272 



DISEASES OF ECONOMIC PLANTS 



above ground, are 

 conspicuous in 

 this disease. 

 Other characters 

 are rotting of the 

 stem, the rosette 

 development of 

 the tops, and a 

 scabby growth 

 upon the tubers. 

 Infected potatoes 

 in storage may 

 give way to a wet 

 rot. In Florida 

 in 1904 scarcely a 

 lot of seed pota- 

 toes free of this 

 disease could be 

 found, and the 

 hibernating con- 

 dition of the fun- 

 gus was evident 

 in 60 per cent of 

 the seed tubers in 

 some instances.* 

 Such infected 

 tubers are largely 



responsible for the contamination of new soil. 



Diseased seed tubers may be recognized by the superficial, 



irregularly shaped, elevated, dark brown patches of fungous 



» Hume, H. H., Fla. Agr. Exp. Sta. Bui. 75, p. 188, August, 1904. 



FiQ. 121. 



-Little potatoes and aerial potatoes. 

 After Rolfa. 



