Some sugar beet varieties like Carissima and Rosalinda coped much better with last winter’s cold weather than others – like Aimanta and Cheetah – that suffered extensive damage, according to new trial results.
The past winter saw extreme cold temperatures in December, followed by a mild and wet January. This resulted in an estimated 1.95m tonnes of unprocessable beet that had to be ploughed in.
New results from a British Beet Research Organisation (BBRO) trial revealed huge varietal differences, with certain varieties showing up to 40% root damage, making them unprocessable, while others had less than 10% damage and no evidence of the gum-like dextran, a substance which blocks sugar filtration in the factory process.
But plant breeders have urged growers to treat the latest BBRO information on varietal differences to frost damage with caution, as it came from one trial at Broom’s Barn in Suffolk.
The trial was originally established to compare varietal differences to rust susceptibility, pointed out the British Society of Plant Breeders Sugar Beet Crop Group, which represents all the sugar beet breeders.
“There’s been huge variability in varietal performance across trials and commercial crops this year, after what is now recognised as the worst December for 100 years,” said the group in a statement.
Pam Chambers of the BBRO added: “It is simply information of interest, which has come from a single trial conducted in one year.”
The coldest temperature at the Broom’s Barn site was -10C, which was recorded on 20 December, she reported. “Obviously in some beet growing areas, such as north Lincolnshire, it was much colder. So there might have been more damage done to crops there.”
Furthermore, reaction to frost was complex, with weather and other local factors affecting variety responses, she said. “We can’t make recommendations on any variety’s ability to withstand frost because these results aren’t transferable to other situations.”
However, it suggested that genetic sources for better frost tolerance might exist, with the BBRO considering new work to look at the genetic and management factors that contribute to frost effects, she says.
Ian Munnery, sugar beet manager for Elsoms, pointed out that every variety carries the risk of frost damage in every year, but it can be minimised by having good leaf cover.
“This particular site was originally a rust trial, so it was only sprayed for mildew. As a result, it suffered from leaf damage, which allowed the frost to penetrate. Having top cover is very important for protection.”
The chances of a one-in-100-year event happening again soon are very low, he added. “It’s another reason why we shouldn’t put too much emphasis on the findings.”
A two-spray programme can help limit frost damage by preserving green top cover, as can the use of a higher seed rate, he believes. “Gaps in crops allow the frost to get in. There’s no substitute for rigorous field monitoring, as we simply don’t know what the weather’s going to do.”
Simon Witheford of KWS agreed the results could be more to do with leaf retention than frost tolerance.
“Some of the least damaged varieties in the Broom’s Barn work have superb disease resistance ratings. Rosalinda, for example, has rust and mildew scores of seven and nine, and came second in the work.”
This is backed up by anecdotal farm evidence – crops that were recoverable after the cold spell were those which had sheltered protection from good leaf cover, he says.
• For more on this winter’s sugar beet crisis, see www.fwi.co.uk/sugarbeetcrisis