Farmers’ leaders have expressed disappointment at a decision by seeds and agrochemicals firm Syngenta to withdraw its application for the emergency use of a crop insecticide, warning it would make growing oilseed rape crops “more difficult” this season.

Cruiser is a neonicotinoid seed treatment insecticide used in crops such as cereals, oilseed rape and sugar beet.

The European Commission decided the use of certain neocotinoids should be suspended following fears from environmentalists about a decline in bee numbers.

Syngenta was trying to get approval for its emergency use for this oilseed rape season but said delays in getting Government approval meant it could not get the necessary European Union derogation, or a partial lifting of the ban under strict conditions, in place in time.

Neonicotinoids were developed in the 1980s and 1990s and the main producers are Syngenta and Bayer CropScience.

National Farmers’ Union vice president Guy Smith, who farms at St Osyth near Clacton, said: “The NFU is disappointed that Syngenta has decided to withdraw its application for the emergency use of Cruiser.

“It is very frustrating that, after the Advisory Committee on Pesticides had indicated that the conditions for approval had been met, it was not possible for a decision to be made in time for Syngenta to prepare seeds for this year’s planting.

“It is also of concern that the whole issue has been heavily politicised and manipulated with misinformation by campaign groups with their own agenda against pesticide use, without concern for the consequences for this country’s productive capacity or indeed for the potential unintended consequences for bee populations.

“This loss of this treatment will make it more complicated to grow oilseed rape this season. The NFU will closely monitor the effects with a view to supporting a further application next year.”

Syngenta said: “Following an assessment of the current planting schedule for growers, Syngenta has decided to withdraw its application for the emergency use of its neonicotinoid seed treatment on winter oilseed rape in the UK. Whilst the Advisory Committee on Pesticides has indicated that the criteria for emergency use has been met, there has been insufficient time to conclude on the conditions for verifying and auditing planting locations which were specific to this limited use application. In making the application, Syngenta was clear that in order to supply the product to British farmers and, importantly, to ensure its effective stewardship, an approval from government was required by the end of June.

“As the first year in which farmers will be unable to use neonicotinoid treated seed for winter oil seed rape, we welcome the fact that the government will be assessing the establishment of the crop in the UK this season. Based on this assessment, Syngenta will consider making a new application for the 2015/16 season to ensure British farmers have access to a technology which helps them to grow crops sustainably and which is safe for bees. We also welcome the fact that the government’s opposition to the EU-wide restriction of neonicotinoid pesticides remains unchanged.

“More broadly, Syngenta remains supportive of the government’s National Pollinator Strategy and fully intends to continue our work with farmers to provide food and habitat for bees, which is the key driver for their long term health, through Operation Pollinator.”