GRASSES OF IOWA. 237 



smut would infect only wheat plants. Oat smut would not pro- 

 duce wheat scQut, nor barley smut produce smut in wheat. 

 Kellerman and Swingle* give a full bibliography. It is 

 described under U. segetum in the works cited below: 



Distribution and damage. — This disease occurs wherever 

 wheat grows. We have observed it abundant in many porlions 

 of Iowa where wheat is grown; also in Minnesota and Wis- 

 consin. According to Dr. Erwin P. Smitb, it is common in 

 Michigan. Kellerman and Swingle also report it as common 

 in Michigan. In a collection c f smuts prepared for the World's 

 Fair this was sent to me from many states. It is reported as 

 common in Nebraska (Bessey), Indiana (Arthur), North Dakota 

 (Bolley) and New York (Beach). It is al«o common in Ger- 

 many (Sorauer, Frank, Tubeuf, etc ), England (Plowiight and 

 Marshall Ward). These references suffice to show that this 

 fungus is of wide distribution. The damage caused by this 

 smut is often very considerable. It is the one most familiar to 

 the Iowa farmer. Perhaps the loss to Iowa farmers is not far 

 from .5 per cent. Dr. Er^vin F. Smith reports that he observed 

 in a patch of five acres in Michigan a loss of 50 per cent in 1870. 

 Much of this less can, no doubt, be prevented by judicious 

 culture. 



General characters. — The affected plants are lighter green in 

 color. The smut converts the chaff, and frequently all adher- 

 ing parts except the central stalk, to a powdery mass. The 

 smut is not covered with a membrane. As Professors Keller- 

 man and Swingle say, "The spores are completely free, and in 

 this species is perhaps the dustiest of all lo'^se smuts." The 

 wind removes nearly all of the smut excepting a small portion 

 adhering to the central stalk. Unlike bunt, not all the stalks 

 of a stool are affected. Professor Bessey, some years ago, 

 noted this fact of wheat grown at Ames. 



In 1892 the writer made some observations on two varieties of 

 wheat grown on the college farm in which the same results were 

 ob ained. 



This fact clearly. indicates that the manner of infection is 

 very different than in bunt or loose smut of oats. 



*Rep. Kansas Agrl. Exp. Sta. 1889: 261. 



Tubeuf Pflanzenkrankheiten. 303; under L'. tritici. 



+Saccardo. Syll. Fung. 7: 481. 



Sorauer. Pflanzenkrankheiten. 198. 



Frank. Krankhelten. d. Pflanzen. 110. (Ed. 3.) 



Marshall Ward. Diseases of PI. 86. Plowright. British Ured. and Cstllag. 273. 



