Permaculture Living

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).

This entry was posted on Friday, August 8th, 2008 at 10:32 am and is filed under Plant Information. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.