A swing towards warmer, humid weather has increased the risk of potato blight infection in some regions, according to the British Potato Council (BPC). Several new outbreaks across Great Britain have been reported since June 13.

“Whilst the total number of outbreaks reported in 2005 is lower at this stage than in the previous two years, recent blight incidences have been reported in north Wales, Yorkshire, Lincolnshire, Suffolk and Scotland,” said the BPC’s Mark Prentice. He urges regular visits to the blight mapping website www.potato.org.uk/blight for up-to-date regional reports.

Adas’s Nick Bradshaw comments that while routine spray programmes are being maintained, some are being stretched longer than seven days. “There are also reports that cheaper protectant fungicides are being used. This may need to change,” he warns.

With rapid haulm growth and canopy development resulting from the warm soils, Nick Bradshaw notes that spray volumes may need adjusting to achieve optimum spray coverage. “This is just as important as fungicide choice,” he said.

Now planting is largely complete he adds that it’s opportune to clear stores and dispose of last year’s crop remnants, paying particular attention to primary inoculum sources. “Where haulm growth has been taken out on waste piles, these should be checked for re-growth and treated again as necessary.”

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