Phellinus robiniae

About

Fulvifomes robiniae, commonly called the cracked cap polypore, is a fungus of the family of Hymenochaetaceae. The fungus primarily infests black locusts, aided by openings caused by Megacyllene robiniae infestation, but also grows on various other trees such as Carya, oak, and Acacia. Cracked cap polypore is sympatric with most of its hosts. It has a brown spore print, leaving brown streaks on the tree below the fungus.

Summary from Wikipedia