A banned "bee-harming" pesticide which was controversially approved to save sugar beet crops this spring will now not be used, after freezing weather killed virus-carrying aphids.

Following severe crop damage from virus yellows disease last year, East Anglia's sugar beet growers were granted an emergency authorisation for the "limited and controlled" use of neonicotinoid seed treatments - which were banned in 2019 due to fears over their impact on the health of bees and pollinators.

The chemicals were previously used to kill virus-carrying aphids, which have since infected sugar beet fields and were considered a significant threat to the 2021 crop.

The decision at the start of the year sparked outcry from environmental groups including Norfolk Wildlife Trust.

But following a very cold January and February, Defra has confirmed the trigger threshold for the emergency approval has not been met, after scientific modelling indicated only 8pc of the sugar beet crop was likely to be infected with virus yellows disease this year.

Kit Papworth, a north Norfolk farm contractor who is a member of the National Farmers' Union's sugar board (NFU Sugar) said: "This is the system working as it should.

"There are other European countries who are going to use this chemical whatever happens, but in the UK we said we would not use it if the model says we don't need to - and it doesn't.

"There will be growers who might disagree with that, but the decision is correct and science has won out in the end.

"This is what the future of farming looks like, where we assess the risk, rather than prophylactically spraying or treating because we think something might happen."

Peter Watson, agriculture director of British Sugar, said the cold winter meant virus levels were predicted to be around a tenth of what they were last year.

"It is welcome that the emergency situation that our industry saw in 2020 is not likely to be repeated in 2021," he said. "Growing the crop without the neonicotinoid seed treatment as a result of the freezing weather is the best outcome.

“The application for emergency use of the seed treatment was just that – we committed to only treat the seed if the risk to the crop was significant.

"We will continue to work to progress our plans to tackle virus yellows without the need for neonicotinoids in future years."

Sandra Bell, pesticides campaigner for Friends of the Earth, said: "It’s great news for bees and other pollinators that this ‘banned’ pesticide won’t be used on sugar beet crops this year.

"But our bees have been saved by the weather, not by the government, which was prepared to put pollinators and other wildlife at risk by approving the temporary use of these pesticides.

“This should not be allowed. The government and industry must redouble their efforts to find alternative and effective pest and disease control for farmers – focussing on agroecological methods that work with nature, not against it."