Disease ID (Robinia & Willow)

[Clueless]

Could anyone assist in telling me what this is, I'm assuming it's a disease. It first appeared on a Robinia and then later on a Willow. Both trees are 31 years old and 50 feet apart. Since it appeared on the Robinia, that tree has been desperately trying to start new trees from it;s roots, I assume as a reaction to this. Thanks for any pointers !

 

[Anniekay]

The tree is dieing. That is fungus that grows on rotting wood. Probably a good idea to remove those trees.