A "potentially horrific" proposed EU law to ban an expandable list of invasive species has provoked dismay among horticultural experts.
The plan, due to be voted on by the EU next month, would see a list of banned species "of EU concern" that could not be introduced, transported, put on the market, offered, kept, grown or released in the environment.
But when the added measures of an imported plant levy and a year quarantine for imported trees were suggested at recent Government Environmental Audit Committee meetings, the industry was spooked.
HTA horticulture head Raoul Curtis Machin said: "It's potentially very serious. What blindsided us was the question about potential levies. We'd been looking at banned lists but when that question came out it was spooky. Sometimes that's their way of testing potential policy. But it's potentially horrific for the industry."
The RHS is also concerned and said it favours a "blacklist" approach that "would see plants that present a clear environmental threat being restricted". Originally the EU law limited the banned list to 50, but this was changed to a an unlimited number.
The RHS said it wants "a robust and evidence-based approach" to drawing up the list and is urging the EU to "draw on its internationally recognised expertise in taxonomy" when identifying plant species.
TV ethnobotanist James Wong called the plans "pretty crazy" on Twitter. He agreed with the RHS view that climatic differences should be considered - plants that are invasive in some climates may be fine in the UK.
Curtis Machin said costs should be borne by the Government, not the industry, calling it "not fair" on the trade in a competitive market. "Invasives can cause problems but only a handful such as Himalayan balsam and Japanese knotweed do. Less than two per cent of land mass is affected by invasives."
But Renato Canale, managing director of Hertfordshire-based Europlants, which only sells imported varieties, said he could not see a levy happening.
"It would affect us in a big way," he predicted. "It would make our products so much more expensive. But I don't think they would be able to do it." He added that protection already exists with the current block on some trees.
Tighter controls - Better defences endorsed
Kew Gardens arboretum head Tony Kirkham said: "We have to tighten up bio-security. No trees should be imported straight to landscapers. It will be more expensive but priceless when you get a disease you can't control."
Horticulture is an adaptable industry and nurseries and landscapers will discover means to work around such a move, he added.
Campaign group Buglife called for imports of pot plants to be banned after it said the introduction of the New Guinea flatworm threatens native snails in the UK. Oak processionary moth "very likely" came in on pot plants, it added.