It looks like a bad case of whiteflies, Kirk. Spraying with soapy water--about 3-5 ml of organic dish soap per liter of water--should do the trick, though you may have to spray every day for 3-5 days. Putting out yellow cards smeared with petroleum jelly, on stakes, will help prevent re-infestation.

Do you have these plants indoors? Improving ventilation and light will help stop future infestation. Give them as much sun as possible & open a nearby window. A little wind does a lot of good, even and electric fan will help.

Anything that strengthens the plants will help them to resist these pests.