A disease epidemic project aims to communicate the incoming threat of the bacterial disease syndrome basses richesses (SBR) and its impact on sugar beet.

Although not currently present in the UK, SBR is problematic in Europe with data from the Continent suggesting up to a 5% sugar loss, with root yields reduced by 30% in infected plants.

Prof James Bell, entomologist at Keele University and project partner, explains that syndrome basses richesses is French for “sugar reducing disease” and, when combined with the threat of virus yellows, can be a real concern for growers.

See also: Video: Sugar beet harvest 2024 starts with highs of 100t/ha

Reed planthopper

The bacteria is spread by the insect vector Pentastiridius leporinus, also known as the reed planthopper.

The insect is present in the UK, but has not yet been known to infect UK sugar beet crops with SBR.

“Reed planthoppers on the Continent, however, have expanded their host range and made the switch to wheat and sugar beet etc,” says James.

Significant outbreaks of virus yellows and SBR are thought to be responsible for the major loss of sugar beet yields in 2020 in western Switzerland, which prompted calls for urgent control measures.

James Bell © Keele University

The Tackling Epidemics project, funded by UK Research and Innovation, plans to deliver a roadmap for growers, policymakers, scientists and the wider industry on how best to mitigate the disease in the UK.

“We plan to discuss methods of first detection, containment and mitigation to motivate planning and scouting for the threat of this disease,” says James.

He notes the project aims to bring the sugar beet sector together to address this issue, be it researchers, growers or crop consultants.

“It is a major challenge to identify a new disease in the UK sugar beet crop which totals 10bn sugar beet plants across 100,000ha.”

Life cycle and symptoms

The project aims to raise awareness of the disease, the plant hopper’s life cycle and the symptoms growers should look out for.

Larvae normally develop in winter wheat where they overwinter on crop roots.

In the spring and summer, once they are adult hoppers, they fly into sugar beet fields to transmit SBR by feeding on crops directly.

“Plant hoppers are related to aphids but look quite different with roof-like wings,” says James.

Symptoms include the development of asymmetric new leaves and yellowing of older leaves. 

“Similar to virus yellows, symptoms are only apparent once the crop has been infected for some time when the yellowing becomes visible during mid-summer.

“Look out for unusually long, lanceolate or wonky leaves,” says James.

Infected sugar beet roots also show evidence of deadening cells that look brown with necrosis.

If you cut open a sugar beet, this can be seen with decaying vascular root bundles which are phloem and xylem tissues.

However, James notes that to have absolute confirmation, a molecular diagnostics test is required.

The good news is that there are three SBR-tolerant varieties available on the Continent. These are Fitis, Kakadu and Josephina.

“These varieties are not commercially used in the UK as there is currently no need for them, but it puts the UK in a fortunate position going forward as this provides a useful mitigation method.”

Josephina is licensed in the UK for 2025 sowing.

A change in crop rotation, avoiding wheat, sunflowers and maize may disrupt future infestations, but more evidence is needed.

Perhaps a more realistic strategy is to use tolerant varieties if SBR establishes, says James.

“If a yield penalty is present, it’s not known what this will be in UK conditions,” highlighting the importance of the Tackling Epidemics project.