Pest Profile

Loose smut is a seed and wind-borne fungal disease. The pathogen survives in the wheat seed until germination and then grows up the shoot and infects the head. Healthy wheat plants can be infected during the first two days of flowering by wind-borne spores from infected plants. Rain and insects can also help spread the fungus. Humid weather, including light rain and heavy dew, and cool to moderate temperatures, between 60 and 71°F (16-22°C), promote infection. When spores land on healthy flowers, they germinate and become dormant within the ovary until seeds germinate. Yield loss is in direct proportion to the number of smutted heads present.

Disease symptoms usually are not apparent until heading. However, diseased heads tend to eme ge earlier than normal plants from the boot stage (approximately 1-3 days). Brown to black fungal spore masses develop in the diseased heads of the plants. The mem­brane ruptures during flowering and smut spores are dispersed leaving only the dark, bare rachis.

It is not possible to visibly tell the difference between infected seed and healthy seed. Plant high quality, certified seed treated with an effective fungicide.