Tilletia caries

of Tilletia spp The pathogen grows within the terminal meristem via mycelium and completes its life cycle by transforming the mycelial cells into teliospores. The smutted wheat kernels that are full of teliospores break open and release upon harvest, which allows for the teliospores to overwinter on the seed and are blown away by currents onto the soil, thus completing the life cycle. == Morphology ==

Teliopsores are thick-walled, globiose, reticulate and 13–23 μm in diameter. == Hosts ==

Agropyron (wheatgrass), Bromus (bromegrasses), Elymus (wildrye), Festuca (fescues), Hordeum (barleys), Lolium (ryegrasses), Poa (meadow grass), Secale cereale (rye), Triticale, Triticum spp. (wheats) – including T. aestivum (common wheat), T. dicoccum (hulled wheat), T. turgidum (durum wheat) – and other Poaceae (other grasses). == Signs and symptoms ==

It is difficult to detect Tilletia caries early in its infection period; by the time symptoms are able to be detected, the pathogen is systemic throughout the plant. When the mature kernels are broken, they are full of a black, powdery mass of the fungal spores. These fungal spores give off a distinctive fishy smell and are oily to the touch. == History and significance ==

ca. 1902|alt=Combine harvester pulled by 33 horses, Walla Walla, ca. 1902 From the late 1800s until the 1930s, stinking smut was a devastating disease of wheat. For example, infection levels over 20% were common in Washington State in the early 1900s. One of the most extreme cases was in Kansas in 1890 where the yield was reduced 20–50% because of Tilletia caries. Only when seed treatments became available after 1930 did losses from smut drop to much lower levels. Today, losses from smut rarely occur unless a grower chooses not to plant treated seed, but, if left untreated, bunt can reduce yield by more than 50%. In modern agriculture, if an infection occurs, losses are 5–10%. == Management ==

The most effective and widely used management strategy for common bunt is to treat seed with fungicide before planting. According to the University of Nebraska–Lincoln Institute of Agriculture and Natural Resources, it is recommended to buy certified, fungicide-treated seed or have it cleaned and treated by a commercial seed conditioner. There are ways that farmers can manipulate the severity of the infection to a certain extent. For example, they can plant the seed when the soil temperature is higher than what is ideal for teliospore germination, e.g., above . For winter wheat this means planting in early fall and for spring wheat planting in late spring. This tactic can reduce the amount of smut that occurs, but it typically does not eliminate the disease. Typically, smut poses more of a problem in winter wheat than in spring wheat because in autumn, when winter wheat is planted, there is a longer period of more favorable temperatures for teliospore germination than compared to the planting season for spring wheat. == See also ==