BLIGHT RISK continues to remain high across the country, according to the latest British Potato Council reports.
Twice as many outbreaks have been confirmed so far this season compared to last year (77 versus 40) and cases have been scattered across the country and within fields, the BPC said.
The scattered nature of infections indicates there is plenty of airborne inoculum around, said ADAS’s blight expert Nick Bradshaw.
“From now on it would be a wise precaution to incorporate fungicides with activity against tuber blight into spray programmes.
“Foliar blight does not need to be severe to result in substantial amounts of tuber infection.”
Crops should be monitored closely and spray intervals kept tight (seven days), as close as possible to lifting, he advised. Particular attention should be paid to areas around obstacles such as pylons and at row ends.
“A number of blight outbreaks at row ends have been associated with the use of low drift nozzles where output pressure is automatically linked to sprayer speed. This results in a very coarse spray at row ends which has allowed blight in.”
While there is a range of products available with zoospore activity (the main infection route for tuber blight), it is important to alternate between them to reduce the risk of resistance development, added Bayer CropScience’s Eileen Bardsley.
Growers can monitor the localised blight threat via the BPC’s blight mapping programme, available at www.potato.org.uk/blight