Faced with a dwindling armoury of pesticides, an East Anglian farmer is trialling a new way of keeping a damaging aphid infestation out of his carrots – by covering them with fleece.
The Elveden Estate, near Thetford, which grows 10,000 acres of vegetables and cereals around the Norfolk-Suffolk border, has had problems in recent years with attacks on its early carrot crops by willow carrot aphid, peach potato aphid and parsnip aphids.
Farm manager Andrew Francis said last year saw yield losses of up to 70pc as the carrot yellow leaf virus – carried in the pest's saliva glands and transferred when it feeds – caused internal browning that rendered much of the crop unsaleable to customers with a damage tolerance of less than 2pc. The farm has adopted a seed treatment that helps protect against aphid attack – although this requires the pest to feed on the plant – and a more expensive new insecticide which is being precision-sprayed in bands using a new piece of machinery.
But with many crop protection sprays at risk of bans from the EU, Mr Francis is comparing these treatment regimes against trial strips of carrots covered with fleece, to see whether a physical barrier is more effective than a chemical one.
Mr Francis said: 'We have got this aphid problem in conjunction with a reduced armoury of persistent insecticide products which gave us protection for a few weeks.
'But there are not many of these more persistent products around. So if we lose that what else do we do? We have to find our own solutions.
'The fleece has its problems. We have a lot of deer around here and when they walk across it will rip and the aphids will get in the holes. It is also labour-intensive. I've worked out it costs £700 per hectare to lay this on this particular field, so that's £42,000 additional cost over 60 hectares.
'For us, having had three bad years, it is decision time. Do we carry on with early carrots, or not bother? We cannot keep swallowing that amount of loss and, with the lack of willingness from the customers to mitigate it, it is the grower that carries all the risk.
'Using the band sprayer is simpler and more cost-effective, so it will be interesting to see if there is a difference between the band sprayer and the fleece because the fleece is more expensive.
'If we do nothing at all, then early carrot production here and throughout the Brecks becomes even riskier. And farming is risky enough. So if we are getting into systems where we are adding more risk then we would have to think harder about whether it is worthwhile doing or not.'
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