Be warned, your trendy olive tree might come with a free snake

Telegraph

31-01-2025

A new study from the University of Cambridge is
While few gardeners can say they have found a salamander in their garden centre shopping basket, imported insect pests (which constituted more than 80per cent of the pests cited in the study), transported from overseas on cut flowers and potted plants, do have the potential to harm nature.
The researchers of the study, published in the journal
Bioscience
, say they found
Dr Silviu Petrovan, a researcher in the University of Cambridge's Department of Zoology and a senior author of the paper, says hidden 'hitchhikers' are getting through customs import checks all the time, but adds: 'Snake imports in the UK are unlikely to be a major risk. However, the Italian wall lizard is spreading rapidly in Europe. And yes, one of the main pathways for introduction is via transport of ornamental plants, often potted olive trees.'
At
Priest says he doesn't think the lizards, identified by experts at Cotswold Wildlife Park, compete with anything, and he believes the chances of reptiles being imported these days are low, because of stricter post-Brexit controls at the border.
The olive trees he believes the lizards arrived on remain fashionable features on all the best doorsteps, and a 1,000-year old specimen can cost £50,000.
Olive-tree importers say they have never found any ectotherms (cold-blooded mammals) on their consignments. Jason Hales of supplier
Defra says accidental occurrences of snakes, lizards and similar animals in horticultural imports are 'extremely rare', and 'even on the rare possibility snakes and geckos are accidentally imported into the UK – the chance of these sorts of animals establishing populations in Great Britain is very unlikely.'
According to Petrovan, 'Amphibians and reptiles are almost certainly not the group we should be most worried about. Those are insects and invertebrates such as flatworms.'
He believes our warming climate is making it more likely that pests and diseases will survive over winter in the UK. The global plant supply chain also brings greater risks.
In 2022 the worldwide export value of cut flowers and foliage was US$10 billion (£8 billion), and for live plants and bulbs was $13 billion (£10.5 billion).
Plants, trees and flowers produced domestically in the UK were valued at £1.7 billion in 2023, while imports of plants and plant material totalled £780 million, with 99 per cent sourced from the EU.
The researchers admit the ornamental plant trade is important for economies worldwide and supports many people and their families in rural areas. They call for more certifications and better regulation, and for importers 'to better understand the risks and how to mitigate them'.
In 2012, trade magazine HortWeek reported that
Petrovan lauds Defra for making data on contaminants publicly available, saying, 'A major issue in understanding risks from ornamental plant trade is the fact that countries don't make this data available and as such comprehensive analyses are almost impossible at international scale.'
As for his advice for gardeners, he says: 'For the public, it is important first of all not to try and circumvent legal routes. You sometimes see people buying potted plants on holiday and bringing them home in their luggage. That is definitely not a good idea, especially if the plants are in pots of soil. You could bring all manner of flatworms, invasive and pest insects as well as plant diseases. Also, for international imports, buying seeds and bulbs is generally much safer compared to buying potted plants. Finally, if they bought plants from the shop and see insects or other organisms on them, it would be important to try and contain them and then report them to Defra.'
Plants and cut flowers that could house unwanted pests and diseases
Oak
Oak processionary moth
Spruce
Larger eight-toothed European spruce bark beetle
Ash
Ash dieback disease/emerald ash borer
Tree ferns
The RHS says semi-mature trees, palms and tree ferns have large canopies and root balls, which can make it difficult to carry out thorough plant health inspections, increasing biosecurity risk.
Olives
Snakes, lizards, Xylella
Cut roses and imported rose bushes
Frogs, citrus long-horned beetle, leaf miners, whitefly
Cut chrysanthemums
Fall armyworm
Heuchera
Obama flatworm
Coffee plants
Polygala and Spanish broom: Xylella