IQ TIMOTHY RUST IN THE UNITED STATES. 



the vigor of the infection was concernetl, the rehitive rust resistance 

 of strains as obtained in the field was fairly well maintamed in the 

 greenhouse experiments and that the differences in resistant and sus- 

 ceptible strains were marked. 



Having determined, then, that there are wide differences in timothy 

 strains with regard to resistance and susceptibility to rust, the prob- 

 lem in timothy-rust prevention is one of breeding. This may not be 

 as difficult as it appears at first, since up to the present time timo- 

 thies have not been highly bred and there are not only great differ- 

 ences between varieties but apparently unusual variations within a 

 varietv. Response to selection, therefore, may be both rapid and 

 well marked. Such breeding, however, to be of any value must be 

 carried on in places w^here the rust is abundant or where either natur- 

 ally or artificially a rust attack occurs every year. 



SUMMARY. 



Timothy rust was reported in the United States as early as 1882. 

 It was reported from Iowa in 1891. From 1891 to 1906 no men- 

 tion of the parasite has been found. In 1906 the rust became epi- 

 demic at the Arlington Experimental Farm, near Washington, D. C, 

 and since then has been found to be widespread, having been reported 

 from ]\Iaine to Ontario and northern ^Minnesota and south to Iowa, 

 Kentucky, and Virginia. 



Timothy rust is similar in general appearance and morphological 

 characteristics to Puccinia graminifi Pers. on wheat. 



Inoculation experiments with timothy rust at Washington, D, C, 

 show that it can be transferred easily to various grasses. Similar 

 results have been obtained by Eriksson in Europe. This demonstrates 

 that the rust in the United States and the rust in Europe are identical. 

 That it is not a well-fixed species is substantiated. By using bridging 

 hosts timothy rust can be made to transfer to various cereals which 

 it will not attack directly. That such transfers take place in nature 

 to some extent is probable. 



The secidial stage of this rust is not definitely known. Eriksson and 

 Henning in numerous inoculations with the teleutospores on bar- 

 berries obtained negative results except in one instance. On this 

 basis they consider the rust a distinct species, naming it Puccinia 

 pTilei-pratenms. Kern has observed several imsuccossful inoculations 

 on the barberry in tliis country. From the one apparently positive 

 result of Eriksson and Henning, however, he believes that the rust is 

 not entitleil to specific rank and should be included under Puccinia 

 graminis Pers. Evans accepts the name Puccinia pTilei-'pratensis and 

 shows that there are well-marked tlifferences in the details of the 

 infection from the uredospore of this rust and the graminis form on 



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