EARLY EMERGING oilseed rape crops are at risk from exceptionally early phoma spore production, growers have been warned.

Heavy rain this harvest have triggered the early phoma risk, said ADAS disease pathologist, Dr Peter Gladders.

Infection at the cotyledon stage can kill plants he warned.

“Growers must monitor emerging crops regularly for first signs of phoma leaf spotting.

“Infection can spread very quickly on small leaves in warmer early autumn conditions. Prompt action will be vital,” he stressed.

The warning follows reports by the Syngenta Phoma Advance Warning System (SPAWS) that aerial phoma spores have already being discovered in ADAS monitoring traps in Yorkshire – 4-6 weeks earlier than normal.

“Growers have 10 to 14 days from spores landing on new crop leaves to prepare fungicide programmes for when phoma leaf spots first appear,” added Dr Gladders.

Large tracts of rape stubble still uncultivated or even abandoned in the north of England and Scotland had exacerbated the phoma risk, he believed

“Burying or ploughing-in trash will be even more important this season.

“It is crucial growers get the new crops established and growing well to minimise the effects of phoma infection and create a bigger target for more effective fungicide applications.

Growers may need to rethink seed rates if there‘s a high risk of seedling losses to phoma.”