INSECTS, FUNGI, PLANT DISEASES, 



ETC. 



1.57 



by girdling', and, in the case of the potato, covering the 



fungus kind, the trouble is the result of the mycelium 

 entering the tissues and feeding on the starch grains and 

 cellular tissues. 



Only healthy potatoes must be planted for the slips or 

 sprouts, and no sickly slips must be transplanted; do not 

 use hog manures in quantities, as this seems to encourage 

 the development of the fungus; (dear the field of all 

 debris and small potatoes after digging; and in case of 



Fig. 



59— Soft-rot of Sweet Potato. Ehizopu 

 after Halstt ad. 



•■■•' 



nigricans (Ehr.). Redrawn 



infested fields, rotate the crop, planting other than root 

 crops. 



Rhizopus nigricans (Ehr.). Soft rot of the sweet potato. 

 Dr. Byron I), llalsted gives the following account of this 

 disease: This form of decay, while it may be met with in 

 the field at digging time, is usually found most destruc- 

 tive in the storeroom, where it causes the attacked roots 

 to quickly become soft and worthless. In the engraving- 

 is shown a root in which the mould has penetrated for 

 nearly the whole length of the potato. As a rule, the 

 mould effects an entrance through the upper end of the 

 potato, where the latter was separated from the main 

 root, because the rind of the root, on account of its tough- 

 ness, in a measure prevents the entrance of the fungus. 



