114 DISEASES OF THE SWEET PEA 



a charred blackened stub. The fungus 

 sometimes works upon the stem to a dis- 

 tance of two to three inches above ground. 

 It is probably due to this that some work- 

 ers have mistaken this disease for the 

 "streak." Although their root system is 

 destroyed, affected plants seem to lin- 

 ger for a long time. Diseased plants, 

 however, cease growing, and maintain 

 a dwarfed sickly appearance (fig. 13). 

 These are useless for any purpose, as they 

 fail to bloom and merely contaminate the 

 beds by their presence. 



Pathogenicity. Healthy seedlings 

 may be readily infected by placing a pure 

 culture of the fungus in the soil. In two 

 to three weeks the roots of the infected 

 plants will be thoroughly diseased. Over- 

 watering does not seem to be a necessary 

 factor in infection, although it no doubt 

 helps to weaken the plants and furthcu 



