Web integration of a model for Barley yellow dwarf virus (BYDV) risk assessment in cereals

Aphids can transmit barley/cereal yellow dwarf viruses (BYDV) to cereals. Pyrethroid insecticides are often used to manage the principal aphid vectors (bird cherry-oat aphid and grain aphid), especially during autumn, which is the main period for virus transmission.

However, an overreliance reliance on pyrethroids is not sustainable. UK grain aphids are already associated with moderate levels of pyrethroid resistance. Every spray increases the risk of selecting for stronger or new forms of resistance in aphid vectors.

The industry needs a reliable system to indicate when cultural control approaches should be considered and when a spray is likely to be economically worthwhile to help minimise the overall use of insecticides.

An AHDB project (concluded in 2024), developed a decision support system (DSS) that models aphid population dynamics, BYDV epidemiology and risk.

The model provides:

1. A cultural control DSS to assist risk-based decisions ahead of drilling
2. A spray support DSS to guide spray decisions after drilling

The model considers many variables relevant to BYDV management, such as drill date, aphid pressure, the proportion of aphids carrying virus (viruliferous aphids), varietal tolerance and crop economics.

The model outputs showed a very good correlation with BYDV symptoms in surveys of untreated crops. Using the model to time sprays provided effective control of BYDV in field trials (although BYDV pressures were generally low).

This project will create an application programming interface (API) to facilitate the development of software solutions based on the model.

Initially, a web-based decision support system for farmers will be developed by the AHDB digital team.

The project will also refine model parameters to improve field accuracy. For example, the model will be improved to consider weekly data on viruliferous aphids (rather than seasonal averages) and account better for multiple spray recommendations. It will also consider more economic factors in breakeven spray calculations, such as the no-insecticide payment option in the Sustainable Farming Incentive.

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This research project was funded via a levy-payer-led commissioning process.