154 Journal of Agricultural Research voi. xxii, no. 3 



BASIS OF CULTURAL INVESTIGATIONS 



A study of Puccinia trUicina in comparison with other grass rusts with 

 long covered teha shows that it can not be readily separated morpholog- 

 ically from the leafrust of rye. The separation of this form as a species 

 was made by Eriksson {10) because he obtained only slight infection on 

 rye with urediniospores and was not able to obtain infection on Anchusa 

 with basidiospores and because the teliospores germinated in the spring, 

 while those of the rye rust germinated in the fall. The close morphological 

 similarity, however, furnished considerable grounds for the assumption 

 that the aecial host of leafrust of wheat was likely to be some species of 

 Boraginaceae other than Anchusa, especially as another rust of this type, 

 Puccinia hromina Eriks., has since been found to have its aecia on the 

 Boraginaceous hosts Symphytum officinale and Pulmonaria montana, with 

 very weak development of aecia on Anchusa {ig, p. 182-202). Unfin- 

 ished investigations now being conducted in this laboratory strongly 

 indicate that in America certain grass rusts having aecia on Boraginaceous 

 hosts are very similar to the leafrust of wheat and rye. For these reasons 

 it was considered desirable to test as many Boraginaceous hosts as were 

 available, as possible aecial hosts for the leafrust of wheat. 



There is, however, still another group of grass rusts very similar to the 

 orange leafrust of wheat to which Arthur (j, v. 9, p. 304) has called atten- 

 tion. This group has aecia upon various Ranunculaceous hosts and in- 

 cludes forms which have been separated from time to time, according to 

 their aecial connection, together with slight morphological variation, into 

 a number of species, including Puccinia persistens Plowr., P. perplexans 

 Plowr., P. Agropyri, and P. alternans Arth, The writers felt from the 

 beginning that the greatest possibility of success in the search for the 

 aecial stage was to study thoroughly the genera of this family on which 

 aecia were known to occur. 



The idea that Puccinia tritichia has lost its ability to develop an aecial 

 . stage through long propagation by urediniospores, while admittedly pos- 

 sible, was not considered to be fully substantiated. 



CULTURES MADE IN 1919 



With these considerations in mind rather extensive sowings were made 

 in the spring of 19 19 upon a considerable number of species of the fami- 

 lies Ranunculaceae and Boraginaceae and the closely related family 

 Hydrophyllaceae. For this purpose, 20 collections of telia of Puccinia 

 tritici'na were obtained from various sections of the country during the 

 summer and fall of 1918 and placed outdoors to winter. Early in March 

 these began to germinate. Ten of the 20 collections gave good germina- 

 tion and were sown upon various species of the above-named families and 

 upon Ornithogalum umbellatum L., Impaiiens sp., and Catnassia esculenta 

 (Ker.) Robins. (Quamasia hyacinthina). The results obtained are given 

 in Table I. 



