There stood a small, sad looking tree that was pretty hard to spot as being a Lemon tree, because it was absolutely covered in a thick, black, sticky coating on all of it’s leaves.
Not being gardeners of any variety my friends were planning on pulling their Lemon tree out so they could replace it with something that didn’t look so sick, until I offered to help them figure out what was wrong with it.
As soon as I laid eyes on their poor little tree it was clear that it had fallen victim to a severe case of black sooty mould.
What Is Black Sooty Mould
Most common in citrus trees, black sooty mould is as it sounds. A horrible black, sooty like mould that coats the leaves and branches of a plant, making them appear to be rotten and very unwell.
Black sooty mould is actually multiple species of fungi that grow on the secretions made by insects, such as aphids or mealy bugs, who are doing the real damage by piercing the bark of the tree and sucking the sap, then secreting what is known as ‘honeydew’. A misnomer if I ever heard one.
So while black sooty mould might look like a life sentence for your tree, it’s actually not your main problem. It’s more of a sign that your tree has been invaded by insects that are eating at the tree and slowly killing it.
That’s not to say that the black mould is totally innocuous. It can also block out sunlight from the leaves, affecting the plants growth and it certainly makes the tree look horrible and unhealthy.
How To Get Rid Of Black Sooty Mold
The first main task in dealing with the mould is to get rid of the insects that are creating the sap secretions.
Use a horticultural pest clean oil such as Neem oil and spray the foliage of the plant to kill off all the insects that have made your plant their new home.
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Once all of the insects are removed from the tree you can begin to clean off the sooty mould.
Use a small amount of natural detergent to make a spray and coat all parts of the plant covered in the black mould. Make sure to get both sides of the leaves and let the detergent spray soak the leaves.
You can then either wait for the next good dose of rain to fall to wash the detergent off, or give your tree a good wash down with clean, clear water from the hose and you will see the black soot washing away.
You may need to do this step more than once if the mould cover was heavy. Don’t be tempted to scrub the leave or go overboard on the detergent spray for risk of doing more damage than the mould was in the first place.
If after ‘washing’ your tree you find that any of the branches have sustained too much damage due to the infestation, trim back the parts of the tree that are most affected, making sure to not prune your tree too hard, especially if it is a smaller decorative tree.
Once you have your plant looking more like it’s old, healthy self, make sure you keep on top of the insect control and continue to gently remove any of the sooty mould that remains until you have a display of green, shiny leaves once again.