are you just talking about the pruned down stems ...

i presume its just mother nature using fungus to rot out dead parts of the old plant ...

the pix are a bit washed out.. hard to see much else ... i cant tell if there is leaf problems.. or just pic problems ...

ken

If you rub it off is there any kind of creature beneath it? There are several pests which cover themselves with a cottony coating like that. The shrubs are Azaleas and it seems there is an Azalea Mealy Bug which might be a candidate.

Thank you for all the responses on this hot and humid Sunday Morning.

About a month ago I pruned down stems below the white stuff, but it came back. . In the close up there seems to be little tiny grains of rice. It is cottony but I couldnt see a critter, unless it is the rice-like structure.

When I cut it down in the past there was a depression in the center and I added soil. I see some mulch is within the plant. Pull it out? it is next to electrical transformer. Seems damp in the center

From googling:

For this reason, insecticidal soaps are not recommended on azaleas. Apply a 4 percent horticultural oil only when you know for certain that the azalea is dormant. Never attempt this treatment before testing it first on a small section of the plant. A 2 percent horticultural oil solution can be used after eggs have hatched to control crawlers.

maybe cut it back hard this fall then spray with diluted dawn dish soap

It is mealybugs. I cut the shrub down to the ground, disposed of cut pieces in dumpster. Do I spray remaining cut stubby branches with an insecticidal soap? or dig the whole thing out?

Mealy bug or some kind of cottony scale insect? Mealy bug on outdoor plant in zone 6 doesn't compute for me. That's a greenhouse pest.

it has been on the same plant for at least 6 years. the tiny white wormlike critters move. Should I dig the whole thing out?

Well no, you should get a positive ID for the pest, then select a control regimen. Not the other way around. Is there not some expert in your area that can make a correct diagnosis for a few bucks? Treating when you don't know what you are treating is another thing that does not compute for me. As I said, mealy bug is a greenhouse pest in all but the most tropical of places. Cottony scales of many species exist and I suspect this is what you have there. So, if you are able to make certain of that, then you can reach for suggested control regimens. But you're trying to do it backwards....treat the problem, then try and figure out what it is. That's bound to fail.

Many types of scale insects can be controlled with horticultural oil. Timing of application can matter, as it is the "crawler" stage of these insect, basically the immature moving to set up shop somewhere on the plant.=, where they are moist vulnerable. But the oils can work even without this timing, because they can smother the insects and in some cases, even their eggs. So that might be one thing you can do, but really, you need to first identify what you are seeing.

I went out to look at the plant. Nothing white or moving on it at all now that it is cut to 2 to 4 inches. Some of the older cuts are black - normal decay?

The center of the plant is filled with mulch, seems the soil around it was elevated and there is soil and mulch in the center of even the plant. I guess I clean it up and wait for spring and see if there is something to ID...