Answer: Based on your description I can't give you a definite answer about the bushes but it is possible they have been attacked by a fungus, possibly even mildew. You might want to take a sample to your County Extension (566-0673) for a more specific identification and possibly some suggestions for controlling it.
Fungus may appear on the surface of the soil in plant pots for a number of reasons, but the most common would be overly damp soil and/or poor air circulation and/or temperatures that are either too warm or too cool. In my experience things like this often occur when plants are brought inside with garden soil as opposed to plants grown in the relatively "clean" soilless potting mixes. Adjusting the growing conditions may stop it. You might also ask your County Extension about an appropriate fungicide for indoor use or try several light waterings with chamomile tea. It should not spread to your other plants as long as the overall conditions do not favor it and as long as you do not physically introduce it to the other plants by your hands or tools or other equipment.
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