Crop Clinic

Look out for bleached lesions on the stems. Botrytis is associated with a grey fungal mould. Sclerotinia is associated with a white fungal growth and black fungal bodies inside stems.

 

The upper part of the stem will die-back for both these diseases.

We suspect windy but wet weather has caused damage to stems and allowed botrytis to infect crops. 

Wet weather at flowering is a risk factor for sclerotinia, since the fungus infects petals and these petals stick to the stem in wet weather allowing sclerotinia to attack the stem.

Crops most at risk for both diseases are those grown on short oilseed rape rotations.

Mid flowering fungicides for sclerotinia can reduce the risk of botrytis, but systemic fungicides appear to be more effective against botrytis this season.

Sclerotinia poses the biggest long term risk, since the fungus can remain in the soil for many years (i.e. 10+).