The 37_A2 blight strain saw an increase from three to 24 per cent of the sampled UK blight population in 2017.
Dr David Cooke, of the James Hutton Institute said although some of the increase may be due to increased sampling in regions where the strain is more prevalent it was still “a big jump.”
While highest incidence of the 37_A2 strain had been found on Maris Piper, it affected a range of varieties, he said. “The earliest incident was in Kent on July 19. From mid-August to October it was mainly found in the Midlands and northern England. There was nothing in the South West, East and north of Yorkshire. Scotland is free from it.”
Given that the strain has shown resistance to fluazinam, a rethink on timing and use of the active is necessary, added Dr Cooke.
The strain has also been found in tubers and he is keen to examine more tuber blight-infected samples.