More than half of UK sugar beet crop could face virus yellows in 2026

Sugar beet growers face significant virus yellows pressure this season, with a new forecast warning that more than half of the UK crop could be affected.

According to the latest forecast from Rothamsted Research, 59.15% of the national sugar beet crop could become infected with virus yellows in 2026 if no control measures are taken.

The model also predicts the first aphids — which spread the disease — will begin flying on 22 April, marking a key point in the season for growers monitoring their crops.

Run independently by Rothamsted Research for more than 60 years, the model produces a scientific forecast of aphid pressure each spring using weather data from the preceding winter.

Researchers say that despite frosts in January, warmer-than-average temperatures, particularly during February, are likely to have supported overwintering aphid populations.

The projected infection level would represent one of the highest levels of virus yellows pressure faced by the UK sugar beet sector without the use of neonicotinoid seed treatments.

The industry last faced similar pressure during the virus yellows pandemic of 2020, when 38% of the national crop became infected and yields fell by around 25%.

Some growers reported infection levels of up to 80% in individual fields during that season.

With the new forecast indicating significant risk, growers are being urged to remain vigilant as crops develop through the early stages of the growing season.

Control measures may be required if crops reach the spray threshold of one aphid per four plants up to the 12-leaf stage.

Farmers will again have access to a three-spray programme in 2026 using the aphicides acetamiprid, flonicamid and flupyradifurone.

Advisers say careful monitoring and timely spraying decisions will be critical in limiting the impact of virus yellows this season.