It's a type of mold. It could be bad, or it could not be bad. If your plants don't look like they're showing any reaction to it, i.e. no collapsing or wilted leaves, then it should be okay. The mold only eats dead stuff, and it shows your plants have some dead tissue and that it's surviving off of it. If your plants look bad, grow them as well as you can, but keep an eye on them.
It's a type of mold. It could be bad, or it could not be bad. If your plants don't look like they're showing any reaction to it, i.e. no collapsing or wilted leaves, then it should be okay. The mold only eats dead stuff, and it shows your plants have some dead tissue and that it's surviving off of it. If your plants look bad, grow them as well as you can, but keep an eye on them.
Can't tell without pictures but it sounds like mealy bugs... Look up "mealy bug" on Google Images if you don't know what they look like.
sounds more like powdery mildew to me.. but tough to say for sure without pics.
Treat with a Bonide SULFUR based fungicide. Avoid the Bonide Copper based fungicides.. I learned the hard way that that stuff kills plants faster than the mildew.
Trust me.. I'm no Maiden.
I am with NaN, looks like aphid skins. By the time I see these specks or plant damage from the aphids, they have moved on (they like the tender new shoots). Neem Oil or Bayer systemic insecticide should work.
They looks more like mealys to me...