Sooty mould

Hello, this is my first post on here. I have a lemon tree in the greenhouse and it's covered in sooty mould. I've cleaned all the leaves once, sprayed it with a spray suggested by my local garden centre, but it's back again. Does anyone have any advice please?

Have you checked the underside of the leaves for scale insects? If they are responsible then the only insecticide that will get rid of them is not recommended for edible crops, so i wonder if your garden centre has recommended the wrong product. What did you use?

The best way to remove scale insects without using an insecticide is to scrape them off gently with a fingernail and / or wipe the leaves with warm soapy water. 

Hi snowy43, I agree with Gold1locks, the best way to get rid of scale insect (the most likely cause of your sooty mould) is with fingernails and soapy water. I did this with my orange tree a few years ago, which also had mealybug - it took several weeks of regularly cleaning the leaves and removing the scale insects, but then it sorted itself out. I suspect that, when it was growing in the nursery, the tree was regularly sprayed and fertilised, and so had no natural defences to insects. It's now been growing organically for five years and has a few scale insects, but these don't ever reach pest proportions - they live in happy equilibrium with the tree.

Another thing you could do is just pop the lemon tree outside - many ladybird species love a scale insect or two

Kate

Thank you both for your replies.

 I've started doing as you suggested and scraping off the bugs with my nails and washing the leaves with soapy water. It's a long job!

The spray that the garden centre recommended was a general one for insects, so not really what I should have used for a lemon tree.

Kate, I'll put the tree outside as soon as it's warm enough. - not in this rain and wind!