Sclerotinia rot

Sclerotinia sclerotiorum is a highly destructive fungal plant pathogen belonging to the Sclerotiniaceae family. It is the primary cause of white mold, a devastating disease affecting a vast host range of over 400 plant species, including major crops like sunflowers, oilseed rape, soybeans, and various legumes.

The biology of this fungus is centered on the production of sclerotia, which are hard, black, resting structures. These structures act as the primary survival mechanism in the soil, allowing the pathogen to persist for many years even in the absence of a host crop, making it extremely difficult to eradicate.

Development and spread are favored by prolonged periods of high humidity and cool to moderate temperatures. In such conditions, sclerotia germinate to produce apothecia, which release ascospores into the air. These spores then land on senescing plant tissues, such as petals, initiating the infection process.

The economic impact of Sclerotinia infection is severe, often resulting in complete yield loss. The fungus produces enzymes that degrade plant cell walls, leading to soft, watery rot, rapid wilting, and stem collapse. Infected areas frequently develop a characteristic white, cottony mycelium.

Integrated management is essential for control, including:

• Crop rotation with non-host species for 3-5 years.
• Deep tillage to bury sclerotia deep within the soil profile.
• Proper weed management to reduce alternate host availability.
• Strategic application of fungicides during peak flowering stages when the plants are most susceptible.