Sclerotinia

Sclerotinia rot affects a wide range of herb crops particularly non-woody species. Coriander, fennel, mint, parsley, tarragon and basil have all been reported as hosts of Sclerotinia sclerotiorum. The infected area of a plant initially takes on a dark green or brown water-soaked appearance, then may become paler in colour. Dense white cottony mycelium usually develops and the plant begins to wilt (see photo of sclerotinia rot on the right) and eventually dies.

Resting or survival structures (sclerotia) are produced externally on affected plant parts and internally in stem pith cavities.

The sclerotia are hard, black, irregular in shape and mostly 2-4 mm in size (see right). They are difficult to see once incorporated into the soil.

Sclerotia of S. sclerotiorum germinate to produce funnel-shaped fruiting bodies (apothecia) that are approximately 1 cm in diameter.