654 



Journal of Agricultural Research 



Vol. XIII, No. 12 



Table I. — Comparative results of inoculations with uredinospores of the three biologic 

 forms of Piiccinia graminis Pers. on six differential hosts 



Table I contains the summary of these inoculations, together with the 

 results of inoculations with the tritici and triiici-compacti forms on the 

 six diflferential hosts. It will be seen from this table that all of the 

 varieties resistant to either P. graminis tritici or P. graminis triiici- 

 compacti are highly susceptible to the new form. 



From the above facts it is evident that the rust found in Oklahoma 

 is neither P. graminis tritici nor P. graminis tritici-compacti. While 

 only a few differential hosts have been tried, yet the action of the new 

 rust on these hosts is so entirely different from that of the previously 

 described biologic forms, that it must be considered as a distinct form, 

 Extensive cross inoculations and an intensive morphological study are 

 now under way. 



o 



