CEOWN RUST OF OATS. 13 



flower. Doctor Voronin, in his experiments above mentioned, also 

 found that rust of cultivated sunflower would not infect Helianthus 

 tuberosus. In 1901 Ernst Jacky a inoculated the following hosts with 

 teleutospores from Helianthus annum: H \ annum, H cxicumerifolius, 

 II californicus, H. tuberosus, II. maximiliana, II. nvultiflorus, II. 

 scdberimus, and II. rigidm, with resulting infections of the three first- 

 named 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 Helianthus annuus (includ- 

 ing cultivated varieties), II. petiolaris, and II mollis are identical, 

 with the probability that a distinct form exists on II. tuberosus. 



Sunflower rust has been collected by the writer on the following 

 species of Helianthus. including all stages on nearly every species: 

 II. annuus (both wild and cultivated), II. rigidus, II. petiolaris, II. 

 tuberosus, H. hirsutus, H. maximiliana, II. grosse-serratus^ H. orgyalis, 

 II. mollis, and II. ciliaris. The secidium occurs rarely in compari- 

 son with the occurrence of other stages, 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, may be accounted for by the fact that the uredo 

 is often produced by direct teleutosporic infection. 



Crown Rust of Oats (Puccinia rhamni [Pers.] Wettst.). 



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

 that certain infections had just been made showing the connection of 

 the crow T n rust of oats on Phalaris caroliniana and Arrhenatherum 

 elatius with the recidial form on Rhamnus lanceolata. 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 aecidium of Rhamnus lanceolata on oats at Lafayette, 

 Ind. 6 ' The experiments of the writer are here given in detail. 



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

 cinia coronata, was found in great abundance on Phalaris 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 30, 1897, 

 resulting September 7 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 teleutospores had appeared on the original plants of Phalaris 



« Centralb. Bakt. Parasit. u. Infekt., 2 Abt„, Bd. 9, No. 21, pp. 802-804, December, 

 1902. 



h Cereal Rusts of the United States, Bui. No. 16, Div. of Veg. Phys. and Path., 

 U. S. Dept. of Agriculture, 1899. 



o Bui. Lab. Nat. Hist. State Univ. Iowa, Vol. IV, pp. 398-400, December, 1898. 



