AHDB launches £500k BYDV tool to help growers cut sprays

Wheat and barley growers have been given a new tool to help decide when barley yellow dwarf virus (BYDV) sprays are actually worth applying, following more than £500,000 of industry and levy-funded research.

AHDB’s free online system uses aphid activity, virus levels, weather, drilling dates and crop economics to assess barley yellow dwarf virus risk, going significantly further than the long-established temperature-based T-sum approach.

BYDV is spread by aphids and can reduce yields in winter wheat and winter barley, making autumn management decisions particularly important.

The new tool is designed to help growers avoid insecticide applications where the likely financial return does not justify treatment.

It can also show how changing drilling dates may alter BYDV risk, giving growers another way to manage pressure before deciding whether to spray.

Sacha White, lead crop protection scientist at AHDB, said: “The new BYDV tool accounts for many important risk factors not considered by the T-sum tool, such as the number of aphids flying, the proportion that carry virus and the relationship between infection and yield and financial losses in susceptible varieties.”

She added: “Our research shows that using the tool’s spray and sow-date assessments, alongside local knowledge, can help reduce the number of insecticide applications and protect more yield compared to the T-sum tool when BYDV is present.”

The system is primarily based on the bird cherry-oat aphid, now regarded as the most significant BYDV vector across much of the UK.

AHDB said grain aphids can still be important in some situations, including very early-sown crops and where green-bridge management is poor.

Regional aphid data is drawn from the Rothamsted Insect Survey suction-trap network and a Northern Ireland trap operated by the Agri-Food and Biosciences Institute.

Virus screening over several autumns has found that around 20% of aphids carry BYDV on average.

The model also uses historic, current and nine-day forecast temperature data, as well as information on pyrethroid persistence and the diminishing returns from repeat sprays.

Growers only need to enter a small number of field-specific details, including location, crop type, sowing date and whether the field is surrounded entirely by arable land.

Default values are included for plant population, expected yield, grain price and insecticide costs, but these can be replaced with farm-specific figures.

The tool can also take account of whether a farm receives Sustainable Farming Incentive payments for avoiding insecticide use.

For spray decisions, the system compares the likely value of yield losses against the cost of treatment and indicates when the next decision point is reached.

AHDB said autumn remains the most important period for management, with the strongest predictions applying to autumn sprays, particularly the first treatment.

The sowing-date assessment allows growers to compare the effect of drilling earlier or later than their usual target date.

Later drilling can significantly reduce BYDV risk, according to AHDB.

The organisation stressed that the tool should be used alongside local knowledge rather than as a standalone decision-maker.

The free tool is available on the AHDB website from midday on 18 August, with growers able to enter individual field details to generate spray and sowing-date assessments.