I'm trying to identify what is wrong with my lemon tree.

Previously it had aphids and I treated that and they're gone, but now it has some black stuff on the underside of the leafs and is causing them to fall off.

Here's some photos:

enter image description here

enter image description here

  • To make better photos I suggest to cut off a leaf (or a part of it) and attach it to a sheet of paper. Then you can control light and focus.
    – Gyrfalcon
    Jul 16, 2022 at 13:09

1 Answer 1


It is hard to tell from the photos, but perhaps a fungus called black sooty mold

What Causes Black Sooty Mold?

Black sooty mold is actually an airborne fungi spore that latches on to the sweet sticky honeydew secreted by leaf and bark feeding insects.

On Crepe Myrtles and most other plants the culprit here is either sap sucking Aphids or Bark sucking Scale.

This is how it looks like on a lemon tree.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.