|I have several gardenias and have noticed several things on the leaves. 1) Some leaves have some black soot on them. They would come off if I rub them. 2) On some, there are white spots underneath the leaves 3) On the others, they are turning yellow with brown spots. When I touch them, them fall off the branch. Are there any remedies for these problems?|
THe black soot is growing on honeydew, a substance excreted by certain insects such as aphids, whitefies and scale. If you discover the insect then a treatment suggestion can be made. White spots beneath the leaves sound a bit like whitefly pupae. The falling leaves is a sign of stress perhaps due to the insects or perhaps because of dry soil conditions or even poory drained soil conditions.
I suggest you take a sample from the plant to your County Extension Office for help in identifying the insects and for appropriate control options.
Thanks for the question. Please stop in again soon!