Carrot growers can assess the disease risk of sclerotinia in their crops this season by logging on to a new internet monitoring system.

Growers and advisers can log on to the ADAS/BASF sponsored carrot sclerotinia germination tool at www.agricentre.basf.co.uk to assess their disease risk and plan an effective, preventative disease control programme.

The system monitors patterns of germination each week and indicates the extent of disease risk and the need for fungicide treatment.

Peter Gladders, from ADAS Boxworth, says carrot crops are vulnerable to infection by sclerotinia from June to October when the resting bodies or sclerotia germinate.

“Sclerotia germinate when the soil is moist and soil temperatures are 10C and above,” Dr Gladders explains.

“We barely reached this temperature until late April, but in oilseed rape where sclerotia germination of sclerotinia has been monitored since mid-March we have been finding more germination than last year.”

Dr Gladders says early cold conditions this season have not slowed the activity of sclerotinia.

In one location germination of sclerotia reached 54% and petal tests have shown over 74% sclerotinia infection.

Dr Gladders explains that the sclerotinia fungus invades diseased, senescing or decaying leaves of the carrot crop, particularly those in contact with the soil.

“Roots are infected via the leaf petioles and through the crown. So starting the control programme before the canopy closes over is advisable.”

Robert Storer, field vegetable product manager for BASF, agrees timing is key to successful prevention of sclerotinia in carrots.

He recommends BASF’s fungicide Signum (boscalid + pyraclostrobin) for disease control at the first signs of sclerotinia and other diseases in carrots, including alternaria and powdery mildew.