Following the vote by EU member states to restrict the use of neonicotinoid pesticides, Abby Kellett asks how the ban is likely to affect sugar beet growers.
Following the partial neonicotinoid ban on flowering crops in 2013, the latest restriction which was voted on earlier this year, will prevent the use of three neonicotoids - clothianidin, imidacloprid and thiamethoxam – on all outdoor crops.
The European Commission has said that the sale and supply of these actives will cease by September 19, 2018 at the latest, with the sale, storage and use of seed treated with these neonicotinoids ending on December 19, 2018 at the latest, according to the Agricultural Industries Confederation (AIC).
However, it is up to member states how they wish to implement the ban and some may go for an earlier date, says AIC head of crop protection Hazel Doonan. “For the moment we don’t know what the UK position will be. Normally they are quite good at giving a grace period.”
Hopefully growers will still be able to drill winter wheat treated with a neonicotinoid seed dressing this autumn but it is not certain, she says.
Assuming UK growers are permitted to use the seed treatments for autumn drilling, the impact of the restriction is likely to be first seen in next season’s sugar beet crops. Given the crop’s dependence on clothianidin and thiamethoxam, there are concerns about the crop’s future viability.
In 2018, 99 per cent of UK sugar beet crops were protected with a neonicotinoid seed treatment, preventing yield losses of up to £51 million in a high risk year, according to BBRO senior researcher, Dr Mark Stevens.
He says: “The two most commonly used neonicotinoids used by sugar beet growers are Bayer’s Poncho Beta and Syngenta’s Cruiser Force, which protect the sugar beet crop for up to 14 weeks.”
The three main targets for the neonicotinoid seed treatments are virus-carrying aphids; soil pests -such as wireworm and the soil pest complex; and the first generation of leaf miners.
While pyrethroids used to have activity against aphids, widespread resistance means that there are now no foliar insecticides registered for use in sugar beet. “90 per cent of aphids are resistant to pyrethroids and carbamate, so we don’t have another solution beyond neonicotinoids.”
One of the main concerns post-neonicotinoids is the risk of virus yellows – a disease which is already capable of reducing sugar beet yields by up to 49 per cent, according to Dr Stevens.
Because of the country’s maritime climate, he believes the whole of the UK sugar beet area would be at risk from virus yellows. “Because of all the mild winters we have experienced lately, I think we could have had 10 virus yellows epidemics in the last 15 years, if it was not for neonicotinoids.”
Growers are reminded that there are some agronomic measures they can take to reduce damage caused by aphids.
Dr Stevens says: “It is about trying to make sure growers remove potential sources of infection ahead of crop establishment – anything that can harbour aphids and viruses, including sugar beet volunteers and brassicas which may form part of an over winter cover.”
Norfolk-based agronomist, Robin Limb says: “In the absence of seed insecticide treatments, the best line of defence is to establish the crop rapidly, thereby enabling it to out-run the threat of aphid attack. Some pyrethroid sprays are still available, but these are non-selective, and will kill off beneficial insects such as lacewings, ladybirds, and hoverflies, that would otherwise have predated on aphids.
“The establishment of ’beetle bank’ strips could possibly generate an armoury of aphid predators to control their spread.”
But the development of resistant varieties and new products will be important to secure the future of UK sugar beet production.
Dr Stevens says: “Varietal resistance or tolerant varieties are going to be key going forward. The problem we have with virus yellows is that we are not just dealing with one virus, we are dealing with three and there are no single major sources of resistance that can be easily bred into the varieties, so you are often trying to stack minor genes together as well as trying to keep yield, sugar content and bolting resistance.
“We are making progress but it will probably be five years before resistant varieties become commercially available.”
Mr Limb adds: “In theory, there are new products in the pipeline that may yet prove to be a vital life-line for beet growers. Varietal tolerance to virus yellows does exist in the gene pool, but true resistance may only come from GM technology - which at present seems like a pipe dream.”