Nice Tree!
Marty Mann's
seasonal suggestions for March/April suggests:
"Use Benomyl(r), Bravo(r), or Daconil(r) to kill mildew or other signs of fungus on the foliage and the tree bark."
I would protect the soil surface, because there are microflora elements in the soil that can be damaged.
I would be very hesitant to take a toothbrush to a pine!