Yellow spotted lemon tree leaves

Asked August 9, 2015, 1:50 PM EDT

I have a two-year-old Meyer lemon tree that has spotted yellow leaves on it. I have only had the tree since May and live on the East Coast where it is hot and humid now. I have seen little black dots on the leaves and I wipe them off with a wet paper towel. I fertilize with Miracid. I'm hoping to find out what is wrong with the tree soon and would appreciate any help.

1 Response

The picture is helpful for understanding your problem, but not enough for me to be conclusive.

I do believe your problem lies in the area of insects and diseases. What I see in this picture is not nutritional and thus not affected by fertilizer (or lack thereof).

First, I suggest you look closely (with a magnifying glass) at your leaves for spider mites. They can create a bronze, stippled appearance on citrus leaves if the population gets high enough. Horticultural oils (petroleum or botanical (neem) and/or insecticidal soaps can be helpful for clearing up spider mites.

On the plant disease side, you may have melanose (causing tiny black spots) or greasy spot (yellow faded blotches on top side of leaf, corresponding to raised brown to blackish lesions on the opposite side of the leaf). These problems can be helped by applications of neutral copper (basic copper sulfate or copper hydroxide) in the late winter to early budbreak period. The oil treatments described above for mites will help against greasy spot if applied in late May to late June.

It would be preferable for you to know exactly what you have; thus I would recommend you contact a plant disease diagnostic clinic in the state that you are growing these plants for a more precise diagnosis and ultimately better cultural recommendations.