AUTOBASIDIOMYCETES 481 



Diseased roots of cotton and alfalfa, showing an abundance of the 

 fungus, were placed beneath the soil in contact with the healthy 

 roots of half -grown plants. In every case the fungus failed to 

 spread, and after a few months seemed to be dead. These experi- 

 ments, however, were merely preliminary, and the conditions under 

 which the tests were made could not be considered satisfactory. 



Control measures. Control measures, according to Shear, should 

 concern themselves primarily with proper aeration of the soil, espe- 

 cially deep preparation and as close cultivation as may be compatible 

 with other requirements. Fall plowing, under circumstances where 

 this can be practiced without injury to the land, is advised. This 

 is particularly applicable when short rotations are impossible. 

 Rotation of crops is especially important. Grain crops and others 

 known to be free from the fungus should alternate with cotton. 

 An application of a fungicide to the soil at the time of planting 

 seems to be neither effective nor practicable. 



