INTRODUCTIOX. 11 



niiued the a^cidial host of the crown rust of oats for this country,' it 

 is deemed best to retain, for the present, tlie okl name P. voronata; and 

 while Eriksson and lleniiings's division of P. ruhigovem is undoubtedly 

 correct, it seems, nevertheless, preferable to retain this well-known 

 name'^ until it is positively determined whether our species is equiva- 

 lent to P. dispersa or is a new one. It has already been stated that 

 P. ylumarum and probably P. simplex do not occur in this country, and 

 of course P. sorghi does not occur in Sweden. 



Common nomenclature of grain rusts. — The common nomenclature of 

 these rust forms is a complex question. The names above given were 

 decided upon, after much consideration, as being the most accurate and 

 descriptive that could be used. In the case of 7*. graminis and P. 

 ruhigo-vera the names have been given in accordance with the most 

 common and striking characteristics of the species. The former, when 

 it occurs in abundance, exists principally upon the stems and in the 

 black stage, while the latter is most strikingly exhibited on the leaves 

 in the orange-colored uredo stage. The crown rust, although also an 

 orange leaf rust, can not be spoken of as such, as it would thus be con- 

 fused with the orange leaf rust of wheat, which is a different species. 

 Of course, there need be no confusion in the case of the name of the 

 maize rust, it being the only one on maize/^ 



The Departmenfs irork on grain rusts. — AYith a view to thoroughly 

 investigating the cereal rust question, this Division in the spring of 

 1892 sent to crop reporters in the principal wheat-growing States a cir- 

 cular requesting information as to the distribution and abundance of 

 the different rusts, the damage caused by them, etc. Owing to the 

 press of other work, however, nothing further was done in this line, 

 except the spraying experiments in 1892 and 1893, until the writer took 

 charge of the work in the spring of 1894. A circular similar to the 

 above was then prepared and sent to growers in all States where wheat 

 and oats are grown to any extent, the information requested to be 

 based on observations made during the season of 1894. The following 

 table gives a combined summary of the answers received to the two sets 



1 Siuce the above was written a series of inoculation experiments have shown 

 rather conclusively that Ehamnus lanceolaia acts as an tecidial host of the cro>vn rust 

 in this country. 



^The writer has recently had au opportunity to make personal observations on 

 the rusts of wheat in northern Europe — that is, from England to Sweden and south- 

 ward to southern Germany — and not only found these two to be very distinct, but also 

 found that P. glumaruvi was far more common and injurious everywhere during the 

 season of 1898. It seems strange that the two species should have been confounded 

 for so long a time. However, there appear to be very good reasons for still retaining 

 the name P. ruiigo-vera for the species called P. dispersa by Eriksson and Heuniugs, 

 as there is little doubt that it is the same as the one so well known under the former 

 name in all other countries where rusts have been studied. 



*The fact that Eriksson called P. dispersa brown rust — and, judging from his speci- 

 mens, he seems correct— is the only reason for doubting that P. ruMcjo-vera of this coun- 

 try is equivalent to it, as our species is certainly orange color in the uredo stage. 

 The uredo of the black stem rust would be more properly called brown. 



