Spray or stay in SFI? Aphids force tough choice

Widespread reports of aphids, gout fly and leafhoppers are being spotted in emerging cereal crops, putting immediate pressure on growers to consider insecticide use.

Even those who opted for the Sustainable Farming Incentive (SFI) no-insecticide option may consider missing out on the £45/ha payment in favour of a pest spray to keep disease risk under control.

See also: BYDV: Lessons from 2026 on how to reduce risk

A new barley yellow dwarf virus (BYDV) modelling tool launched by the AHDB predicts the disease can cause a 0.5t/ha yield loss in a winter wheat crop drilled on 5 October without insecticide treatment, corresponding to a loss in income of £90/ha.

“This rises to a possible loss of £210/ha if the field is not exclusively surrounded by arable cropping, which can increase disease risk,” explains Agrovista technical manager Mark Hemmant.

“Earlier drilling or winter barley crops will also increase risk,” he says.

Many farms will be loathed to spray insecticides, but given the current high pest pressure and risk of BYDV, economically it could be the right decision.

SFI no-insecticide options

SFI guidance states that where you have C/IPM4 in place, should you need to spray insecticides to prevent a financial loss, you should do so at the earliest opportunity.

Those in this option should carefully weigh up the loss of the subsidy payment with the economic loss from not spraying.

Where a decision is made to apply an insecticide, growers must notify the Rural Payments Agency within two months – ideally as soon as possible – so they can consider whether a reduction in payment is required.

Current pest pressure levels

Rothamsted’s Insect Survey was catching increasing numbers of bird cherry oat aphids in the first week of October, with triple-figure catches at most sites.

More than 50% were winged aphids capable of colonising cereal plants, according to live trapping tests at Rothamsted – a much higher proportion than the 10-year mean of 12.9% – while the proportion carrying virus was nearly 40%, according to AHDB reporting.

“We wondered if the hot summer would make it more difficult for aphids to acquire virus with the lack of green material, but the testing suggests the opposite, so it all points to a much higher risk than normal,” Mark says.

“Remember, both the new AHDB and traditional T-Sum models for timing aphicide sprays are designed to prevent secondary spread of aphids.

“So even if these models are not saying to spray yet, treating to prevent primary infections will be beneficial, especially on low seed rate crops such as hybrid rye or hybrid barley.”

Gout fly and leafhoppers

Gout fly eggs are being widely found across the country, rather than just in regional hot spots like last year.

“This year it seems endemic and again are present from emergence. Treating with a pyrethroid within seven days of egg laying should be a priority for control.”

Cereal leafhoppers are also on the rise, with increasing numbers found in the south of England which spreads wheat dwarf virus.

“Crops are vulnerable from emergence, with early infections causing the greatest yield loss,” Mark says.

“Unlike other viral diseases in cereals, which often form in relatively large distinct patches, wheat dwarf virus symptoms are often relatively spread out in small, peppered patches across the field as the leafhoppers readily move between plants and spread the virus by primary infection.”

The hot, dry summer is likely to have been highly favourable for cereal leafhopper populations, but control is difficult, with pyrethroid efficacy “average at best”, Mark says.