Growers could be forced to stop using neonicotinoid pesticides after a vote by EU agricultural ministers on 14 March.
This may see member states accept an EU-wide temporary restriction on the use of some pesticides linked to the decline in the number of bees. Such a measure could lead to crop protection gaps such as vine weevil problems on ornamental plants, say experts.
Crop protection consultant John Adlam said: "This is one of the main products we have for vine weevil larvae control." After the withdrawal of aldrin dust in 1986-87, the nursery industry had a "huge vine weevil problem" and "we could be in the position again", he added.
Adlam said biological treatments such as nematodes and Met 52 fungus are useful in stopping pests eating plant roots but "limited in what they can do and when". British Crop Protection Council (BCPC) chairman Colin Ruscoe said there is a lack of non-biological alternatives to neonicotinoids.
The EU move follows the conclusion of the European Food Standards Authority that three neonicotinoid pesticides - imidacloprid, thiamethoxam and clothianidin - pose a significant risk to honeybees if used on flowering crops. Opponents to the withdrawal, including Defra, say the tests were laboratory trials rather than field trials and no ornamental crops were tested. They also argue that, with just 0.03 per cent of the chemicals used on ornamentals, horticulture has been unfairly included in an agricultural issue.
Products used on commercial fruit, vegetables and ornamentals could be hit if enough EU countries vote in favour of a proposed two-year restriction at a standing committee meeting on 14 March. The ban would cover all domestic use too.
Defra, neonicotinoid manufacturers Syngenta and Bayer and industry bodies including the HTA, Crop Protection Association, NFU, BCPC and others argue that the science is not sufficiently robust for a ban.
NFU horticulture adviser Dr Chris Hartfield said: "The NFU is lobbying against the proposals because we do not believe they are proportionate, we do not believe they are justified and we do not believe they would improve the bee health situation."
He added: "Considering the commission's approach on this to date has been very broad-brush, we would expect that ornamental crop uses might well be included."
Off-the-shelf bug killers containing imidacloprid and thiamethoxam include Westland's Plant Rescue Bug Killer and Bug Killer concentrate, Bayer Provado Lawn Grub Killer and Ultimate Bug Killer and Doff Portland's Plant Vitality Plus. They are recommended for either lawn, house or garden ornamental plant uses.
Scotts Company's Bugclear Ultra and RoseClear ranges, Bayer CropScience's Multirose, Provado Ultimate Bug Killer 2 and Baby Bio House Plant Insecticide products contain acetamiprid or thiacloprid, which are neonicotinoids, but the NFU said it is "widely accepted" that because of their slightly different chemistry they pose "significantly less risk" to bees than the other three neonicotinoids and are not the focus of current concern.
Many garden centres have already removed the products. Friends of the Earth senior campaigner Paul de Zylva said almost 1,000 retailers removed products after campaigns. "Public confidence has waned around the issue. This is not too dissimilar to the way the public feels about supermarkets and horsemeat. They feel let down."
HTA business development director Tim Briercliffe said gardeners should have "no concerns" about products if used in accordance with labelling instructions. "We don't believe there is evidence of a problem and even if there was it would only be an agricultural issue."
Adlam added: "As an industry, we can do no more than comply with what our Government asks us and the Government is not asking us to withdraw the products. When it does, the industry will comply. The industry is looking to the Government for guidance and this is a critical time at the beginning of the season."
Amenity Forum chairman Dr John Moverley said: "As we understand all matters to date, the ban will not relate to amenity use."
Current approvals - Neonicotinoids used for particular crops
Clayton Divot (M15451).
Imidasect 5GR (M14574 & 14091).
Intercept 70 WG (M 08585).
Merit Turf (M12415).
Nuprid 600FS (M13855).
Imidacloprid + betacyfluthrin: Chinook Blue and Chinook Colourless.
Cruiser SB (M15012).
Fludioxoynil + metalaxyl-M + thiamethoxam: Cruiser OSR.
Beta-cyfluthrin + clothianidin.
Clothianidin + prothioconazole.