Aug. 27, 1917 Puccinia graminis on Cereals and Grasses 



449 



number of leaves of Phleum pratense which became infected in No. i was 

 probably due to the fact that the grass inoculated had been somewhat 

 injured by thrips. When transfers were made to healthy timothy plants, 

 15 out of 15 became infected. 



Table XIX. — Results of inoculations with urediniospores from Festuca pratensis Huds, 



The results of the inoculations recorded in Table XIX show that the 

 common rust on Festuca pratensis is P. graminis phleipratensis and that 

 oats, barley, and rye may be weakly attacked. The rust did not develop 

 well on any of the three, the uredinia always being small. 



One set of inoculations was made with P. graminis from Hordeum 

 caespitosum, collected at Coburg, Mont., on September 22, 1916, The 

 results are given in diagram 7 and show clearly that the rust was P. 

 graminis tritici. 



Diagram 7. — Results of inoculations with urediniospores from Hordeum caespitosum Scribn. 



[wheat- 



Puccinia graminis from Hordeum caespitosum (Coburg, Mont.)-{ 



Rye 



16 



Three biologic forms of P. graminis were found on Hordeum juhatum — 

 viz, P. graminis tritici, P. graminis tritici compacti, and P. graminis 

 secalis (Table XX). Both P. graminis tritici and P. graminis secalis were 

 isolated a number of times from the same lot of grass material. The two 

 forms can be separated easily, as shown by diagram 8. It will be seen 

 by referring to No. 3, Table XX, that all the inoculated leaves of barley, 



