British Sugar is predicting a 15pc drop in sugar beet yields for the forthcoming harvest after extreme weather and diseases put a dent in a decade of crop improvements.

Aided by new seed varieties and the development work of the British Beet Research Organisation (BBRO), the yields of this staple East Anglian crop have increased by 25pc during the last 10 years.

But this year’s beet has been hit hard by prolonged dry periods earlier in the growing season – including the driest May on record – and damaging infestations of aphids carrying virus yellows disease, following the ban on neonicotinoid seed treatments which previously protected the plants from these pests.

Peter Watson, agriculture director for British Sugar, said farmers are now being offered protection through a new £12m virus yellows crop assurance fund, while improved new varieties in the pipeline had the potential to counteract yield losses from disease, and emerging technologies like gene editing could provide the “Holy Grail” of a long-term alternative to pesticides in the future.

Meanwhile, the weather has been this year’s most influential variable.

“This year has been a difficult year for growers, primarily because of the spring weather,” he said. “Although everyone talks about virus yellows, the yield drop-off – like any other spring crop – is mostly due to the seed bed, but also the May drought.

READ MORE: ‘Ground-breaking’ £12m fund will insure farmers against crop virus“For the crop in the ground, we predict we will be 15pc down on yield – two thirds of that is weather-related and one third is virus-related.

“Traditionally we’ve seen a 2.5pc year-on-year improvement, so if you look back ten years this will be one of the first crops that has not seen a year-on-year improvement from seed varieties. So it is a difficult year, but not the worst, and going forward there is a huge uplift in potential.

“It is a challenge, but we have new varieties coming through which will hopefully improve the resilience and help growers with virus yellows. The variety potential is 5pc greater in the coming crop than it was this year. The virus has had an impact of around 5pc this year, so to a certain extent they counteract each other.”

Mr Watson said British Sugar is also working with growers to trial changes in farming practices to remove breeding grounds for virus-carrying aphids, funding research to explore disease-resistant varieties, and lobbying government ministers to ensure a “level playing field” with European growers and to seek assurances about emergency pesticide derogations when needed.

READ MORE: New sugar tariff quota leaves a bitter taste for East Anglian beet farmersAnd he said this week’s announcement of “genuinely ground-breaking” contracts, including the new virus yellows crop assurance fund and an innovative futures-linked pilot scheme, would give growers added protection while helping them to manage the risks of growing sugar beet.

“It is all fairly unprecedented stuff,” he said. “We think there is a need to try and be more flexible and work more closely with our growers to give them more choice. We have got lots of growers that like the certainty of a three-year deal, and some want to take more of a risk.”