Question
A mysterious blob of what looks like yellow vomit appears on my flower bed mulch. It changes appearance after a couple of days becoming splotchy and then it hardens. When watering the flowers, if it is hit by water, then a brown dusty powder is released ino the air. Eventually it goes away. Any idea what this is?   Should I be concerned about the dust that is released and gets all over the flowers?

Answer
David, the substance you are describing is a fungus composed on thousand of tiny spores.  This mold is prevalent in flower beds that are usually covered with too heavy of a layer of mulch.  The fungus is actually harmless and will not do any damage to the plants.  When disturbed, the spores fly into the air and land in other areas of the garden where they will form new masses of spores.

You can spray the bed with a copper fungicide.  This will normally kill the spores.  But even if you do nothing, the good news is that this particular fungus is short lived.  Once the weather turns drier, the fungus disappears.

I hope this answered your question.  Please write again if I can ever be of assistance.

Regards,

Mike