BLIGHT RISK across the country is high due to recent wet and humid conditions, potato growers have been warned.

It is vital that growers stay on top of fungicide applications and ensure spray intervals do not exceed seven days, said Nick Bradshaw of the British Potato Council’s blight advisory team.

“Blight outbreaks at this stage of the season can be very difficult to control. Where spray intervals are delayed, include a fungicide with good ‘kick-back’ activity.”

Where heavy rain occurs soon after spraying, growers should be prepared to re-spray, he added.

In Scotland the number of confirmed blight cases increased from four to five last week (w/e July 4), but more are expected, especially if warm, unsettled conditions continue, said the Scottish Agricultural College’s Fiona Burnett.

“Growers in all areas should consider the risk of blight high and keep spray intervals as tight as possible.”

This period of high blight risk has coincided with very rapid haulm growth and growers should consider matching water volumes to the size of the canopy to improve spray penetration and coverage, she said.

Both experts also urged growers to check dumps and outgrade piles where haulm growth was tackled earlier in the season and re-treat as necessary to reduce the risk of blight infection.

Potato growers should visit the BPC’s blight mapping website www.potato.org.uk/blight to keep track of the latest blight situation in their area, said Mr Bradshaw.