BYDV management resources for winter cereals

Our cereal aphid monitoring activity, weather-based management tool and pest control guidance can keep you one step ahead of yield-robbing BYDV. Jason Pole explains.

Barley yellow dwarf virus (BYDV) is a complex of viruses transmitted to cereals by aphids in the autumn.

Luteovirus (genus)

• BYDV-PAV is spread by several aphids, including bird cherry-oat aphids and grain aphids
• BYDV-MAV is spread by grain aphids

Polerovirus (genus)

• CYDV-RPV* is mainly spread by bird cherry-oat aphids

In most years, aphids stop flying when temperatures drop below about 11ºC and aphid activity greatly reduces below 3ºC (with hard frosts keeping populations in check).

The efficiency with which viruses are transmitted also decreases as temperatures fall (to about 25% at temperatures under 6°C).

During the aphid-flight period, the Rothamsted Insect Survey (RIS) identifies the aphids caught in 16 GB suction traps** and publishes the results in regular bulletins (see insectsurvey.com/aphid-bulletin).

The latest bulletin (number 23 – 1 to 7 September 2025) shows that cereal aphids are active, with average air temperatures keeping the numbers relatively stable. There is a persistent, three-figure bird cherry-oat aphid hotspot at the Gogarbank suction trap site in Scotland, with double figures recorded at several other northerly sites (Dundee, Newcastle and York) and single figures at most sites further south. Numbers of grain aphid (and peach-potato aphid) are low, only reaching single figures at some suction traps. Update: In the subsequent bulletin, cooler air temperatures saw the number of aphids of major economic importance dip.

In 2018, Rothamsted Research developed a molecular method (PCR-based assay) to detect BYDV and CYDV in aphids (even at very low levels).

Since then, we have funded screens of autumn aphid catches from four suction traps across England – up to 96 aphid samples (bird cherry-oat and grain aphids) each week.

Results from previous autumns show that most aphids do not carry viruses associated with BYDV symptoms.

For example, data from the last four autumns (2021–24) reveals that the mean proportion of viruliferous aphids never exceeded 30% (some weekly results exceeded this figure).

The data also reveals over-season trends. For example, virus levels tend to be highest at sites in regions with more permanent grassland (which acts as a reservoir for aphids and BYDV).

The first set of autumn data does not tend follow the standard weekly pattern, mainly due to low aphid numbers in the initial weekly catches. As a result, the first data often pools data from multiple bulletin weeks.

The first data set (released 12 September 2025) was based on 85 aphids:

• 40 bird cherry-oat aphids (10 positive) – Data corresponds to bulletins 22 and 23 (25 August to 7 September 2025).

• 45 grain aphids (13 positive) – Data corresponds to bulletins 15 and 16 (7 to 20 July 2025).

Based on this limited data, on average about 28% of the aphids tested carried virus – mainly BYDV (PAV + MAV).

Update: Relatively low numbers of aphids were recorded in the following data set (released 19 September 2025). Cooling air temperature often results in lower numbers. However, the numbers are particularly low. It could be due to the dry conditions earlier in the year (e.g. keeping numbers low on grasses).

Updates are available every Friday.

Our BYDV management tool estimates when the second aphid generation (most associated with BYDV spread) is likely to be present, based on accumulated daily air temperatures (the temperature sum starts at crop emergence or after a spray).

The tool was refreshed at the start of September and features observed and forecast temperature data to help you time sprays this autumn.

It is being used at Strategic Cereal Farm East, alongside a pilot tool that considers more inputs (including the number of aphids and virus levels) to improve spray targeting further.

In the Recommended Lists for cereals and oilseeds (RL), we use specialist categories and described types to provide specific recommendations for varieties that have novel traits.

BYDV resistance/tolerance in cereals is a specialist trait we added to the RL in recent years (where we ask breeders to provide evidence to support their claims).

There are now several varieties (winter barley and winter wheat) on the RL with resistance/tolerance to BYDV, with more candidate varieties coming through the system (as detailed in the latest RL harvest results commentary).

The next edition of the RL is due online on 1 December 2025, which will reveal the varieties that made it on the lists.

*CYDV stands for Cereal yellow dwarf virus (it was previously called BYDV-RPV and has similar symptoms to BYDV).

**The suction trap network is funded by the Biotechnology and Biological Sciences Research Council (BBSRC).