Farmers must continue to demonstrate the importance and safe use of crop sprays if they want to maintain access to chemicals like glyphosate, said industry leaders.

Agricultural campaigners breathed a sigh of relief this week as the EU finally re-licenced the world's most widely-used weedkiller after a long-running EU debate about its safety, with international health agencies reaching conflicting conclusions over its risk as a potential carcinogen.

The five-year reauthorisation was agreed just weeks before the December 15 expiration date of the controversial chemical's existing licence.

While the decision was welcomed by union leaders, they said to have come so close to losing a tool which is the key ingredient in Roundup and central to many arable systems should galvanise farmers to prove its importance to regulators.

National Farmers' Union (NFU) vice president Guy Smith, who also chairs the Norfolk Farming Conference, spoke while chairing a seminar at the CropTec show in Peterborough this week.

'Effective crop protection is essential to food production in the UK,' he said. 'It is also vital that farmers recognise the importance of professional and responsible stewardship.

'Like most growers I was relieved to see glyphosate given a five year reauthorisation by Brussels earlier this week.

'It's now important that growers continue to have access to key herbicides like glyphosate by demonstrating judicious use and showing regulators the importance of these chemicals to crop production.'

READ MORE: Farmers relieved as EU glyphosate licence finally renewed for five yearsNFU combinable crops board vice chairman Robert Lockhart added: 'Farmers always try to use non-chemical plant control before looking for a chemical solution, and as technology improves these options are becoming more readily available.

'However, the use of plant protection products is integral to any pest management plan and farmers cannot rely on automation alone.

'Farmers must be able to utilise all options on all scales, and this is why the development of new active ingredients and products – and making them safe and accessible – is so important.'

READ MORE: The pesticide divide: Two sides to the glyphosate debateCampaigners against glyphosate include Peter Melchett, policy director of the Soil Association, who also runs an organic farm in west Norfolk.

He said the five-year reauthorisation would not stop efforts to prevent the chemical's use as a pre-harvest desiccant, or in public places.

'The weight of scientific evidence suggesting glyphosate is not safe is increasing all the time,' he said. 'The chronic uncertainty that has so delayed a decision by the EU should not stop (environment secretary) Michael Gove doing things that everyone agrees on, namely banning the spraying of glyphosate on crops immediately pre-harvest and banning glyphosate use in public places like parks, streets and playgrounds, in line with the European Parliament's and the Commission's advice.'