A rapid and reliable method for monitoring the sensitivity of Sclerotinia sclerotiorum to boscalid

Boscalid is a new fungicidal compound registered against Sclerotinia sclerotiorum in different crops in several European countries. For a sustainable use of this compound, the sensitivity of the target pathogen has to be observed. A mycelial growth test in tissue culture plates with liquid YBA medium was developed for a rapid and reliable sensitivity determination. Isolates never exposed to boscalid and field isolates from oilseed rape and beans, which had been isolated after boscalid market introduction and mainly from fields with boscalid treatments, were monitored for their sensitivity. All isolates were totally inhibited within 1.0 mg active ingredient/l. The frequency distribution of the ED50 values was similar both for those isolates which had never been exposed to boscalid and for those isolates collected in 2006.