can an mushroom fungus on 40-50% of a kwanzan cherry tree including surface...
Based on your description, we cannot make a definitive diagnosis of your tree's problem. On the one hand, mushroom fungus suggests the possibility of what are normally called shelf fungus, which are symptomatic of a lethally serious problem with the tree.
Some people may describe harmless lichens as fungi.
Involvement of the roots, however, is also a serious condition, so it may be that the tree is terminally 'ill' and should be removed.
If you can take a digital photo of the tree, load the photo(s) into your computer and send us a follow-up question with the photos, we would like to make a more authoritative diagnosis.