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Botrytis (Grey Mould)

Botryotinia fuckeliana (asexual stage Botrytis cinerea)




Oilseed Rape, also found on a very wide range of crop and weed species.


Grey/fawn leaf spots or stem lesions, tissue rotting and the growth of a grey/fawn mould.


The fungus usually infects damaged stems, flower stalks or leaves during flowering. The sites of infection then sporulate and can infect all other aerial parts of the plant. Botrytis is a prolific producer of air- borne spores.

Favourable Factors

Cool, wet weather after flowering, frost damage to flower heads, fertiliser scorch to leaves or flower heads and pest damage to pods.


Potentially serious yield losses, but outbreaks have been limited in the UK.


• There are no known resistant varieties
• Avoid crop damage by fertiliser scorch, mechanical injury or pest infestation.
• Foliar fungicides for control of oilseed diseases can be effective in controlling Botrytis 

Botrytis On OSR Stem LibBotrytis on OSR stem
Grey Mould Osr A3 LibDead inflorescence caused by Botrytis
Grey Mould Osr A2 LibLeaf infection
Grey Mould Fallen Petals Osr A4 LibBotrytis developing on fallen petals

Identification and Management of OSR diseases

Find out more information on the key disease threats to your oilseed rape crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.

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