Taking the fight to virus yellows

The earliest understanding of beet yellows virus (BYV) goes back about 90 years, but it was not until the early 1950s that the aphid species responsible for transmitting the virus were identified, Strube’s managing director Richard Cogman explained.  

Since that time and up to the early 1990s, controlling aphids with foliar insecticides was our primary line of defence against a virus that had the potential to reduce yields by almost 50%.  

Again, in the 1950s, another less yield-impactful virus was identified, commonly known as beet mild yellows virus (BMYV). In the 1980s to 1990s, a new virus was discovered, formally named beet clorosis virus (BChV) in 2002 – giving growers the three-virus complex we face today.  

“The ability for the aphid population to adapt and develop almost complete resistance to insecticides was of significant concern, and therefore the introduction of neonicotinoid (NNI) seed treatment offered growers and the beet sugar industry almost season-long aphid control.  

“The ban on this chemistry from 2019 due to environmental concerns left a void that returned us to foliar insecticides requiring frequent crop inspections to support timing based on aphid threshold,” Mr Cogman said.  

The very high incidence of virus yellows in 2020 was valued at over £65 million, equivalent to c. 25% yield loss, leading our industry to seek Emergency Authorisation to use NNI on a risk-managed basis using the Rothamsted Research model. 

This successfully permitted the use of NNI seed treatment between 2022 and 2024 with c. 60% uptake each year. With the loss of this option, looking to the immediate future, well-managed aphicide sprays and varietal tolerance to viruses will be our defence options.  

Anticipating that the reliance on NNIs was under threat, Strube actively commenced breeding and field trialling for virus yellow tolerance in 2015.  

This research focus and investment are now delivering the first generation of virus yellows tolerant varieties to growers. 

ST Tweed for virus yellows tolerance  

Results from the 2024 BBRO Goliath trial showed Strube’s ST Tweed to be highly tolerant to poleroviruses; BChV and BMYV, when compared to the controls. 

It is well documented that the poleroviruses can reduce yield by c. 24% to 27%, and this risk is increased by their greater prevalence in recent years when compared to the closterovirus BYV, which is generally more fluctuating.  

Whilst Strube’s variety Morgan delivered the highest yield and performed well overall, ST Tweed retained c. 88% and 95% of its yield against 100% inoculation of BChV and BMYV. This demonstrates ST Tweed’s tolerance to both viruses, the company said.  

ST Tweed offers a high level of protection in conjunction with aphicides applied at threshold, before the crop reaches ‘mature plant resistance’ at the 12 to 14 leaf growth stage.  

Furthermore, ST Tweed is very low bolting and has an excellent canopy health, scoring 8 out of 9 for Cercospora (2026 RL) and is also better than average for rust and powdery mildew. 

Strube Varieties for 2026 

In addition to ST Tweed, Strube UK offers Morgan, which is proven to be a reliable and consistent performer.  

Button is again well proven and best suited as a Beet Cyst Nematode (BCN) tolerant variety where it gives its best performance. The RL yield data is in the absence of BCN.  

Seed treatment and packaging

Strube’s ‘3D+’ prime, pellet and seed pack was commercially available for the first time in 2025, attracting new market share. This proven and constantly improved prime and pellet combination matches the Germains Enrich product for performance.  

These prime and pellet seed treatment options will be available again for growers to choose from in 2026. Additionally, a number of growers who tried our ‘3D+’ this spring commented favourably on the seed packaging and its ease of use in the field. This will remain unchanged for 2026. 

Looking to the future 

Following the recent acquisition of Strube by the RAGT Group, the company will have greater capability arising from increased investment and resources into sugar beet breeding.  

Over the next 10 years and beyond, growers can expect to see further significant progress to support yield stability from pest and disease pressure through resilient genetics and the combination of multi-tolerance traits.  

This will be the direction of our candidate pipeline into trialling for national (now VL) listing, then RL listing and commercial reality, breeding progress together.

Read more on Strube’s varietal offers.

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