Sclerotinia sclerotiorum and Sclerotinia minor

Fungal Disease

White mould, caused by Sclerotinia sclerotiorum and Sclerotinia minor, is a fungal disease affecting a variety of crops and weeds. It’s resilient, surviving in the soil for years without a host.

Key Points

• Symptoms:

  • Water-soaked areas that develop fluffy white mould.
  • Black sclerotia (fungal structures) form—S. sclerotiorum produces rice-grain-sized sclerotia; S. minor produces smaller, rounded ones (0.5–2 mm).
  • Infected stems become bleached and stringy; lesions can spread, encircling stems.
  • Advanced infection can lead to wilting, lodging, and plant death.

• Spread:

  • Spores (ascospores) are released from apothecia—small, tan, cup-shaped structures (3–6 mm in diameter).
  • Ideal conditions for apothecia development:
    • Moist, cool soil (below 20°C).
    • Dense crop canopy, especially during flowering stages.
  • Infection thrives with temperatures lower than 29°C and frequent moisture (rain, fog, dew).

• Risk Factors:

  • Early canopy closure due to narrow row spacing, high plant populations, and dense canopy crops.
  • Fields with a history of white mould and susceptible crops in rotation are at higher risk.

• Management Tips:

  • Rotate crops to break the disease cycle.
  • Manage canopy density through row spacing and plant population control.
  • Monitor soil moisture and temperature conditions, especially in susceptible fields.

By understanding the lifecycle and favorable conditions for white mould, proactive management can significantly reduce crop losses! Let me know if you’d like to adjust anything.