Sooty Mould

Sooty mould looks just like the name implies – like a layer of black or grey fireplace soot over the leaves and branches.

It might sound strange but sooty mould is actually a problem caused by sap sucking insects like aphids, scale, whitefly, mealybugs and mites. These insects exude a sugary substance called honeydew which the sooty mould grows off.  Ants will also feed on the honeydew so it is common to see ants and sooty mould together on plants.  Aside from being unsightly the sooty mould can block sunlight to leaves and reduce plant vigour in severe cases.

To get rid of the sooty mould you need to address the pest problem. Once you have that under control and they are no longer producing the honeydew, the sooty mould will dry up and flake off.

Plants Attacked
All plants can be affected by sooty mould.

Identify what sap sucking insect is present and treat accordingly. If you can’t see any pests then there’s a pretty good chance of it being:

• scale (some types are very good at camouflage) or,
• mites (very small and difficult to spot with the naked eye).

OCP eco-oil, OCP eco-neem and OCP eco-pyrethrum PLUS will all control a broad range of sap-sucking insects.  Whichever product you choose ensure good spray coverage and monitor plants closely in case follow up sprays are needed.

Once the sooty mould starts to dry and flake hosing can help to remove the flaky bits faster.

There are also various predatory insects which eat sap sucking insects but they sometimes take time to get established and bring the pests under control. If your sooty mould is severe then get on top of it quickly by spraying first.  You can learn more about beneficial insects in The Garden Guardians book.