Area of impact: Head

Description: Symptoms appear between heading and maturity. Blackened diseased heads emerge before healthy green ones. A dry black spore mass is contained within a thin membrane.

Pathogen involved: Ustilago tritici (a fungus)

Timing/Conditions: Occurs only during flowering and prefers wet cool weather.

Contributing factors: This fungus is strictly seedborne. Spore formation is timed so they can be blown into the flowers of host plants.

Management practices: Plant disease-free seed and treat with systemic fungicides.