DISEASES OF PLANTS. 59 



excellent returns, bat when mixed with a few times its bulk of soil and 

 a little dropped in the hole it seemed to be too concentrated to be placed 

 near the young plants. 



For both Irish and sweet potato diseases experimented on, the sug- 

 gestion has already been made that sulphur and kainit at the rate of 

 about 300 lbs. per acre in the open row is a substantial remedy for scab 

 and soil rot. 



Corn smut, A. S. Hitchcock and J. B. S. Norton (Kansas Sta. Bui. 

 62, pp. 169-214, pis. lo). — The object of this bulletin is to record 

 observations and experiments made during the last 3 years upon the 

 life history of the smut and upon conditions favoring the spread of the 

 disease. The attempt was made to ascertain the amount of damage 

 caused by smut and the number of clean and smutted stalks in 52 rows 

 of corn. The figures show that the average weight of the corn on clean 

 stalks was 103 gin. and on the smutted stalks 12(i gin. — a loss of about 

 one-third. The loss is confined chiefly to the grain, the stalks being 

 nearly or quite as heavy in smutted as in sound corn. Ou«t of 2,984 

 stalks, 724 stalks were more or less affected by the smut, and observa- 

 tions conducted in a number of fields showed a considerably higher 

 percentage of affected plants, although per cent is considered a fair 

 average. Observations were made during the summers of 1S04, 1895, 

 and 189G in numerous cornfields adjacent to the station. In all, about 

 200,000 plants were examined, and the results obtained in some of the 

 most characteristic fields are given in tabular form. 



An attempt was also made to ascertain the relative susceptibility of 

 different varieties to the attacks of corn smut. Although considerable 

 differences were noted, no variety was found to be smut proof. The dif- 

 ferences are thought to be the result of accident rather than the power 

 to resist disease. 



Efforts were made to determine the relation between the amount of 

 smut and the age of corn, and it became apparent that smut does not 

 usually make its appearance on corn until it is 2 months old, and. other 

 conditions being equal, all corn becomes equally smutted regardless of 

 the time of planting. 



A general description of smut and its life history is given, including 

 descriptions of spores, germination, methods of culture, and germina- 

 tion in various nutrient solutions. 



Infection experiments with the corn plant were conducted which 

 seem to indicate that — 



"(1) Infection may take place at any time of the season when the corn is growing, 

 and does not depend so much on the time of the season as on the stage of develop- 

 ment of the plant. 



"(2) Infection may take place in any part of the plant where growing tissue is 

 present, and at any time in its life, but scarcely ever before the plant has attained 

 the height of 3 ft. 



"(3) After the tissues are hardened the smut can not penetrate them, and conse- 

 quently infection does not take place in older parts of the corn, but only in the 



