Common Bunt ( Tilletia spp.) of Wheat in Canada

Common bunt of wheat, also known as covered smut or stinking smut, is a seed-borne fungal disease caused by two fungal species, Tilletia caries (DC.) Tul. & C. Tul. syn T.tritici (Bjerk.) Wint. and Tilletia foetida (Wallr.) Liro.). The spores of these pathogens produce trimethylamine, which has a fishy pungent smell. The disease has been known since the beginning of agriculture and continues to affect wheat production worldwide. Both T. caries and T. foetida are primarily transmitted via teliospores carried on the surface of otherwise healthy wheat grains. Following infection, the pathogens invade developing wheat spikes and replace the kernels with masses of black teliospores, resulting in reduced yield and seed quality. In Canada, grain lots contaminated with common bunt spores at levels as low as 0.01% by weight are downgraded to animal feed or rendered unmarketable, in part because of the offensive odor. Common bunt caused substantial losses prior to the widespread adoption of fungicide seed treatments and remains a concern in regions where seed treatment is unaffordable or undesirable, such as in organic wheat production systems. This review provides an overview of disease symptoms, pathogen life cycle, and management strategies for common bunt of wheat in Canada. Information © The Author 2026