THE BEHAVIOR OF TELIA OF PUCCINIA 

 GRAMINIS IN THE SOUTH 



H. R. Rosen 



Since July, 1918, the writer has had under observation the be- 

 havior of telia of Puccinia graminis Pers. on various grasses and 

 the relationship of this spore stage to the overwintering and dis- 

 semination of the rust. It is well known that barberries, both 

 native and introduced, are present in- the southern states, and yet 

 infections on this alternate host are apparently rare. Stakman 

 (Separate from Yearbook of the United States Dept. of Agric. 

 No. 796, 1918, p. 25) says, "There can be no question whatever 

 that the barberry is the most important factor in the spread of 

 rust in the northern half of the Mississippi basin. In the South 

 it is less important." In a previous paper Rosen and Kirby 

 (Phytopathology 9: 569-573. 1919, p. 571) record the absence 

 in the Arthur Herbarium of aecial collections of P. graminis 

 from the southern states. It was with the thought that a study 

 of the behavior of telia might shed some light on the lack of bar- 

 berry infections that these observations were undertaken at 

 Fayetteville, Arkansas, latitude 36 0 . While the average tem- 

 peratures prevailing at Fayetteville are lower than those in a 

 major part of the state, the observations made in other sections 

 indicate a close similarity in the behavior of stem rust. 



As a rule black stem rust is not nearly as widespread or as de- 

 structive as the various leaf rusts. Occasionally, as in 1919, the 

 wheat leaf- rust, Puccinia triticinia Erikss., is so destructive that 

 fields are abandoned and left unharvested, while the stem rust is 

 only rarely observed. However, the stem rust of red top, Agros- 

 tis palustris Huds. (A. alba of authors) of timothy, Phlenm pra- 

 tense L., and of Elymus australis Scrib. and Ball is often preva- 

 lent. Perhaps it will be worth while to point out that the main 

 difference between the urediniospores of the stem and leaf rusts 

 is' in the arrangement of the pores, being always equatorially dis- 

 posed in the stem rust and always scattered in the leaf rusts. 

 Such characters as color, shape, and size of the spores vary with 



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