Tag Archives: sooty mould

Sooty mould on leaf and stem

Sooty Mould

Sooty Mould; what it is and how to deal with it

What is Sooty Mould?

Sooty mould is a general umbrella term used for the growth of several kinds of funghi. Sooty mould can be found on any plant and even outdoor furniture or glass panes of greenhouses. It is identifiable by the following symptoms;

  • Sooty mould on leaf and stem– The most obvious symptom is the dark brown or black and ‘sooty’ mould spores and fungal growth that are usually found on the top side of the leaf
  • – This can be a sheet like growth that is very thick and can almost be peeled off the surface or it can be a very powdery and fine collection.
  • – Usually, sooty moulds are associated with sap-sucking animals pests such as whiteflies, mealybugs and aphids. Ants may also be found around the area.
  • – The stems, leaves and fruit of the affected plant may be found with sticky honeydew on them.

The cause of sooty mould

Sooty mould forms anywhere where there is sufficient nutrients to grow and survive. A prime type of nutrients for the fungi is honeydew. This is excreted by aphids, whiteflies, mealybugs and may other sap-sucking pests.  The sooty moulds thrive off the drops of this honeydew which lands on leaves and uses it to grow and survive. Sooty moulds will thrive in humid areas with poor circulation that often remain damp well after rain.

The affect of Sooty moulds

Whilst the plant is not under a direct threat from the Sooty Moulds however they can block the sunlight from entering the leaves subsequently reducing the rate of photosynthesis and the strength and success of the plant.

Combating Sooty Mould

Luckily, this kind of mould is generally easy to control.

To treat the problem the cause (the sap-sucking pests) must be eliminated.

Removing the mould- simple non chemical methods such as sponging the affected area with water may be enough to get rid of the growth however this isn’t the source of the problem so it may redevelop. Use lukewarm water to try and remove the honeydew as well as the mould.

To prevent the problem recurring the pests must be eliminated – we suggest using a pesticide such as;

BugClear Ultra Vine Weevil Killer (£7.50)– a 2 in 1 that both kills and prevents many pests including aphids, mealybugs and whitefly which are the predominant causers of Sooty mould. Use pesticides safely, read the instructions on the label before use.

Biological equivalents;

Neudorff NemaSprayer (£14) or Neudorff Nematodes Soluble Sachets (£14.99)