April, 1902.] 



Smut Infection Experiments. 



259 



The corn selected for the experiment was growing on the Ohio 

 State University farm and was in good healthy condition. At 

 the beginning of the experiment, July 30, it averaged about six 

 feet in height and was partly in tassel. 



In order to keep the 

 different parts of the 

 experiment as distinctly 

 separate as possible every 

 twentieth row was chosen 

 and the second row west 

 of this was taken as a 

 check- row. 



Rozu No. I. 



Each stalk in this row 

 (972 stalks in all) was 

 mutilated on east side, 

 but at no given height, 

 by being scraped with a 

 piece of broken hack-saw 

 blade. The work was 

 done in late afternoon, 

 between 6 and 8 p. m. A 

 fairly heavy dew fol- 

 lowed but no rain for 

 several da^'s. 



Results : 15 per cent, 

 of the stalks were smut- 

 ted while the correspond- 

 ing check-row showed 

 but 9.7 per cent affected. 

 The percentage of smut 

 on the ear, as compared 

 to the total smut on the 

 whole plant, showed that 

 of the total smut on the 

 mutilated row only 29.2 

 per cent, was on the ear, 

 while the check- row on 

 the other hand showed 

 32.9 per cent. The dif- 

 ference is probably due 

 to the fact that the ears 



Fig', r. Sorghum, 3 years old, artificially infected 

 throusli the seed. 



were not developed sufficiently to be affected by the mutilation ; 

 /. e., the stalks were mutilated while the ears were not. The 

 position of the smut balls in relation to the wounds was quite 



