A Study of Meadow-Crop Diseases in New York 91 



Puccinia phlei-pratensis. The same authors the next year, however, 

 establish Puccinia graminis phlei-pratensis comb. nov. (1917), and yet 

 they use the name Puccinia phlei-pratensis in many places in the same 

 paper. In being thus inconsistent, they admit that the relation of the 

 rust to Puccinia graminis is still probably debatable, but they favor 

 including it as a biologic form of Puccinia graminis (1917:482). 



Arthur, in the North American Flora lists the fungus as Diaceoma 

 poculiforme (Jacq.) Arth. (Puccinia graminis Pers.), but in his new book 

 on plant rusts (1929:328) he calls it Puccinia graminis phlei-pratensis. 

 Stakman (1922:251) reverts to Eriksson's original name in summing up 

 the diseases of cereal and forage crops in the United States in 1921, for 

 there he lists the timothy rust organism as Puccinia phlei-pratensis Eriks. 

 & Henn. 



It is obvious from this brief review of the literature that the name of 

 this fungus has been changed about considerably by taxonomists of the 

 rusts. In view of the following facts, the author favors retaining the 

 name Puccinia phlei-pratensis: (1) the fungus has produced neither pyenia 

 nor aecia under controlled conditions; (2) the uredinial mycelium is appre- 

 ciably smaller than that of Puccinia gramin s; (3) teliospores are rare; 



(4) the fungus overwinters in the uredinial condition in northern latitudes; 



(5) no evidence of biologic specialization has been obtained; (6) the uredinia 

 are distinctively linear instead of oval or elliptical; (7) the urediniospores 

 are predominantly pyriform rather than oval, elliptical, or elongate; 

 (8) the author who made it a biologic form of Puccinia graminis subse- 

 quently calls it Puccinia phlei-pratensis. 



Pathogenicity. Certainly the array of inoculations already cited under 

 the discussion of the suscepts leaves no doubt of the pathogenicity of 

 P. phlei-pratensis. 



Only one paper seems to exist reporting inoculations with collections of 

 the rust from different places to see if any specialization occurs within the 

 species. Barker and Hayes (1924:309-370) inoculated various clonal lines 

 with collections of timothy rust from different parts of the United States 

 and Canada. " No definite evidence of biologic specialization of Puccinia 

 graminis phleipratensis was found." In view of the rather recent work of 

 Craigie (1927) this may be due to the absence of an aecial suscept. 



Life history. That the fungus overwinters as perennial mycelium is 

 hardly to be doubted. Eriksson and Henning (1894:141) first advanced 

 evidence in support of this hypothesis. Johnson (1911) developed uredinial 

 sori from overwintered green leaves and he also determined that viable 

 urediniospores may be found after they have passed the winter. Hunger- 

 ford (1914:337) gives supporting evidence for this opinion. 



More than twenty-five separate experiments by the writer on the toxic- 

 ity of chemicals in which many thousands of spores were examined have 

 revealed some interesting characteristics of the process of spore germination. 



