My azaleas, which are in pots, started looking sickly about halfway through the summer. The top of the leaves are yellow and mottled, and underneath the leaves there are black and dark brown fuzzy spots that brush off easily. Most of the leaves did NOT drop off the plants. I don't see any sign of insect infestation. The pots are on the east side of the house (i.e. morning sun, afternoon shade) and are watered frequently, although they probably did get a little dry at certain points during the summer. One other thing: they were sitting next to a rosebush that also seems to have some yuck on the leaves, although not nearly as badly (I haven't looked closely at the rose yet). Does anyone know what this might be, and what should I do for my azaleas?
I'll try to post a picture later today (I'm at work now...see option #whatever on the quiz :) ) but figured I'd put the description out now and see if anyone recognized my description and has any advice.
If this is a deciduous azalea, I'd say it sounds like leaf rust, caused by a fungus. In general, they say to avoid watering at night, and clean up fallen leaves from under the plant. But yours are in pots, so I dunno. NC State U. has a good site about azalea diseases and pests
Are those spots under the leaves really teensy? Like maybe insect poop? There is an azalea lace bug that lives under the leaves and sucks the juice from the leaves, causing them to become mottled on the top side. The little black dots are quite diagnostic for them.
I took a close look at my azaleas and the black spots could indeed be bug poop--plus I saw a few small black fly-looking critters on the underside of the leaves, which could possibly be lace bugs. (I'll check out pest pix to make sure.)
My question now is, What should I do for my azaleas? Can I trim off the diseased leaves and hope new ones will grow back? Spray with insecticidal soap? ???
Update: Yup, they're lace bugs. The ag extension stuff I've read recommends hosing off the plants, insecticidal soaps, or insecticides. I do not want to use insecticides other than ivory soap...a few azaleas aren't worth nasty chemicals in and around my yard. I was wondering (as I mentioned above) if I could trim off and destroy the infected leaves? Or would that kill the plant if I removed most or all of the leaves?
If you are not willing to use even soap or insecticidal soap, I suggest you rid your yard of azaleas. This is a very common ailment of azaleas, and getting rid of the leaves is not the solution. First, they need the leaves in order to manufacture food, second, the lace bugs will still be around, and when new leaves grow out, they will be right back having lunch...
Most insecticidal soaps aren't "nasty chemicals", you can eat a sprayed plant the same day. You said your azaleas are in pots, you could try moving them to an even shadier spot. Since they're in pots you have a better chance of spraying the bottoms of the leaves where they live. Lace bugs are a major nuisance, but I don't think they can kill a whole plant, maybe a branch or two
Oh, I AM willing to use insecticidal soaps, just not the real heavy duty pesticides...sorry, I was unclear! I think I'll try the combination of insecticidal soaps + shadier location. I will either need to bring them inside soon (in isolation, I'm assuming?) or mulch the pots heavily, as we're starting to have frost here.
Ah. I got a couple someone was giving away by the side of the road this fall, so far so good. My neighbor chopped up one of his a few weeks ago, wish I had known beforehand, it was at least forty years old. O well...