Answer: A very scary predicament indeed. It sounds like you have an infestation of mealy bugs or perhaps white fly. Either way I would treat them the same. Does your plant have pale foliage, leaf drop, or stunted growth? All of these are caused by mealy bug. If they are just starting their dirty work you may not see symptoms yet. First of all and foremost, yes, they will spread to your other plants so lets plan on treating them all. She is probably salvagable but maybe not...lets give it a try. For the Diffenbachia, dip a cotton swab into rubbing alcohol and wipe off all affected areas of your plant. Then wash the plant in a mild solution of soapy water (a gentle soap such as Ivory dish liquid works well). Rinse all of the soap off. If it were my plant I would discard the soil it is in now and repot. If at all possible do the above procedure to all of your houseplants that are in the same room or have come in contact with materials used on the affected plant (trowels, misters, watering cans, etc. - these tools will need to be disinfected with a solution of 1 part bleach to 10 parts water or run through the hottest cycle of a dishwasher and heat dried). At the very least, clean the other plants with rubbing alcohol, particularly the undersides. Try to backtrack and think how this may have started. Have you brought any new plants home recently? Repotted plants with new containers? Added different soil? Were your plants outside for the summer? If you can track it down you may be able to prevent reoccurence. I'm pulling for you!
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