184 Diseases of Truck Crops 



may be accomplished by the use of fans or blowers 

 run by electricity or by a small gasoline motor. 



WEEDS 



There are but few weeds in this family which 

 are subject to the same diseases as the sweet potato. 

 The wild morning-glory {Ipomcea purpurea), the 

 wild sweet potato {Ipomcsa pandurata) , and the 

 small and great bindweed {Convolvulus arvensis and 

 C. septum) are all subject to black rot, Sphceronema 

 fimbriatum. All these weeds are also attacked by 

 white rust, Cystopus ipomcece- pandurana. Whether 

 this rust is the same as the white rust of the sweet 

 potato, or whether it is another physiological species 

 or race, still remains to be determined. But in any 

 case, these weeds must be kept out of sweet potato 

 fields if we desire to keep the black rot of sweet 

 potato in check. 



