SCRI researcher Dave Cooke told last month's Potato Council Blight Forum in Peterborough that the more aggressive A2 Blue 13 strain now accounts for most of the UK population of the Phytophthora infestans pathogen, according to Potato Council surveys.
"Its onward march is really quite clear," Cooke said. "Testing in 2008 showed it now represents 80 per cent of the blight population, up from 70 per cent the previous year." He said the regional variations had disappeared and Blue 13 was dominant over the whole of Britain.
Potato Council knowledge transfer manager Rob Clayton said the Blue 13 strain could operate at lower temperatures than the strains growers had been used to.
"If blight is earlier, late season control is even more important. When we lose sulphuric acid as a desiccant - which has some blight control properties - growers will be reliant on fungicide programmes, which bring resistance management and residues implications."