Looks like powdery mildew. A fungal disease. Hard to treat on ornamental house plants as often the fungicide will kill those plants. Check labels of various products. If untreated it will kill plant. Make sure you never water foliage. No misting!

If it's Powdery Mildew,a Baking Soda spray will help.Also a mixture of 10 parts water to 1 part Skim Milk is used.Neem oil will block it. Brady

Here is a link that might be useful: Control Powdery Mildew

The problem is those organic treatments are preventatives. So will work on any foliage not infected, but all infected leaves will still die. You have to go heavy industrial synthetic if you want to kill it. Problem is many house plants cannot tolerate the treatment. Like Hibiscus, ferns etc.
If it can survive the removal of the infected leaves, remove them!

Looks like wooly aphid. Ugh. Spray with Malathion and leave it in the basement where you cannot smell the fumes. Or take it out doors to spray then bring it into a warm room you do not go into. (fumes nastier than the aphids).

If it's wooly aphid, you should see them. That's better news!
If you use an oil or soap it's not as bad. I would first take it outside and spray off with water as many of the aphids as possible, then use an oil, it can also help with powdery mildew if that is what this is?

Sorry, made a mistake, 'Mealy Bugs', thats what they look like. Mrs. G

You can wash them off of the leaves with luke warm water and a light dish soap ( no bleach or anti bacterial) type. Then spray the soil, that is where they live. Ugly things. Mrs. G

Wooly aphids are mealy bugs. Same thing. They can be hard to get rid of. Malathion might be a good way to go, but the wool repells insecticides, so does the waxy skin. This bug makes sense and yea they were probably in the new soil. Best to again transplant to new soil. Sterlize the pot. Treat three times, treat plant and new soil or old soil if you decide to keep it. Read label directions as to how often usually repeat 7-10 days.
Best treat all your plants, they spread easily! Wet plants before treating.

An easy treatment, and one of the best for this is Bonide Products 951 Houseplant Systemic Insect Control Granules.
It doesn't smell. You can keep the dirt, and it lasts for 8 weeks. So just one treatment to all of your plants that are non-edible will work! No worries about the waxy skin or wooly hair repelling anything. It's a systemic, as they feed, they take up the poison.

I myself would wash as many as I can off, give the granules, hit them with horticultural (Insecticidal) soap (plants and soil). The granules take time to work, so the other treatments will set them back and give time for the granules to be absorbed by the plant. It looks like you have a bad infection, so best to hit them hard. Your other plants if they look OK, you can probably just give them the granules. If you do this, you will get rid of them.

Having the soap will come in handy. if you have plants outside for the summer, it's a good treatment to use before you bring them in. So you don't bring any bugs in the house. It also works well on other insects, you can use it up pretty easily.

As you can tell their are lot's of treatments you can use. Up to you on how you proceed. Good luck!
You can get all these products at a good garden center (not at big box stores, a small private garden center), or even off Amazon.
You can also make your own soap, but risk damaging the plant by using the wrong type of soap, or the wrong dosage. too high will damage the plant, too low will be ineffective. So best to buy the product IMHO.

This post was edited by Drew51 on Fri, Nov 29, 13 at 1:41