204 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



interested a<rencies. No definite records of these were obtained. 

 Records to date show that a total of 2,405,426 bushes have been 

 h)cated on ;K>,r)()8 projxMties and 2,;5()5,142 liavo been removed from 

 i>6,2G9 properties, makin<2: a «,M-and total on June 30, 1920, of 3,805,426 

 bushes located and 3,705,142 bushes removed. 



LEAF RUSTS OF WHEAT, BARLEY. AND RYE. 



Research on the various leaf rusts is conducted in cooperation with 

 the Indiana Agricultural Experiment Station and, to a limited 

 extent, with other State experiment stations. 



LIKE HISTOUIKS, HIOJ.OCIC KOUAIS, AND HOSTS ()!• I.KAl UlSTS. 



Greenhouse research has ^'esulted in the production of the SBcial 

 stage of the leaf rust of wheat, thus for the first time demonstrat- 

 ing the complete life cycle of this rust. These results show that 

 various si)eiics belonging to one genus of the family Ranunculacea; 

 are the alternate hosts for the leaf rust of wheat. The leaf rust of 

 rye also has been carried through its complete life cycle in the green- 

 house, and the results obtained by other workers have been dupli- 

 cated and somewhat extended, oeeia being produced for a consider- 

 able period of time on Anchusa oijicinalis. 



Considerable progress has been made during the past year in the 

 studies to discover biologic forms of the leaf rusts. At least two 

 apparently quite distinct strains are present in the leaf rust of wheat 

 in this country. The leaf rusts of rye and barley so far liave given 

 negative results. The work of the previous seasons upon hosts and 

 relationships of the leaf rusts has been extended and amplified, re- 

 sulting in a better understanding of the relationship of the forms 

 on cereals and the related forms of these rusts on grasses. 



WHEAT VAIUETIKS RESISTANT TO LEAF RUST. 



Field and greenhouse experiments during the past two years have 

 resulted in the discovery of a number of wheat varieties which are 

 fairly resistant to leaf rust. Of the various wheat subspecies or 

 groups, the clubs have been found to be extremely susceptible, the 

 spells and poulards usually only moderately infected, while the 

 durums, emmers. einkorn, and Polish wheat, on the other hand, are 

 generally rather highly resistant. 



In the 300 or more varieties and selections of the bread wheats 

 studied, all gradations were found from extreme susceptibility to 

 almost complete ininnmity. The most resistant of these wheats were 

 discovered in a numl)er of varieties belonging to the Crimean group. 

 Of these, five were found which have shown a high degree of re- 

 sistance in greenhouse and field, especiallv so in the eastern and 

 southern localities. These varieties are ^falakoff, C. I. 4898, and 

 four selections of a Turkey )< Bearded Minnesota hybrid. The vari- 

 ous Kan red selections have shown a high degree of resistance in 

 sowings made in Wisconsin. Illinois, Indiana, and Tennessee and at 

 the Arlington Experimental Farm, near Washington, D. C. Besides 

 these, about 10 or 12 other hard winter wheats have shown consider- 

 able resistance to leaf rust, and, what is more important for south- 

 ern conditions, several soft winter wheats liave shoAvn considerable 

 promise of resistance, which it is hoped may be increased by selection. 



