Controlling the spread of white mould in cabbages

Sclerotinia sclerotiorum, the fungus responsible for white mould, spreads via the soil and airborne spores. Speedy action is required

- Bill Kerr.

The fungus Sclerotinia sclerotiorum attacks a number of plant species, causing the disease white mould. Although currently not common in cabbages, it is highly destructive when it does appear, so care should be taken to prevent it from landing up on the crop in the first place or, if required, from spreading further.

The fungus is unlikely to enter the crop via seed, yet it can happen. Because of this, certain countries (such as Zimbabwe) require phytosanitory certificates declaring that imported seed is free of the fungus.

S. sclerotiorum is often seen in beans and sunflowers, with the fungus attacking the root system of the latter. A client of mine once bought a parcel of land from his neighbour, and experienced an outbreak of white mould on his cabbage crop. Only afterwards did he discover that the land had been planted to sunflowers prior to the sale!

LIFE CYCLE 

The fungus manifests as a white cottony mass, or mould, which usually starts on one side of a cabbage, then spreads over the entire head.