Seeds are entirely replaced by masses of brown teliospores. Photo courtesy of Bruce Watt, U. of Maine, Bugwood.org.

• Early symptoms are minor and can range from yellow leaf streaks to stiff, dark green leaves.
• Spikelets of wheat are replaced with the fungus, appearing as sooty black teliospores.
• Infected plants head out early and are visibly darker than a normal wheat head.
• Spores quickly blow away in the wind or are disturbed by raindrops because they are not enclosed in a seed coat.

Close up of teliospores on what would have been a wheat head. Photo courtesy of Bruce Watt, U. of Maine, Bugwood.org.

• The pathogen overwinters within infected wheat seeds and becomes active when the seed germinates.
• After germination, the fungus colonizes the meristem tissue, growing systemically within the plant.
• Ustilago tritici matures in the growing point and the developing grain of the infected plant.
• Dark colored teliospores completely replace the rachis, and can be blown to uninfected plants during flowering or kernel development.

• Because this disease is seedborne, seed should not be saved from infected fields for future planting.
• Certified seed is required to have a low amount of disease, planting certified seed ensures that Ustilago tritici will not be present in fields.
• If planting certified seed is not preferable, systemic fungicide seed treatments are readily available, and effective against this pathogen.

Loose smut of wheat with darker coloration. Photo courtesy of Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org.

• Crop Protection Network. (n.d.). Loose Smut of Wheat. Retrieved from Crop Protection Network.
• Wegulo, S. 2009. Loose Smut Found in Wheat Fields. Retrieved from Cropwatch.