors include contaminated wood packaging, hitchhiking insects on shipping pallets, airborne fungal spores crossing from continental Europe, and even infested components within furniture imports.
To counter these challenges, Apha has ramped up inspections and environmental monitoring, employing innovative methods such as detector dogs, drones, helicopter surveys, and satellite imagery with spectral analysis to identify diseased plants and tree species. However, these efforts face difficulties in accessing remote or rewilded woodland areas, where infestations like those caused by eight-toothed spruce bark beetles have been spotted but remain hard to control.
As Spence steps down, the agency she leaves behind counts roughly 400 inspectors compared to 100 at her appointment, and its pest and disease risk register has more than doubled in scope. Though the identity of her successor has yet to be announced, Spence plans to continue her involvement with plants and trees as a trustee of the RHS. At next year’s Chelsea Flower Show, she expects to attend in a more relaxed capacity, passing on the responsibility for protecting British horticulture from emerging threats to the next generation.