Oats Covered Smut

Covered smut and loose smut are very similar in appearance and covered smut is also known to occur anywhere oats are grown. Covered smut is not detectable until head emergence. Infested heads will typically emerge earlier than healthy heads. The fungus is presen on the surface of the seed and is activated when the infested seed germinates. The head produced by an infested plant will contain olive-brown to brown-black powdery spore masses where healthy grain would have been present. Spore masses emerge within a grayish-white membrane that can persist until the chaff dries or the grain is harvested. Spores can be windblown onto the flowering heads of healthy plants. The fungus can then enter the ovaries and developing grain and infect seed that may be used in subsequent years. Soil temperature (optimum 59 to 77 F) and moisture (optimum 35 to 40%) and the time of planting may increase infection of untreated seed.