Sugar beet varieties that are resistant to beet cyst nematodes rather than just tolerant are being developed by Syngenta Seeds.

The first, Sanetta, has been put into BBRO/British Sugar trials this year, and follows the recommendation of Sentinel, a beet cyst nematode-tolerant variety, on the 2010/11 NIAB/BBRO Recommended List.

Resistant varieties should help growers reduce beet cyst nematode populations as well as maintain yields in infested land. Tolerant varieties maintain yields, but do not help with population control.

Sanetta is one of the varieties sown into sites in Norfolk where there is a high level of beet cyst nematode infestation, Colin Walters, agricultural research and communications manager at British Sugar told Farmers Weekly. “But it is only year one of the trials.”

Sanetta worked by preventing the nematode from going through the breeding cycle of the plant and multiplying, whereas tolerant varieties only limited the pest’s effect, Mr Walters explained.

The variety has to be approved for inclusion on the RL before it can be sold commercially.

Joakim Herrstrom (pictured), breeding project leader for Syngenta Seeds, Sweden, revealed the trials on Sanetta at a press briefing near Peterborough on 13 May.

Speaking about beet in his country, Mr Herrstrom gave a glimpse of how the market could be shaped in the UK over the coming years.

He said 45% of the Swedish 2010 sugar beet crop had been sown with varieties which had combined beet cyst nematode and rhizomania tolerance.

But using a nematode-resistant sugar beet variety was the only possibility for growers to actually lower nematode populations, he said.

That didn’t mean growers had to use a beet cyst nematode-resistant variety every time beet was grown in the rotation, however. Using a combination of both resistant and tolerant varieties would enable growers to continue with the crop by keeping infestation levels down to manageable levels, he explained.

Two beet cyst nematode-tolerant varieties, Sentinel from Syngenta and KWS’s Annouschka have been added to the RL for next season’s crop. Both are also tolerant to rhizomania.

Syngenta Seeds’ UK crop manager Richard Powell said Sentinel would offer growers an affordable answer to beet cyst nematode.

It had showed good results compared with the leading non-beet cyst nematode tolerant RL control variety, Bullfinch, in trials carried out by Armstrong Fisher in Norfolk last year.

In areas of the field where no symptoms of beet cyst nematode infestation were observed, the adjusted root yield from Sentinel was 77.8t/ha compared with Bullfinch’s 71.8t/ha – a £180/ha financial benefit versus the control.

But in infested areas, Sentinel gave 69.7t/ha compared with 37.5t/ha for Bullfinch – a financial benefit of £966 per hectare versus control.