THE FULL cost to farmers of the neonicotinoid ban in 2016 was £18.4 million and resulted in almost 28,800ha of lost crop.

The figures are the result of a study funded by Rural Business Research and the Institute of Agri-Food Research and Innovation.

Perhaps more alarming was the increased use of alternative pesticides as farmers tried to control cabbage stem flea beetle (CSFB).

Farmers in the Derogation Area (DA) who had access to neonicotinoid treated seed used 75 per cent less chemicals than those who used non-neonicotinoid treated seed.

The research by Charles Scott and Paul Bilsborrow sampled a sub-set of winter oilseed rape (WOSR) growers from the Farm Business Survey.

It followed their initial investigation in 2015, which found a three per cent loss of WOSR area to CSFB and 2.5-fold increase in pesticide use to tackle the problem.

The new report found the impact in 2016 was more severe, with five per cent of the national WOSR area lost to CSFB.

Farms in the East suffered the greatest with 16 per cent of the Suffolk crop area failing and 13 per cent in East Yorkshire.

Dr Bilsborrow said that farms hardest hit by CSFB were more likely to be located in the Derogation Area: "Even if the problem didn’t result in crop failure and re-drilling, it was likely to have had an impact on yield," he said.

Across the country, 72 per cent of farms used insecticides to treat CSFB – the most common being pyrethroids and pyridine azomethine – 136,600 litres of chemicals were used to combat CSFB, totalling 17,500kg of active substance.

The chemicals alone cost £4.3 million and the cost of applying them was £8.5 million. Where crops were lost and not re-drilled, the bill was £2.9 million and £2.6 million when re-drilled.

Mr Scott said the area of WOSR in the UK fell for the fourth year from a peak of 756,000ha in 2012 to just 597,000 ha in 2016. "Among participants in the study, CSFB was among a range of factors cited for farmer’s reducing their OSR area, including rotational position and price pressures."

Where higher levels of insecticide were applied, levels of CSFB damage were lower – Lincolnshire accounted for 24 per cent of insecticide used nationally, but suffered one of the lowest proportions of crop losses from CSFB, at just three per cent.

Dr Bilsborrow said: "Chemicals are clearly a vital weapon in the battle against CSFB but our study also shows farmers are utilising a range of cultural strategies to combat the pest." Nationally, 42 per cent of OSR growers changed drilling dates and within the DA 61 per cent of farmers opted to drill earlier, a further 11 per cent increased seed rates and 19 per cent increased spray applications.

But Mr Scott said: "The ban is obviously having a major impact on the viability of OSR in England. Without access to treated seed in the high-risk areas, especially in Eastern England for 2017, it’s possible that CSFB damage will be even greater this year."