You've probably come across this plant disease somewhere in your travels. It’s called sooty mould. You see it on lots plants - natives, citrus, gardenias, ixoras to name a few. It looks ugly and it causes a lot of stress to the host plant because it blocks out the light that’s needed for photosynthesis.
So what causes it? Well it’s due to the feeding activities of sap sucking insects… like scale, aphids, mealy bug and white fly. They suck the goodness from the plant (causing additional stress) and secrete a sweet honey like residue which feeds the mould.
So to stop this unsightly sooty mould growing on the leaves of your plants, you have to control the sapsuckers. All it takes is a spray with a safe to use oil based product like a white oil. There are plenty of different products on the market, but it’s easy to make your own at home. Here’s how you do it.
Simply take an empty plastic bottle, pour in a cup of ordinary cooking oil, half a cup of water and a little squirt of dishwashing liquid. Give it a good shake - you'll see it turning white - and there you have it; a simple yet effective homemade white oil.
That’s your concentrate. To dilute it, mix up 25 mls per litre of water in your sprayer, shake it up and spray it on. Make sure you cover the under surface of the leaves and any crevices where sapsuckers hide.
A regular spray will keep most sapsuckers under control and that means no more sooty mould. Just be sure to do it on a cool part of the day because it can burn the foliage when temperatures are over 25 degrees or so.
