Looks like mealy bugs...sort of cottony-looking, soft? If the infestation is not too heavy, try removing them by hand. Next choice would be least toxic insecticide, reading label to see if mealybugs are listed pests that can be treated. Good luck!
It's either mealybugs or scale. I would use a Neem oil. Ask at your local nursery for a good one.
Oh Goodness you have got a really bad case of mealy bugs Aphids and I am afraid to say also a good dose of Whitefly from what I can determine from your really well taken photographs. Powdery Mildew may well be at play here also. As Douglas, above well recommends Need oil, which I completely agree, I would first try and tackle this "Now" . Get clean spray bottle fill with two spoons worth of liquid dish-soap , room temp water, shake and spray the plant from top to bottom. Then after this sits, if have access to tube or shower put in there and shower the plant for good 30 minutes,.The water pressure with help loosen the half dying pest that the spray help kill, and the shower water does the rest by washing away any remnants. I highly recommend before returning the plant from shower back to it's regular home that you remove the first top inch of all surrounding soil and discard immediately away from all other containment's.
If you have a green or plant room or even small shed or greenhouse I would suggest you buy some Lady Bugs ASAP.These pretty little ladies do all the work and you are feeding them as they naturally feast off your plants parasites. Win Win for all. Hope all this helps you a tad bit more.This has happened to me also years ago devastating, but look what I learned.And now others as well.
Scale, spray with dormant oil, this will smother the critters
Rubbing alcohol kills mealy bugs. I used to clean my grandmother's African Violets with a Q-tip and alcohol. I don't know if that's what's on your plant or not. Just throwing this out there. (...and of course an African Violet is way smaller than what you're dealing with.) Good luck!
I think it looks like mealy bugs also. I think scale is usually on the back of leaves and not so white, at least that has been my experience.
I had this on some plants last summer. Made up a spray bottle of dish soap and water, shake and give a good spray. Do the underside also. It worked for....hope idea helps.
It looks like cottony cushion scale and a pretty bad case of it. The use of a horticultural insecticidal oil spray will kill the critters but will not remove them. Make sure to spray the top and bottom of the plants with the insecticidal oil. To check if you have killed all of the little critters scrap with you finger, if you see yellow on your finger spray again.
You may have mealy bugs but the oil will also take care of them. Good luck
If you are going to spray with anything oil based, do it in the evening or at least not on a hot day as the oil (depending what you use but especially if you use a mix of dish wash detergent and oil) can cause the leaves to burn on a hot day. Check with your local nursery - taking an infected leaf in to show them is a good idea so they can recommend something to knock it on the head. Agree you will need to spray the undersides of the leaves to most likely to get it all.
Looks like the scale Eugenia gets often. Someone recommended Neem Oil...excellent choice! Dormant Oil is good, too... like Doug said tho ... do it in the evening, w/ either product. the oil would burn the leaves in heat of the day....spray and then re-spray in 7=10 days. Will help clean up that sooty mold type stuff you have on the leaves too!
I hope my photo helps you. I have a mealy bug infestation. Yours does not look like mine.