AHDB launches a new online Barley Yellow Dwarf Virus (BYDV) tool, to give farmers better control over virus-spreading aphids in winter wheat and winter barley.

The web-based tool is the result of AHDB-led levy and industry funded investment of over £500,000 over the last 10 years, with most of the research led by independent agricultural and environmental consultancy ADAS.

It is designed to turn years of levy funded research into practical, field-level guidance, helping growers manage BYDV risk while avoiding insecticide applications where the evidence suggests they are unlikely to pay.

Underpinned by decades of aphid biology science, virus epidemiology and computer modelling, it considers many more risk factors than the long-established temperature-based (T-sum) tool.

As well as helping growers make spraying decisions, the new tool also shows how drilling dates affect the risk of BYDV.

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.

“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.”

Built on years of research

The tool is powered by a model trained on the bird cherry-oat aphid, now recognised as the most significant BYDV vector across the UK in most situations. (Exceptions include crops sown very early, and those where there is poor green-bridge management, where grain aphids can also be problematic).

The new BYDV tool uses regional data on bird cherry-oat aphid numbers (historic and actual) from the Rothamsted Insect Survey (RIS) suction-trap network and a suction trap in Northern Ireland run by Agri-Food and Biosciences Institute (AFBI). Based on virus screens over several autumns, about 20% of aphids carry BYDV on average.

The model uses this historical data to determine aphid infectivity levels but replaces this data with regional virus estimates during the season.

The use of aphid data is a major advance over the T-sum tool, which assumes that virus-carrying aphids are present at crop emergence or after a spray.

The BYDV tool also automatically uses many other inputs, such as historic, actual and forecast temperature (for the next nine days) data, as well as information on pyrethroid insecticide persistence and the diminishing returns associated with follow-up sprays.

Practical and easy to use

During 2026, AHDB worked closely with farmer groups to ensure the tool is practical, intuitive and effective.

To obtain an assessment, users need only enter a small number of farm-specific details, including field location, crop type, sowing date and whether the field is surrounded exclusively by arable land.

The tool also includes default values representing typical UK cropping situations, covering factors such as plant population, expected yield, grain price, insecticide treatment costs and whether the farm is receiving Sustainable Farming Incentive (SFI) payments for not using insecticides. Growers can replace the defaults with field-specific values to generate a more tailored assessment.

Supporting spray and sowing decisions

The tool’s spray assessment indicates the date when the next spray decision is needed.

This is based on the economic threshold, which is the predicted point at which the cost associated with yield loss equals the treatment cost.

The tool predicts infection impacts for several weeks, with the autumn particularly critical for management.

The predictions are strongest for autumn-applied sprays (especially the first spray), but the tool also indicates risk during winter (when colder temperatures reduce crop-infection events).

The tool’s sow-date assessment reveals how BYDV risk could change when crops are drilled earlier or later than the farm’s standard target sowing date (drilling later can significantly reduce BYDV risks).

The free BYDV tool can be found on the AHDB website from 12 noon on Tuesday 18 August: ahdb.org.uk/bydv