25 September 1998

Outbreak of rhizomania strikes resistant variety

RHIZOMANIA has been confirmed on four new sugar beet farms this year and resistant variety Ballerina is apparently succumbing to the disease. Two fodder beet crops have also been infected.

Five of this seasons outbreaks to date have occurred in Ballerina, the only rhizomania-resistant variety allowed to be grown on non-infested fields on known outbreak farms.

"This is disappointing, but growers who have suffered rhizomania should still use Ballerina on clean fields," says rhizo-expert Dr Mike Asher of IACR Brooms Barn, Suffolk. "If a susceptible variety had been grown where infection occurred in the resistor it would have been far worse."

Although Delitzschs Rosanna and KWSs Rebecca have resistance from the same source as Ballerina, both yield better. Due for NIAB consideration in February, they could be commercially available in 18 months.

Favourable conditions for the disease mean more new cases could come to light this year, forecasts Dr Asher. "One crumb of comfort is that the virus seems to be concentrating itself in already established areas. All this seasons new cases have been confined to lightland areas of East Anglia." &#42