Question
I have a holly bush completely covered with what appears to be a black sooty mold and white dots (cotton scale?). Is it salvageable? How do I treat it? Thanks!

Answer
The white dots are a scale of a type.  The insects feed by sucking the juice out of the plant.  What you are seeing are females that have embedded themselves into the plant and they do not move once feeding begins.  The bugs give off "honey-dew", a sugary substance during feeding which then attracts the black sooty mold.  The sooty mold itself, is not parasitic to the plant, but with a heavy coverage can prevent light from getting to the leaves.  I would recommend taking a Safer Soap Product and spraying the plant until runoff.  Then with a strong stream of water, I would see if I could wash off some of the sooty mold.  Next--- go to Home Depot or Wally World and buy Bayer Advanced Tree and Shrub Insecticide.  This is a systemic insecticide that you will mix with water and pour on the soil around the base of the plant.  Mix according to label instructions for the size of your plant.  The product will be taken up by the plant in about 2 weeks and will kill the scale and prevent future infestations for up to 6 months.  You can use this product on any other non-food plant in the landscape.  Good Luck.