22 



THE RUSTS OF GRAINS IN THE UNITED STATES. 



experiments no infections to wheat after barley and only one to oats 

 after barley were obtained with the rye rust, but only a small number 

 of attempts on wheat and oats were made from the rust on barley. 

 There is little doubt that rye rust can be made to go to wheat after 

 passmg to barley, as has been shown by Derr's experiments previously 

 cited. Diagram 13, summarized from diagram 11, shows the direct 

 infections obtained with stem rust from rye. 



Diagram 13. — Summary of the direct inoculations of barley and rye with stem rust from rye. 



R 



IR 25 



IB 



23 

 31' 



Diagram 14 shows the possibility of infection of all four cereals 

 by passing to barley. 



Diagram 14. — Summary of inoculations by stem rust of rye directly to two cereals and 



through barley to wheat and oats. 



fB W (Derr). 



R 



R 



25' 



B ^ 

 ^ 31 



-O 



22 



Diagram 15 presents a summary of inoculation experiments with 

 Puccinia graminis avenae (stem rust) from oats: 



Diagram 15. — Summary of inoculation experiments with stem rv^tfrom oats. 



O 



^ 87 

 -0 88- 



-W 



100 



-B 



84 



-r1 



^ 82 



" 10 



of 



Diagram 16 presents a summary of the successful infections^ shown 

 in diagram 15. 



Diagram 10. — Summary of successful inoculations shown in diagram 15. 



87 



O 



O 



■^ 84 



-B 



10 



I Derr reports having obtained a direct infection of oats to wheat and one of oats to rye. In the case of the 



wheat the rust was further transferred as follows: O >W >B >W. He also further carried 



the oats to barley and transferred infection as follows: 



(O O. 



fO- 



o- 



t 



B. 



216 



