We bought a sixteen year old house and I am clearing a lot of overgrown landscaping to prepare for a new front yard. I went in to trim and shape a huge old Pyracantha and found the most appalling situation…under the green overgrowth the entire shrub was covered with this ashen gray substance and all the branches looked like they had been in a fire. The main plant looks as if it’s dead. The ashen part of whatever it is, seems to be kind of powdery and it makes a cloud of white when I try to remove the undergrowth. First question…what the heck is it? Second question…is it dangerous to my other landscaping plants or to me? And third question…is there a safe way to get rid of the whole shrub? I live in Livermore Ca and I would hate to find that it could infect neighbors landscaping or escape to damage the many wine grapes that are grown here…any help on this would be very much appreciated!