New rhizo resistance-breaking strain spreads into north Norfolk

‘Closing the gap’ between potential and actual delivered yield was the theme of the 2012 British Beet Research Organisation’s annual winter conference at the East of England showground. Teresa Rush reports from Peterborough.

Results from the 2011 BBRO rhizomania survey reveal the AYPR resistance-breaking strain of the disease has now spread to North Norfolk, Dr Mark Stevens, of Broom’s Barn Research Centre, told the British Beet Research Organisation’s winter conference.

Of the 30 rhizomania outbreaks confirmed following last year’s survey, many were of the standard strain but there were also further identifications of the AYPR resistance breaking strain and a slight varian, AFPR, in the traditional Woodbridge/ Orford hotspots and in the Thetford area for a second season, together with a new outbreak in North Norfolk.

Root weights

“We are used to seeing root weights down by 60-70 per cent with the AYPR strain and sugar down by up to 4 per cent. And that is certainly what we saw in North Norfolk,” he said.

Root yields were down by 60 per cent and sugar 3 per cent in the small patch of crop that was affected. Standard resistant varieties continued to protect against most rhizomania strains in the UK, said Dr Stevens.

The new strain, however, was continuing to spread in East Anglia so growers need to be vigilant. Breeders were developing new varieties with enhanced rhizomania resistance, added Dr Stevens.

BBRO’s 2011 rhizomania survey

  • Over 85 per cent of beet area growing rhizomania-resistant varieties
  • Sampling concentrated on susceptible varieties and potential resistance breaking strains
  • Dry weather in spring 2011 was not favourable for rhizomania development
  • 30 samples received
  • 28 of those were rhizomania positive
  • In two remaining cases, symptoms were attributed to beet cyst nematode

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