Loose Smut [Ustilago segetum tritici]

Spread / transmission

Smut heads develop on infected plants in place of kernels. The smut spores infect blooming, still healthy heads via air currents. They germinate in the open flower and produce a mycelium, which infects the unpollinated embryo and forms thick-walled resting hyphae. The mycelium can survive for several years in the grain in the form of a resting mycelium. When the grain germinates, the mycelium grows and is carried systemically upward. Considerably thickened hyphae form during ear development and develop into smut spores at maturity.

Diagnosis

Infected heads emerge from the boot before the healthy ones and release a dark brown to black spore mass during the blooming stage. An empty, blackish, and erect spindle is all that remains. Partial infection can occur.

Control

Preventative agricultural measures

• Use pathogen-free seed
• Sow in late fall or in early spring

Fungicide measures

• Seed treatment