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Ministry of Agriculture, Food and Rural Affairs

Sooty Mould

Sooty mould on shoot Sooty mould on underside of leaf Sooty mould on pears Sooty mould on pear
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Beginner

This pest affects:

Pear

Scientific Names
Sooty mould is caused by a complex of fungi including Cladosporium, Aureobasidium, Fumago, Antennariella, Limacinula, Scorias, and Capnodium.

Identification
Leaves, shoots, fruit

  • Black velvety coating
  • Easily removed by rubbing
  • Only found on honeydew produced by large populations of sap-feeding insects
  • When only a few insects are present on host plants excreting only a small amount of honeydew, sooty mould appears in spots. When insect secretions are abundant, the surfaces of leaves and fruit might have a near-continuous coating of the black, tissue-paper-thin, sooty mould

Trunks

  • Pear trees with past problems of excessive honeydew characteristically have black bark due to the sooty mould.

Period of Activity
When psylla populations are high.

Scouting Notes
Sooty moulds are more common under warm conditions and prefer an acidic environment for their growth.

Thresholds 
No thresholds for treatment for sooty mould, just for psylla.  Tolerance for fruit marking is very low.

Advanced

This pest affects:

Scientific Names
Sooty mould is caused by a complex of fungi including Cladosporium, Aureobasidium, Fumago, Antennariella, Limacinula, Scorias, and Capnodium.

Identification
Leaves, shoots, fruit

  • Black velvety coating
  • Easily removed by rubbing
  • Only found on honeydew produced by large populations of sap-feeding insects
  • When only a few insects are present on host plants excreting only a small amount of honeydew, sooty mould appears in spots. When insect secretions are abundant, the surfaces of leaves and fruit might have a near-continuous coating of the black, tissue-paper-thin, sooty mould

Trunks

  • Pear trees with past problems of excessive honeydew characteristically have black bark due to the sooty mould.

Biology
Sooty mould attacks many plants and is most common on pear, although it can affect all tree fruits and tree nuts as well as ornamental plants.

The fungi causing sooty mould live on the surface of plant parts. They are dark-pigmented fungi which are nonparasitic, saprophytic, and superficial on plants. They survive the winter on the surfaces of trunks and limbs.  When temperatures rise in the spring, they resume growth. Spores are spread to green tissue by air currents, rain wash or rain splash. Spores land on a leaf or fruit upon which a layer of honeydew has been deposited by sap-feeding insects such as pear psylla or Comstock mealybug.  Using the sugary honeydew as a food source, the sooty mould fungi begin to grow on the plant sugars deposited by insects upon foliage, turning the surface various shades of black.

When sooty mould occurs on the leave, it also reduce photosynthesis.

Period of Activity
When psylla populations are high.

Scouting Notes
Sooty moulds are more common under warm conditions and prefer an acidic environment for their growth.

Thresholds 
No thresholds for treatment for sooty mould, just for psylla.  Tolerance for fruit marking is very low.

Management Notes
Control is directed against the insects producing the honeydew, primarily psylla. Some of the fungicides applied for scab control may have some effect on sooty mould as well.

Some information from above was excerpted from: