Dwarf Bunt in Winter Wheat Justin Clawson, Claudia Nischwitz, Margaret Krause, and Will Krause Dwarf bunt or stinking smut (Tilletia controversa Kühn, Figure 1) is a fungal disease that affects winter wheat (Triticum aestivum L.). The disease first appeared in Utah in the early 1930s in Cache County near the city of Paradise. The disease was soon found in Box Elder County near Hansel Valley. The outbreak of dwarf bunt became so severe that it affected other crops, such as barley. The impacts of this disease in 1932 affected an estimated 95% of a field near Logan, Utah (Figure 2). Researchers at Utah State University (USU) set out to find wheat varieties that were resistant to the fungus. Figure 2. Field With 95% Dwarf Bunt Infection Near Logan, Utah, 1932 (Woodward et al., 1932)
Small Grains Research The USU Small Grains Program is the result of research for resistant varieties. The first variety released by the Utah Agriculture Experiment Station was ‘Relief’ in 1934 to replace ‘Ridit’ released by the Washington Agriculture Experiment Station in 1923 (Dalley, 1931). The variety ‘Cache’ was released in 1936 from the Utah Agriculture Experiment Station.
Figure 1. Tilletia controversa Kühn Spores at 400x Magnification (B.J. Goates, USDA Agricultural Research Service, Bugwood.org)
In 1976, Cache and Box Elder counties cut their first clean wheat in years (Woodward & Tingey, 1944). New cultivars of wheat resistant to dwarf bunt are still screened in the program today. The USU Small Grains Program is currently the only program in the United States screening for the disease and has become of more interest due to organic production. The program screens varieties from Idaho, Washington, Oregon, Turkey, and Austria.