442 



Journal of Agricultural Research 



Vol. X. No. 9 



occasionally. A. alba has, however, been infected by P. graminis 

 avenae in the greenhouse, although the writers have not found this form 

 on it in the field. It is possible but not demonstrated, therefore, that it 

 may be important as a host for P. graminis avenae (Table VII) . 

 TablS VIII. — Results of inoculations with urediniospores from Agrostis exarata Trin. 



Agrostis exarata was heavily rusted in a number of localities, especially 

 in valleys in western Montana. The rust was evidently P. graminis 

 avenae. It has been used in many inoculation experiments in the green- 

 house, and, although it apparently is an ordinary strain in most respects, 

 the morphology of the urediniospores is slightly different from that of 

 some of the other strains. No sharp differences in parasitic capabilities 

 have yet been noticed (Table VIII). 



Table 1^.— Results of inoculations with urediniospores of Agrostis stolonifera Vasey 



Diagram 2.— Results of inoculations from uredinia produced in No. 4, Table IX. 



P. graminis agrostis from A . stolonifera'. 



A . stolonifera ~ Wheat — 



50 34 



A . canina — — Wheat — 

 7 19 



A . alba Calamagrostis canadensis — ■ 



60 4S 



Diagram 3. — Results of inoculations from uredinia produced on oats and rye in No. 5, Table IX. 



Oats 



P. graminis agrostis from A. stoloniferai 



Rye — — Rye — 



