One of the most economically important diseases affecting sunflowers

Sclerotinia survives in the soil for up to four years as irregularly-shaped fungal bodies called sclerotes. The sclerotes germinate in the spring, producing either mycelia that infect sunflower roots causing wilt or mushroom-like structures (apothecia) that release wind-borne spores that infect the other part of the plants (stem, head, flower bud)- necrotic roots on the picture.

Recognising sclerotinia

Sunflowers are susceptible to head sclerotinia attacks during flowering. Rainy conditions increase infection risk:

  • Head back becomes brown.
  • Fungus invades progressively the spongy parts and cause beige spots of rot on the head back. 
  • Then fungus grows and produces a white mycellium on the flowery part.  
  • Black sclerotes are visible inside this mycellium.  
  • At the end, the head is totally destroyed – Sclerotinia stem rot on the picture

What causes sclerotinia infections?

The staging of the sunflowers  is important for the attack intensity, with the sensitive period during the flowering:  

  • A rainy period during the beginning of flowering can highly increase infection risks.  
  • When there are lots of rain during flowering period, we observe an increase of number of cases in field. 

Disease Management for Sunflower Cultivation

HelioSMART label is the insurance to secure the yield potential under all disease pressure situations

Preventing sclerotinia

Sclerotinia infections can drastically decrease sunflower yields – up to 50%. There are however practices to help minimize the risk of infection: 

  • Use a tolerant variety to reduce the impact 
  • Avoid irrigation during flowering period 
  • Avoid a late harvest   
  • Increase the duration between sunflower crops – because sclerotes can stay many years in soil 

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