False loose smut is a fungal disease of barley caused by Ustilago nigra.

This fungus is very similar to U. nuda, the cause of loose smut, and was first distinguished from it in 1932.

These membranes break shortly after the smutted heads have emerged and expose a dark brown to black, powdery mass of spores.

[3] The disease cycle of Ustilago nigra is similar to that of U. hordei, the cause of covered smut of barley.

As the plant enters the boot stage, the mycelium grows rapidly into the floral tissue which is converted to masses of black teliospores.