Aug. 27, 1917 Puccinia graminis on Cereals and Grasses 



443 



Only the three species of Agrostis (Table IX) were really susceptible 

 to P. graminis agrostis from A . stolonifcra. The cereals were infected in 

 much the same manner as were those inoculated with the rust from 

 A. alba. The character of the infection was the same. None of the 

 cereals was a congenial host. The uredinia were all very small, but 

 were not surrounded by much dead leaf tissue. Diagram 3 shows that 

 the rust develops only weakly on oats and rye and does not acquire 

 increased virulence as a result of successive transfers. None of the bio- 

 logic forms commonly found on cereals was found on A. stolonifera, 

 although there is reason to suspect that it can be infected naturally by 

 P. graminis avenae, since successful transfers were made in the green- 

 house. 



RESULTS OF INOCULATIONS WITH UREDINIOSPORES FROM AVENA 



SATIVA 



Oats affected with stemrust were collected at various places in Minne- 

 sota, North Dakota, and Montana. Inoculations were usually made only on 

 oats, however, and the resulting rust kept as stock cultures. The results 

 are included, therefore, in Table XXXI, Only P. graminis avenae was 

 found. 



Table X. — Results of inoculations with uredinios pores front Anthoxanthum puelli Lecoq. 



and Lamotte 



Further inoculations were made with the rust developed on oats. The 

 results are given in diagram 4. 



Diagram 4. — Results of inoculations with urediniospores developed on oats recorded in Table X. 



I„ 22 



Oats — — 

 Barley a2. 

 It 



Oats — 



22 



Phleutn pratense o— 



"■ Uredinia extremely minute. 



Only a small number of inoculations were made with P. graminis from 

 Anthoxanthum puelli, but from the results given above, it seems clear 

 that the grass may be a host for P. graminis avenae. A number of inocu- 

 lations with urediniospores of P. graminis avenae were made on seedlings 

 of the grass. Some resulted in successful infection, while others did not. 



