Sclerotinia and Botrytis

(grey mould)

Although often observed on the upper parts of the stem Sclerotinia sclerotiorum is sometimes found close to soil line. It causes moist, dark brown to brown lesions, covered occasionally by a fleecy white felting and white, later to become  black sclerotia (figures 1 and 2). If the sclerotia  are not present , we suggest you to place samples (altered portions of stems) in a plastic bag with wet paper, ("towel"). In case Sclerotinia sclerotiorum is responsible for lesions observed, it will soon produce mycelium and sclerotia (Figure 3) the presence of which will allow you to identify the pathogen. For further information, see the fact sheet of Sclerotinia sclerotiorum.
 
The fungus, Botrytis cinerea, behaves similarly to Sclerotinia sclerotiorum. It also causes more or less beige cankers located at  the collar or close to it (Figure 3). Those cankers are the  result of  the poor management of this fungus in the nursery. For a better understanding of this pathogen, see the fact sheet of Botrytis cinerea.