Factors that increase the risk of sclerotinia development in a field:
- Sclerotinia present in area previous year
- Sclerotia needs 10 days of moist soil conditions (above wilting point) in order to develop apothecia
- High density of crop canopy
Infection
Sclerotia can overwinter in canola stubble. In wet conditions, and temperatures between 15-25 degrees, sclerotia develop into apothecia that will produce spores. The spores are released and are carried by wind onto petals of the flowering plant. The infected petals fall onto the lower portions of the plant canopy where hyphae spread through the contact point. They then form a sclerotia body in the stem or branch, cutting off the nutrient supply to the plant. This turns the branch above the infected area white and kills that part of the plant. When the main stem is infected the whole plant will die. In thicker stands or stands with lodging, stem to stem transference of Sclerotinia will greatly increase the field infection rate.
Timing and Staging
The application window for fungicides is in the 20%- 50% flowering stage. However for optimal performance fungicides should be applied at the 20% – 30% flowering.
- 10% flower is reached approximately four days after first flower, with an increase of roughly 4% each following day.
- 20% flower is reached approximately 7 days after first flower.
Products available:
BASF: Lance 20 acres/ jug
Bayer: Proline 40 acres/ jug
Syngenta: Astound 20 acres/jug
Dupont: Vertisan 20 acres/jug