CKOWN Kl'ST OF OATS. 13 



flower. Doctor Voronin, in his experiineiits above iiietitioiied, also 

 found that rust of cultivated sunflower would not infect ILIlitnthuti 

 tuherofoi.s. In 1!^()1 P]rnst Jack}' " inoculated the foUowin*^ hosts with 

 tcleutospores from I[ellanth>isannHHi<: II. luinxus, II. <ncaint'nf(>llu)<., 

 II. eallforxicHs^ II. ti(her<»<>is^ II. iixi.i-iinllunxi.. II. inKltilforxK, II. 

 scahei'iiints^ and II. rujklxs^ with resultinj^ infections of the three flrst- 

 naiued species, but no infection of any of the others. 



The evidence from all these experiments just quoted and those of 

 the writer shows at least that the rusts of Ilelhmthus annuua (includ- 

 ing;- cultivated varieties), //. petlolarus., and //. nidllis are identical, 

 with the probability that a distinct form exists on II. tnherosu.s. 



Sunflower rust has been collected by the writer on the following- 

 species of Helianthus. including all sta<»-es on nearly every species: 

 II. annnns (both wild and cultivated), //. rigidu.'i, II. jfetiolarls., II. 

 tiiberosus., II. Mrsutius, II. niaxiinlJliina, II. (/ross'e-scrr'ffifs, II. onjiiaJ)^^ 

 II. moUi.s., and IF. eUiaris. The lecidium occurs rarely in compari- 

 son with the occurrence of other stag-es, but is to be found on a num- 

 ber of hosts and occasionally in considerable abundance. This rarity 

 of its occurrence, together with the occurrence of spermogonia so 

 often with the uredo, ma}^ be accounted for by the fact that the uredo 

 is often produced by direct teleutosporic infection. 



Crown Rust of Oats {Pnccinla rhuiiuil [Pers.] Wettst.). 



In a mere note in a previous bulletin of this Department'' it is stated 

 that certain infections had just been made showing the connection of 

 the crown rust of oats on Phalarls carollniana and Arrhenatheruni 

 elatlux with the secidial form on Rhamnus hmceolata. No other dem- 

 onstration of such a connection of forms had been reported up to that 

 time. During the same season, however. Doctor Arthur obtained 

 infections with the »cidium of Rhamnus lanceolata on oats at Lafayette, 

 lnd.<^ The experiments of the writer are here given in detail. 



On August 23, 1897, the uredo stage of a rust, supposed to be Puc- 

 clnia coronata., was found in great abundance on Phalarls caroliniana 

 at Stillwater, Okla. This host, with the rust, was transferred to a green- 

 house of the Agricultural College at Manhattan, Kans., and inocula- 

 tions were made on oats, wheat, and orchard grass on August 3(>, IS07, 

 resulting September T in a good infection of oats, a poor one of the 

 orchard grass, and no infection at all of wheat. Other inoculations 

 were made September 1 on wheat and rye, with no result. By October 

 8 the tcleutospores had appeared on the original plants of Phalaris 



«Cen trail). Bakt. Parasit. u. Infekt., 2 Abt., Bd. 9, No. 21, pp. 802-804, December, 

 1902. 



^Cereal Rusts of the United States, Bui. No. 16, Div. of ^"eg. Phys. and Path., 

 U. S. Dept. of Agriculture, 1899. 



<^ Bui. Lab. Nat. Hist. State Univ. Iowa, Vol. IV, pp. 398-100, December, 1898, 



