BUREAU OF PLANT INDUSTRY. 207 



treatment. Several of these were established in Indiana in 1919, 

 and many farmers had small lots of grain, usually 5 to 10 bushels, 

 treated for the fall sowing. 



The results of the treatment have proved very satisfactory. In 

 general, loose smut was not so prevalent in 1920 as in previous years. 

 However, the wheat from untreated seed usually showed from 5 to 12 

 per cent of loose smut, Avhile occasionally even higher percentages 

 were recorded. On the other hand, wheat grown from the same seed 

 but treated b}^ the hot-water method proved practically free from 

 loose smut. 



Much remains to be done to simplify and cheapen the methods of 

 treatment. Experiments are in progress on the drying of the seed 

 grain following treatment, the improvement of the apparatus used, 

 and the determination of the comparative values of steam and hot 

 water. Interesting results have been obtained on the effect of differ- 

 ent modifications of hot-water and steam treatments on seed injury 

 and on the control of loose smut. 



LEAF SMUT OF WHEAT. 



Distribution of leaf smut. — Leaf smut, or flag smut, of wheat has 

 been found to be more abundant in Madison County, 111., this j^ear 

 than in 1919, when it was first reported. Last year it was found in 

 33 fields, comprising about 825 acres. Usually only a trace of the 

 disease was present, though occasionally as much as 1 to 2 per cent 

 was found. This year leaf smut has been found in 111 fields, com- 

 prising about 2,.500 acres. These fields, however, are confined to an 

 area of about 47 square miles, which was ((uarantined last year on 

 account of leaf smut and the so-called take-all. Usually the per- 

 centage of infection is low, but in parts of some fields it runs as high 

 as 15 to 20 per cent. 



Fairly good evidence has been obtained for the occurrence of soil 

 infestation. The problem of control is increased on account of the 

 occurrence of viable spores in the soil as well as on the seed. 



Varietal resistance of loheat. — In the experimental field near Gran- 

 ite City, 111., records were obtained on the resistance of 71 varieties 

 or strains to leaf smut. The most susceptible varieties proved to be 

 Dawson (Dawson (xolden Chaff), Fultz, Jones Winter Fife, K. B. 

 No. 2, liCap (Leap Prolific), Mealy, Purple Straw, Red Cross, Rocky 

 Mountain, and " Salzer's Prizetaker." The highest percentage of 

 infection, about 20 per cent, was obtained in the Red Cross variety, 

 which is very similar to, if not identical with, the so-called " Salzer's 

 Prizetaker," the variety so commonly infected on farms in the leaf- 

 smut district. Manv other varieties showed onlv a slight infection. 

 A few varieties also proved to be free from the disease. -These ex- 

 periments have been conducted but one year and can not be accepted 

 as at all conclusive. 



Experiments were conducted with 30 different varieties in the 

 greenhouse, where conditions were particularly favorable for infec- 

 tion. Several Australian varieties, as well as common winter and 

 spring varieties of the United States, were used. The following 

 varieties gave the indicated percentages of ])lants infected: (1) 

 Highly susceptible — Bobs, 95.3; Cowra, 92.G; Defiance, 88.3; Early 



