Symptoms

  • Severe during summer months.
  • Charcoal black, grey-black, velvety, crust-like fungal coating on the surface of leaves, twigs and spikes (Image1).
  • This fungus is not pathogenic to plant's but obtains its nourishment from honeydews secreted by insect pests like aphids, soft scales, mealy bugs etc.
  • On leaves, this coat of mould screens out light and reduces the plants photosynthetic ability.
  • Coated leaves may fall prematurely.
  • Severely affected plant may be predisposed to further injury by other insects, diseases or environmental stresses.

Control Measures

  • Sooty mould can be washed off, but unless the causal insects are controlled, it will reappear.
  • To prevent sooty mould, control the insects by spraying broad spectrum insecticides.
  • Spray 1% starch solution. After drying, spray with a solution of mild soap and warm water to remove the mould.