Mild winter and aphid invasion poses threat to country’s beet crops, warns Norwich scientist

Sugar Industry Programme visit to BBRO at Norwich Research Park. Dr Mark Stevens with, from left: Li

Sugar Industry Programme visit to BBRO at Norwich Research Park. Dr Mark Stevens with, from left: Lizzie Matthews, Jonathan Gill, Matthew Murfitt and Henry Catling.Photo: Bill Smith

An early invasion of aphids could pose one of the biggest threats to beet crops across eastern England for 20 years, a top Norwich scientist has warned.

The country's 3,500 growers were warned yesterday by the British Beet Research Organisation that the risk of serious crop damage from virus yellows was the highest for more than two decades.

The mild winter and lack of frost has been ideal for the early arrival of the peach potato aphid, which transmits and infects young growing beet plants, said Dr Mark Stevens, who is based at BBRO's headquarters at the Norwich Research Park.

He said that these aphids could result in yield losses of between 25pc and 50pc in unprotected crops and that this risk was spread across the entire beet growing area.

However, about 96pc of the beet area was drilled with treated seed, which would protect crops. Dr Stevens was concerned that in a high risk virus yellows season that some growers were still planning to drill untreated seed.

In the latest BBRO forecast, he warned that 'in the absence of any control from seed treatments the risk is very high indeed and between 70pc and 86pc of the crop would go yellow by the end of August without any control, depending on drilling and the factory area.'

'The good news is that seed treatments will stop that happening. We're looking at one between one to two per cent of the crop showing yellowing in late August because there are more aphids and they will come in earlier,' he added.

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'It just highlights the issue that if we lost the seed treatments for various reasons there are not many reliable alternatives to control the problem,' said Dr Stevens.

He said that treated seed, which contained a protective insecticide coating, had prevented serious crop damage over the past two decades. 'We've not had a problem for 20-odd years because the seed treatments have stopped it happening. After adoption of neonicotinoids in 1994 for beet seed treatments, since then over 50pc of the crop has been protected by seed treatments since 1996.

'Although there would have been potentially 10 epidemics in the past 13 years because of very mild winters, the seed treatments have done their job.

'If we lost them for politics or resistance, or both, then virus yellows, then the consequences because of the maritime climate in eastern England would be severe,' he added.

Dr Stevens said that the harsher continental climate reduced the risk from virus yellows because most of the aphid populations were knocked out. 'Normally the maritime influence of the north Norfolk coast would increase the risk because a milder climate enables aphids to survive. This winter, it has been so mild that the risk is spread from Yorkshire to Essex,' he added.

As the temperature in the east of England had been about 4C warmer in the January and February period than last year, it has significantly increased the risk of earlier arrival of aphids. 'There are three different yellowing viruses, which can decrease yield between 25 and 50pc depending on the virus,' said Dr Stevens.

'Those growers who have chosen not to use treated seed really need to be aware. I would argue that 100pc of the crop should be treated with a seed treatment because the risk is so high,' he added.

Newark factory sliced out mid-week and Wissington, near Downham Market, was expected to complete processing yesterday.

Fenland grower William Martin, pictured, who is chairman of the National Farmers' Union's sugar board and farms at Littleport, has been re-elected . The vice-chairman's post, which was held by Robert Law, remains vacant. An election will take place at the next sugar board meeting in May.