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.