azalea - black spots on back of leaf
my azalea (3yrs old, unknown variety) is currently in a pot awaiting transplanting. Over the last month or so i noticed the leaves turning yellow/white on the front and there are tiny black spots on the back sides. Otherwise it looks pretty healthy and has been growing steadily. how can i get rid of this pest?
Montgomery County Maryland
Thanks for your question. Your azalea is infested with the azalea lace bug. The female lays eggs on the underside of the leaf, and when the eggs hatch, the nymphs and adults insert their piercing/sucking mouthparts into the leaf, and suck out the chlorophyll. That's why the leaves look yellow--no chlorophyll! The black spots that you're seeing are their fecal waste.
Here's a link to U of Maryland Extension Service article, that explains more, and suggests control mechanisms. Over time, other insects will probably control them, but in the meantime, we can only monitor and spray, if necessary (on the underside of the leaves) at the time they are present on the leaf and past the egg stage.
Hope this is helpful. Good luck!