15/02/2011image expired

A strain of rhizomania that can affect previously resistant varieties of sugar beet, found around Woodbridge in Suffolk, is spreading with infections in Norfolk and Essex. The strain, identified in 5 fields in East Anglia in 2009, has since spread to more than twice that number. In UK conditions the rhizomania strain can decrease root weight by 50-60% and reduce sugars by 4%. While the effects are not so drastic in resistant sugar beet, bred with wild beet species for increased resistance, these varieties still lose 1% of their sugar when infected with the virus.

The first symptoms that usually alert growers to rhizomania infection are leaves of small patches of beet showing pale green symptoms around late July to August. Often petioles of infected beet become extended, making the plants appear more upright. Affecting fields in localised epidemics, the aggressive rhizomania has decreased yields by up to 40%. Plant pathologist Mark Stevens has said analysis of the virus has revealed it to be a modified version of the "A" strain commonly found in the UK, not the more aggressive "P" strain.