BYDV management tool

Barley/cereal yellow dwarf viruses (BYDV) are mainly transmitted by the bird cherry–oat aphid and the grain aphid.

Initially, aphids colonise relatively few crop plants. When the second generation offspring are produced, these tend to move away from the plant originally colonised. Controlling this generation is a key component of a BYDV management strategy.

The timing of the second generation can be approximated by accumulating daily average air temperatures above a baseline temperature of 3ºC. It takes around 170 ‘day degrees’ (DD) for the second generation to be produced.

This tool can be used to calculate when the 170DD threshold has been reached at sites in our weather station network.

Download more information on the BYDV tool

Aphid News

Regional information on aphid numbers at key times of year is published at

Virus management in cereals and oilseeds

How to use the BYDV tool

Select a weather station site or sites (‘region’).

Use the ‘Starting Date’ slider to set the start date for temperature accumulation. This should be either:

  • When aphids are present and protection from neonicotinoid-treated seed has run out (around eight weeks after sowing)
  • On the date of emergence for other crops
  • Following a pyrethroid application (account for product persistence, see label)

Once 170DD has been accumulated, the relevant line on the chart displayed enters the yellow zone. At this stage, crops are estimated to be at an unacceptable risk and treatment should be considered.

Click Aphid Monitoring sites to reveal the latest data for bird cherry–oat aphid. 

Explore the full aphid data (sites and species)