Sooty Mould on Citrus Trees
I worked in the Edible Landscapes nursery for a few days and answered (or tried to answer) a lot of customer questions. The following question about sooty mould on citrus trees was pretty common.
Question: My mandarin tree has a black mould on the leaves and is not bearing as much as usual. How do I fix this?
Answer: It has sooty mould, a fungus growing on the leaves, which means there is a sap-sucking insect problem like aphids, scale, white fly or mealy bugs. The insects suck the sap from the leaves and exude honeydew, which drips back onto the leaves, and the mould grows on the sweet substance.
Spray it with white oil to kill the sap-suckers and thus get rid of the mould. To make white oil, mix together:
- 1 cup of cooking oil
- 2 cups of water
- 1 tsp of dishwashing liquid
- Dilute the mixture at 3 teaspoons per half a litre of water and spray on the affected leaves.
Make sure to use it in the cool of the day so it doesn’t burn the leaves. The mould should then wash off in the next rain (or hose it if you’re impatient and then reapply).
September 4th, 2008 at 1:47 pm
What type of cooking oil do you use vege/oil/peanut? Appreciate your help on this one.
September 4th, 2008 at 2:12 pm
Any cheap cooking oil like canola or vegie is fine. No need to use the expensive oils.
January 1st, 2009 at 5:17 am
Do you have any photographs of orange trees and fruit that have the mould to identify it?
Our trees have blackening leaves, blackened spots and areas on the fruit which is small and dropping.
January 1st, 2009 at 4:50 pm
Hi Jennie, I don’t personally have photos of affected trees, but here are some examples from other websites…
Image 1
Image 2
December 22nd, 2009 at 2:51 pm
The stuff in the link takes sooty mold right off, and does a wonderful job at controlling many insects and fungus, naturally.