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Black or Sooty Mould

Sooty mould, categories 0-5 & Sooty mould on wheat ear (Photo C. Lincoln)

Pathogen

Fungus

Hosts

Wheat

Symptoms

Ears become discoloured late in the season by the growth of sooty black mould. They are easily distinguished from powdery mildew or glume blotch on the ear. Their appearance is often patchy and associated with previous crop stress or damage or aphid infections which have left deposits or honeydew on the crops. Black moulds only invade dead or senescing plant tissues.

Development

Airborne spores from dead or dying material act as the source of inoculum. Once an infection is established it can spread from ear to ear through the standing crop.

Favourable factors

Cool, wet and humid conditions from ear emergence onward. Plants that have already been affected by disease, drought or aphid infestation are predisposed to attack.

Importance

The effect on yield is not dramatic but quality is substantially reduced with a shrivelled, dull and dirty sample. Germination, importance for seed crops or brewing grains will be impaired. The thousand grain weight will be reduced indicating the amount of shrivelled grain. If the infected grain is not dried properly, hot spots can be formed in the grain stores reducing quality even further. Generally only a problem in stored grain but the inoculum arises from grain which is infected during ear ripening.

Control

Fungicides can offer some degree of reduction or control.