Rothamsted Research has confirmed that the virus yellows prediction for the 2021 sugar beet crop remains very low, with first flights of aphids likely to be six weeks later than last year.
As a result the economic trigger for treating seed with Cruiser SB (thiamethoxam) has not been met.
The Rothamsted virus model, which is used to predict the proportion of the crop which will be infected by virus yellows at the end of August shows the cold weather has had a significant impact on overwintering aphid populations, both reducing their numbers and delaying the date of their migration into the 2021 crop.
The March 1 forecast predicts that 8.37% of the national sugar beet area will be affected by virus yellows by the end of August 2021.
The forecast also predicts that the date of first aphids arriving in crops will be from the May 18. This is much later than when aphids were first recorded in crops in 2020 which was in late March.
BBRO said: ‘Clearly, the cold weather has had a significant impact on overwintering aphid populations, both reducing their numbers as well as the date of their migration into the 2021 crop. This is a very similar national forecast to that in 2018. Aphids were first recorded in crops in late May 2018. This is very welcome news for crops in 2021.’
Cambridgeshire grower and NFU sugar board member, Tom Clarke says: "This is fantastic news and shows that a cold winter is by far the best way to reduce the risk of virus yellows.
"It also proves that we were only asking to use the neonic seed treatment as a very last resort. We volunteered the tightest rules for our emergency authorisation, and while UK homegrown sugar will be neonic-free again this year, nearly all imported sugar will be grown using neonics or other banned chemicals. British consumers can buy homegrown sugar knowing it is the greenest choice."
Peter Watson, British Sugar Agriculture director says: “It is welcome that the emergency situation that our industry saw in 2020 is not likely to be repeated in 2021. Growing the crop without the neonicotinoid seed treatment as a result of the freezing weather is the best outcome.
“The application for emergency use of the seed treatment was just that – we committed to only treat the seed if the risk to the crop was significant. We have followed the science, using a proven model that has been in place for over 55 years, and minimised impact where possible. We will continue to work to progress our plans to tackle virus yellows without the need for neonicotinoids in future years.”