The Behavior of Telia of Puccinia Graminis in the South

Abstract

Since July, I918, the writer has had under observation the behavior of telia of Puccinia graminis Pers. on various grasses and the relationship of this spore stage to the overwintering and dissemination 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, I918, 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. I919, p. 57I) 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 barberry infections that these observations were undertaken at Fayetteville, Arkansas, latitude 36°. While the average temperatures 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 destructive as the various leaf rusts. Occasionally, as in I919, 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, Agrostis palustris Huds. (A. alba of authors) of timothy, Phleum pratense L., and of Elymus australis Scrib. and Ball is often prevalent. 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 disposed in the stem rust and always scattered in the leaf rusts. Such characters as color, shape, and size of the spores vary with