Several of the leaves on my Meyer lemon tree have these brown leaf splotches. The degree varies based on the leaf and most splotches are on very mature leaves, but not all. The leaves with splotches are starting to yellow and fall off. Does anyone know what the cause could be? I have had a lot of issues with this plant recently including a fungus gnat infestation but it has sentimental value and I am determined to keep it alive. I would really appreciate any help available! :)
If you had fungus gnats then it is likely there was an issue with too much watering or poor drainage. Check the soil to make sure it is not staying too wet for too long. Allow the soil to dry between waterings. The marks on the leaves look like a fungus, possibly a mild case of sooty mold. The thing about sooty mold is that it does not normally form on citrus without a reason behind it, like bugs feeding on the citrus and the sooty mold then forms on the bug excretions. Sooty mold itself is generally not harmful and can be wiped off, but be sure to look closely to see if there is a bug infestation of some kind, like scale. Here is a link with information on sooty mold: Sooty mold - techniques and organic treatments to avoid blackish leaves
