Heartwood is dead, but in the case of pines its pores are filled with resins and in general, very resistant to the roting. Here is the fomitopsis annosa fungus which can attack our pinus sylvestris heartwood (the root rot), but this is very rare situation here. If pine can develop the taproot, it is resistant to the stump rotting. On wet or rocky shallow soils, where pine cant develop taproot, it is more prone to the root rot and hertwood damage in the stump area.
Through dead limbs phellenius pini is attacking some amount of our old pines and causes heartwood rotting.
Pruning of pine limbs is recommended here in winter (early spring) or in summer
Pinus strobus is presented here as only the planted trees in parks. Europe has a bad fungus: peridermium strobi, which has intermediate growing stage on gooseberry and currants and causes on lot of white pines the bark inflammation and the death at their "middle age".
This fungus was exported onto America continent too with gooseberries and killed there a lot of white pine stands. I dont know how the situation is now.
If peridermium strobi is on the area, the bark and other wounds are dangerous for the white pine.
If the growing site is very dry and sandy (no water and nutrients) then the pitch is thick and not good protector. Fertilizing increased the pitch protective capability on pinus sylvestris as was observed in some experiments done here.
