MORE THAN twice as many new rhizomania affected fields were spotted from the air last summer than the previous record set in 2001.
But the virus disease is no longer the big threat to UK growers it once was, as resistant varieties yield as well as conventional types.
Indeed, new varieties in NIAB trials and destined for the Recommended List in 2006 will out-yield most susceptible types, says Mike Asher of Brooms Barn Research Station.
Last summer the industry-sponsored aerial survey, which over-flew 80% of UK beet fields, detected 154 new affected fields on 153 farms. Most of them were in East Anglia, but there was also a big rise in Lincs, Notts and South Yorks.
“Disease development and the appearance of symptoms in 2004 were encouraged by a warm spell in late May followed by a generally wet summer,” Dr Asher says. “Widespread use of Gaucho also made detection easier, as symptoms were not masked by virus yellowing.”
There was concern that new cases of the more aggressive “P” strain of the virus would be found, which might overwhelm resistant varieties. Despite checking 300 suspect fields no new outbreaks were found. Only two outbreaks have so far been confirmed in the Norwich area.
Resistant varieties for use this spring yield as well as most conventional types, but fall short of the highest yielders Dominika and Cinderella by 2-3%. Further performance improvements are coming for 2006 as most of the highest yielders in NIAB trials are rhizomania resistors.