Looks like mealybugs.

Or scale?

Insecticides seldom do anything to control scale or mealybugs although they do kill off the predators that can help control them. Most often control can be gotten with applications of horticultural oils, summer oils when planta are growing and dormant oils when plants are dormant.

Here is a link that might be useful: About Scale and Mealybugs

I don't use any oils or pesticides for insect control as I grow organically. google Arbico. they specialize in beneficial insects. I ordered three praying manti egg cases. one for my yard and for my neighbors on both sides. one egg case hatches abou two hundred manti. They devour every insect you hate. and once they live out their life cycle they lay their own egg cases. so now I have an ongoing population of manti. I live an hour north of death Valley so its a desrt hot blazing summers freezing winters if my manti can stay alive year after year your area will support them as well. also consider Ladybugs these are literalyy the toughest bug in the pack they eat every single pest bug you can imagine problem is when they eat everything they move on to find more food. I even take my baby manti indoors to work over my bonsai and houseplants I leave a couple of windows open all the time for my cats to get in and out. so manti have an escape, or entrance if they choose. I grow vegetables, tobacco, fruit, housplants and bonsai. this was a permanent and inexpensive solution to my bug problem. Good Luck!!!!

Definitely a scale insect. The location along the major and minor veins of the leaf (rather than the axils) helps ID this insect. Too bad the image is so blurry, or a genus and species would be able to be attached.

I hope that someone besides me has reported idiot Sean to Gardenweb.

Thank you all for the tips. After some some further research, it does appear to be scale. the infestation is so bad that I plan to destroy the affected plants before the scale spreads. Can anyone advise me how long I should wait before replanting? I definitely don't want this problem again. Thanks again for your help.

The plant looks familiar, but I'm not sure what kind it is. Do you know? We can help answer your questions better,if we know.

Scale doesn't spend part of its lifetime in the soil, so replanting won't be a problem in that regard.

HOWEVER, some plants are notoriously susceptible to certain kinds of scale (or other insect species) infestations and it is a very good idea to avoid those plants, if possible.

As a matter of fact, one of the very important steps in a good Insect Pest Management (IPM) program is to avoid bringing in susceptible plants into the garden and landscape in the first place. I certainly try to follow that guideline, with the exception of some of my veggie garden plants.

Left unchecked, scale can really multiply quickly. If you spot an infestation early on, you can control it with applications of horticultural oils, as stated in Kimmsr's comments. By the way, the removal of badly infested plants is often recommended and I think that you probably did the right thing.

What did Sean do?

Don't have to wait top re-plant. Not in the soil.