Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Department name when degree awarded


Committee Chair(s)

D. C. Tingey


D. C. Tingey


Covered smut is a fungus disease that has caused serious losses of wheat for centuries. Its origin is not known, but it was well known to early Romans as evidenced by the fact that they had a god, Robigus, whose special work was to watch over crops to "avert the mildew" (45). It is often referred to as "bunt" or "stinking smut of wheat". Throughout this paper the term "bunt" will be used to designate this disease in order to avoid confusing it with other smuts of wheat.

Bunt is worldwide in its distribution, but it is especially prevalent in the Pacific Northwest and certain other sections of western United States. It was estimated in 1914 that in eastern Washington a loss of 5-10 million bushels of wheat was caused by this disease (69).

Yield reduction is the most serious loss, but other losses include: (1) lower quality and grade of wheat, (2) expense of treating seed, (3) loss of seed due to effects of the fungicide on viability, (4) losses from fires and explosions (61) (28). A survey conducted by Price and McCormick (47) in eastern Washington and Idaho showed that during the harvest season as many as 6-10 explosions per day were set off by static electricity igniting explosive smut-dust and air mixtures around threshing machines. Stephens and Woolman (61) reported that bunt is the cause of a greater aggregate loss to the world than any other crop pest.