Didnt know where to post this... One of my coworkers was just asking me about this exprerience she had at work in the garden center. A customer brought a Bonnie vegetable plant (a tomato) up to the counter and she said the soil seemed -really- dry. It was a rusty/orangish/whitish color. When she went to water it, this smokey stuff came out of the soil. She asked one of the Bonnie vendors but he had no clue. I dont have a pic...anybody have any ideas??
Sounds like a fungus in the soil. I have had that happen before on outdoor plants, you turn the hose on them and the black powdery/smoky looking stuff flies out....that's probably where all the little fungus comes from that is growing in several places in the backyard. I don't think it is harmful. If no one here has a definitive answer, she could call the local Cooperative Extension office..gov. website has a list for all offices around the country http://www.csrees.usda.gov/Extension/
